【Java】（二）MyBatis从入门到入土——开发一个Mybatis项目

• Z时代
• 2024-01-10
• 分类：技术分享

/*创建数据库mybatisdemo*/
DROP DATABASE IF EXISTS `mybatisdemo`;
CREATE DATABASE `mybatisdemo`;
USE `mybatisdemo`;
/*创建表结构*/
DROP TABLE IF EXISTS `user`;
CREATE TABLE user (
id BIGINT AUTO_INCREMENT PRIMARY KEY COMMENT '主键，用户id，自动增长',
`name` VARCHAR(32) NOT NULL DEFAULT '' COMMENT '姓名',
`age` SMALLINT NOT NULL DEFAULT 1 COMMENT '年龄',
`salary` DECIMAL(12,2) NOT NULL DEFAULT 0 COMMENT '薪水'
) COMMENT '用户表';
SELECT * FROM user;

 <properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- 配置maven编译的时候采用的编译器版本 -->
<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
<!-- 指定源代码是什么版本的，如果源码和这个版本不符将报错，maven中执行编译的时候会用到这个配置，默认是1.5，这个相当于javac命令后面的-source参数 -->
<maven.compiler.source>1.8</maven.compiler.source>
<!-- 该命令用于指定生成的class文件将保证和哪个版本的虚拟机进行兼容，maven中执行编译的时候会用到这个配置，默认是1.5，这个相当于javac命令后面的-target参数 -->
<maven.compiler.target>1.8</maven.compiler.target>
<mybatis.version>3.5.3</mybatis.version>
<mysql.version>5.1.47</mysql.version>
<lombok.version>1.18.10</lombok.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
</dependencies>
</dependencyManagement>

    <dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</dependency>
</dependencies>

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<logger name="zhonghu" level="debug" additivity="false">
<appender-ref ref="STDOUT" />
</logger>
</configuration>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="zhonghu.mybatis.chat01.UserMapper">
<!-- 插入 -->
<insert id="insert" parameterType="zhonghu.mybatis.chat01.UserModel" keyProperty="id" useGeneratedKeys="true">
<![CDATA[ INSERT INTO `user` ]]>
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id!=null">
<![CDATA[ `id`, ]]>
</if>
<if test="name!=null">
<![CDATA[ `name`, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age`, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary`, ]]>
</if>
</trim>
<![CDATA[ VALUES ]]>
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id!=null">
<![CDATA[ #{id}, ]]>
</if>
<if test="name!=null">
<![CDATA[ #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ #{salary}, ]]>
</if>
</trim>
</insert>
<!-- 批量插入 -->
<insert id="insertBatch" parameterType="map">
<![CDATA[ INSERT INTO `user` (`id`, `name`, `age`, `salary`) VALUES ]]>
<foreach collection="list" separator="," item="item">
(#{item.id}, #{item.name}, #{item.age}, #{item.salary})
</foreach>
</insert>
<!-- 更新 -->
<update id="update" parameterType="zhonghu.mybatis.chat01.UserModel">
<![CDATA[ UPDATE `user` ]]>
<set>
<if test="name!=null">
<![CDATA[ `name` = #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age` = #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary` = #{salary}, ]]>
</if>
</set>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</update>
<!-- 更新 -->
<update id="updateByMap" parameterType="map">
<![CDATA[ UPDATE `user` ]]>
<set>
<if test="name!=null">
<![CDATA[ `name` = #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age` = #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary` = #{salary}, ]]>
</if>
</set>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</update>
<!-- 删除 -->
<delete id="delete" parameterType="map">
<![CDATA[
DELETE FROM `user`
]]>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</delete>
<!-- 查询记录 -->
<select id="getModelList" parameterType="map" resultType="zhonghu.mybatis.chat01.UserModel">
<![CDATA[
SELECT
]]>
<choose>
<when test="tableColumnList!=null and tableColumnList.size() >= 1">
<foreach collection="tableColumnList" item="item" separator=",">
<![CDATA[ ${item} ]]>
</foreach>
</when>
<otherwise>
<![CDATA[
`id`,
`name`,
`age`,
`salary`
]]>
</otherwise>
</choose>
<![CDATA[
FROM
`user` a
]]>
<where>
<if test="id!=null and id.toString()!=''">
<![CDATA[ AND a.`id` = #{id} ]]>
</if>
<if test="idList!=null and idList.size() >= 1">
<![CDATA[ AND a.`id` IN ]]>
<foreach collection="idList" item="item" open="(" separator="," close=")">
<![CDATA[ #{item} ]]>
</foreach>
</if>
<if test="name!=null and name.toString()!=''">
<![CDATA[ AND a.`name` = #{name} ]]>
</if>
<if test="age!=null and age.toString()!=''">
<![CDATA[ AND a.`age` = #{age} ]]>
</if>
<if test="salary!=null and salary.toString()!=''">
<![CDATA[ AND a.`salary` = #{salary} ]]>
</if>
<if test="nameLike!=null and nameLike.toString()!=''">
<![CDATA[ AND a.`name` like '%${nameLike}%' ]]>
</if>
<if test="salaryGte!=null and salaryGte.toString()!=''">
<![CDATA[ AND a.`salary` >= #{salaryGte} ]]>
</if>
</where>
<if test="sort!=null and sort.toString()!=''">
<![CDATA[ order by ${sort} ]]>
</if>
<if test="skip!=null and pageSize!=null">
<![CDATA[ LIMIT #{skip},#{pageSize} ]]>
</if>
</select>
</mapper>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatisdemo?characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/user.xml"/>
</mappers>
</configuration>

package zhonghu.mybatis.chat01;
import java.util.List;
import java.util.Map;
public interface UserMapper {
/**
* 插入用户信息
*
* @param userModel
* @return
*/
void insert(UserModel userModel);
/**
* 批量插入用户信息
*
* @param userModelList
*/
void insertBatch(List<UserModel> userModelList);
/**
* 更新用户信息
*
* @param userModel
* @return
*/
int update(UserModel userModel);
/**
* 通过map来更新用户记录
*
* @param map
* @return
*/
int updateByMap(Map<String, Object> map);
/**
* 通过map来删除用户记录
*
* @param map
* @return
*/
int delete(Map<String, Object> map);
/**
* 查询用户列表
*
* @param map
* @return
*/
List<UserModel> getModelList(Map<String, Object> map);
}

package zhonghu.mybatis.chat01;
import lombok.*;
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder
@ToString
public class UserModel {
private Long id;
private String name;
private Integer age;
private Double salary;
}

package zhonghu.mybatis.chat01;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
@Slf4j
public class UserUtil {
private static SqlSessionFactory sqlSessionFactory = build();
public static SqlSessionFactory build() {
try {
return new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
} catch (IOException e) {
log.error(e.getMessage(), e);
throw new RuntimeException(e);
}
}
@FunctionalInterface
public interface SessionCall<O> {
O call(SqlSession session) throws Exception;
}
@FunctionalInterface
public interface MapperCall<T, O> {
O call(T mapper) throws Exception;
}
public static <T, O> O callMapper(Class<T> tClass, MapperCall<T, O> mapper) throws Exception {
return call(session -> mapper.call(session.getMapper(tClass)));
}
public static <O> O call(SessionCall<O> sessionCall) throws Exception {
try (SqlSession session = sqlSessionFactory.openSession(true);) {
return sessionCall.call(session);
}
}
}

package zhonghu.mybatis.chat01;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import java.util.*;
import java.util.stream.Collectors;
@Slf4j
public class UserMapperTest {
//动态插入
@Test
public void insert() throws Exception {
UserModel userModel1 = UserModel.builder().name("Java冢狐").build();
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insert(userModel1);
return null;
});
log.info("插入结果：{}", this.getModelById(userModel1.getId()));
log.info("---------------------");
UserModel userModel2 = UserModel.builder().name("冢狐").age(23).salary(50000.00).build();
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insert(userModel2);
return null;
});
log.info("插入结果：{}", this.getModelById(userModel2.getId()));
}
//批量插入
@Test
public void insertBatch() throws Exception {
List<UserModel> userModelList = new ArrayList<>();
for (int i = 1; i <= 5; i++) {
userModelList.add(UserModel.builder().name("Java冢狐-" + i).age(23 + i).salary(10000.00 * i).build());
userModelList.add(UserModel.builder().name("Mybatis-" + i).age(18 + i).salary(10000.00 * i).build());
}
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insertBatch(userModelList);
return null;
});
List<UserModel> userModelList1 = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(null));
log.info("结果:{}", userModelList1);
}
//根据用户id删除数据
@Test
public void delete() throws Exception {
Map<String, Object> map = new HashMap<>();
//需要删除的用户id
map.put("id", 1);
Integer count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.delete(map));
log.info("删除行数：{}", count);
}
//动态更新
@Test
public void update() throws Exception {
//将userId=2的name修改为：修改冢狐
Long userId1 = 2L;
Integer count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.update(UserModel.builder().id(userId1).name("修改冢狐").build()));
log.info("更新行数：{}", count);
log.info("---------------------");
//将userId=3的name修改为：修改冢狐,薪水为：6666.66
Long userId2 = 3L;
count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.update(UserModel.builder().id(userId2).name("修改冢狐").salary(6666.66D).build()));
log.info("更新行数：{}", count);
}
//按用户id查询
public UserModel getModelById(Long userId) throws Exception {
//查询指定id的数据
Map<String, Object> map = new HashMap<>();
map.put("id", userId);
return UserUtil.callMapper(UserMapper.class, mapper -> {
List<UserModel> userModelList = mapper.getModelList(map);
if (userModelList.size() == 1) {
return userModelList.get(0);
}
return null;
});
}
//查询所有数据
@Test
public void getModelList1() throws Exception {
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(null));
log.info("结果:{}", userModelList);
}
//查询多个用户id对应的数据
@Test
public void getModelListByIds() throws Exception {
List<Integer> idList = Arrays.asList(2, 3, 4).stream().collect(Collectors.toList());
Map<String, Object> map = new HashMap<>();
map.put("idList", idList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
//多条件 & 指定返回的列
@Test
public void getModelList2() throws Exception {
//查询姓名中包含Java冢狐以及薪资大于3万的用户id、姓名
Map<String, Object> map = new HashMap<>();
map.put("nameLike", "Java冢狐");
map.put("salaryGte", 30000.00D);
//需要返回的列
List<String> tableColumnList = new ArrayList<>();
tableColumnList.add("id");
tableColumnList.add("name");
map.put("tableColumnList", tableColumnList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
//条件过滤 & 排序 & 分页查询数据 & 只返回用户id、salary
@Test
public void getPage() throws Exception {
//查询姓名中包含Java冢狐以及薪资大于3万的用户id，按照薪资倒叙，每页5条取第1页
Map<String, Object> map = new HashMap<>();
map.put("nameLike", "Java冢狐");
map.put("salaryGte", 30000.00D);
//加入排序参数
map.put("sort", "salary desc");
//加入分页参数
int page = 1;
int pageSize = 5;
map.put("skip", (page - 1) * pageSize);
map.put("pageSize", pageSize);
//加入需要返回的列
List<String> tableColumnList = new ArrayList<>();
tableColumnList.add("id");
tableColumnList.add("salary");
map.put("tableColumnList", tableColumnList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
}

29:45.734 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==>  Preparing: INSERT INTO `user` ( `name` ) VALUES ( ? )
29:45.755 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==> Parameters: Java冢狐(String)
29:45.843 [main] DEBUG z.mybatis.chat01.UserMapper.insert - <==    Updates: 1
29:45.859 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` = ?
29:45.859 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 1(Long)
29:45.871 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 1
29:45.871 [main] INFO  z.mybatis.chat01.UserMapperTest - 插入结果：UserModel(id=1, name=Java冢狐, age=1, salary=0.0)
29:45.873 [main] INFO  z.mybatis.chat01.UserMapperTest - ---------------------
29:45.873 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==>  Preparing: INSERT INTO `user` ( `name`, `age`, `salary` ) VALUES ( ?, ?, ? )
29:45.874 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==> Parameters: 冢狐(String), 23(Integer), 50000.0(Double)
29:46.081 [main] DEBUG z.mybatis.chat01.UserMapper.insert - <==    Updates: 1
29:46.082 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` = ?
29:46.082 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 2(Long)
29:46.083 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 1
29:46.083 [main] INFO  z.mybatis.chat01.UserMapperTest - 插入结果：UserModel(id=2, name=冢狐, age=23, salary=50000.0)

33:49.134 [main] DEBUG z.m.chat01.UserMapper.insertBatch - ==>  Preparing: INSERT INTO `user` (`id`, `name`, `age`, `salary`) VALUES (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?)
33:49.155 [main] DEBUG z.m.chat01.UserMapper.insertBatch - ==> Parameters: null, Java冢狐-1(String), 24(Integer), 10000.0(Double), null, Mybatis-1(String), 19(Integer), 10000.0(Double), null, Java冢狐-2(String), 25(Integer), 20000.0(Double), null, Mybatis-2(String), 20(Integer), 20000.0(Double), null, Java冢狐-3(String), 26(Integer), 30000.0(Double), null, Mybatis-3(String), 21(Integer), 30000.0(Double), null, Java冢狐-4(String), 27(Integer), 40000.0(Double), null, Mybatis-4(String), 22(Integer), 40000.0(Double), null, Java冢狐-5(String), 28(Integer), 50000.0(Double), null, Mybatis-5(String), 23(Integer), 50000.0(Double)
33:49.378 [main] DEBUG z.m.chat01.UserMapper.insertBatch - <==    Updates: 10
33:49.387 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a
33:49.387 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters:
33:49.397 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 12
33:49.397 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=1, name=Java冢狐, age=1, salary=0.0), UserModel(id=2, name=冢狐, age=23, salary=50000.0), UserModel(id=3, name=Java冢狐-1, age=24, salary=10000.0), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0), UserModel(id=5, name=Java冢狐-2, age=25, salary=20000.0), UserModel(id=6, name=Mybatis-2, age=20, salary=20000.0), UserModel(id=7, name=Java冢狐-3, age=26, salary=30000.0), UserModel(id=8, name=Mybatis-3, age=21, salary=30000.0), UserModel(id=9, name=Java冢狐-4, age=27, salary=40000.0), UserModel(id=10, name=Mybatis-4, age=22, salary=40000.0), UserModel(id=11, name=Java冢狐-5, age=28, salary=50000.0), UserModel(id=12, name=Mybatis-5, age=23, salary=50000.0)]

33:49.378 [main] DEBUG z.m.chat01.UserMapper.insertBatch - <==    Updates: 10

44:52.064 [main] DEBUG z.mybatis.chat01.UserMapper.delete - ==>  Preparing: DELETE FROM `user` WHERE `id` = ?
44:52.083 [main] DEBUG z.mybatis.chat01.UserMapper.delete - ==> Parameters: 1(Integer)
44:52.383 [main] DEBUG z.mybatis.chat01.UserMapper.delete - <==    Updates: 1
44:52.386 [main] INFO  z.mybatis.chat01.UserMapperTest - 删除行数：1

45:44.648 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==>  Preparing: UPDATE `user` SET `name` = ? WHERE `id` = ?
45:44.670 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==> Parameters: 修改冢狐(String), 2(Long)
45:44.788 [main] DEBUG z.mybatis.chat01.UserMapper.update - <==    Updates: 1
45:44.790 [main] INFO  z.mybatis.chat01.UserMapperTest - 更新行数：1
45:44.792 [main] INFO  z.mybatis.chat01.UserMapperTest - ---------------------
45:44.793 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==>  Preparing: UPDATE `user` SET `name` = ?, `salary` = ? WHERE `id` = ?
45:44.793 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==> Parameters: 修改冢狐(String), 6666.66(Double), 3(Long)
45:44.980 [main] DEBUG z.mybatis.chat01.UserMapper.update - <==    Updates: 1
45:44.981 [main] INFO  z.mybatis.chat01.UserMapperTest - 更新行数：1

46:56.345 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a
46:56.364 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters:
46:56.376 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 11
46:56.380 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=2, name=修改冢狐, age=23, salary=50000.0), UserModel(id=3, name=修改冢狐, age=24, salary=6666.66), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0), UserModel(id=5, name=Java冢狐-2, age=25, salary=20000.0), UserModel(id=6, name=Mybatis-2, age=20, salary=20000.0), UserModel(id=7, name=Java冢狐-3, age=26, salary=30000.0), UserModel(id=8, name=Mybatis-3, age=21, salary=30000.0), UserModel(id=9, name=Java冢狐-4, age=27, salary=40000.0), UserModel(id=10, name=Mybatis-4, age=22, salary=40000.0), UserModel(id=11, name=Java冢狐-5, age=28, salary=50000.0), UserModel(id=12, name=Mybatis-5, age=23, salary=50000.0)]

47:46.118 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` IN ( ? , ? , ? )
47:46.139 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 2(Integer), 3(Integer), 4(Integer)
47:46.150 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
47:46.151 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=2, name=修改冢狐, age=23, salary=50000.0), UserModel(id=3, name=修改冢狐, age=24, salary=6666.66), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0)]

48:34.925 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT id , name FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ?
48:34.945 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 30000.0(Double)
48:34.955 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
48:34.955 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=7, name=Java冢狐-3, age=null, salary=null), UserModel(id=9, name=Java冢狐-4, age=null, salary=null), UserModel(id=11, name=Java冢狐-5, age=null, salary=null)]

49:03.709 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT id , salary FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ? order by salary desc LIMIT ?,?
49:03.728 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 30000.0(Double), 0(Integer), 5(Integer)
49:03.739 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
49:03.740 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=11, name=null, age=null, salary=50000.0), UserModel(id=9, name=null, age=null, salary=40000.0), UserModel(id=7, name=null, age=null, salary=30000.0)]

SELECT id , salary FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ? order by salary desc LIMIT ?,?

这是mybatis系列第2篇。没看前文的建议先去【Java冢狐】公众号中查看前文，方便理解和掌握这篇文章主要接着前文介绍了如何创建并使用Mybatis。

实战演练

上一篇文章中我们大体介绍了MyBatis是如何使用的以及其内部的一些逻辑，也辅助了一些代码进行了讲解，下面我们就把这些代码写完，让整个程序运行起来。

准备数据库

mysql中运行下面脚本：创建一个数据库

/*创建数据库mybatisdemo*/
DROP DATABASE IF EXISTS `mybatisdemo`;
CREATE DATABASE `mybatisdemo`;
USE `mybatisdemo`;
/*创建表结构*/
DROP TABLE IF EXISTS `user`;
CREATE TABLE user (
id BIGINT AUTO_INCREMENT PRIMARY KEY COMMENT '主键，用户id，自动增长',
`name` VARCHAR(32) NOT NULL DEFAULT '' COMMENT '姓名',
`age` SMALLINT NOT NULL DEFAULT 1 COMMENT '年龄',
`salary` DECIMAL(12,2) NOT NULL DEFAULT 0 COMMENT '薪水'
) COMMENT '用户表';
SELECT * FROM user;

实现的功能

基于user表，我们主要使用mybatis来演示以下几个功能

• 通用的插入操作：支持动态插入。根据传入的字段的值，动态生成insert语句
• 批量插入功能
• 通用的更新操作：支持动态更新。根据传入的字段的值，动态生成update语句
• 通用的查询操作：支持各种组合条件查询、分页、排序等各种复杂查询需求

创建maven项目

idea中创建maven项目，创建一个父项目mybatis-demo和一个子项目chat01，如下所示

项目结构

如下图：

引入mybatis依赖

mybatis-demo/pom.xml内容如下：

 <properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- 配置maven编译的时候采用的编译器版本 -->
<maven.compiler.compilerVersion>1.8</maven.compiler.compilerVersion>
<!-- 指定源代码是什么版本的，如果源码和这个版本不符将报错，maven中执行编译的时候会用到这个配置，默认是1.5，这个相当于javac命令后面的-source参数 -->
<maven.compiler.source>1.8</maven.compiler.source>
<!-- 该命令用于指定生成的class文件将保证和哪个版本的虚拟机进行兼容，maven中执行编译的时候会用到这个配置，默认是1.5，这个相当于javac命令后面的-target参数 -->
<maven.compiler.target>1.8</maven.compiler.target>
<mybatis.version>3.5.3</mybatis.version>
<mysql.version>5.1.47</mysql.version>
<lombok.version>1.18.10</lombok.version>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.2.3</version>
</dependency>
</dependencies>
</dependencyManagement>

chat01/pom.xml内容如下：

    <dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</dependency>
</dependencies>

上面我们引入了mybatis需要的包、mysql jdbc驱动、lombok、单元测试需要的junit包、日志输出需要的logback包。

配置logback

mybatis在运行过程中会输出一些日志，比如sql信息、sql的参数信息、执行的结果等信息，mybatis中会通过logback输出出来。

在chat01/src/main/resources目录中新建文件logback.xml，内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
</encoder>
</appender>
<logger name="zhonghu" level="debug" additivity="false">
<appender-ref ref="STDOUT" />
</logger>
</configuration>

创建mybatis相关文件

user.xml

chat01/src/main/resources目录中新建user.xml，内容如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="zhonghu.mybatis.chat01.UserMapper">
<!-- 插入 -->
<insert id="insert" parameterType="zhonghu.mybatis.chat01.UserModel" keyProperty="id" useGeneratedKeys="true">
<![CDATA[ INSERT INTO `user` ]]>
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id!=null">
<![CDATA[ `id`, ]]>
</if>
<if test="name!=null">
<![CDATA[ `name`, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age`, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary`, ]]>
</if>
</trim>
<![CDATA[ VALUES ]]>
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="id!=null">
<![CDATA[ #{id}, ]]>
</if>
<if test="name!=null">
<![CDATA[ #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ #{salary}, ]]>
</if>
</trim>
</insert>
<!-- 批量插入 -->
<insert id="insertBatch" parameterType="map">
<![CDATA[ INSERT INTO `user` (`id`, `name`, `age`, `salary`) VALUES ]]>
<foreach collection="list" separator="," item="item">
(#{item.id}, #{item.name}, #{item.age}, #{item.salary})
</foreach>
</insert>
<!-- 更新 -->
<update id="update" parameterType="zhonghu.mybatis.chat01.UserModel">
<![CDATA[ UPDATE `user` ]]>
<set>
<if test="name!=null">
<![CDATA[ `name` = #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age` = #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary` = #{salary}, ]]>
</if>
</set>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</update>
<!-- 更新 -->
<update id="updateByMap" parameterType="map">
<![CDATA[ UPDATE `user` ]]>
<set>
<if test="name!=null">
<![CDATA[ `name` = #{name}, ]]>
</if>
<if test="age!=null">
<![CDATA[ `age` = #{age}, ]]>
</if>
<if test="salary!=null">
<![CDATA[ `salary` = #{salary}, ]]>
</if>
</set>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</update>
<!-- 删除 -->
<delete id="delete" parameterType="map">
<![CDATA[
DELETE FROM `user`
]]>
<where>
<if test="id!=null">
<![CDATA[ AND `id` = #{id} ]]>
</if>
</where>
</delete>
<!-- 查询记录 -->
<select id="getModelList" parameterType="map" resultType="zhonghu.mybatis.chat01.UserModel">
<![CDATA[
SELECT
]]>
<choose>
<when test="tableColumnList!=null and tableColumnList.size() >= 1">
<foreach collection="tableColumnList" item="item" separator=",">
<![CDATA[ ${item} ]]>
</foreach>
</when>
<otherwise>
<![CDATA[
`id`,
`name`,
`age`,
`salary`
]]>
</otherwise>
</choose>
<![CDATA[
FROM
`user` a
]]>
<where>
<if test="id!=null and id.toString()!=''">
<![CDATA[ AND a.`id` = #{id} ]]>
</if>
<if test="idList!=null and idList.size() >= 1">
<![CDATA[ AND a.`id` IN ]]>
<foreach collection="idList" item="item" open="(" separator="," close=")">
<![CDATA[ #{item} ]]>
</foreach>
</if>
<if test="name!=null and name.toString()!=''">
<![CDATA[ AND a.`name` = #{name} ]]>
</if>
<if test="age!=null and age.toString()!=''">
<![CDATA[ AND a.`age` = #{age} ]]>
</if>
<if test="salary!=null and salary.toString()!=''">
<![CDATA[ AND a.`salary` = #{salary} ]]>
</if>
<if test="nameLike!=null and nameLike.toString()!=''">
<![CDATA[ AND a.`name` like '%${nameLike}%' ]]>
</if>
<if test="salaryGte!=null and salaryGte.toString()!=''">
<![CDATA[ AND a.`salary` >= #{salaryGte} ]]>
</if>
</where>
<if test="sort!=null and sort.toString()!=''">
<![CDATA[ order by ${sort} ]]>
</if>
<if test="skip!=null and pageSize!=null">
<![CDATA[ LIMIT #{skip},#{pageSize} ]]>
</if>
</select>
</mapper>

mybatis-config.xml

chat01/src/main/resources目录中新建mybatis-config.xml，内容如下：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatisdemo?characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/user.xml"/>
</mappers>
</configuration>

UserMapper接口

package zhonghu.mybatis.chat01;
import java.util.List;
import java.util.Map;
public interface UserMapper {
/**
* 插入用户信息
*
* @param userModel
* @return
*/
void insert(UserModel userModel);
/**
* 批量插入用户信息
*
* @param userModelList
*/
void insertBatch(List<UserModel> userModelList);
/**
* 更新用户信息
*
* @param userModel
* @return
*/
int update(UserModel userModel);
/**
* 通过map来更新用户记录
*
* @param map
* @return
*/
int updateByMap(Map<String, Object> map);
/**
* 通过map来删除用户记录
*
* @param map
* @return
*/
int delete(Map<String, Object> map);
/**
* 查询用户列表
*
* @param map
* @return
*/
List<UserModel> getModelList(Map<String, Object> map);
}

UserModel类

package zhonghu.mybatis.chat01;
import lombok.*;
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder
@ToString
public class UserModel {
private Long id;
private String name;
private Integer age;
private Double salary;
}

UserUtil类

package zhonghu.mybatis.chat01;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
@Slf4j
public class UserUtil {
private static SqlSessionFactory sqlSessionFactory = build();
public static SqlSessionFactory build() {
try {
return new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
} catch (IOException e) {
log.error(e.getMessage(), e);
throw new RuntimeException(e);
}
}
@FunctionalInterface
public interface SessionCall<O> {
O call(SqlSession session) throws Exception;
}
@FunctionalInterface
public interface MapperCall<T, O> {
O call(T mapper) throws Exception;
}
public static <T, O> O callMapper(Class<T> tClass, MapperCall<T, O> mapper) throws Exception {
return call(session -> mapper.call(session.getMapper(tClass)));
}
public static <O> O call(SessionCall<O> sessionCall) throws Exception {
try (SqlSession session = sqlSessionFactory.openSession(true);) {
return sessionCall.call(session);
}
}
}

创建单元测试类UserMapperTest

chat01\src\test\java\zhonghu\mybatis\chat01中创建UserMapperTest，代码如下：

package zhonghu.mybatis.chat01;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import java.util.*;
import java.util.stream.Collectors;
@Slf4j
public class UserMapperTest {
//动态插入
@Test
public void insert() throws Exception {
UserModel userModel1 = UserModel.builder().name("Java冢狐").build();
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insert(userModel1);
return null;
});
log.info("插入结果：{}", this.getModelById(userModel1.getId()));
log.info("---------------------");
UserModel userModel2 = UserModel.builder().name("冢狐").age(23).salary(50000.00).build();
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insert(userModel2);
return null;
});
log.info("插入结果：{}", this.getModelById(userModel2.getId()));
}
//批量插入
@Test
public void insertBatch() throws Exception {
List<UserModel> userModelList = new ArrayList<>();
for (int i = 1; i <= 5; i++) {
userModelList.add(UserModel.builder().name("Java冢狐-" + i).age(23 + i).salary(10000.00 * i).build());
userModelList.add(UserModel.builder().name("Mybatis-" + i).age(18 + i).salary(10000.00 * i).build());
}
UserUtil.callMapper(UserMapper.class, mapper -> {
mapper.insertBatch(userModelList);
return null;
});
List<UserModel> userModelList1 = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(null));
log.info("结果:{}", userModelList1);
}
//根据用户id删除数据
@Test
public void delete() throws Exception {
Map<String, Object> map = new HashMap<>();
//需要删除的用户id
map.put("id", 1);
Integer count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.delete(map));
log.info("删除行数：{}", count);
}
//动态更新
@Test
public void update() throws Exception {
//将userId=2的name修改为：修改冢狐
Long userId1 = 2L;
Integer count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.update(UserModel.builder().id(userId1).name("修改冢狐").build()));
log.info("更新行数：{}", count);
log.info("---------------------");
//将userId=3的name修改为：修改冢狐,薪水为：6666.66
Long userId2 = 3L;
count = UserUtil.callMapper(UserMapper.class, mapper -> mapper.update(UserModel.builder().id(userId2).name("修改冢狐").salary(6666.66D).build()));
log.info("更新行数：{}", count);
}
//按用户id查询
public UserModel getModelById(Long userId) throws Exception {
//查询指定id的数据
Map<String, Object> map = new HashMap<>();
map.put("id", userId);
return UserUtil.callMapper(UserMapper.class, mapper -> {
List<UserModel> userModelList = mapper.getModelList(map);
if (userModelList.size() == 1) {
return userModelList.get(0);
}
return null;
});
}
//查询所有数据
@Test
public void getModelList1() throws Exception {
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(null));
log.info("结果:{}", userModelList);
}
//查询多个用户id对应的数据
@Test
public void getModelListByIds() throws Exception {
List<Integer> idList = Arrays.asList(2, 3, 4).stream().collect(Collectors.toList());
Map<String, Object> map = new HashMap<>();
map.put("idList", idList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
//多条件 & 指定返回的列
@Test
public void getModelList2() throws Exception {
//查询姓名中包含Java冢狐以及薪资大于3万的用户id、姓名
Map<String, Object> map = new HashMap<>();
map.put("nameLike", "Java冢狐");
map.put("salaryGte", 30000.00D);
//需要返回的列
List<String> tableColumnList = new ArrayList<>();
tableColumnList.add("id");
tableColumnList.add("name");
map.put("tableColumnList", tableColumnList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
//条件过滤 & 排序 & 分页查询数据 & 只返回用户id、salary
@Test
public void getPage() throws Exception {
//查询姓名中包含Java冢狐以及薪资大于3万的用户id，按照薪资倒叙，每页5条取第1页
Map<String, Object> map = new HashMap<>();
map.put("nameLike", "Java冢狐");
map.put("salaryGte", 30000.00D);
//加入排序参数
map.put("sort", "salary desc");
//加入分页参数
int page = 1;
int pageSize = 5;
map.put("skip", (page - 1) * pageSize);
map.put("pageSize", pageSize);
//加入需要返回的列
List<String> tableColumnList = new ArrayList<>();
tableColumnList.add("id");
tableColumnList.add("salary");
map.put("tableColumnList", tableColumnList);
List<UserModel> userModelList = UserUtil.callMapper(UserMapper.class, mapper -> mapper.getModelList(map));
log.info("结果:{}", userModelList);
}
}

项目最终结构如下

测试：动态插入

运行动态插入，输出如下：

29:45.734 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==>  Preparing: INSERT INTO `user` ( `name` ) VALUES ( ? )
29:45.755 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==> Parameters: Java冢狐(String)
29:45.843 [main] DEBUG z.mybatis.chat01.UserMapper.insert - <==    Updates: 1
29:45.859 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` = ?
29:45.859 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 1(Long)
29:45.871 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 1
29:45.871 [main] INFO  z.mybatis.chat01.UserMapperTest - 插入结果：UserModel(id=1, name=Java冢狐, age=1, salary=0.0)
29:45.873 [main] INFO  z.mybatis.chat01.UserMapperTest - ---------------------
29:45.873 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==>  Preparing: INSERT INTO `user` ( `name`, `age`, `salary` ) VALUES ( ?, ?, ? )
29:45.874 [main] DEBUG z.mybatis.chat01.UserMapper.insert - ==> Parameters: 冢狐(String), 23(Integer), 50000.0(Double)
29:46.081 [main] DEBUG z.mybatis.chat01.UserMapper.insert - <==    Updates: 1
29:46.082 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` = ?
29:46.082 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 2(Long)
29:46.083 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 1
29:46.083 [main] INFO  z.mybatis.chat01.UserMapperTest - 插入结果：UserModel(id=2, name=冢狐, age=23, salary=50000.0)

• 数据库数据变为：

这个方法主要有4步操作：

• 插入一条用户记录，用户记录只有name字段有值
• 去db中查询步骤1中插入的记录
• 插入一条用户记录，这次插入的记录所有字段都指定了值
• 去db中查询步骤3中插入的记录

两次插入调用都是mapper.insert方法，传入的都是UserModel对象，唯一不同的是这个对象构建的时候字段的值不一样，最后再认真看一下上面输出的sql，产生的2个insert也是不一样的，这个mapper.insert方法可以根据UserModel对象字段是否有值来组装我们需要的sql，这就实现了动态插入

测试：批量插入

运行批量插入，输出如下：

33:49.134 [main] DEBUG z.m.chat01.UserMapper.insertBatch - ==>  Preparing: INSERT INTO `user` (`id`, `name`, `age`, `salary`) VALUES (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?) , (?, ?, ?, ?)
33:49.155 [main] DEBUG z.m.chat01.UserMapper.insertBatch - ==> Parameters: null, Java冢狐-1(String), 24(Integer), 10000.0(Double), null, Mybatis-1(String), 19(Integer), 10000.0(Double), null, Java冢狐-2(String), 25(Integer), 20000.0(Double), null, Mybatis-2(String), 20(Integer), 20000.0(Double), null, Java冢狐-3(String), 26(Integer), 30000.0(Double), null, Mybatis-3(String), 21(Integer), 30000.0(Double), null, Java冢狐-4(String), 27(Integer), 40000.0(Double), null, Mybatis-4(String), 22(Integer), 40000.0(Double), null, Java冢狐-5(String), 28(Integer), 50000.0(Double), null, Mybatis-5(String), 23(Integer), 50000.0(Double)
33:49.378 [main] DEBUG z.m.chat01.UserMapper.insertBatch - <==    Updates: 10
33:49.387 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a
33:49.387 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters:
33:49.397 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 12
33:49.397 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=1, name=Java冢狐, age=1, salary=0.0), UserModel(id=2, name=冢狐, age=23, salary=50000.0), UserModel(id=3, name=Java冢狐-1, age=24, salary=10000.0), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0), UserModel(id=5, name=Java冢狐-2, age=25, salary=20000.0), UserModel(id=6, name=Mybatis-2, age=20, salary=20000.0), UserModel(id=7, name=Java冢狐-3, age=26, salary=30000.0), UserModel(id=8, name=Mybatis-3, age=21, salary=30000.0), UserModel(id=9, name=Java冢狐-4, age=27, salary=40000.0), UserModel(id=10, name=Mybatis-4, age=22, salary=40000.0), UserModel(id=11, name=Java冢狐-5, age=28, salary=50000.0), UserModel(id=12, name=Mybatis-5, age=23, salary=50000.0)]

这次批量插入了10条用户记录，可以看到有这样的输出：

33:49.378 [main] DEBUG z.m.chat01.UserMapper.insertBatch - <==    Updates: 10

上面这个表示插入影响的行数，10表示插入了10行。

批量插入之后，又执行了全表查询，这次插入了10条，加上前面的2个单条插入，表中总计12条记录。

• 数据库数据变为：

测试：根据用户id删除数据

运行删除，输出如下：

44:52.064 [main] DEBUG z.mybatis.chat01.UserMapper.delete - ==>  Preparing: DELETE FROM `user` WHERE `id` = ?
44:52.083 [main] DEBUG z.mybatis.chat01.UserMapper.delete - ==> Parameters: 1(Integer)
44:52.383 [main] DEBUG z.mybatis.chat01.UserMapper.delete - <==    Updates: 1
44:52.386 [main] INFO  z.mybatis.chat01.UserMapperTest - 删除行数：1

• 数据库结果如下：

测试：动态更新

运行动态更新代码，输出如下：

45:44.648 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==>  Preparing: UPDATE `user` SET `name` = ? WHERE `id` = ?
45:44.670 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==> Parameters: 修改冢狐(String), 2(Long)
45:44.788 [main] DEBUG z.mybatis.chat01.UserMapper.update - <==    Updates: 1
45:44.790 [main] INFO  z.mybatis.chat01.UserMapperTest - 更新行数：1
45:44.792 [main] INFO  z.mybatis.chat01.UserMapperTest - ---------------------
45:44.793 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==>  Preparing: UPDATE `user` SET `name` = ?, `salary` = ? WHERE `id` = ?
45:44.793 [main] DEBUG z.mybatis.chat01.UserMapper.update - ==> Parameters: 修改冢狐(String), 6666.66(Double), 3(Long)
45:44.980 [main] DEBUG z.mybatis.chat01.UserMapper.update - <==    Updates: 1
45:44.981 [main] INFO  z.mybatis.chat01.UserMapperTest - 更新行数：1

2个更新，调用都是mapper.update方法，传入的都是UserModel类型的参数，只是2个UserModel对象的字段值不一样，最后产生的2个update语句也是不一样的，这个update语句是mybatis动态组装的，mybatis可以根据UserModel中字段是否为NULL，来拼装sql。

• 数据库结果

测试：动态查询

查询所有数据

运行查询有数据代码，输出如下：

46:56.345 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a
46:56.364 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters:
46:56.376 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 11
46:56.380 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=2, name=修改冢狐, age=23, salary=50000.0), UserModel(id=3, name=修改冢狐, age=24, salary=6666.66), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0), UserModel(id=5, name=Java冢狐-2, age=25, salary=20000.0), UserModel(id=6, name=Mybatis-2, age=20, salary=20000.0), UserModel(id=7, name=Java冢狐-3, age=26, salary=30000.0), UserModel(id=8, name=Mybatis-3, age=21, salary=30000.0), UserModel(id=9, name=Java冢狐-4, age=27, salary=40000.0), UserModel(id=10, name=Mybatis-4, age=22, salary=40000.0), UserModel(id=11, name=Java冢狐-5, age=28, salary=50000.0), UserModel(id=12, name=Mybatis-5, age=23, salary=50000.0)]

可以看到sql是没有查询条件的。

查询多个用户id对应的数据

运行查询多个用户id对应数据，输出如下：

47:46.118 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT `id`, `name`, `age`, `salary` FROM `user` a WHERE a.`id` IN ( ? , ? , ? )
47:46.139 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 2(Integer), 3(Integer), 4(Integer)
47:46.150 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
47:46.151 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=2, name=修改冢狐, age=23, salary=50000.0), UserModel(id=3, name=修改冢狐, age=24, salary=6666.66), UserModel(id=4, name=Mybatis-1, age=19, salary=10000.0)]

上面这个按照id列表查询也是比较常用的，比如我们在电商中查询订单列表，还需要查询每个订单对应的商品，此时可以先查询订单列表，然后在通过订单列表拿到所有的商品id集合，然后通过商品id集合去通过上面的方式检索商品信息，只需要2次查询就可以查询出订单及商品的信息了。

多条件 & 指定返回的列

运行多条件查询语句，查询姓名中包含Java冢狐以及薪资大于3万的用户id、姓名，输出如下：

48:34.925 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT id , name FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ?
48:34.945 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 30000.0(Double)
48:34.955 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
48:34.955 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=7, name=Java冢狐-3, age=null, salary=null), UserModel(id=9, name=Java冢狐-4, age=null, salary=null), UserModel(id=11, name=Java冢狐-5, age=null, salary=null)]

看一下上面select语句，select后面只有id,name2个字段，where后面有多个条件，这种查询也是比较常用的，有些表可能有几十个字段，可能我们只需要几个字段，就可以使用上面这种查询。

条件过滤 & 排序 & 分页查询数据 & 只返回用户id、salary

运行分页查询，查询姓名中包含Java冢狐以及薪资大于3万的用户id，按照薪资倒叙，每页5条取第1页，输出如下：

49:03.709 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==>  Preparing: SELECT id , salary FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ? order by salary desc LIMIT ?,?
49:03.728 [main] DEBUG z.m.chat01.UserMapper.getModelList - ==> Parameters: 30000.0(Double), 0(Integer), 5(Integer)
49:03.739 [main] DEBUG z.m.chat01.UserMapper.getModelList - <==      Total: 3
49:03.740 [main] INFO  z.mybatis.chat01.UserMapperTest - 结果:[UserModel(id=11, name=null, age=null, salary=50000.0), UserModel(id=9, name=null, age=null, salary=40000.0), UserModel(id=7, name=null, age=null, salary=30000.0)]

大家主要看一下输出的sql，如下：

SELECT id , salary FROM `user` a WHERE a.`name` like '%Java冢狐%' AND a.`salary` >= ? order by salary desc LIMIT ?,?

这个sql会根据查询条件，自动构建出我们需要的sql，十分的方便和简洁

案例总结

上面列举的一些用例基本上包含了我们对db所需的大部分操作，动态sql处理方面体现的最为强劲，如果让我们自己写，我们需要写很多判断，而用mybatis这么简单就实现了，我们在java代码中没有看到一个判断拼接语句，而这些sql的判断拼接都在一个文件中：user.xml中，这个就是mybatis中核心的文件，我们需要写的sql及判断逻辑基本上都在这个xml中，大家可以认真去看一下这个xml文件。

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