设计模式责任链模式【二】

Z时代
2024-01-10
分类：综合

什么是责任链模式？

客户端发出一个请求，链上的对象都有机会处理这个请求，客户端不需要知道谁是具体的处理对象。

好处:

发送者和接受之间结耦，并且客户端可以实现动态组合责任链，编程更加方便灵活。

应用场景:

过滤器，api限流，权限控制，参数过滤，session过滤，表单过滤，请求头过滤等

项目结构和结果

这里我们以拦截关的形式，链表形式，开始上代码！

数据库表结构

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for gateway_handler
-- ----------------------------
DROP TABLE IF EXISTS `gateway_handler`;
CREATE TABLE `gateway_handler` (
  `ID` int(11) NOT NULL AUTO_INCREMENT COMMENT "主键ID",
  `handler_name` varchar(32) DEFAULT NULL COMMENT "handler名称",
  `handler_id` varchar(32) DEFAULT NULL COMMENT "handler主键id",
  `prev_handler_id` varchar(32) DEFAULT NULL,
  `next_handler_id` varchar(32) DEFAULT NULL COMMENT "下一个handler",
  PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=19 DEFAULT CHARSET=utf8 COMMENT="权限表";
-- ----------------------------
-- Records of gateway_handler
-- ----------------------------
BEGIN;
INSERT INTO `gateway_handler` VALUES (16, "Api接口限流", "currentLimitHandler", NULL, "blacklistHandler");
INSERT INTO `gateway_handler` VALUES (17, "黑名单拦截", "blacklistHandler", "currentLimitHandler", "conversationHandler");
INSERT INTO `gateway_handler` VALUES (18, "会话验证", "conversationHandler", "blacklistHandler", NULL);
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;

pom.xml 配置

   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <dependencies>
        <!-- sprinboot web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>
        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!-- mysql 依赖 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>    </dependencies>

application.yml 配置文件

###服务启动端口号 server: port: 80 spring: ###数据库相关连接 datasource: username: root password: root driver-class-name: com.mysql.jdbc.Driver url: jdbc:mysql://127.0.0.1:3306/design?useUnicode=true&characterEncoding=UTF-8 ####打印MyBatias日志 logging: level: ### 开发环境使用DEBUG 生产环境info或者error

com.mayikt.daiison.mapper: DEBUG

启动类

@SpringBootApplication
@MapperScan("com.daiison")
public class APP {
    public static void main(String[] args) {
        SpringApplication.run(APP.class,args);
    }}

springUtils可以根据类名小写获取类

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
@Component
public class SpringUtils implements ApplicationContextAware {
    private static ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
    //获取applicationContext
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }
    //通过name获取 Bean.
    public static Object getBean(String name){
        return getApplicationContext().getBean(name);
    }
    //通过class获取Bean.
    public static <T> T getBean(Class<T> clazz){
        return getApplicationContext().getBean(clazz);
    }
    //通过name,以及Clazz返回指定的Bean
    public static <T> T getBean(String name,Class<T> clazz){
        return getApplicationContext().getBean(name, clazz);
    }
}

pojo实体类

import lombok.Data;
import java.io.Serializable;
@Data
public class GatewayHandlerEntity implements Serializable, Cloneable {
    /**
     * 主键ID
     */
    private Integer id;
    /**
     * handler名称
     */
    private String handlerName;
    /**
     * handler主键id
     */
    private String handlerId;
    /**
     * 下一个handler
     */
    private String nextHandlerId;
}

mapper

import com.daiison.handler.mapper.entity.GatewayHandlerEntity;
import org.apache.ibatis.annotations.Select;
public interface GatewayHandlerMapper {
   /**
    * 获取第一个GatewayHandler
    * @return
    */
   @Select("SELECT  handler_name AS handlerName,handler_id AS handlerid ,prev_handler_id AS prevhandlerid ,next_handler_id AS nexthandlerid  FROM gateway_handler WHERE  prev_handler_id is null;")
   public GatewayHandlerEntity getFirstGatewayHandler();
   @Select("SELECT  handler_name AS handlerName,handler_id AS handlerid ,prev_handler_id AS prevhandlerid ,next_handler_id AS nexthandlerid   FROM gateway_handler WHERE  handler_id=#{handlerId}")
   public GatewayHandlerEntity getByHandler(String handlerId);
}

public abstract class GatewayHandler {
/**
     * 执行下一个handler
     */
protected GatewayHandler nextGatewayHandler;
/**
     * 实现的handler 处理方案 强制必须实现
     */
public abstract void service();
    public void setNextGatewayHandler(GatewayHandler nextGatewayHandler) {
this.nextGatewayHandler = nextGatewayHandler;
}
protected void nextService() {
if (nextGatewayHandler != null)
nextGatewayHandler.service();// 指向下一关黑名单
}
}

import com.daiison.handler.GatewayHandler;
import com.daiison.handler.mapper.GatewayHandlerMapper;
import com.daiison.handler.mapper.entity.GatewayHandlerEntity;
import com.daiison.utils.SpringUtils;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class GatewayHandlerService {
@Autowired
private GatewayHandlerMapper gatewayHandlerMapper;
    private GatewayHandler firstGatewayHandler;
    public GatewayHandler getDbFirstGatewayHandler() {
if (firstGatewayHandler != null) {
return firstGatewayHandler;
}
// 1.从数据库中查询地址hanlder
GatewayHandlerEntity firstGatewayHandlerEntity = gatewayHandlerMapper.getFirstGatewayHandler();
        if (firstGatewayHandlerEntity == null) {
return null;
}
// 2.获取springboot注入容器id
String handlerId = firstGatewayHandlerEntity.getHandlerId();
GatewayHandler firstGatewayHandler = SpringUtils.getBean(handlerId, GatewayHandler.class);
// 3.获取下一个handler容器beanid
String nextHandlerId = firstGatewayHandlerEntity.getNextHandlerId();
// 4. 记录当前循环hanlder对象
GatewayHandler tempGatewayHandler = firstGatewayHandler;
        while (!StringUtils.isEmpty(nextHandlerId)) {
// 5.从springboot容器获取下一个handerl对象
GatewayHandler nextGatewayHandler = SpringUtils.getBean(nextHandlerId, GatewayHandler.class);
tempGatewayHandler.setNextGatewayHandler(nextGatewayHandler);
// 6.设置下一个nextHandlerId
GatewayHandlerEntity nextGatewayHandlerEntity = gatewayHandlerMapper.getByHandler(nextHandlerId);
            if (nextGatewayHandlerEntity == null) {
break;
}
            nextHandlerId = nextGatewayHandlerEntity.getNextHandlerId();
tempGatewayHandler = nextGatewayHandler;
}
this.firstGatewayHandler = firstGatewayHandler;
        return firstGatewayHandler;
}
}

三个实现

@Component
public class CurrentLimitHandler extends GatewayHandler {
public void service() {
        System.out.println("第一关-->api 接口的限流。。。");
nextService();
}
}

@Component
public class ConversationHandler extends GatewayHandler {
public void service() {
        System.out.println("第三关-->api 黑名单拦截。。。");
}
}

@Component
public class BlacklistHandler extends GatewayHandler {
public void service() {
        System.out.println("第二关-->api 用户会话拦截。。。");
nextService();// 指向下一关黑名单
}
}

最后controller

@RestController
public class HandlerController {
    @Autowired
    private GatewayHandlerService gatewayHandlerService;
    @RequestMapping("/clentHanlder")
    public String clentHanlder() {
        GatewayHandler firstGatewayHandler = gatewayHandlerService.getDbFirstGatewayHandler();
        firstGatewayHandler.service();
        return "success";
    }}

以上是设计模式责任链模式【二】的全部内容，来源链接： utcz.com/z/514593.html

设计模式责任链模式【二】

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