详解Spring Boot读取配置文件与配置文件优先级

Spring Boot" title="Spring Boot">Spring Boot读取配置文件

1)通过注入ApplicationContext 或者 Environment对象来读取配置文件里的配置信息。

package com.ivan.config.controller;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.context.ApplicationContext;

import org.springframework.core.env.Environment;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

@RestController

public class ConfigController {

@Autowired

ApplicationContext context;

@Autowired

Environment environment;

@RequestMapping(value="/config", method={RequestMethod.GET})

public String getConfigContent(){

String name = context.getEnvironment().getProperty("db.user.name");

return name;

}

@RequestMapping(value="/configEnv", method={RequestMethod.GET})

public String getConfigEnvironment(){

String name = environment.getProperty("db.user.name");

return name;

}

}

2)通过@ConfigurationProperties配合@PropertySource读取配置文件里的配置信息。

1:通过@PropertySource指定当前类里属性的配置文件地址,ConfigurationProperties可以指定配置的前缀,@Configuration用于定义一个配置类:

package com.ivan.config.entity;

import org.springframework.boot.context.properties.ConfigurationProperties;

import org.springframework.context.annotation.Configuration;

import org.springframework.context.annotation.PropertySource;

@Configuration

@PropertySource("classpath:config/druid.properties")

@ConfigurationProperties(prefix = "druid")

public class DruidConfig {

private int initialSize;

private int minIdle;

private int maxActive;

private int maxWait;

private String validationQuery;

private boolean testWhileIdle;

private boolean testOnBorrow;

private boolean testOnReturn;

public int getInitialSize() {

return initialSize;

}

public void setInitialSize(int initialSize) {

this.initialSize = initialSize;

}

public int getMinIdle() {

return minIdle;

}

public void setMinIdle(int minIdle) {

this.minIdle = minIdle;

}

public int getMaxActive() {

return maxActive;

}

public void setMaxActive(int maxActive) {

this.maxActive = maxActive;

}

public int getMaxWait() {

return maxWait;

}

public void setMaxWait(int maxWait) {

this.maxWait = maxWait;

}

public String getValidationQuery() {

return validationQuery;

}

public void setValidationQuery(String validationQuery) {

this.validationQuery = validationQuery;

}

public boolean isTestWhileIdle() {

return testWhileIdle;

}

public void setTestWhileIdle(boolean testWhileIdle) {

this.testWhileIdle = testWhileIdle;

}

public boolean isTestOnBorrow() {

return testOnBorrow;

}

public void setTestOnBorrow(boolean testOnBorrow) {

this.testOnBorrow = testOnBorrow;

}

public boolean isTestOnReturn() {

return testOnReturn;

}

public void setTestOnReturn(boolean testOnReturn) {

this.testOnReturn = testOnReturn;

}

@Override

public String toString() {

return "DruidConfig [initialSize=" + initialSize + ", minIdle=" + minIdle + ", maxActive=" + maxActive + ", maxWait=" + maxWait + ", validationQuery=" + validationQuery + ", testWhileIdle=" + testWhileIdle + ", testOnBorrow=" + testOnBorrow + ", testOnReturn=" + testOnReturn + "]";

}

}

2:对应的配置文件:

druid.initialSize=5

druid.minIdle=5

druid.maxActive=20

druid.maxWait=60000

druid.validationQuery=select 'x'

druid.testWhileIdle=true

druid.testOnBorrow=true

druid.testOnReturn=true

3:在需要用到的类通过@Autowired注入

package com.ivan.config.controller;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import com.ivan.config.entity.DruidConfig;

@RestController

public class DruidConfigController {

@Autowired

public DruidConfig druidConfig;

@RequestMapping(value="/druidConfig", method={RequestMethod.GET})

public String getDruidConfig(){

return druidConfig.toString();

}

}

3)通过@Value注解

1:需要得到配置属性的类如下,可以在任何需要得到配置的地方用@Value注解

package com.ivan.config.entity;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Configuration;

@Configuration

public class ValueTest {

@Value("${db.user.name}")

private String username;

public String getUsername() {

return username;

}

public void setUsername(String username) {

this.username = username;

}

}

2:测试Controller类通过@Autowired注入实体类

package com.ivan.config.controller;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RequestMethod;

import org.springframework.web.bind.annotation.RestController;

import com.ivan.config.entity.ValueTest;

@RestController

public class ValueController {

@Autowired

private ValueTest value;

@RequestMapping(value="/configValue", method={RequestMethod.GET})

public String getConfig(){

return value.getUsername();

}

}

Spring boot 配置文件优先级:

1:命令行参数。(以--开头的参数,比如可以设置:--server.port对同一套代码设置不同的参数)

2: 通过 System.getProperties() 获取的 Java 系统参数。

3:操作系统环境变量(这解释了为什么你通过application.properties设置的user.name取的是系统的用户名了)

4:从 java:comp/env 得到的 JNDI 属性。

5: 应用 Jar 文件之外的属性文件(系统的application.properties文件)

6:应用 Jar 文件内部的属性文件。

7: 在应用配置 Java 类(包含“@Configuration”注解的 Java 类)中通过“@PropertySource”注解声明的属性文件。

8: 通过“SpringApplication.setDefaultProperties”声明的默认属性。

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