4.18 Environment 和 PropertySourc

所有系统属性，环境变量和应用程序属性都由Environment提供，spring启动时将填充该接口

chapter04/environment源码

package com.apress.prospring5.ch4;

import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.core.env.MutablePropertySources;

import java.util.HashMap;
import java.util.Map;

public class EnvironmentSampleFirst {

    public static void main(String... args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
        ctx.refresh();

        ConfigurableEnvironment env = ctx.getEnvironment();
        MutablePropertySources propertySources = env.getPropertySources();

        Map<String,Object> appMap = new HashMap<>();
        appMap.put("user.home", "application_home");
        //addFirst
        propertySources.addFirst(new MapPropertySource("prospring5_MAP", appMap));

        System.out.println("user.home: " + System.getProperty("user.home"));
        System.out.println("JAVA_HOME: " + System.getenv("JAVA_HOME"));

        System.out.println("user.home: " + env.getProperty("user.home"));
        System.out.println("JAVA_HOME: " + env.getProperty("JAVA_HOME"));

        ctx.close();
    }
}

执行结果

user.home: /Users/chujun
JAVA_HOME: /Library/Java/JavaVirtualMachines/jdk1.8.0_211.jdk/Contents/Home
user.home: application_home
JAVA_HOME: /Library/Java/JavaVirtualMachines/jdk1.8.0_211.jdk/Contents/Home

debug查看属性源列表如截图

Environment propertySources列表.png

package com.apress.prospring5.ch4;

import org.springframework.context.support.GenericXmlApplicationContext;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.core.env.MutablePropertySources;

import java.util.HashMap;
import java.util.Map;

public class EnvironmentSampleLast {

    public static void main(String... args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
        ctx.refresh();

        ConfigurableEnvironment env = ctx.getEnvironment();
        MutablePropertySources propertySources = env.getPropertySources();

        Map<String,Object> appMap = new HashMap<>();
        appMap.put("application.home", "application_home");
        //addLast
        propertySources.addLast(new MapPropertySource("prospring5_MAP", appMap));

        System.out.println("user.home: " + System.getProperty("user.home"));
        System.out.println("JAVA_HOME: " + System.getenv("JAVA_HOME"));

        System.out.println("user.home: " + env.getProperty("user.home"));
        System.out.println("JAVA_HOME: " + env.getProperty("JAVA_HOME"));

        System.out.println("application.home: " + env.getProperty("application.home"));

        ctx.close();
    }
}

user.home: /Users/chujun
JAVA_HOME: /Library/Java/JavaVirtualMachines/jdk1.8.0_211.jdk/Contents/Home
user.home: /Users/chujun
JAVA_HOME: /Library/Java/JavaVirtualMachines/jdk1.8.0_211.jdk/Contents/Home
application.home: application_home