Spring PropertyPlaceholderConfigurer Usage - 使用系统变量替换spring配

最新推荐文章于 2023-05-10 11:31:32 发布

原创最新推荐文章于 2023-05-10 11:31:32 发布 · 215 阅读

0 ·

CC 4.0 BY-SA版权

本文详细介绍了如何在Spring框架中使用PropertyPlaceholderConfigurer类来处理属性配置，包括从properties文件和系统环境中读取属性值的方法。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

分享一下我老师大神的人工智能教程！零基础，通俗易懂！http://blog.youkuaiyun.com/jiangjunshow

也欢迎大家转载本篇文章。分享知识，造福人民，实现我们中华民族伟大复兴！

前一篇文章说了关于spring中PropertyPlaceholderConfigurer类的使用http://blog.youkuaiyun.com/kongxx/archive/2010/08/26/5842009.aspx

但是在有些情况下我们的属性并不是配置在properties文件中，而是通过Java启动时的-Dname=value参数设置在java系统环境中，此时如果在java里我们可以使用System.getProperty(name)来获取属性值，而在spring里我们就可以通过PropertyPlaceholderConfigurer类来获取。

1. 首先创建一个Java Bean

[java] view plain copy print ?

package test;
import org.apache.commons.lang.builder.ToStringBuilder;
public class MyBean {
private String name;
private String prop1;
private String prop2;
private String prop3;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getProp1() {
return prop1;
}
public void setProp1(String prop1) {
this.prop1 = prop1;
}
public String getProp2() {
return prop2;
}
public void setProp2(String prop2) {
this.prop2 = prop2;
}
public String getProp3() {
return prop3;
}
public void setProp3(String prop3) {
this.prop3 = prop3;
}
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this);
}
}

package test;import org.apache.commons.lang.builder.ToStringBuilder;public class MyBean { private String name; private String prop1; private String prop2; private String prop3; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getProp1() { return prop1; } public void setProp1(String prop1) { this.prop1 = prop1; } public String getProp2() { return prop2; } public void setProp2(String prop2) { this.prop2 = prop2; } public String getProp3() { return prop3; } public void setProp3(String prop3) { this.prop3 = prop3; } @Override public String toString() { return ToStringBuilder.reflectionToString(this); }}

2. 创建spring.xml文件

[xhtml] view plain copy print ?

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd"
default-lazy-init="true">
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>classpath:test/spring.properties</value>
</property>
<property name="systemPropertiesMode">
<value>1</value>
</property>
<property name="searchSystemEnvironment">
<value>true</value>
</property>
<property name="ignoreUnresolvablePlaceholders">
<value>true</value>
</property>
</bean>
<bean id="myBean" class="test.MyBean">
<property name="name"><value>${name}</value></property>
<property name="prop1"><value>${prop1}</value></property>
<property name="prop2"><value>${prop2}</value></property>
<property name="prop3"><value>${prop3}</value></property>
</bean>
</beans>

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd" default-lazy-init="true"> <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <value>classpath:test/spring.properties</value> </property> <property name="systemPropertiesMode"> <value>1</value> </property> <property name="searchSystemEnvironment"> <value>true</value> </property> <property name="ignoreUnresolvablePlaceholders"> <value>true</value> </property> </bean> <bean id="myBean" class="test.MyBean"> <property name="name"><value>${name}</value></property> <property name="prop1"><value>${prop1}</value></property> <property name="prop2"><value>${prop2}</value></property> <property name="prop3"><value>${prop3}</value></property> </bean></beans>

配置文件中使用${name},${propx}来说明需要使用properties文件中的内容替换

3. 创建spring.properties文件，这里变量可以递归引用当前properties文件中定义的别的变量

[java] view plain copy print ?

name=kongxx
prop1=111
prop2=${prop1}222
prop3=${prop2}333

name=kongxxprop1=111prop2=${prop1}222prop3=${prop2}333

4. 写一个测试程序

[java] view plain copy print ?

package test；
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Test {
public static void main(String[] args) {
System.setProperty("name", "Mandy");
System.setProperty("prop1", "111");
System.setProperty("prop2", "222");
System.setProperty("prop3", "333");
ApplicationContext ctx = new ClassPathXmlApplicationContext(
"/test/spring.xml");
MyBean myBean = (MyBean) ctx.getBean("myBean");
System.out.println(myBean);
}
}

package test；import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Test { public static void main(String[] args) { System.setProperty("name", "Mandy"); System.setProperty("prop1", "111"); System.setProperty("prop2", "222"); System.setProperty("prop3", "333"); ApplicationContext ctx = new ClassPathXmlApplicationContext( "/test/spring.xml"); MyBean myBean = (MyBean) ctx.getBean("myBean"); System.out.println(myBean); }}

这里去我在启动前通过System.setProperty(key)来模拟java中通过-D传递参数的情况。运行测试程序，输出如下：

test.MyBean@1649b44[name=kongxx,prop1=111,prop2=222,prop3=333]

这里其实spring是忽略的properties文件里的配置而使用的系统环境中的值。