我要评论Spring框架中引入外部配置文件属性值
以连接池的配置文件为例
1.在Spring的xml配置文件中写入
需要管理的类Bean4 用来封装配置信息
public class Bean4 {
Properties properties;
public void setProperties(Properties properties) {
this.properties = properties;
}
@Override
public String toString() {
return "Bean4{" +
"properties=" + properties +
'}';
}
} xml文件配置
<?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.xsd">
<bean name="bean4" class="com.example.di.Bean4">
<property name="properties">
<props>
<prop key="jdbc.driver">com.mysql.jabc.Driver</prop>
<prop key="jdbc.url">jdbc:mysql:///jp</prop>
<prop key="jdbc.username">root</prop>
<prop key="jdbc.password">root</prop>
</props>
</property>
</bean>
</beans> Demo4类进行获取
public class Demo4 {
public static void main(String[] args) {
ClassPathXmlApplicationContext context=null;
context = new ClassPathXmlApplicationContext("com/example/demo1.xml");
Bean4 bean4 = context.getBean("bean4", Bean4.class);
System.out.println(bean4.toString());
}
}
打印结果：
当然这里全部都是配置在xml中不合适，下面进行外部properties加载
2.注入外部properties配置文件中的内容
2.1 方式一
定义一个Spring提供的特殊的类作为bean,类是 PropertyPlaceholderConfigurer
它的使用方式，是通过设置它的 Location 或 Locations 属性，指定 properties 文件的位置。
db-config.properties文件：
jdbc.driver=com.mysql.jabc.Driver
jdbc.url=jdbc:mysql:///jp
jdbc.username=root
jdbc.password=root demo.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--拿到properties文件源-->
<bean name="configSource" class="org.springframework.core.io.ClassPathResource" c:path="com/example/db-config.properties"></bean>
<!--配置Spring自带PropertyPlaceholderConfigurer类-->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" ref="configSource"></property>
</bean>
<bean name="bean1" class="com.example.Bean1">
<property name="properties">
<props>
<prop key="jdbc.driver">${jdbc.driver}</prop>
<prop key="jdbc.url">${jdbc.url}</prop>
<prop key="jdbc.username">${jdbc.username}</prop>
<prop key="jdbc.password">${jdbc.password}</prop>
</props>
</property>
</bean>
</beans> Bean1类代码：
import java.util.Properties;
public class Bean1 {
Properties properties;
public void setProperties(Properties properties) {
this.properties = properties;
}
@Override
public String toString() {
return "Bean1{" +
"properties=" + properties +
'}';
}
} Demo1类
public class Demo1 {
public static void main(String[] args) {
ClassPathXmlApplicationContext context=null;
context= new ClassPathXmlApplicationContext("com/example/demo.xml");
Bean1 bean1 = context.getBean("bean1", Bean1.class);
System.out.println(bean1.toString());
}
}
显示结果：
2.1.1简化资源获取方式：
对获取properties文件资源的方式Spring也有简化方式
修改位置：
demo.xml文件修改后：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<!--配置Spring自带PropertyPlaceholderConfigurer类-->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location" value="classpath:com/example/db-config.properties"></property>
</bean>
<bean name="bean1" class="com.example.Bean1">
<property name="properties">
<props>
<prop key="jdbc.driver">${jdbc.driver}</prop>
<prop key="jdbc.url">${jdbc.url}</prop>
<prop key="jdbc.username">${jdbc.username}</prop>
<prop key="jdbc.password">${jdbc.password}</prop>
</props>
</property>
</bean>
</beans>
显示结果一致：
2.2 方式二
使用<context:property-placeholder>标签
<context:property-placeholder location="classpath:com/example/db-config.properties"></context:property-placeholder>
简化后的demo.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:c="http://www.springframework.org/schema/c"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
<context:property-placeholder location="classpath:com/example/db-config.properties"></context:property-placeholder>
<bean name="bean1" class="com.example.Bean1">
<property name="properties">
<props>
<prop key="jdbc.driver">${jdbc.driver}</prop>
<prop key="jdbc.url">${jdbc.url}</prop>
<prop key="jdbc.username">${jdbc.username}</prop>
<prop key="jdbc.password">${jdbc.password}</prop>
</props>
</property>
</bean>
</beans> 显示结果一致
本文地址：https://blog.csdn.net/Guesshat/article/details/108244880
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