Spring配置PropertyOverrideConfigurer

Spring的配置文件为applicationContext.xml，但是有些常量参数一般不配置在applicationContext.xml中，而是放在单独的properties文件中，如数据库连接信息。
applicationContext.xml配置外部的properties文件时，需要PropertyOverrideConfigurer对象，指定properties文件的位置，然后指定属性。

下面是mysql的配置文件，jdbc.properties:

#配置数据驱动  
    jdbc.driverClassName=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://127.0.0.1:3306/test?characterEncoding=UTF-8
    jdbc.username=root
    jdbc.password=toor  

下面是在applicationContext.xml中配置该properties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:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="     
          http://www.springframework.org/schema/beans     
          http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     
          http://www.springframework.org/schema/context     
          http://www.springframework.org/schema/context/spring-context-3.0.xsd 
          http://www.springframework.org/schema/aop     
          http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"
    default-autowire="byName">

    <!-- 配置数据库信息源 -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"></property>
        <property name="url" value="${jdbc.url}"></property>
        <property name="username" value="${jdbc.username}"></property>
        <property name="password" value="${jdbc.password}"></property>
    </bean>
    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:jdbc.properties"></property>
    </bean>
    </beans>  

程序在运行时，PropertyConfigurer对象会寻找jdbc.properties文件中，寻找相应的变量。
下面是测试代码，SpringTest.java

package com.yeetrack.mavenSpring;

    import java.sql.Connection;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;

    import javax.sql.DataSource;

    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;

    public class SpringTest
    {

        public static void main(String[] args)
        {
            //获取ApplicationContext容器
            ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
            //通过Spring代理类ProxyFactoryBean获取ServiceImpl实例
            IService hello = (IService) context.getBean("service");
            hello.sayHello("Good Day!");
            DataSource data = (DataSource) context.getBean("dataSource");
            Connection conn = null;
            ResultSet result = null;
            try
            {
                conn = data.getConnection();
                Statement stat = conn.createStatement();
                String sql = "select * from user";
                result = stat.executeQuery(sql);
                while(result.next())
                {
                    System.out.print(result.getString(1)+"  ");
                    System.out.print(result.getString(2)+"  ");
                    System.out.println(result.getString(3));

                }
                result.close();
                conn.close();
            } catch (SQLException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

    }

Tags: java代码技术