JavaEE互联网轻量级框架整合开发（书籍）阅读笔记（12）:XML配置自动扫描包，自动加载*.properties文件

一、XML和注解组合使用

　　前几篇的测试案例都是在Java类中配置，现在换一种使用方式，在XML中配置，使Spring IoC容器在启动之后自动去扫描配置的包路径，扫描加载指定路径下的properties文件。

关键配置信息如下：

<?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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:util="http://www.springframework.org/schema/util" 
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd   
        http://www.springframework.org/schema/aop 
        http://www.springframework.org/schema/aop/spring-aop-4.2.xsd   
        http://www.springframework.org/schema/task  
        http://www.springframework.org/schema/task/spring-task-4.2.xsd 
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-4.2.xsd" >
</beans>

  特别说明一下：

　　在Spring框架的配置文件中，xmlns代表xml的命名空间，xmlns:xsi代表当前配置xml所要遵循的标准，简而言之，下面2条是Spring配置文件的最核心也是最基本的配置。 

<?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-4.2.xsd " >
</beans>

        当然，Spring配置文件中能够使用的标签有很多，这需要我们手动引入命名空间，然后给出xsd文件的位置。比如下面：

引入：上下文标签的命名空间

xmlns:context="http://www.springframework.org/schema/context"

 引入：面向切面aop相关标签的命名空间

xmlns:aop="http://www.springframework.org/schema/aop"

 引入：事务管理相关标签的命名空间

http://www.springframework.org/schema/tx

 引入：定时任务相关标签的命名空间

xmlns:task="http://www.springframework.org/schema/task"

 引入：加载SpringMVC框架相关标签的命名空间

xmlns:mvc="http://www.springframework.org/schema/mvc"

 引入：一些工具类先关标签的命名空间

xmlns:util="http://www.springframework.org/schema/util"

 等等..............

二、测试案例

创建一个测试配置文件：applicationContext.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:context="http://www.springframework.org/schema/context"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:util="http://www.springframework.org/schema/util" 
    xmlns:task="http://www.springframework.org/schema/task"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-4.2.xsd   
        http://www.springframework.org/schema/aop 
        http://www.springframework.org/schema/aop/spring-aop-4.2.xsd   
        http://www.springframework.org/schema/task  
        http://www.springframework.org/schema/task/spring-task-4.2.xsd 
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-4.2.xsd" >
    <!--扫描加载指定相对路径下的所有properties文件 -->
    <context:property-placeholder location="classpath:com/xfwl/spring/profile/*.properties" />
    <!--将针对注解的处理器配置好 -->
    <context:annotation-config/>
    <!-- 自动扫描指定包中的Bean:通配符统一批量设置 -->
    <context:component-scan base-package="com.xfwl.spring.context"/>
    <!-- 依赖注入 -->
    <bean id="user" class="com.xfwl.spring.profile.UserBean">
        <property name="uname" value="${uname}"/>
        <property name="upwd" value="${upwd}"/>
    </bean>
</beans>

 创建一个Properties属性文件：user.properties 

#简单测试一下：用properties文件存放用户数据
uname=xfwl
upwd=123456

 创建一个POJO类：UserBean.java 

package com.xfwl.spring.context;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Component;

public class UserBean {
    private String uname;
    private String upwd;
    public UserBean(){}
    public UserBean(String uname,String upwd){
        this.uname=uname;
        this.upwd=upwd;
    }
    public String getUname() {
        return uname;
    }
    public void setUname(String uname) {
        this.uname = uname;
    }
    public String getUpwd() {
        return upwd;
    }
    public void setUpwd(String upwd) {
        this.upwd = upwd;
    }
    @Override
    public String toString() {
        return "UserBean [uname=" + uname + ", upwd=" + upwd + "]";
    }
}    

  创建一个管理类:Manager.java

package com.xfwl.spring.context;

import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;
@Component("manager")
public class Manager{
    @Autowired
    private UserBean user;
    /****setter******/
    public void setUser(UserBean user) {
        this.user = user;
    }
    public void manage(){
        System.out.println(this.user.toString());    
    }
}

  创建一个测试类：TestBean.java

package com.xfwl.spring.context;
import java.sql.SQLException;

import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestBean {
    //项目相对路径:ClassPathXmlApplicationContext/ApplicationContext
    private static final String xmlRelPath="com/xfwl/spring/profile/applicationContext.xml";
    public static void main(String[] args) throws SQLException {
        //拿到解析对象
        ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext(xmlRelPath);
        //开始测试
        Manager manager=(Manager)ctx.getBean("manager");
        manager.manage();
    }
}

  测试结果：（XML+注解同时被正常使用）

log4j:WARN No appenders could be found for logger (org.springframework.core.env.StandardEnvironment).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
UserBean [uname=xfwl, upwd=123456]

 最后补充一点：除了在XML中配置加载properties文件，也可以使用注解加载properties文件，比如下面代码：

package com.xfwl.spring.profile;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;
import org.springframework.test.context.ContextConfiguration;
@ContextConfiguration
@PropertySource(value={"classpath:com/xfwl/spring/profile/*.properties"},
                ignoreResourceNotFound=true)
public class UserBean {
    @Value("${tom.uname}")
    private String uname;
    @Value("${tom.upwd}")
    private String upwd;
    public UserBean(){}
    public UserBean(String uname,String upwd){
        this.uname=uname;
        this.upwd=upwd;
    }
    public String getUname() {
        return uname;
    }
    public void setUname(String uname) {
        this.uname = uname;
    }
    public String getUpwd() {
        return upwd;
    }
    public void setUpwd(String upwd) {
        this.upwd = upwd;
    }
    @Override
    public String toString() {
        return "UserBean [uname=" + uname + ", upwd=" + upwd + "]";
    }
}