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 + "]";
     }
 }