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

2023-08-21 08:07:16

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 + "]";

     }

 }

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