• Spring学习四----------Bean的配置之Bean的配置项及作用域


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    Bean的作用域(每个作用域都是在同一个Bean容器中)

    1.singleton:单例,指一个Bean容器中只存在一份(默认)

    2.prototype:每次请求(每次使用)创建新的实例,destory方式不生效

    3.request:每次http请求创建一个实例且仅在当前request内生效(只能在web中使用

    4.session:同上,每次http请求创建一个实例,当前session内有效(只能在web中使用

    5.global session:基于portlet的web中有效(portlet定义了global session),如果是在单个web中,同session。(只能在web中使用

    实例

    1.singleton和prototype

      1.1 目录结构

      1.2 pom.xml

    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    
    	<groupId>org.spring</groupId>
    	<artifactId>Spring</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<packaging>jar</packaging>
    
    	<name>Spring</name>
    	<url>http://maven.apache.org</url>
    
    	<properties>
    		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    		<spring.version>4.3.7.RELEASE</spring.version>
    	</properties>
    
    	<dependencies>
    		<!-- junit依赖 -->
    		<dependency>
    			<groupId>junit</groupId>
    			<artifactId>junit</artifactId>
    			<version>4.12</version>
    			<scope>test</scope>
    		</dependency>
    		<!-- spring依赖 -->
    		<dependency>
    		    <groupId>org.springframework</groupId>
    		    <artifactId>spring-core</artifactId>
    		    <version>${spring.version}</version>
    		</dependency>
    		<dependency>
    		    <groupId>org.springframework</groupId>
    		    <artifactId>spring-beans</artifactId>
    		    <version>${spring.version}</version>
    		</dependency>
    		<dependency>
    		    <groupId>org.springframework</groupId>
    		    <artifactId>spring-context</artifactId>
    		    <version>${spring.version}</version>
    		</dependency>
    	</dependencies>
    </project>
    

      1.3 spring-beanscope.xml(scope="singleton" || scope="prototype")

    <?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 id="beanScope" class="org.spring.bean.BeanScope" scope="singleton"/>        
            
    </beans>
    

      1.4 BeanScope.java

    package org.spring.bean;
    
    public class BeanScope {
    
    	public void say () {
    		
    		System.out.println("hashCode:" + this.hashCode());//通过hashCode判断是否是同一个实例
    		
    	}
    
    }
    

      1.5 UnitTestBase.java

    package org.spring.ioc.test;
    
    import org.junit.After;
    import org.junit.Before;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.util.StringUtils;
    
    /**
     * 单元测试初始化类
     *
     */
    public class UnitTestBase {
    	
    	private ClassPathXmlApplicationContext context;
    	private String springXmlPath;
    	
    	/**
    	 * 无参构造器
    	 */
    	public UnitTestBase() {
    		
    	}
    
    	/**
    	 * 含参构造器
    	 * 
    	 * @param springXmlPath
    	 * 						spring配置文件路径
    	 */
    	public UnitTestBase(String springXmlPath) {
    		
    		this.springXmlPath = springXmlPath;
    		
    	}
    	
    	/**
    	 * 初始化spring配置文件
    	 */
    	@Before//在@Test注解的方法执行前执行
    	public void before() {
    		
    		if(StringUtils.isEmpty(springXmlPath)) {//默认spring配置文件路径
    			springXmlPath = "classpath*:spring-*.xml";
    		}
    		//加载配置文件,一个context表示一个容器
    		context = new ClassPathXmlApplicationContext(springXmlPath.split("[,\s]+"));
    		//启动组件
    		context.start();
    		
    	}
    	
    	/**
    	 * 销毁spring组件
    	 */
    	@After//在@Test注解的方法执行后执行
    	public void after() {
    		
    		context.destroy();//销毁组件
    		
    	}
    	
    	/**
    	 * 获取spring中定义的bean实例
    	 * 
    	 * @param beanId
    	 * 					
    	 * @return
    	 */
    	@SuppressWarnings("unchecked")
    	protected <T extends Object> T getBean(String beanId) {
    		
    		return (T) context.getBean(beanId);
    		
    	}
    	
    	/**
    	 * 获取spring中定义的bean实例
    	 * 
    	 * @param clazz
    	 * 				
    	 * @return
    	 */
    	protected <T extends Object> T getBean(Class<T> clazz) {
    		
    		return (T) context.getBean(clazz);
    		
    	}
    
    }
    

      1.6 TestBeanScope.java

    package org.spring.ioc.test;
    
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.junit.runners.BlockJUnit4ClassRunner;
    import org.spring.bean.BeanScope;
    
    @RunWith(BlockJUnit4ClassRunner.class)//指定JUnit默认执行类
    public class TestBeanScope extends UnitTestBase {
    	
    	public TestBeanScope() {//通过构造方法传入spring配置文件路径
    		
    		super("classpath*:spring-beanScope.xml");
    		
    	}
    	
    	@Test
    	public void testScope() {
    		
    		BeanScope beanScope = super.getBean("beanScope");
    		beanScope.say();
    		
    		/**
    		 * 若在两个方法中执行这两行代码,则hashCode会不同。
    		 * 因为每个test方法执行前都会执行@Before,会重新加载spring配置文件,此时是在两个容器中,所以不同
    		 */
    		BeanScope beanScope2 = super.getBean("beanScope");
    		beanScope2.say();
    		
    	}
    	
    }
    

      1.7 singleton效果预览

      1.8 prototype效果预览

     2.request和session

      2.1 项目结构

       2.2 pom.xml

    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    	
    	<modelVersion>4.0.0</modelVersion>
    	
    	<groupId>org.spring</groupId>
    	<artifactId>springBeanScope</artifactId>
    	<packaging>war</packaging>
    	<version>0.0.1-SNAPSHOT</version>
    	<name>springBeanScope Maven Webapp</name>
    	<url>http://maven.apache.org</url>
    	
    	<properties>
    		<spring.version>4.3.7.RELEASE</spring.version>
    	</properties>
    	
    	<dependencies>
    		<!-- junit依赖 -->
      		<dependency>
    		    <groupId>junit</groupId>
    		    <artifactId>junit</artifactId>
    		    <version>4.12</version>
    		    <scope>test</scope>
    	  	</dependency>
    	  	<!-- spring核心依赖 -->
    		<dependency>
    		    <groupId>org.springframework</groupId>
    		    <artifactId>spring-core</artifactId>
    		    <version>${spring.version}</version>
    		</dependency>
    	  	<!-- spring web层依赖 -->
    	  	<dependency>
    		    <groupId>org.springframework</groupId>
    		    <artifactId>spring-webmvc</artifactId>
    		    <version>${spring.version}</version>
    		</dependency>
    		<!-- jstl -->
    		<dependency>
    		    <groupId>jstl</groupId>
    		    <artifactId>jstl</artifactId>
    		    <version>1.2</version>
    		</dependency>
    		<!-- servlet -->
    	<dependency>
    	    <groupId>javax.servlet</groupId>
    	    <artifactId>javax.servlet-api</artifactId>
    	    <version>3.1.0</version>
    	</dependency>
    		
    	</dependencies>
      
      	<build>
        	<finalName>springBeanScope</finalName>
      	</build>
      	
    </project>
    

      2.3 mvc-dispatcher-servlet.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"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc.xsd">
            
        <!-- 开启包扫描 -->
        <context:component-scan base-package="org.spring.*"/>
        
        <!-- 开启注解 -->
        <mvc:annotation-driven/>
        
        <!-- 定义视图解析器 -->
        <bean id="viewResolver" 
        	class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        	<property name="prefix" value="/WEB-INF/jsp/"/>
        	<property name="suffix" value=".jsp"/>	
       	</bean>
       	
    </beans>
    

      2.4 BeanScope.xml

    package org.spring.bean;
    
    public class BeanScope {
    
    	public int say () {
    		
    		return this.hashCode();//通过返回的hashCode判断是否是同一个实例
    		
    	}
    
    }
    

      2.5 spring.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"
        xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd">
          
        <bean id="beanScope" class="org.spring.bean.BeanScope" scope="singleton"/>
            
    </beans>
    

      2.6 web.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://java.sun.com/xml/ns/javaee"
    	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                          http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
      	version="3.0" metadata-complete="true">
      	
      	<!-- 启动spring的监听器,默认加载applicationContext.xml -->
      	<listener>
      		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
      	</listener>
      	
      	<!-- 自定义spring配置文件路径 -->
      	<context-param>
      		<param-name>contextConfigLocation</param-name>
      		<param-value>classpath:spring.xml</param-value>
      	</context-param>
      	
      	<!-- 拦截所有请求,交由springMVC处理 -->
      	<servlet>
      		<servlet-name>springMVC</servlet-name>
      		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
      		<init-param>
      			<param-name>contextConfigLocation</param-name>
      			<param-value>classpath:mvc-dispatcher-servlet.xml</param-value>
      		</init-param>
      	</servlet>
      	<servlet-mapping>
      		<servlet-name>springMVC</servlet-name>
      		<url-pattern>/</url-pattern>
      	</servlet-mapping>
      	
    </web-app>

      2.7 BeanScopeAction.java

    package org.spring.action;
    
    import java.util.ArrayList;
    import java.util.List;
    
    import javax.servlet.http.HttpSession;
    
    import org.spring.bean.BeanScope;
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.ModelMap;
    import org.springframework.web.bind.annotation.RequestMapping;
    
    @Controller
    public class BeanScopeAction implements ApplicationContextAware {
    
    	private ApplicationContext context;
    	
    	@RequestMapping("/")
    	public String testScope(ModelMap map, HttpSession session) {
    		
    		BeanScope scope = (BeanScope) context.getBean("beanScope");
    		List<Integer> list = new ArrayList<Integer>();
    		for(int i = 0; i < 3; i++){
    			list.add(scope.say());
    		}
    		map.addAttribute("list", list);
    		map.addAttribute("session", session);
    		return "scope";
    		
    	}
    
    	public void setApplicationContext(ApplicationContext context) throws BeansException {
    		
    		this.context = context;
    		
    	}
    	
    }
    

      2.8 scope.jsp

    <%@ page language="java" contentType="text/html; charset=UTF-8"
        pageEncoding="UTF-8"%>
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Spring作用域测试</title>
    </head>
    <body>
    	<font color="red">Session:${session }</font><br/>
    	<c:forEach var="hashCode" items="${list }" varStatus="status">
    		第${status.index + 1 }次获取实例:${hashCode }<br/>
    	</c:forEach>
    </body>
    </html>

      2.9 效果预览

        需刷新才能看见效果,截图表达不清晰,可复制代码自行运行刷新查看结果。

    3.global session

      需多个项目才能看见结果,此处不做测试。

    参考:http://www.imooc.com/video/3750/

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  • 原文地址:https://www.cnblogs.com/jinjiyese153/p/6689155.html
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