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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。