Spring(五)基于XML裝配bean(作用域)

bean的作用域

用于确定Spring建立bean執行個體的個數

預設為singleton

可以用scope進行配置

scope取值

我們常用的：

singleton:單例模式（servlet）

prototype:多例，即執行一次getBean便獲得一個執行個體.（struct-action）

測試

測試流程

Users類

xml配置

junit測試

修改xml檔案bean的scope

junit

singleton

Users類

package com.scx.scope.test;

public class Users {
    private Integer uid;
    private String username;
    private Integer age;

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

}      

xml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.xsd">

    <bean id="UsersId" class="com.scx.scope.test.Users" scope="singleton"></bean>
</beans>      

junit測試

package com.scx.scope.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test {
    @org.junit.Test
    public void testScope() {
        String xmlPath = "com/scx/scope/test/applicationContext.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                xmlPath);
        Users user1 = applicationContext.getBean("UsersId", Users.class);
        Users user2 = applicationContext.getBean("UsersId", Users.class);
        System.out.println(user1);
        System.out.println(user2);
        System.out.println(user1==user2);      

運作結果

兩次輸出的結果一樣 ，為單例模式

prototype

修改xml檔案bean的scope為prototype

<bean id="UsersId" class="com.scx.scope.test.Users" scope="prototype"></bean>      

運作結果：