singleton和prototype

 public class testScope {

     @Test
     public void test() {
         //默任singleton
         ApplicationContext ctx= new ClassPathXmlApplicationContext(
                 "applicationContext.xml");

         //客户端1拿到的东西
         User user = ctx.getBean("user",User.class);
         System.out.println(user.getUsername());
         user.setUsername(user.getUsername()+"1");

         //客户端2拿到的东西(对唯一实例的修改)
         User user2 = ctx.getBean("user",User.class);
         System.out.println(user2.getUsername());
         user2.setUsername(user.getUsername()+"2");

         //客户端3拿到的东西(对唯一实例的修改)
         User user3 = ctx.getBean("user",User.class);
         System.out.println(user3.getUsername());

         System.out.println(user==user2);
         System.out.println(user==user3);

     }
 }

去掉scope="prototype"就是scope="singleton"
 1 <?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-3.2.xsd
 http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans-3.2.xsd ">
      <bean id="userDao" class="com.bdqn.dao.UserDaoImpl"></bean>
      <bean id="userService" class="com.bdqn.service.UserService">
          <!-- setter方法 -->
          <property name="dao" ref="userDao"></property>
          <!-- 构造方法注入    index编号从0开始-->
         <constructor-arg index="0" ref="userDao"></constructor-arg>
          <!-- ref引用 -->
      </bean>
      <!-- singleton -->
      <bean id="user" class="com.bdqn.entity.User" scope="prototype">
          <property name="username" value="admin"></property>
          <property name="password" value="123"></property>
      </bean>
      

singleton:所有的客户端拿到的都是同一个实例，所以后面都是加上去，输出的是admin，admin1，admin2 ，true,true

prototype：所有客户端拿到的都是自己的实例，输出的都是admin，admin，admin，false，false