spring之方法注入,单例和多例，方法替换

Spring bean 作用域默认是单例 singleton；可以通过配置 prototype ，实现多例；

People people=(People)ac.getBean("people1");
People people2=(People)ac.getBean("people1");
System.out.println(people.getDog()==people2.getDog());

打印的输出是true

更改beans.xml文件可以是spring每次创建的bean是新的（多例），加上scope="prototype"这句话

输出为false

方法注入 lookup-method，输出为true

<?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">

People类代码

package com.java1234.entity;

public abstract class People {

   private int id;
   private String name;
   private int age;
   private Dog dog;


   public int getId() {
       return id;
   }
   public void setId(int id) {
       this.id = id;
   }
   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   public int getAge() {
       return age;
   }
   public void setAge(int age) {
       this.age = age;
   }
   public abstract Dog getDog();

   public void setDog(Dog dog) {
       this.dog = dog;
   }
   @Override
   public String toString() {
       return "People [id=" + id + ", name=" + name + ", age=" + age
               + ", dog=" + dog.getName() + "]";
   }

}

方法替换（用people2中dog的名字Tom替换掉people的狗名字jack）

package com.java1234.entity;

public class People {

   private int id;
   private String name;
   private int age;
   private Dog dog;


   public int getId() {
       return id;
   }
   public void setId(int id) {
       this.id = id;
   }
   public String getName() {
       return name;
   }
   public void setName(String name) {
       this.name = name;
   }
   public int getAge() {
       return age;
   }
   public void setAge(int age) {
       this.age = age;
   }

   public Dog getDog() {
       Dog dog=new Dog();
       dog.setName("Jack");
       return dog;
   }
   public void setDog(Dog dog) {
       this.dog = dog;
   }
   @Override
   public String toString() {
       return "People [id=" + id + ", name=" + name + ", age=" + age
               + ", dog=" + dog.getName() + "]";
   }

}

People2.java

package com.java1234.entity;

import java.lang.reflect.Method;

import org.springframework.beans.factory.support.MethodReplacer;

public class People2 implements MethodReplacer {

   @Override
   public Object reimplement(Object arg0, Method arg1, Object[] arg2)
           throws Throwable {
       Dog dog=new Dog();
       dog.setName("Tom");
       return dog;
   }

}

beans.xml

Test类

package com.java1234.test;

import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.java1234.entity.People;

public class T {

private ApplicationContext ac;

   @Before
   public void setUp() throws Exception {
       ac=new ClassPathXmlApplicationContext("beans.xml");
   }

   @Test
   public void test1() {
       People people=(People)ac.getBean("people1");
       System.out.println(people.getDog().getName());
   }

}

//输出结果位Tom

spring之方法注入,单例和多例，方法替换

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