Spring 的注入方式有很多种，方法的注入方式更加体现了Spring容器覆盖容器管理的bean上的方法的能力，方法注入的方式也是多种，本例以Lookup方式，采用xml配置和注解两种不同的方式。

使用Lookup方法注入需要注意：
1.为了使这个动态子类化工作，Spring bean容器将子类化的类不能是final，并且要重写的方法也不能是final。
2.注入的方法需要有返回值。
3.方法必须是public或protected修饰
4.必须是无参数的方法
方法格式如下：

1
<public|protected> [abstract] <return-type> theMethodName(no-arguments);

使用的技术及工具：
1.eclipse 4.4.2
2.Maven 3.1
3.JDK 1.7
4.Spring 4.3.5
5.Junit 4.12

XML配置的方式：

注：实例一和二都是使用相同的配置

1.pom.xml

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<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>com.devnp</groupId>
  <artifactId>Spring4Demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>Spring4Demo</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <spring.version>4.3.5.RELEASE</spring.version>
  </properties>

  <dependencies>
  	<dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${spring.version}</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

2.Java 代码

HelloService.java

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package com.devnp.SpringDemo;

public class HelloService {

	public void print(){
		System.out.println("Hello World.");
	}
}

MethodDIDemo.java

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package com.devnp.SpringDemo.method.DI;

import com.devnp.SpringDemo.HelloService;

public abstract class MethodDIDemo {

	public void process(){
		HelloService helloService = createHelloService();
		
		helloService.print();
	}
	
	protected abstract HelloService createHelloService();
}

3.xml 配置

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<bean id="helloService" class="com.devnp.SpringDemo.HelloService"></bean>

<bean id="methodDIDemo" class="com.devnp.SpringDemo.method.DI.MethodDIDemo">
	<lookup-method name="createHelloService" bean="helloService" />
</bean>

4.Junit 测试

MethodDIDemoTest.java

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package com.devnp.SpringDemo.method.DI;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:ApplicationContext.xml")
public class MethodDIDemoTest {

	@Autowired
	private MethodDIDemo methodDIDemo ;
	
	@Test
	public void processTest(){
		methodDIDemo.process();
	}
	
}

5.结果

Hello World.

实例二 采用注解的形式

@Lookup(“helloService”)

1.java 代码

MethodDIDemo2.java

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package com.devnp.SpringDemo.method.DI;

import org.springframework.beans.factory.annotation.Lookup;

import com.devnp.SpringDemo.HelloService;

public abstract class MethodDIDemo2 {

	public void process(){
		HelloService helloService = createHelloService();
		
		helloService.print();
	}
	
	@Lookup("helloService")
	protected abstract HelloService createHelloService();
}

2.xml 配置

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<bean id="methodDIDemo2" class="com.devnp.SpringDemo.method.DI.MethodDIDemo2"/>

3.Junit 测试

MethodDIDemo2Test.java

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package com.devnp.SpringDemo.method.DI;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:ApplicationContext.xml")
public class MethodDIDemo2Test {

	@Autowired
	private MethodDIDemo2 methodDIDemo2 ;
	
	@Test
	public void processTest(){
		methodDIDemo2.process();
	}
	
}

4.运行结果

Hello World.

代码下载：

Spring4Demo.zip