1、 添加maven支持
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.0.2.RELEASE</version>
</dependency>
基本的注入,只要这一个依赖项即可
2、 编写几个测试类
假设场景: 有一个程序员jimmy, 他有几台电脑, 一个宠物,每天下班回家后,宠物会用某种形式欢迎他回家.
package com.cnblogs.yjmyzz.domain;
public abstract class Computer {
public abstract void showInfo();
}
package com.cnblogs.yjmyzz.domain;
public class MacBook extends Computer {
@Override
public void showInfo() {
System.out.println("\tApple MAC Book");
}
}
package com.cnblogs.yjmyzz.domain;
public class ThinkPad extends Computer {
@Override
public void showInfo() {
System.out.println("\tLenovo ThinkPad");
}
}
package com.cnblogs.yjmyzz.domain;
public abstract class Pet {
public abstract void welcomeMeToHome();
}
package com.cnblogs.yjmyzz.domain;
public class Dog extends Pet {
@Override
public void welcomeMeToHome() {
System.out.println("\twang! wang!");
}
}
package com.cnblogs.yjmyzz.domain;
import java.util.List;
public class Programmer {
private String name;
private Pet pet;
private List<Computer> computers;
public void setName(String name) {
this.name = name;
}
public List<Computer> getComputers() {
return computers;
}
public void setComputers(List<Computer> computers) {
this.computers = computers;
}
public void setPet(Pet pet) {
this.pet = pet;
}
public void show() {
System.out.print("My name is " + name);
System.out.print(", and I have " + computers.size() + " computer" + (computers.size() > 1 ? "s" : "") + ":");
System.out.println();
for (Computer c : computers) {
c.showInfo();
}
System.out.println("And I have a pet, everyday,when I go home, it will welcome me by ");
pet.welcomeMeToHome();
}
}
3、 spring的配置文件
<?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="jimmy" class="com.cnblogs.yjmyzz.domain.Programmer">
<property name="name" value="jimmy.yang"/>
<property name="pet" ref="wangcai"/>
<property name="computers">
<list>
<ref bean="t60"/>
<ref bean="macbook_pro"/>
</list>
</property>
</bean>
<bean id="t60" class="com.cnblogs.yjmyzz.domain.ThinkPad"/>
<bean id="macbook_pro" class="com.cnblogs.yjmyzz.domain.MacBook"/>
<bean id="wangcai" class="com.cnblogs.yjmyzz.domain.Dog"/>
</beans>
这个配置文件SimpleBeans.xml中,一共配置了4个bean实例, 该配置被Spring容器加载后,这些对象都会被实例化(默认是单例模式实例化),并保持在容器中,需要使用的时候,可以手动通过ApplicationContext的getBean方法获取
4、 测试注入
为了注入方便,先写一个简单的工具类SpringUtils
package com.cnblogs.yjmyzz.utils;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class SpringUtils {
private static ApplicationContext applicationContext;
private static ApplicationContext getContext() {
if (applicationContext == null) {
applicationContext = new ClassPathXmlApplicationContext("SimpleBeans.xml");
}
return applicationContext;
}
public static <T> T getBean(Class<T> clazz, String beanName) {
return getContext().getBean(beanName, clazz);
}
}
然后就可以用这个工具类,通过getBean来获取注入的对象实例
package com.cnblogs.yjmyzz.test;
import com.cnblogs.yjmyzz.domain.Programmer;
import com.cnblogs.yjmyzz.utils.SpringUtils;
import org.junit.Test;
public class TestSpring {
@Test
public void testSimpleInject(){
Programmer jimmy= SpringUtils.getBean(Programmer.class,"jimmy");
jimmy.show();
}
}
运行效果: My name is jimmy.yang, and I have 2 computers: Lenovo ThinkPad Apple MAC Book And I have a pet, everyday,when I go home, it will welcome me by wang! wang!
下一篇将学习如何自动注入,以及如何使用properties属性文件来注入对象属性.