Spring使用注解代替XML配置

1.导入命名空间

XML Catalog中除了要导入spring-beans以外，还要导入spring-context。

2.在applicationContext.xml文件中，添加

<context:component-scan base-package="Object"></context:component-scan>

其中，base-package中表示要扫描的包名。我这里表示扫描Object包及其子包下所有的注解。

3.为要创建Bean对象的JAVABean对象添加注解：

@Component("user") //user为Bean的name

//以下三个注解作用和Component完全相同，只是为了在MVC中方便查看
@Service("user")//service层
@Controller("user")//web层
@Repository("user")//dao层

4.设置Bean对象的作用范围

@Scope(scopeName="singleton") //单例

@Scope(scopeName="prototype") //多例

5.属性注入

在要注入属性的Set方法上添加注解：

//值类型
@Value(value="wxs") //wxs为属性值

//对象类型
@Resource(name="car") //car为Car类的Bean对象

6.生命周期

@PostConstruct//在对象被创建后调用

@PreDestroy//在对象被销毁前掉调用

Demo:

<!--src/applicationContext.xml -->

<?xml version="1.0" encoding="UTF-8"?>

<beans 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xmlns="http://www.springframework.org/schema/beans" 
	xmlns:context="http://www.springframework.org/schema/context" 
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd ">

	<context:component-scan base-package="Object"></context:component-scan>
	 
</beans>

//Object.User.java:

package Object;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component("user")
@Scope(scopeName="singleton")
public class User {
	private String name;
	private Integer age;
	private Car car;
	public Car getCar() {
		return car;
	}
	@Resource(name="car")
	public void setCar(Car car) {
		this.car = car;
	}
	public String getName() {
		return name;
	}
	@Value("wxs")
	public void setName(String name) {
		this.name = name;
	}
	public Integer getAge() {
		return age;
	}
	@Value("18")
	public void setAge(Integer age) {
		this.age = age;
	}
	@Override
	public String toString() {
		return "User [name=" + name + ", age=" + age + ", car=" + car + "]";
	}
	@PostConstruct
	public void init(){
		System.out.println("init...");
	}
	@PreDestroy
	public void destory() {
		System.out.println("destory...");
	}
}

//Object.Car.java:

package Object;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("car")
public class Car {
	private String name;
	private String color;
	public String getName() {
		return name;
	}
	@Value("兰博基尼")
	public void setName(String name) {
		this.name = name;
	}
	public String getColor() {
		return color;
	}
	@Value("绿色")
	public void setColor(String color) {
		this.color = color;
	}
	@Override
	public String toString() {
		return "Car [name=" + name + ", color=" + color + "]";
	}
	
}

//Demo.UserTest.java:

package Demo;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import Object.User;

public class UserTest {
	@Test
	public void f1(){
		//这里只是为了能够调用ac.close()方法，才使用ClassPathXmlApplicationContext。正常应使用ApplicationContext
		ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");
		User u = (User)ac.getBean("user");
		System.out.println(u);
		ac.close();
	}
}

运行结果：

init...
User [name=wxs, age=18, car=Car [name=兰博基尼, color=绿色]]
destory...