Spring使用注解的方式注入对象

Spring使用注解的方式在对象中注入对象

Product.class文件

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

public class Product {

	private int id;
	private String name;
	@Autowired
	private Category category;

	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 Category getCategory() {
		return category;
	}

	public void setCategory(Category category) {
		this.category = category;
	}
}

Category.class 

public class Category {
    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;
    }
    private int id;
    private String name;
}

 applicationContext.xml中配置 

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context     
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<!--  以上为配置文件常用开头  -->

<!--   下面context 表示告诉Spring要用注解的方式进行配置-->
<context:annotation-config/>
  <!--  准备在Product中注入Category对象  -->
    <bean name="c" class="com.zouch.Category">
        <property name="name" value="category 1" />
    </bean>
    <bean name="p" class="com.zouch.Product">
        <property name="name" value="product1" />
    </bean>
  
</beans>

方法一：在Product.java的category属性前加上@Autowired注解

@Autowired
private Category category;

方法二：setCategory方法前加上@Autowired

@Autowired
public void setCategory(Category category) 
 

方法三：在Product.java的category属性前加上@Resource注解

@Resource(name="c")
private Category category;

上述例子是对注入对象行为的注解，那么bean对象本身，比如Category,Product可不可以移出applicationContext.xml配置文件，也通过注解进行呢？
接下来就讲解如何对Bean进行注解配置

1. 修改applicationContext.xml，什么都去掉，只新增：

<context:component-scan base-package="com.how2java.pojo"/>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context     
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
 <!-- 告诉Spring，bean都放在com.zouch.pojo这个包下-->
    <context:component-scan base-package="com.zouch.pojo"/>
     
</beans>

为Product类加上@Component注解，即表明此类是bean

@Component("p")

public class Product {
为Category 类加上@Component注解，即表明此类是bean

@Component("c")

public class Category {

另外，因为配置从applicationContext.xml中移出来了，所以属性初始化放在属性声明上进行了。

private String name="product 1";

private String name="category 1";

三种方式得到的结果一致。