Spring学习笔记3——使用注解的方式完成注入对象中的效果

第一步：修改applicationContext.xml

添加<context:annotation-config/>表示告诉Spring要用注解的方式进行配置

 <?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">

   <context:annotation-config/>
     <bean name="category" class="com.spring.cate.Category">
         <property name="name" value="category 3333" />
     </bean>
     <bean name="product" class="com.spring.cate.Product">
         <property name="name" value="product 3333" />
     </bean>

 </beans>

第二步：在Product.java的category属性前加上@Autowired注解

 package com.spring.cate;

 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;
     }
 }

第三步：测试

 package com.spring.test;

 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 import com.spring.cate.Product;

 public class TestSpring {

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         ApplicationContext context = new ClassPathXmlApplicationContext(new String[] { "applicationContext.xml" });
         Product p = (Product) context.getBean("product");
         System.out.println(p.getName());
         System.out.println(p.getCategory().getName());
     }

 }

第四步：除了前面的在属性前加@Autowired这种方式外，也可以在setCategory方法前加上@Autowired，这样来达到相同的效果

第五步：除了@Autowired之外，@Resource也是常用的手段

 package com.spring.cate;

 import javax.annotation.Resource;

 //@Component("product")
 public class Product {
     private int id;
     // private String name = "product1";
     private String name;
     @Resource(name = "category")
     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;
     }
 }

第六步：对Bean的注解

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

第七步：修改applicationContext.xml

修改applicationContext.xml，什么都去掉，只新增： <context:component-scan base-package="com.spring.cate"/>

其作用是告诉Spring，bean都放在com.spring.cate这个包下

第八步：@Component

为Product类加上@Component注解，即表明此类是bean

为Category 类加上@Component注解，即表明此类是bean

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。

Product.java

 package com.spring.cate;

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

 @Component("product")
 public class Product {
     private int id;
     private String name = "product1";
     @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.java

 package com.spring.cate;

 import org.springframework.stereotype.Component;

 @Component("category")
 public class Category {
     private int id;
     private String name = "category1";

     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;
     }
 }

结果：