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：