java框架之spring（三）

注解方式 IOC/DI

在本知识点中，讲演示如何使用注解的方式完成注入对象中的效果

1、修改applicationContext.xml文件

添加<context:annotation-config/>表示告诉Spring要用注解的方式进行配置，注入对象注释掉，这个行为在后面将使用注解来完成

<?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="hjsy" class="com.hjsy.pojo.Category">
        <property name="name" value="花季岁月" />
    </bean>
    <bean name="hjsy1" class="com.hjsy.pojo.Product">
        <property name="name" value="花季岁月1" />
        <!-- <property name="category" ref="hjsy" /> -->
    </bean>
</beans>

2、在Product.java的category属性前加上@Autowired注解

package com.hjsy.pojo;

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;
    }
}

3、测试

package spring;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.hjsy.pojo.Product;
public class TestSpring {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext(new String[] { "applicationContext.xml" });
        Product product = (Product) context.getBean("hjsy1");
        System.out.println(product.getName());
        System.out.println(product.getCategory().getName());
	}
}

4、运行输出结果

5、除了前面在属性前加上@Autowired的这种方式外，也可以在setCategory方法前加上@Autowired，这样来达到相同的效果

package com.hjsy.pojo;

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

public class Product {
    private int id;
    private String name;
  
    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;
    }
    @Autowired
    public void setCategory(Category category) {
        this.category = category;
    }
}

6、除了@Autowired之外，@Resource也是常用的手段

package com.hjsy.pojo;

import javax.annotation.Resource;

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

public class Product {
    private int id;
    private String name;
    //@Autowired
    @Resource(name="hjsy")
    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;
    }
}

7、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

8、修改applicationContext.xml，什么都去掉，只新增

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

9、为Product类加上@Component注解，即表明此类是bean

package com.hjsy.pojo;

import javax.annotation.Resource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component("hjsy1")
public class Product {
    private int id;
    private String name="花季岁月1";
    @Autowired
    //@Resource(name="hjsy")
    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;
    }
}

10、为Category 类加上@Component注解，即表明此类是bean

package com.hjsy.pojo;

import org.springframework.stereotype.Component;

@Component("hjsy")
public class Category {
	private int id;
        private String name="花季岁月";
	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;
	}
}

11、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。

如上：private String name="花季岁月1";和private String name="花季岁月";

12、测试

package spring;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.hjsy.pojo.Product;
public class TestSpring {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext(new String[] { "applicationContext.xml" });
        Product product = (Product) context.getBean("hjsy1");
        System.out.println(product.getName());
        System.out.println(product.getCategory().getName());
	}
}

13、运行输出结果


源码：链接：https://pan.baidu.com/s/1mkrapKW 密码：euto