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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