Java框架spring 学习笔记（六）：属性注入

属性注入：创建对象的时候，向类里面的属性设置值。

Java属性注入有三种方法：

使用set方法注入

有参数构造注入

使用接口注入



Spring框架里面的属性注入方式

有参数构造属性注入

set方法属性注入

有参数构造属性注入

编写User.java

1 package com.example.spring;
2
3 public class User {
4     private String name;
5     private Integer age;
6     private String country;
7
8     //基于构造函数的属性注入
9     public User(String name, Integer age, String country) {
10         this.name = name;
11         this.age = age;
12         this.country = country;
13     }
14
15     public String toString() {
16         return name + " is " + age + " years old, living in " + country;
17     }
18 }

编写Beans.xml，使用constructor-arg为属性赋值

1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 5
6     <bean id="user" class="com.example.spring.User" >
7         <constructor-arg name="name" type="java.lang.String" value="Jacky" />
8         <constructor-arg name="age" type="java.lang.Integer" value="22"/>
9         <constructor-arg name="country" type="java.lang.String" value="China"/>
10     </bean>
11
12 </beans>

编写Application.java

package com.example.spring;

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

public class Application {
public static void main(String[] args) {
//bean配置文件所在位置 D:\\IdeaProjects\\spring\\src\\Beans.xml
//使用AbstractApplicationContext容器
AbstractApplicationContext context = new ClassPathXmlApplicationContext("file:D:\\IdeaProjects\\spring\\src\\Beans.xml");
User user = (User)context.getBean("user");
System.out.println(user);
}
}

运行输出

Jacky is 22 years old, living in China

set方法属性注入

编写User.java

1 package com.example.spring;
2
3 public class User {
4     private String name;
5     private Integer age;
6     private String country;
7
8     //基于set方法的属性注入
9     public void setName(String name) {
10         this.name = name;
11     }
12     public void setAge(Integer age) {
13         this.age = age;
14     }
15     public void setCountry(String country) {
16         this.country = country;
17     }
18
19     public String toString() {
20         return name + " is " + age + " years old, living in " + country;
21     }
22 }

编写Beans.xml，使用property关键字为属性赋值

1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 5
6     <bean id="user" class="com.example.spring.User" >
7         <property name="name" value="Jacky"></property>
8         <property name="age" value="22"></property>
9         <property name="country" value="China"></property>
10     </bean>
11
12 </beans>

编写Application.java

1 package com.example.spring;
2
3 import org.springframework.context.support.AbstractApplicationContext;
4 import org.springframework.context.support.ClassPathXmlApplicationContext;
5
6 public class Application {
7     public static void main(String[] args) {
8         //bean配置文件所在位置 D:\\IdeaProjects\\spring\\src\\Beans.xml
9         //使用AbstractApplicationContext容器
10         AbstractApplicationContext context = new ClassPathXmlApplicationContext("file:D:\\IdeaProjects\\spring\\src\\Beans.xml");
11         User user = (User)context.getBean("user");
12         System.out.println(user);
13     }
14 }

运行输出

Jacky is 22 years old, living in China