spring 属性注入

1、创建对象时，向类属性里面设置值

2、java属性注入的三种方式

• set方法

  
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• 有参构造

  
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• 接口注入

  
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3、在spring中只支持两种方式

（1）set方法注入

PropertyUser.java

package work.zhangdoudou.Property;

public class PropertyUser {
    private String username;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }   
}

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
 xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
    <!-- set方法注入属性 -->
    <bean id="propertyUser" class="work.zhangdoudou.Property.PropertyUser">
        <!-- set方法注入属性 -->
        <property name="username" value="lisi"></property>
    </bean>
</beans>

测试类TestPropertyUser.java

package work.zhangdoudou.test;

import static org.junit.Assert.*;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import work.zhangdoudou.Property.PropertyUser;

public class TestPropertyUser {

    @Test
    public void test() {
        //1加载配置文件，根据创建对象
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        //2得到创建的对象
        PropertyUser propertyUser=(PropertyUser) context.getBean("propertyUser");
        System.out.println(propertyUser.getUsername());
    }

}

运行结果

image.png

（2）有参数构造注入

PropertyUser1.java

package work.zhangdoudou.Property;

public class PropertyUser1 {
    private String username;

    public PropertyUser1(String username) {
        this.username = username;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }   
}

applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans
 xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> 
    <!-- 有参数构造注入属性 -->
    <bean id="propertyUser1" class="work.zhangdoudou.Property.PropertyUser1">
        <!-- 有参数构造注入 -->
        <constructor-arg name="username" value="zhangsan"></constructor-arg>
    </bean>
</beans>

测试类TestPropertyUser1.java

package work.zhangdoudou.test;

import static org.junit.Assert.*;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import work.zhangdoudou.Property.PropertyUser1;

public class TestPropertyUser1 {

    @Test
    public void test() {
        //1加载配置文件，根据创建对象
        ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");
        //2得到创建的对象
        PropertyUser1 propertyUser1=(PropertyUser1) context.getBean("propertyUser1");
        System.out.println(propertyUser1.getUsername());
    }

}

运行结果

image.png