Spring依赖注入的实现方式

在Spring中，有两种实现依赖注入的方式：

1. 属性setter方法注入
2. 构造方法注入

第一种，通过setter方法

注意：使用该方法时，bean类种需要为该类的成员变量设置set方法
bean类

public class Teacher implements User {
    private String jobNum;
    private String name;
    private int age;
    private String phoneNum;

    public String getJobNum() {
        return jobNum;
    }

    public void setJobNum(String jobNum) {
        this.jobNum = jobNum;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getPhoneNum() {
        return phoneNum;
    }

    public void setPhoneNum(String phoneNum) {
        this.phoneNum = phoneNum;
    }

    @Override
    public String toString() {
        return "Teacher{" +
                "jobNum='" + jobNum + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", phoneNum='" + phoneNum + '\'' +
                '}';
    }

在配置文件当中applicationContext.xml中

<?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.xsd">

    <bean id="Teacher" class="com.gk.homework.pojo.Teacher">
        <property name="age" value="40"></property>
        <property name="jobNum" value="2018131905"></property>
        <property name="name" value="Joe"></property>
        <property name="phoneNum" value="16817328033"></property>
    </bean>
</beans>

测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:applicationContext.xml"})
public class TestTeacher {
    @Autowired
    Teacher teacher;

    @Test
    public void testToString(){
        System.out.print(teacher.toString());
    }
}

测试结果：

第二种，通过构造方法

注意：在bean类中需要设置该类有参数的构造方法
bean类：

Teacher(String name,int age,String jobNum,String phoneNum){
        this.name = name;
        this.age = age;
        this.jobNum = jobNum;
        this.phoneNum = phoneNum;
    }

（这里只补充bean类的关键代码）

在applicationContext.xml中：

<?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.xsd">

    <bean id="Teacher" class="com.gk.homework.pojo.Teacher">
        <constructor-arg name="name" value="Mike"></constructor-arg>
        <constructor-arg name="age" value="55"/>
        <constructor-arg name="jobNum" value="2018131905"/>
        <constructor-arg name="phoneNum" value="13928430321"/>
    </bean>
</beans>

test类与上文相同。

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