Springset注入(掌握)

Posted 2021-12-06 王六六的IT日常

创建spring配置文件

Alt insert ---->xml 👇

对应包的spring配置文件：

String config = "bao1/applicationContext.xml";
ApplicationContext ctx = new ClassPathXmlApplicationContext(config);

applicationContext.xml

<bean id="mystudent" class="com.bjpowernode.bao1.Student">
</bean>

Student.java

public class Student {
    private String name;
    private int age;

    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;
    }

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

MyTest.java

@Test
public void test01(){
      String config = "bao1/applicationContext.xml";
      ApplicationContext ctx = new ClassPathXmlApplicationContext(config);
      Student student = (Student) ctx.getBean("mystudent");
      System.out.println("Studen:" + student);
}

此时没有给属性赋值：

DI:给属性赋值

简单类型: java中的基本数据类型和String

简单类型的set注入： spring调用类的set()方法，通过set()方法完成属性赋值

语法：

 <bean id="xxx" class="yyy">
	<property name="属性名" value="简单类型属性值"/>
    ...
 </bean>

applicationContext.xml

<bean id="mystudent" class="com.bjpowernode.bao1.Student">
     <property name="name" value="丸子"/> <!--setName("丸子")-->
     <property name="age" value="19"/>  <!--setAge(19)-->
</bean>

执行test01👇

在set方法中添加输出语句：

public class Student {
    private String name;
    private int age;

    public void setName(String name) {
        System.out.println("setName=="+name);
        this.name = name;
    }

    public void setAge(int age) {
        System.out.println("setAge=="+age);
        this.age = age;
    }

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

添加一个无参构造：

public class Student {
    private String name;
    private int age;

    public Student() {
        System.out.println("Student的无参数构造方法");
    }
    
    public void setName(String name) {
        System.out.println("setName=="+name);
        this.name = name;
    }

    public void setAge(int age) {
        System.out.println("setAge=="+age);
        this.age = age;
    }

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

若将set方法去掉则会报错：

set()方法里面是由自己实现的:

添加一个setEmail()方法:

👇
给属性赋值看的是set方法,与属性名无关,与有没有属性无关,看的只是set方法,有set就是正确的

给非自定义类属性赋值

引用类型set注入

语法：

<bean id="xxx" class="yyy">
	 <property name="属性名" ref="bean的id"/>
	...
</bean>

Student.java

public class Student {
    private String name;
    private int age;

    //引用类型
    private School school;

    public Student() {
        System.out.println("Student的无参数构造方法");
    }

    public void setName(String name) {
        System.out.println("setName=="+name);
        this.name = "Hello" + name;
    }
    
    public void setAge(int age) {
        System.out.println("setAge=="+age);
        this.age = age;
    }

    public void setSchool(School school) {
        System.out.println("setSchool==" + school);
        this.school = school;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\\'' +
                ", age=" + age +
                ", school=" + school +
                '}';
    }
}

School.java

public class School {
    private String name;
    private String address;

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

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "School{" +
                "name='" + name + '\\'' +
                ", address='" + address + '\\'' +
                '}';
    }
}

用spring体现一下:

School声明在student前后的顺序无所谓(id和ref区分大小写)

<!--引用类型set注入-->
    <bean id="mystudent" class="com.bjpowernode.bao2.Student">
        <property name="name" value="王六六"/>
        <property name="age" value="20"/> 

        <!--引用类型的赋值-->
        <property name="school" ref="mySchool" /><!--setSchool(mySchool)-->

    </bean>
    
<!--声明School-->
    <bean id="mySchool" class="com.bjpowernode.bao2.School">
        <property name="name" value="北京大学"/>
        <property name="address" value="北京的海淀区"/>
    </bean>