依赖注入

set方法注入

set注入发生再容器调用无参构造器构造一个对象后。下面这个类只能使用set方法注入参数。

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

    public String getName() {
        return name;
    }

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

    public String getAddress() {
        return address;
    }

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

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

    <bean id="school" class="com.sora.services.School">
        <property name="name" value="成都信息工程大学"/>
        <property name="address" value="成都"/>
   </bean>

package com.sora.services;

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

/**
 * @Classname: SchoolTest
 * @Description:
 * @Author: Stonffe
 * @Date: 2023/3/29 22:51
 */
public class SchoolTest {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        School school = context.getBean("school", School.class);
        System.out.println(school);
    }
}

School{name='成都信息工程大学', address='成都'}

构造方法注入

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

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = 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 +
                '}';
    }
}

    <bean id="student" class="com.sora.services.Student">
        <constructor-arg name="age" value="20"/>
        <constructor-arg name="name" value="xiao"/>
    </bean>

public class StudentTest {
    @Test
    public void test(){
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        Student bean = context.getBean(Student.class);
        System.out.println(bean);
    }
}

Student{name='xiao', age=20}

对象中注入属性

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

    public Student() {
    }

    public Student(String name, int age) {
        this.name = name;
        this.age = age;
        this.school = school;
    }

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

使用构造函数

    <bean id="student" class="com.sora.services.Student">
        <constructor-arg name="age" value="20"/>
        <constructor-arg name="name" value="xiao"/>
        <constructor-arg name="school" ref="school"/>
	</bean>
    <bean id="school" class="com.sora.services.School">
        <property name="name" value="成都信息工程大学"/>
        <property name="address" value="成都"/>
    </bean>

使用set方法

    <bean id="student" class="com.sora.services.Student">
        <property name="age" value="22"/>
        <property name="name" value="xiao"/>
        <property name="school" ref="school"/>
    </bean>
    <bean id="school" class="com.sora.services.School">
        <property name="name" value="成都信息工程大学"/>
        <property name="address" value="成都"/>
    </bean>

Student{name='xiao', age=22, school=School{name='成都信息工程大学', address='成都'}}