Spring依赖注入

一、构造器注入

二、Set方式注入【重点】

依赖注入：

• 依赖：bean对象的创建依赖于容器！
• 注入：bean对象中的所有属性，由容器来注入！

环境搭建：

2.1、复杂类型

package com.massimo.pojo;

public class Address {
    private String address;

    public String getAddress() {
        return address;
    }

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

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

2.2、真实测试对象

package com.massimo.pojo;

import java.util.*;

public class Student {

    private String name;
    private Address address;
    private String[] books;
    private List<String> hobbys;
    private Map<String , String> card;
    private Set<String> games;
    private String wife;
    private Properties info;

    public String getName() {
        return name;
    }

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

    public Address getAddress() {
        return address;
    }

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

    public String[] getBooks() {
        return books;
    }

    public void setBooks(String[] books) {
        this.books = books;
    }

    public List<String> getHobbys() {
        return hobbys;
    }

    public void setHobbys(List<String> hobbys) {
        this.hobbys = hobbys;
    }

    public Map<String, String> getCard() {
        return card;
    }

    public void setCard(Map<String, String> card) {
        this.card = card;
    }

    public Set<String> getGames() {
        return games;
    }

    public void setGames(Set<String> games) {
        this.games = games;
    }

    public String getWife() {
        return wife;
    }

    public void setWife(String wife) {
        this.wife = wife;
    }

    public Properties getInfo() {
        return info;
    }

    public void setInfo(Properties info) {
        this.info = info;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", address=" + address.toString() +
                ", books=" + Arrays.toString(books) +
                ", hobbys=" + hobbys + "\n" + 
                ", card=" + card +
                ", games=" + games +
                ", wife='" + wife + '\'' +
                ", info=" + info +
                '}';
    }
}

2.3、beans.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.xsd">

    <bean id="address" class="com.massimo.pojo.Address">
        <property name="address" value="湖南"/>
    </bean>

    <bean id="student" class="com.massimo.pojo.Student">
        <!--第一种，普通注入，value-->
        <property name="name" value="马西莫"/>

        <!--Bean注入，ref-->
        <property name="address" ref="address"/>

        <!--数组-->
        <property name="books">
            <array>
                <value>三国演义</value>
                <value>红楼梦</value>
                <value>水浒传</value>
                <value>西游记</value>
            </array>
        </property>

        <!--list-->
        <property name="hobbys">
            <list>
                <value>听歌</value>
                <value>敲代码</value>
                <value>看书</value>
            </list>
        </property>

        <!--Map-->
        <property name="card">
            <map>
                <entry key="身份证" value="12242133513412514151234"/>
                <entry key="银行卡" value="9879871298571983472193"/>
            </map>
        </property>

        <!--Set-->
        <property name="games">
            <set>
                <value>LOL</value>
                <value>COC</value>
                <value>BOB</value>
            </set>
        </property>

        <!--null-->
        <property name="wife">
            <null/>
        </property>

        <!--Properties-->
        <property name="info">
            <props>
                <prop key="studyId">202002130440</prop>
                <prop key="url">男</prop>
                <prop key="username">root</prop>
                <prop key="password">123456</prop>
            </props>
        </property>

    </bean>


</beans>

2.4、测试类

import com.massimo.pojo.Student;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyTest {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = (Student) context.getBean("student");
        System.out.println(student.toString());
    }
}

2.5、效果

三、拓展方式注入

3.1、p命名空间注入

3.1.1、实体类

package com.massimo.pojo;

public class User {

    private int id;
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

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

3.1.1、配置中导入约束

xmlns:p="http://www.springframework.org/schema/p"

3.1.1、测试

效果：

3.2、c命名空间注入

3.2.1、实体类

沿用上面的实体类，再添加两个构造方法！

3.2.2、配置中导入约束

xmlns:c="http://www.springframework.org/schema/c"

3.2.3、测试

效果：

注意：p命名和C命名空间不能直接使用，需要导入xml约束!