DI依赖注入

一.依赖注入

1.构造器注入

 

 

 二.set方式注入【重点】

依赖注入：set注入！

依赖：bean对象的创建依赖容器!

注入：bean中所有对象的属性，由容器来注入！

 【环境搭建】

1.复杂类型

package top.lostyou.pojo;

public class Address {
    private String address;

    public String getAddress() {
        return address;
    }

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

 

2.真实测试对象

 

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;
}

 

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="top.lostyou.pojo.Address">
    <property name="address" value="重庆"/>
</bean>
<bean id="Student" class="top.lostyou.pojo.Student">
    <!-- 第一种，普通值注入 -->
    <property name="name" value="msf"/>
    <!-- 第二种，bean（对象）注入 -->
    <property name="address" ref="address"/>
    <!-- 数组注入 -->
    <property name="books">
        <array>
            <value>三国演义</value>
            <value>西游记</value>
            <value>水浒传</value>
            <value>红楼梦</value>
        </array>
    </property>
    <!-- list(集合)注入 -->
    <property name="hobbys">
        <list>
            <value>听歌</value>
            <value>写程序</value>
            <value>看电视剧</value>
        </list>
    </property>
    <!-- map注入 -->
    <property name="card">
        <map>
            <entry key="username" value="maming"/>
            <entry key="password" value="123456"/>
        </map>
    </property>
    <!-- set注入 -->
    <property name="games">
        <set>
            <value>原神</value>
            <value>部落冲突</value>
            <value>数独</value>
        </set>
    </property>
    <!-- null注入 -->
    <property name="wife">
        <null/>
    </property>
    <!-- properties注入 -->
    <property name="info">
        <props>
            <prop key="driver">mysql.jdbc.java.Driver</prop>
            <prop key="username">root</prop>
            <prop key="password">123456</prop>
        </props>
    </property>
</bean>

</beans>

 

 

4.测试类

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());
    }
}

 5.测试结果

 

 总结：spring为了给我们提供容器，把绝大部分的属性和对象类型装载了，十分方便的可以是我们完成注入，其中最常用的包括：普通注入，bean注入，数组注入，map注入

 

 

三.其它注入（p命名空间，c命名空间）

1.工具类

package top.lostyou.pojo;

public class user {
    private String name;
    private String sex;

    public user() {
    }

    public user(String name, String sex) {
        this.name = name;
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

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

 

2.spring的xml文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">


    <!-- P命名空间注入，可以直接注入属性的值，适用于无参构造，property  -->
<bean id="user" class="top.lostyou.pojo.user" p:name="jay周" p:sex="男"/>
    <!-- C命名空间注入，通过构造器注入，适用于有参构造，construct-args  -->
<bean id="user2" class="top.lostyou.pojo.user" c:name="程奕迅" c:sex="男"/>


</beans>

 

3.测试

    @Test
    public void tset1(){
        ClassPathXmlApplicationContext con = new ClassPathXmlApplicationContext("userBeans.xml");
        user user2 = con.getBean("user2", user.class);
        System.out.println(user2);
    }