依赖注入（DI）

0.依赖注入

• 依赖注入（Dependency Injection,DI）
• 依赖：指Bean对象的创建依赖于容器。Bean对象的依赖资源
• 注入：指Bean对象所依赖的资源，由容器来设置和装配

1.set注入

要求被注入的属性，必须有set方法，set方法的方法名由set+属性首字母大写，如果属性是boolean类型，没有set方法，是is

项目目录

创建pojo类 

Address.java

public class Address {
    private String address;

    public String getAddress() {
        return address;
    }

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

Student.java

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;
    }

    public void show(){
        System.out.println("name="+name+",address="+address.getAddress()+",book=");
        for (String book:books){
            System.out.println(book);
        }
        System.out.println("爱好="+hobbys);
        System.out.println("card="+card);
        System.out.println("games="+games);
        System.out.println("wife="+wife);
        System.out.println("info="+info);
    }
}

 

添加配置文件bean.xml，配置头

<?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">


</beans>

 

1.常量注入

<bean id="student" class="com.dz.pojo.Student">
        <property name="name" value="dz"/>
</bean>

 

测试

public class applicationtest {
    @Test
    public void test01(){
        ClassPathXmlApplicationContext classPathXmlApplicationContext = new ClassPathXmlApplicationContext("beans.xml");
        Student student = (Student) classPathXmlApplicationContext.getBean("student");
        System.out.println(student.getName());
    }
}

 

2.Bean注入

Bean注入对象，这里的值是一个引用，ref

<!-- 这里的值是一个引用，ref-->
<property name="address" ref="addr"/>
<bean id="addr" class="com.dz.pojo.Address">
        <property name="address" value="北京"></property>
    </bean>

 

3.数组注入

<!-- 数组注入-->
        <property name="books">
            <array>
                <value>java1</value>
                <value>java2</value>
                <value>java3</value>
            </array>
        </property>

 

4.List注入

<!-- List注入-->
        <property name="hobbys">
            <list>
                <value>听歌</value>
                <value>看电影</value>
                <value>爬山</value>
            </list>
        </property>

 

5.Map注入

<!-- Map注入-->
        <property name="card">
            <map>
                <entry key="dz1" value="11111111111"></entry>
                <entry key="dz2" value="22222222222"></entry>
            </map>
        </property>

 

6.set注入

 <!-- set注入-->
        <property name="games">
            <set>
                <value>LOL</value>
                <value>DOTA</value>
            </set>
        </property>

 

7.Null注入

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

 

8.Properties注入

<!-- Properties注入-->
        <property name="info">
            <props>
                <prop key="学号">1212121</prop>
                <prop key="性别">男</prop>
                <prop key="姓名">dz</prop>
            </props>
        </property>

 

结果：