spring学习4-DI

依赖注入（DI）

• 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 .

构造器注入

我们在之前的03已经详细讲过了

settet注入 (重点)

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 .

pojo类

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

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

public class Student {
    private String name;
    private Address address;
    private String[] books;
    private List<String> hobbies;
    private Map<String,String> card;
    private Set<String> games;
    private String wife;
    private Properties info;

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

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

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

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

    public void setHobbies(List<String> hobbies) {
        this.hobbies = hobbies;
    }

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

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

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

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

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
        https://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--常量注入-->
    <bean id="addr" class="com.cong.pojo.Address">
        <property name="address" value="耀华里***"/>
    </bean>
    <bean id="cong" class="com.cong.pojo.Student">
        <property name="name" value="cong"/>
        <!--bean注入，用ref-->
        <property name="address" ref="addr"/>
        <!--数组注入-->
        <property name="books">
            <array>
                <value>红楼梦</value>
                <value>水浒传</value>
                <value>西游记</value>
                <value>三国演义</value>
            </array>
        </property>
        <!--list注入-->
        <property name="hobbies">
            <list>
                <value>听歌</value>
                <value>码字</value>
                <value>看电影</value>
            </list>
        </property>
        <!--map注入-->
        <property name="card">
            <map>
                <entry key="idCard" value="4408*******************"/>
                <entry key="countCard" value="6201***************"/>
                <entry key="studentCard" value="201*****"/>
            </map>
        </property>
        <!--set注入-->
        <property name="games">
            <set>
                <value>lol</value>
                <value>魔兽</value>
                <value>刀塔</value>
            </set>
        </property>
        <!--null注入-->
        <property name="wife">
            <null/>
        </property>
        <!--properties注入-->
        <property name="info">
            <props>
                <prop key="姓名">rainbow</prop>
                <prop key="学号">2014****</prop>
                <prop key="性别">female</prop>
            </props>
        </property>
    </bean>
</beans>

测试类

public class TestDI {
    @Test
    public void test1(){
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        Student cong = (Student) context.getBean("cong");
        System.out.println(cong.toString());
    }
}

结果

Student{
    name='cong', 
    address=Address{address='耀华里***'}, 
    books=[红楼梦, 水浒传, 西游记, 三国演义], hobbys=[听歌, 码字, 看电影], 
    card={idCard=4408*******************, 
          countCard=6201***************, 
          studentCard=201*****}, 
    games=[lol, 魔兽, 刀塔], 
    wife='null', 
    info={学号=2014****, 性别=female, 姓名=rainbow}
}

扩展，命名空间注入

pojo类

package com.cong.pojo;

public class User {
    private String name;
    private int age;
    public User() {
    }
    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

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

    public void setAge(int age) {
        this.age = age;
    }

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

beans.xml

注意要导入约束

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

<?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
        https://www.springframework.org/schema/beans/spring-beans.xsd">
    <!--P(属性: properties)命名空间 , 属性依然要设置set方法-->
    <bean id="user" class="com.cong.pojo.User" p:name="cong" p:age="3"/>
    <!--C(构造: Constructor)命名空间 , 属性依然要设置set方法-->
    <bean id="user2" class="com.cong.pojo.User" c:name ="cong2" c:age="3"/>
</beans>

测试类

    @Test
    public void test2(){
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        User user = (User) context.getBean("user");
        System.out.println(user.toString());
        User user2 = (User) context.getBean("user2");
        System.out.println(user2.toString());
    }