Spring基础04

依赖注入

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

构造器注入：
- 使用无参构造方法创建。
```
<bean id="hello" class="Hello">
</bean>
```

实体类中有有参构造方法，使用有参构造方法创建。

下标方式：

 <!-- 有参构造  下标方式-->
<bean id="hello" class="Hello">
   <constructor-arg index="0" value="hello"/>
</bean>

type方式（类型重复，不推荐）：

    <!-- 有参构造  type方式-->
<bean id="hello" class="Hello">
   <constructor-arg type="java.lang.String" value="hello"/>
</bean>

直接通过参数名：

<!-- 有参构造  通过参数名-->    
<bean id="hello" class="Hello">
  <!-- 如果参数是对象，就使用ref -->    
  <constructor-arg name="str" value="hello"/>
</bean>

Set方法注入：

编写实体类：

import java.util.*;

public class Student {

    private String name;
    private Address address;
    private List<String> hobbies;
    private String[] books;
    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 List<String> getHobbies() {
        return hobbies;
    }

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

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

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

    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 +
                ", hobbies=" + hobbies +
                ", books=" + Arrays.toString(books) +
                ", card=" + card +
                ", games=" + games +
                ", wife='" + wife + '\'' +
                ", info=" + info +
                '}';
    }
}

public class Address {
    
    public Address() {
    }

    public Address(String address) {
        this.address = 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 + '\'' +
                '}';
    }
}

编写Spring配置类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
		https://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="address" class="Address">
        <property name="address" value="苏州"/>
    </bean>

    <bean id="student" class="Student">
        <!-- 第一种：普通值注入，value-->
        <property name="name" value="张三"/>

        <!-- 第二种：bean注入，ref-->
        <property name="address" ref="address"/>

        <!-- 第三种：数组注入-->
        <property name="books">
            <array>
                <value>book1</value>
                <value>book2</value>
                <value>book3</value>
            </array>
        </property>

        <!-- 第四种：集合注入-->
        <property name="hobbies">
            <list>
                <value>singing</value>
                <value>coding</value>
                <value>playing basketball</value>
            </list>
        </property>

        <!-- 第五种：Map注入-->
        <property name="card">
            <map>
                <entry key="idCard" value="123456"/>
                <entry key="bankCard" value="123456"/>
            </map>
        </property>

        <!-- 第六种：Set注入-->
        <property name="games">
            <set>
                <value>LOL</value>
                <value>COC</value>
            </set>
        </property>

        <!-- 第七种：null注入-->
        <property name="wife">
           <null/>
        </property>

        <!-- 第八种：property注入-->
        <property name="info">
            <props>
                <prop key="学号">01</prop>
                <prop key="性别">男</prop>
            </props>
        </property>
    </bean>

</beans>

编写测试类：

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

public class Test {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Student student = (Student)context.getBean("student");
        Address address = (Address)context.getBean("address");
        System.out.println(student); // 输出Student{name='张三', address=Address{address='苏州'}, hobbies=[singing, coding, playing basketball], books=[book1, book2, book3], card={idCard=123456, bankCard=123456}, games=[LOL, COC], wife='null', info={学号=01, 性别=男}}
        System.out.println(address); // 输出Address{address='苏州'}
    }
}

拓展方法注入：P命名空间，C命名空间

Spring配置文件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
		https://www.springframework.org/schema/beans/spring-beans.xsd"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:c="http://www.springframework.org/schema/c">  <!-- 引入P命名空间，C命名空间约束 -->

    <!-- P命名空间注入。可以直接注入属性的值，property -->
    <bean id="address" class="Address" p:address="苏州">
    </bean>

    <!-- C命名空间注入。通过构造器注入， constructor-args-->
    <bean id="address1" class="Address" c:address="南京">
    </bean>

</beans>

编写测试类：

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

public class Test {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
        Address address = (Address)context.getBean("address");
        Address address1 = (Address)context.getBean("address1");
        System.out.println(address); //输出Address{address='苏州'}
        System.out.println(address1); //输Address{address='南京'}
    }
}

注意点：P命名空间和C命名空间不能直接使用，需要导入xml约束！

<?xml version="1.0" encoding="UTF-8"?>
<beans
xmlns:p="http://www.springframework.org/schema/p"
xmlns:c="http://www.springframework.org/schema/c">
</beans>

Spring基础04

Spring基础04

依赖注入

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