Spring多種方式實現依賴注入

         平常的Java開發中，程序員在某個類中需要依賴其它類的方法。

    通常是new一個依賴類再調用類實例的方法，這種開發存在的問題是new的類實例不好統一管理。

    Spring提出了依賴注入的思想，即依賴類不由程序員實例化，而是通過Spring容器幫我們new指定實例並且將實例注入到需要該對象的類中。

    依賴注入的另一種說法是"控制反轉"。通俗的理解是：平常我們new一個實例，這個實例的控制權是我們程序員。

    而控制反轉是指new實例工作不由我們程序員來做而是交給Spring容器來做。

1.Set注入

構建一個Student對象

package cn.happy.entity;

/**
 * Created by CKW on 2017/3/19.
 */
public class Student {
    private String sname;
    private Integer sage;

    public Integer getSage() {
        return sage;
    }

    public void setSage(Integer sage) {
        this.sage = sage;
    }


    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

}

在配置applicationContext.xml中：

    <!--set 注入  prototype  原型   singletion  單例-->
    <bean id="stu" class="cn.happy.entity.Student" scope="prototype">
        <property name="sname" value="張三"></property>
        <property name="sage" value="11"></property>
    </bean>

測試類中：

    //被Spring管理的bean默認都是單例的
    @Test
    public void myTest1(){
        //ac  就是Spring容器
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu=(Student) ac.getBean("stu");
        Student stu1=(Student) ac.getBean("stu");
        System.out.println(stu+"\n"+stu1);
    }

2.構造器注入

在對象中添加構造

配置中：

    <!--構造注入-->
    <bean id="car1" class="cn.happy.entity.Car">
        <property name="cname" value="圖驢子"></property>
    </bean>
    <bean id="stu1" class="cn.happy.entity.Student">
        <!--(2)創建構造器注入,如果主類有帶參的構造方法則需添加此配置-->
        <constructor-arg index="0" value="哇哈哈"></constructor-arg>
        <constructor-arg index="1" value="11"></constructor-arg>
        <constructor-arg index="2" ref="car1"></constructor-arg>
    </bean>

測試類：

    //構造注入  
    @Test
    public void myTest2(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu1=(Student) ac.getBean("stu1");
        Student stu2=(Student) ac.getBean("stu2");
        System.out.println("構造："+stu1);

    }

 

3.空間命名注入

<?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:aop="http://www.springframework.org/schema/aop" xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
">

    <!--命名空間P注入-->
    <bean id="car2" class="cn.happy.entity.Car">
        <property name="cname" value="毛驢"></property>
    </bean>
    <bean id="stu2" class="cn.happy.entity.Student" p:sname="李四" p:sage="18" p:car-ref="car2"></bean>

    //構造注入   命名空間注入
    @Test
    public void myTest2(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu1=(Student) ac.getBean("stu1");
        Student stu2=(Student) ac.getBean("stu2");
        System.out.println("構造："+stu1+"\n命名空間："+stu2);

    }

4.集合注入

    <!--list集合屬性注入-->
    <bean id="collection1" class="cn.happy.entity.MyCollection">
        <property name="list">
            <list>
                <value>哈哈</value>
                <value>呵呵</value>
                <value>嘿嘿</value>
            </list>
        </property>
    </bean>

    <!--set集合屬性注入-->
    <bean id="collection2" class="cn.happy.entity.MyCollection">
        <property name="set">
            <set>
                <value>哈哈</value>
                <value>呵呵</value>
                <value>嘿嘿</value>
            </set>
        </property>
    </bean>

    <!--Map集合屬性注入-->
    <bean id="collection3" class="cn.happy.entity.MyCollection">
        <property name="map">
            <map>
                <entry key="001">
                    <value>呵呵</value>
                </entry>
                <entry key="002">
                    <value>哈哈</value>
                </entry>
                <entry key="003">
                    <value>嘿嘿</value>
                </entry>
            </map>
        </property>
    </bean>

5.注解注入

package cn.happy.entity;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;

/**
 * Created by CKW on 2017/3/22.
 */
@Component("car") //不分層
/*@Repository  //dao層*/
/*@Service  //biz層*/
/*@Controller  //action層*/
public class Car {
    @Value("特斯拉")
    private String cname;
    
    @Override
    public String toString() {
        return getCname();
    }

    public Car() {
    }

    public Car(String cname) {
        this.cname = cname;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }
}

package cn.happy.entity;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;

/**
 * Created by CKW on 2017/3/22.
 */

@Component("student")
public class Student {
    @Value("撒打發")
    private String sname;
    @Value("20")
    private Integer sage;
    //jdk注解
//    @Resource
    @Autowired
    @Qualifier("car")
    private Car car;

    @Override
    public String toString() {
        return "name="+getSname()+",age="+getSage()+",car="+getCar();
    }

    public Car getCar() {
        return car;
    }

    public void setCar(Car car) {
        this.car = car;
    }


    public Student() {

    }

    public String getSname() {
        return sname;
    }

    public Student(String sname, Integer sage, Car car) {
        this.sname = sname;
        this.sage = sage;
        this.car = car;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public Integer getSage() {
        return sage;
    }

    public void setSage(Integer sage) {
        this.sage = sage;
    }
}

在配置applicationContext.xml中：

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
">

  <!--注解-->
    <!--配置包掃描器-->
    <context:component-scan base-package="cn.happy.entity"></context:component-scan>

測試類：

    //注解
    @Test
    public void myTest4(){
        ApplicationContext ac=new ClassPathXmlApplicationContext("applicationContext.xml");
        Student stu=(Student)ac.getBean("student");
        System.out.println(stu.getCar().getCname());
    }