Spring IoC — 基于注解的配置

基于XML的配置，Bean定义信息和Bean实现类本身是分离的，而采用基于注解的配置方式时，Bean定义信息即通过在Bean实现类上标注注解实现。

@Component：对类进行标注，Spring容器自动将POJO转换为容器管理的Bean；

@Repository：用于对DAO实现类进行标注；

@Service：用于对Service实现类进行标注；

@Controller：用于对Controller实现类进行标注。

1、自动装配Bean：

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"

    xmlns:context="http://www.springframework.org/schema/context"

    xsi:schemaLocation="http://www.springframework.org/schema/beans

         http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

         http://www.springframework.org/schema/context

         http://www.springframework.org/schema/context/spring-context-3.0.xsd"

         >

   <context:component-scan base-package="com.ioc.ch4_10"/>

   <bean id="ls" class="com.ioc.ch4_10.LogonService"></bean>

   <!-- context:component-scan base-package="com.baobaotao" resource-pattern="anno/*.class"/ -->

   <!-- context:component-scan base-package="com.baobaotao">

       <context:include-filter type="regex" expression="com\.baobaotao\.anno.*Dao"/>

       <context:include-filter type="regex" expression="com\.baobaotao\.anno.*Service"/>

       <context:exclude-filter type="aspectj" expression="com.baobaotao..*Controller+"/>

   </context:component-scan -->

</beans>

LogDao类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

@Component("logDao")

public class LogDao {

}

UserDao_1类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

@Component("userDao_1")

//自动被Spring容器识别，Spring容器自动将POJO转换为容器管理的Bean

//等价于XML配置的<bean id="userDao_1" class="com.ioc.ch4_10.UserDao_1">

public class UserDao_1 {

    private String name;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public String toString() {

        return "UserDao_1{" +

                "name='" + name + '\t' +

                '}';

    }

    public UserDao_1() {

        System.out.println("userDao");

    }

}

UserDao_2类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

/**

 * Created by gao on 16-3-25.

 */

@Component("userDao_2")

public class UserDao_2 {

    private String name;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public String toString() {

        return "UserDao_2{" +

                "name='" + name + '\t' +

                '}';

    }

    public UserDao_2() {

        System.out.println("userDao_2");

    }

}

UserDao_3类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

/**

 * Created by gao on 16-3-25.

 */

@Component("userDao_3")

public class UserDao_3 {

    private String name;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public String toString() {

        return "UserDao_3{" +

                "name='" + name + '\t' +

                '}';

    }

    public UserDao_3() {

        System.out.println("userDao_3");

    }

}

LogonService类：

package com.ioc.ch4_10;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.stereotype.Service;

@Service

public class LogonService{

    //使用@Autowired进行自动注入

    @Autowired

    private LogDao logDao;

    @Autowired

    private UserDao_1 userDao1;

    //使用@Autowired的required属性，设置为false表示找不到匹配的Bean完成注入也不要抛出异常

    @Autowired(required = false)

    private UserDao_2 userDao_2;

    //使用@Qualifier指定注入Bean的名称

    @Autowired

    @Qualifier("userDao_3")

    private UserDao_3 userDao_3;

    public LogDao getLogDao() {

        return logDao;

    }

    public UserDao_1 getUserDao1() {

        return userDao1;

    }

    public UserDao_2 getUserDao2() {

        return userDao_2;

    }

    public UserDao_3 getUserDao3() {

        return userDao_3;

    }

    public void printSomething(){

        userDao1.setName("LogonService-userDao1");

        System.out.println(userDao1.toString());

        userDao_2.setName("LogonService-userDao2");

        System.out.println(userDao_2.toString());

        userDao_3.setName("LogonService-userDao3");

        System.out.println(userDao_3.toString());

    }

}

LoginService_2类：

package com.ioc.ch4_10;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.stereotype.Service;

/**

 * Created by gao on 16-3-25.

 */

@Service

public class LogonService_2 {

    private LogDao logDao;

    private UserDao_1 userDao_1;

    //自动将LogDao传给方法入参

    @Autowired

    public void setLogDao(LogDao logDao) {

        System.out.println("auto setlogdao");

        this.logDao = logDao;

    }

    //自动将名为userDao的Bean传给方法入参

    @Autowired

    public void setUserDao_1(UserDao_1 userDao_1) {

        System.out.println("auto setuserdao");

        this.userDao_1 = userDao_1;

    }

    @Autowired

    public void init(@Qualifier("userDao_1")UserDao_1 userDao,LogDao logDao){

        System.out.println("multi param inject");

        this.userDao_1 = userDao;

        this.logDao =logDao;

    }

}

测试类：

package com.ioc.ch4_10;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

/**

 * Created by gao on 16-3-25.

 */

public class Test {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:com\\ioc\\ch4_10\\beans.xml");

        LogonService ls = (LogonService) ctx.getBean("ls");

        ls.printSomething();

    }

}

输出结果：

userDao

userDao_2

userDao_3

multi param inject

auto setlogdao

auto setuserdao

UserDao_1{name='LogonService??userDao1}

UserDao_2{name='LogonService-userDao2 }

UserDao_3{name='LogonService-userDao3 }

2、对集合类进行标注

Plugin接口：

package com.ioc.ch4_10;

public interface Plugin {

}

onePlugin类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

@Component

public class OnePlugin implements Plugin {

}

twoPlugin类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

@Component

public class TwoPlugin implements Plugin {

}

MyComponent类：

package com.ioc.ch4_10;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Component;

import java.util.List;

@Component

public class MyComponent {

    //Spring会将容器中所有类型为Plugin的Bean注入到这个变量中

    @Autowired(required=false)

    private List<Plugin> plugins;

    public List<Plugin> getPlugins() {

        return plugins;

    }

}

mycomponent.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"

    xmlns:context="http://www.springframework.org/schema/context"

    xsi:schemaLocation="http://www.springframework.org/schema/beans

         http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

         http://www.springframework.org/schema/context

         http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="com.ioc.ch4_10">

        <context:include-filter type="aspectj" expression="com.baobaotao.anno.*Plugin+"/>

        <context:include-filter type="aspectj" expression="com.baobaotao.anno.MyComponent"/>

    </context:component-scan>

</beans>

MyComponentTest类：

package com.ioc.ch4_10;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MyComponentTest {

    public static void main(String[] args) throws Throwable {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:com\\ioc\\ch4_10\\mycomponent.xml");

        MyComponent myComponent = ctx.getBean(MyComponent.class);

        System.out.println("pulgin.size:"+myComponent.getPlugins().size());

    }

}

输出结果：

userDao

userDao_2

userDao_3

multi param inject

auto setlogdao

auto setuserdao

pulgin.size:2

3、Bean作用范围及生命过程方法

使用Scope指定作用范围

package com.ioc.ch4_10;

import org.springframework.beans.factory.config.BeanDefinition;

import org.springframework.context.annotation.Scope;

import org.springframework.stereotype.Component;

//指定Bean的作用范围为prototype

@Scope(BeanDefinition.SCOPE_PROTOTYPE)

@Component

public class Car {

    private int maxSpeed;

    public String brand;

    private double price;

    ......

}

Boss类：

package com.ioc.ch4_10;

import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;

import javax.annotation.PreDestroy;

import javax.annotation.Resource;

@Component

public class Boss {

    private Car car;

    public Boss(){

        System.out.println("construct...");

    }

    @Resource

    private void setCar(Car car){

        System.out.println("execute in setCar");

        this.car = car;

    }

    @PostConstruct

    private void init1(){

        System.out.println("execute in init1");

    }

    @PostConstruct

    private void init2(){

        System.out.println("execute in init1");

    }

    @PreDestroy

    private void destory1(){

        System.out.println("execute in destory1");

    }

    @PreDestroy

    private void destory2(){

        System.out.println("execute in destory2");

    }

}

测试类：

package com.ioc.ch4_10;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

/**

 * Created by gao on 16-3-25.

 */

public class Test {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("classpath:com\\ioc\\ch4_10\\beans.xml");

        Car car1 = (Car) ctx.getBean("car");

        Car car2 = (Car) ctx.getBean("car");

        System.out.println(car1 == car2); //false

        UserDao_2 ud1 = (UserDao_2) ctx.getBean("userDao_2");

        UserDao_2 ud2 = (UserDao_2) ctx.getBean("userDao_2");

        System.out.println(ud1 == ud2); //true

        ((ClassPathXmlApplicationContext)ctx).destroy();

    }

}

输出结果：

construct...

execute in setCar

execute in init1

false

true

execute in destory2

execute in destory1

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