Ioc的推荐实现方式

Ioc的两种实现方式

 

Ioc（Inversion of Control）中文翻译为“控制反转”，Ioc的抽象概念是依赖关系转移，即“程序与实现必须依赖于抽象”。

 

控制反转最常见的实现方式就是依赖注入（Depedency Injection），依赖注入的含义是：保留抽象接口，让组件依赖抽象接口，当组件要与其他对象发生依赖关系时，通过抽象接口来注入依赖的实际对象。

 

在解说Ioc之前，先看一个设计的例子：
设计一个保存数据到软盘、USB设备的程序。

 

 

一、Ioc

 

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:13:32

 * 反面教材

 * 具体组件

 */

publicclass FloppyWriter {

    publicvoid saveToDevice() {

        System.out.println("调用FloppyWriter.saveToDevice()方法: 保存到了Floppy设备上!");

    }

}

 

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:14:25

 * 反面教材

 * 业务逻辑

 */

publicclass BusinessObject {

    private FloppyWriter floppyWriter;

    public FloppyWriter getFloppyWriter() {

        returnfloppyWriter;

    }

    publicvoid setFloppyWriter(FloppyWriter floppyWriter) {

        this.floppyWriter = floppyWriter;

    }

    publicvoid save() {

        System.out.println("----开始调用业务组件BusinessObject的save()方法....");

        floppyWriter.saveToDevice();

        System.out.println("----结束调用业务组件BusinessObject的save()方法....");

    }

}

 

 

 

 

 

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 1:15:17

 * 反面教材

 * 客户端

 */

publicclass Client {

    publicstaticvoid main(String args[]){

        //构造并配置业务逻辑对象

        BusinessObject businessObject=new BusinessObject();

        FloppyWriter floppyWriter=new FloppyWriter();

        businessObject.setFloppyWriter(floppyWriter);

        //调用业务逻辑方法

        businessObject.save();

    }

}

 

 

 

 

 

 

 

 

二、Iocsetter

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:38:32

 * 抽象组件接口

 */

publicinterface IDeviceWriter {

    publicvoid saveToDevice();

}

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:44:46

 * 组件,存储到软盘设备

 */

publicclass FloppyWriter implements IDeviceWriter{

    publicvoid saveToDevice() {

        System.out.println("调用FloppyWriter.saveToDevice()方法: 保存到了Floppy设备上!");

    }

}

 

 

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:44:57

 * 组件,存储到USB设备

 */

publicclass USBWriter implements IDeviceWriter{

    publicvoid saveToDevice() {

        System.out.println("调用USBWriter.saveToDevice()方法: 保存到了USB设备上!");

    }

}

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:40:24

 * 可重用的业务逻辑

 */

publicclass BusinessObject {

    private IDeviceWriter writer;

    public IDeviceWriter getWriter() {

        returnwriter;

    }

    publicvoid setWriter(IDeviceWriter writer) {

        this.writer = writer;

    }

    /**

     * 通用的保存业务方法

     */

    publicvoid save(){

        System.out.println("----开始调用业务组件BusinessObject的save()方法....");

        writer.saveToDevice();

        System.out.println("----结束调用业务组件BusinessObject的save()方法....");

    }

}

 

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:51:09

 * 客户端调用

 */

publicclass Client {

    publicstaticvoid main(String args[]){

        //构造两个组件对象

        IDeviceWriter floppyWriter=new FloppyWriter();

        IDeviceWriter usbWriter=new USBWriter();

        //构造两个业务对象

        BusinessObject businessObject1=new BusinessObject();

        BusinessObject businessObject2=new BusinessObject();

        //构造业务对象并执行通用的保存方法

        businessObject1.setWriter(floppyWriter);

        businessObject1.save();

        System.out.println();

        //构造业务对象并执行通用的保存方法

        businessObject2.setWriter(usbWriter);

        businessObject2.save();

    }

}

 

 

 

 

 

 

 

 

 

 

 

 

 

三、Iocconstructor

setterIDeviceWriterFloppyWriterUSBWriterBusinessObject和

 

 

 

 

 

 

 

Client类修改为：

 

 

 

 

 

 

 

 

 

  

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:32:03

 * 可重用的业务逻辑

 */

publicclass BusinessObject {

    private IDeviceWriter writer;

    public BusinessObject() {

    }

    public BusinessObject(IDeviceWriter writer) {

        this.writer = writer;

    }

    public IDeviceWriter getWriter() {

        returnwriter;

    }

    publicvoid setWriter(IDeviceWriter writer) {

        this.writer = writer;

    }

    /**

     * 通用的保存业务方法

     */

    publicvoid save() {

        System.out.println("----开始调用业务组件BusinessObject的save()方法....");

        writer.saveToDevice();

        System.out.println("----结束调用业务组件BusinessObject的save()方法....");

    }

}

 

 

 

 

 

/**

 * Created by IntelliJ IDEA.

 * User: leizhimin

 * Date: 2007-9-25

 * Time: 11:35:52

 * 客户端调用

 */

publicclass Client {

    publicstaticvoid main(String args[]){

        //构造两个组件对象

        IDeviceWriter floppyWriter=new FloppyWriter();

        IDeviceWriter usbWriter=new USBWriter();

        //构造两个业务对象

        BusinessObject businessObject1=new BusinessObject(floppyWriter);

        BusinessObject businessObject2=new BusinessObject(usbWriter);

        //执行业务逻辑对象的保存方法

        businessObject1.save();

        System.out.println();

        businessObject2.save();

   }

}

 

 

 

两种实现方式执行的结果相同：

 

----开始调用业务组件BusinessObject的save()方法....
调用FloppyWriter.saveToDevice()方法: 保存到了Floppy设备上!
----结束调用业务组件BusinessObject的save()方法....

 

----开始调用业务组件BusinessObject的save()方法....
调用USBWriter.saveToDevice()方法: 保存到了USB设备上!
----结束调用业务组件BusinessObject的save()方法....

 

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