Framework-zz-24-code-aa

  在Android平台上来实践上述范例的架构，兹建立Android开发项目(Project)如下： 

 

代码范例：Framework部分

// IPlugin.java接口

package Framework;

public interface IPlugin{

     boolean execute(int code, int arg);

}

 

// Plugin.java类

package Framework; 

public abstract class Plugin implements IPlugin{ 

        @Override public boolean execute(int code, int arg) {

                return onExecute(code, arg);

        }

        protected abstract boolean onExecute(int code, int arg);

} 

 

代码范例：App部分 

// UC1_Stub.java类

package Service;

import Framework.Plugin;

public abstract class UC1_Stub extends Plugin { 

        @Override protected boolean onExecute(int code, int arg) {

                if(code == 0)  play(arg);   //播放目前音樂

                else if(code == 1)  stop();  //停止播放

                return false;

        }

        public abstract void play(int arg);

        public abstract void stop();

} 

 

    这曹操类的主要任务是：

• 实现了天子的接口，也就是onExecute()抽象函数。
• 提供了自己的新接口，也就是play()和stop()两个函数。

 

// UC1_Plugin.java类

package Service;

import android.content.Context;

import android.media.MediaPlayer;

import android.util.Log;

public class UC1_Plugin extends UC1_Stub{

        private MediaPlayer mPlayer = null;

        private Context ctx;

       

        public UC1_Plugin(Context context){  ctx = context;     }

        @Override public void play(int arg) {

                if(mPlayer != null) return;

                mPlayer = MediaPlayer.create(ctx, arg);

                try { mPlayer.start();

                } catch (Exception e) { Log.e("StartPlay", "error: " + e.getMessage(), e);        }

        }

        @Override public void stop() {

                if (mPlayer != null) {

                 mPlayer.stop();    mPlayer.release();    mPlayer = null;

                }

  }} 

 

    这个App类(及子民类)只需要实现曹操的接口就行了，也就是实现play()和stop()函数。

 

// MainActivity.java类

package com.example.cx01;

import Framework.IPlugin;

import Service.UC1_Plugin;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.LinearLayout;

public class MainActivity extends Activity implements OnClickListener {

        private Button btn, btn2, btn3;

        private IPlugin ip; 

    public void onCreate(Bundle icicle) {

                super.onCreate(icicle);

                LinearLayout layout = new LinearLayout(this);

                layout.setOrientation(LinearLayout.VERTICAL);

                btn = new Button(this);      btn.setId(101);

                btn.setBackgroundResource(R.drawable.paint);

                btn.setText("play");         btn.setOnClickListener(this);

                LinearLayout.LayoutParams param =

                    new LinearLayout.LayoutParams(150, 75);

                param.topMargin = 10;      param.leftMargin = 10;

                layout.addView(btn, param);

                btn2 = new Button(this);     btn2.setId(102);

                btn2.setBackgroundResource(R.drawable.heart);

                btn2.setText("stop");        btn2.setOnClickListener(this);

                layout.addView(btn2, param);

                btn3 = new Button(this);     btn3.setId(103);

                btn3.setBackgroundResource(R.drawable.heart);

                btn3.setText("exit");         btn3.setOnClickListener(this);

                layout.addView(btn3, param);

                setContentView(layout);

                //-------------------------------

                ip = new UC1_Plugin(this);

                }

           public void onClick(View v) {

               switch(v.getId()){

                   case 101:  play(); break;

                   case 102:  stop(); break;

                   case 103:  stop();  finish();  break;

               }

             }

            public void play(){  ip.execute(0, R.raw.jp_song);       }

            public void stop(){  ip.execute(1, -1);  }

}