#眉標=Mobile、Android、ANR
#副標=剖析Android平台手機程式開發
#大標=解決Android手機發生ANR問題的技巧
#作者=文／圖 花繼利


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程式1
package example.demo;
import example.demo.tools.Utilities;
import example.demo.perfectprogress.CallbackHandler;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import demo.ui.UserLogin;
public class ProgressDemo extends Activity
{
  private String realm = null;
  private String altMsg = null;
  private Handler handler = new Handler();
  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
	super.onCreate(savedInstanceState);
	super.setContentView(R.layout.main);　 // 顯示來自layout資源設定的UI內容
	this.initNetworkResource();　// 呼叫initNetworkResource() 初始化網路資源
  }
  private void initNetworkResource()
  {     // 呼叫startCallbackHandler() 顯示進度對話視窗(計時30秒，計時截止警告訊息)
  Utilities.startCallbackHandler(this, 30000, CallbackHandler. WARNING_MSG);
   new Thread()
   {
  	public void run()
	{ // 呼叫isNetworkStarted() 在執行緒中檢驗網路資源是否正常
	 if (ProgressDemo.this.isNetworkStarted())
	 {　 
	  ProgressDemo.this.getRealm();
	  if (ProgressDemo.this.realm == null) // 警告未取得伺服器回應
	  ProgressDemo.this.alertWarning("伺服器沒有回應！");
	 else
	{ // 退出進度對話視窗
	 Utilities.stopCallbackHandler();　
	 // 開啟HelloWorld sub-Activity
	 ProgressDemo.this.startActivity(new 
　　　Intent(ProgressDemo.this, HelloWorld.class));
	}
  }  // 警告無網路設備
	else　ProgressDemo.this.alertWarning("請設定網路設備！");
	Utilities.stopCallbackHandler();　// 退出進度對話視窗
 }
}.start();
}
 public void alertWarning(String altMsg) 
 {
  this.altMsg = altMsg;
  this.handler.post(new Runnable()　// 在執行緒中透過Handler來顯示使用者介面
  {
	@Override
	public void run()
	{// 顯示警告對話視窗
	 Utilities.alertDialog(ProgressDemo.this, ProgressDemo.this.altMsg, 
     true);
	}
  });
 }
private String getRealm()
{
 //模擬向網路伺服器取得網域值
  return this.realm;
}

private boolean isNetworkStarted()
{
//模擬網路設備連線檢查
  return true;
}
}

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程式2
package example.demo.tools;
import example.demo.perfectprogress.CallbackHandler;
import android.content.DialogInterface.OnClickListener;
import android.content.*;
import android.app.AlertDialog;
public class Utilities
{
  private static CallbackHandler callbackHandler = null;
  public static CallbackHandler startCallbackHandler(Context context, long time, int finishHandleMsg)
  {
  callbackHandler = new CallbackHandler(context, "正在進行運算中。。。",
  finishHandleMsg); //初始化設定進度對話視窗處理器
  callbackHandler.setupCallBackTimer(time); //初始化設定計時器 
  callbackHandler.sendMessage(callbackHandler.obtainMessage(CallbackHandler.
  START_PROGRESS_BAR));
  return callbackHandler;
  }
 public static void stopCallbackHandler()
 {
  if (callbackHandler != null)
　callbackHandler.sendMessage(callbackHandler.obtainMessage(CallbackHandler.
　 STOP_PROGRESS_BAR));
  callbackHandler = null;
 }
 public static AlertDialog alertDialog(Context context, String msg, Boolean enableDismissButton) //建構警告對話視窗
 {
  AlertDialog alertDlg = new AlertDialog.Builder(context).create();
  alertDlg.setMessage(msg);　 //設定警告對話視窗主體內容
  alertDlg.setTitle(“警告”);　 //設定警告對話視窗標題
  alertDlg.setIcon(android.R.drawable.ic_dialog_alert);　// 設定警告對話視窗圖示
  alertDlg.setCancelable(false);　 //不允許強制退出警告對話視窗
   if (enableDismissButton)　 //顯示退出警告對話視窗的按鈕
    alertDlg.setButton(“確定”, new OnClickListener()
    {
     @Override
     public void onClick(DialogInterface dialog, int which)
     {
     dialog.dismiss();//退出警告對話視窗
     }
    });
    alertDlg.show(); //開始顯示警告對話視窗
    return alertDlg;
	}
} 

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==========<BOX>============
程式3

package example.demo.perfectprogress;
import example.demo.ProgressDemo;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.*;
import android.util.Log;
public class CallbackHandler extends Handler
{
  private final String TAG = this.getClass().getSimpleName();	
  public static final int EMPTY_MSG = -1; 
  public static final int WARNING_MSG = 0; 
  public static final int START_PROGRESS_BAR = 98;
  public static final int STOP_PROGRESS_BAR = 99; 
  private static final long TICKER = 1000;
  private int finishHandleMsg = EMPTY_MSG;
  private Context context = null;
  private String progressLabel = null;
  private ProgressDialog progDlg = null;
  private CountDownTimer callbackTimer = null;
  public CallbackHandler(Context context, String label, int finishHandleMsg)
  {
	this.context = context;
	this.progressLabel = label; // 設定進度指示對話視窗主體內容
	this.finishHandleMsg = finishHandleMsg; // 超過期限時送給Handler處理的訊息
	this.progDlg = new ProgressDialog(context); // 建立進度指示對話視窗
  }
  @Override
  public void handleMessage(Message msg)　// 依據所接收到的handler訊息進行處理
  {
    switch (msg.what)
	{
	case START_PROGRESS_BAR:
Log.i(TAG, "CallbackHandler process : msg.what = START_PROGRESS_BAR !!!");
	 this.progDlg.setTitle("請稍候片刻"); //設定進度指示對話視窗標題
	 this.progDlg.setIndeterminate(true);
	 this.progDlg.setCancelable(false); //不允許強制退出進度指示對話視窗
	 this.progDlg.show();//開始顯示進度指示對話視窗
	 if (this.callbackTimer != null)this.callbackTimer.start();//開始計時
	 break;
	  case STOP_PROGRESS_BAR:
Log.i(TAG, "CallbackHandler process : msg.what = STOP_PROGRESS_BAR !!!");
	 if (this.callbackTimer != null)  this.callbackTimer.cancel();//取消計時
	 this.progDlg.dismiss();//退出進度指示對話視窗的顯示
	 break;				
	  case WARNING_MSG: //送出警告對話視窗
	  ((ProgressDemo) this.context).alertWarning(“請設定網路設備！”);
	 break;
default:
//送給Handler請求退出進度指示對話視窗顯示處理的訊息  
this.sendMessage(CallbackHandler.this.obtainMessage(
STOP_PROGRESS_BAR));
}
super.handleMessage(msg);
}
  public void setupCallBackTimer(long time)
  {
   Log.d(TAG, "Setup CallbackHandler.class Timer ..."); 
   this.callbackTimer = new CountDownTimer(time, CallbackHandler.TICKER)
   {//初始化設定計時器
	public void onTick(long millisUntilFinished)
	{//每隔millisUntilFinished毫秒，更新進度指示對話視窗主體內容顯示
CallbackHandler.this.progDlg.setMessage(CallbackHandler.this.
progressLabel + " ( " + millisUntilFinished / 1000 + " )");
  }
  public void onFinish()
  {// 計時截止時，退出進度指示對話視窗顯示
   CallbackHandler.this.sendMessage(CallbackHandler.this.
    obtainMessage(STOP_PROGRESS_BAR));
  if (CallbackHandler.this.finishHandleMsg != CallbackHandler.EMPTY_MSG)
{//送給Handler請求處理的訊息	            CallbackHandler.this.sendMessage(CallbackHandler.this.
obtainMessage(CallbackHandler.this.finishHandleMsg));
}
}
};
}
}
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參考文獻
●《Android應用框架原理與程式設計36技》，第一章認識應用框架。
●《Unlocking Android,A Developer’s Guide》，Chapter 1:Targeting Android。
●《Professional Android Application Development》，Chapter 1:Hello, Android。
●《Good Android SDK開發範例大全》，第三章使用者人機介面。
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