Android開發之ProgressDialog的使用

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ProgressDialog類似於ProgressBar類。

用於顯示一個過程，通常用於耗時操作。

幾個方法介紹：

1.setMax()

設定對話方塊中進度條的最大值。

2.setTile()

設定標題。

3.setProgressStyl()

設定對話方塊中進度條的樣式。例如：環形和水平。

參數：

ProgressDialog.STYLE_SPINNER    環形精度條

ProgressDialog.STYLE_HORIZONTAL     水平樣式的進度條

4.setMessage()

設定顯示的內容。

示範執行個體：

用於類比一個耗時的串連操作。

圖：

   

MainActivity.java

public class MainActivity extends Activity {Button button, button2;ProgressDialog progressDialog;public final static String ABOUT_SERVER = "Connect";// 資訊廣播接收BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context c, Intent intent) {String str = intent.getStringExtra("DATA");if (str.equals("0")) {progressDialog.setMessage("開始串連");} else if (str.equals("1")) {progressDialog.setMessage("串連完畢");} else {progressDialog.dismiss();}}};@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 註冊廣播監聽IntentFilter intentFilter = new IntentFilter();intentFilter.addAction(ABOUT_SERVER);registerReceiver(broadcastReceiver, intentFilter);}public void click(View v) {progressDialog = new ProgressDialog(MainActivity.this);progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);progressDialog.setMessage("準備建立串連·············");progressDialog.show();Intent intent = new Intent(MainActivity.this, ServerActivity.class);startService(intent);}}

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="${relativePackage}.${activityClass}" >    <Button        android:id="@+id/but"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:onClick="click"        android:text="點擊" />    </LinearLayout>

ServerActivity.java

public class ServerActivity extends Service {Handler handler = new Handler() {public void handleMessage(Message msg) {Intent intent = new Intent(MainActivity.ABOUT_SERVER);if (msg.what == 0) {intent.putExtra("DATA", "0");} else if (msg.what == 1) {intent.putExtra("DATA", "1");} else {intent.putExtra("DATA", "2");ServerActivity.this.stopSelf();}sendBroadcast(intent);};};@Overridepublic void onCreate() {super.onCreate();Thread thread = new Thread(new Runnable() {@Overridepublic void run() {// 要做的事try {for (int i = 0; i < 3; i++) {Thread.sleep(1000);Message message = new Message();message.what = i;handler.sendMessage(message);}} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}});thread.start();}@Overridepublic IBinder onBind(Intent arg0) {// TODO Auto-generated method stubreturn null;}}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.test"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="21" />            <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name" >                <service android:name="com.example.test.ServerActivity"></service>                <activity            android:name=".MainActivity"            android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

在做此執行個體時，遇到報錯，一大串紅字，最關鍵的一句話：

This message is already in use. 從網上查得：與handler發送Message相關，訊息已經在訊息佇列了，而且正被使用，而如果往同一個隊列發送相同的對象就會報錯。 造成這個錯誤是因為：

final Message message = new Message();Thread thread = new Thread(new Runnable() {@Overridepublic void run() {// 要做的事try {for (int i = 0; i < 3; i++) {Thread.sleep(1000);message.what = i;handler.sendMessage(message);}} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}});thread.start();

使用了同一個Message。用的API 19（4.4）與4.4模擬器，不顯示錯誤，只是卡住，用的API 19（4.4）與2.2模擬器就報錯了。

Android開發之ProgressDialog的使用