本文实例讲述了Android实现静态广播监听器的方法。分享给大家供大家参考。具体实现方法如下:
package lab.sodino.broadcastaction; import lab.sodino.util.DatabaseOpenHelper; import lab.sodino.util.SodinoOut; import android.app.Activity; import android.content.ContentResolver; import android.database.ContentObserver; import android.database.Cursor; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.ViewGroup.LayoutParams; import android.widget.Button; import android.widget.LinearLayout; import android.widget.ScrollView; import android.widget.TextView; /** * 本例子将记录可静态注册的广播被监听到的频度。<br/> * 1.建立一表{ACTION_NAME广播名称,LAST_TIME最近一次发生时间,COUNT总共记录到的次数}<br/> * 2.在ActionReceiver中监听广播,并记录。 <br/> * 3.在DBContentProvider中更新数据库记录<br/> * 4.在BroadcastActionRecordAct.ActionDBObserver中监听数据库的变化, * 并使用Handler机制将最新情况显示在txtInfo上。<br/> * 5.DatabaseOpenHelper将实现基本的数据库操作。 * * @author Sodino */ public class BroadcastActionRecordAct extends Activity implements Button.OnClickListener { private TextView txtInfo; private DatabaseOpenHelper dbHelper; private Button btnRefresh; /** clear功能未完善。 */ private Button btnClear; private Handler handler = new Handler() { public void handleMessage(Message msg) { String info = (String) msg.obj; txtInfo.setText(info); } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); LayoutParams lpPC = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT); LayoutParams lpCC = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); btnRefresh = new Button(this); btnRefresh.setLayoutParams(lpCC); btnRefresh.setText("Refresh"); btnRefresh.setOnClickListener(this); btnClear = new Button(this); btnClear.setLayoutParams(lpCC); btnClear.setText("ClearTable"); btnClear.setOnClickListener(this); LinearLayout subLayout = new LinearLayout(this); subLayout.setLayoutParams(lpPC); subLayout.setOrientation(LinearLayout.HORIZONTAL); subLayout.addView(btnRefresh); subLayout.addView(btnClear); txtInfo = new TextView(this); txtInfo.setLayoutParams(lpPC); txtInfo.setTextColor(0xff0000ff); txtInfo.setBackgroundColor(0xffffffff); txtInfo.setText("Starting..."); txtInfo.setTextSize(15); ScrollView scrollView = new ScrollView(this); scrollView.setLayoutParams(lpPC); scrollView.addView(txtInfo); LinearLayout mainLayout = new LinearLayout(this); mainLayout.setLayoutParams(lpPC); mainLayout.setOrientation(LinearLayout.VERTICAL); mainLayout.addView(subLayout); mainLayout.addView(scrollView); setContentView(mainLayout); dbHelper = new DatabaseOpenHelper(this); ContentResolver contentResolver = getContentResolver(); contentResolver.registerContentObserver(DBContentProvider.CONTENT_URI, false, new ActionDBObserver(handler)); } public void onClick(View view) { if (view == btnRefresh) { refreshRecord(); } else if (view == btnClear) { clearRecord(); } } public void refreshRecord() { dbHelper.openReadableDatabase(); String info = dbHelper.getAllOrderedList(DatabaseOpenHelper.DESC); dbHelper.close(); if (info != null) { txtInfo.setText(info); } else { txtInfo.setText("<NULL/>"); } dbHelper.close(); } public void clearRecord() { dbHelper.openWritableDatabase(); dbHelper.clearRecord(); dbHelper.close(); } private class ActionDBObserver extends ContentObserver { private Handler handler; public ActionDBObserver(Handler handler) { super(handler); this.handler = handler; } public void onChange(boolean selfChange) { super.onChange(selfChange); String[] projection = { "ACTION_NAME", "LAST_TIME", "COUNT" }; // String selection = "select * from ActionTable"; String sortOrder = "COUNT DESC"; // dbHelper.openReadableDatabase(); // Cursor cursor = dbHelper.query(projection, null, null, // sortOrder); Cursor cursor = managedQuery(DBContentProvider.CONTENT_URI, projection, null, null, sortOrder); String info = ""; String line = ""; int actionIdx = 0; int timeIdx = 1; int countIdx = 2; while (cursor.moveToNext()) { line += cursor.getString(actionIdx) + " "; line += cursor.getString(timeIdx) + " "; line += cursor.getString(countIdx) + "/n"; info += line; line = ""; } Message msg = new Message(); msg.obj = info; handler.sendMessage(msg); cursor.close(); // dbHelper.close(); SodinoOut.out("Database does changed!!!"); } public boolean deliverSelfNotifications() { return super.deliverSelfNotifications(); } } }
希望本文所述对大家的Android程序设计有所帮助。