ApiDemos中的Android Widget例子解析

 今天繼續我們的android Widget開發之旅，看看android SDK中ApiDemos上的Widget例子，下面的代碼分為3個文件可以清楚的看到整個框架，主要是AppWidgetProvider類中的onUpdate、onDeleted、 onEnabled、onDisabled和updateAppWidget方法之間的狀態改變，使用Logcat仔細分析一個widget的生命周期。

package com.example.android.apis.appwidget;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.SystemClock;
import android.util.Log;
import android.widget.RemoteVIEws;

import Java.util.ArrayList;
import com.example.android.apis.R;

涉及到的文件有

ExampleAppWidgetConfigure.Java
ExampleBroadcastReceiver.Java
res/layout/appwidget_configure.XML
res/layout/appwidget_provider.XML
res/xml/appwidget_provider.XML


public class ExampleAppWidgetProvider extends AppWidgetProvider {

private static final String TAG = "ExampleAppWidgetProvider"; //logcat調試信息

public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
Log.d(TAG, "onUpdate");

// - 創建一個RemoteVIEws 對象
// - 設置RemoteVIEws 對象的文本
// - 告訴AppWidgetManager 顯示 vIEws對象給widget.

final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
int appWidgetId = appWidgetIds[i];
String titlePrefix = ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId);
updateAppWidget(context, appWidgetManager, appWidgetId, titlePrefix);
}
}

public void onDeleted(Context context, int[] appWidgetIds) {
Log.d(TAG, "onDeleted");
// 當用戶刪除Widget時觸發該
final int N = appWidgetIds.length;
for (int i=0; i<N; i++) {
ExampleAppWidgetConfigure.deleteTitlePref(context, appWidgetIds[i]);
}
}

public void onEnabled(Context context) {
Log.d(TAG, "onEnabled");
// 當widget創建時注冊TIMEZONE_CHANGED 和 TIME_CHANGED改變的廣播獲取這些時間和區域的改變事件

PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}

public void onDisabled(Context context) {

Log.d(TAG, "onDisabled");
Class clazz = ExampleBroadcastReceiver.class;
PackageManager pm = context.getPackageManager();
pm.setComponentEnabledSetting(
new ComponentName("com.example.android.apis", ".appwidget.ExampleBroadcastReceiver"),
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP);
}

static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
int appWidgetId, String titlePrefix) {
Log.d(TAG, "updateAppWidget appWidgetId=" + appWidgetId + " titlePrefix=" + titlePrefix);

CharSequence text = context.getString(R.string.appwidget_text_format,
ExampleAppWidgetConfigure.loadTitlePref(context, appWidgetId),
"0x" + Long.toHexString(SystemClock.elapsedRealtime()));

RemoteViews views = new RemoteVIEws(context.getPackageName(), R.layout.appwidget_provider);
views.setTextVIEwText(R.id.appwidget_text, text);

appWidgetManager.updateAppWidget(appWidgetId, vIEws);
}
}

package com.example.android.apis.appwidget;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.os.SystemClock;
import android.util.Log;
import android.widget.RemoteVIEws;

import Java.util.ArrayList;

import com.example.android.apis.R;

public class ExampleBroadcastReceiver extends BroadcastReceiver {

public void onReceive(Context context, Intent intent) {
Log.d("ExmampleBroadcastReceiver", "intent=" + intent);

// For our example, we'll also update all of the widgets when the timezone
// changes, or the user or network sets the time.
String action = intent.getAction();
if (action.equals(Intent.ACTION_TIMEZONE_CHANGED)
|| action.equals(Intent.ACTION_TIME_CHANGED)) {
AppWidgetManager gm = AppWidgetManager.getInstance(context);
ArrayList<Integer> appWidgetIds = new ArrayList();
ArrayList<String> texts = new ArrayList();

ExampleAppWidgetConfigure.loadAllTitlePrefs(context, appWidgetIds, texts);

final int N = appWidgetIds.size();
for (int i=0; i<N; i++) {
ExampleAppWidgetProvider.updateAppWidget(context, gm, appWidgetIds.get(i), texts.get(i));
}
}
}

}

package com.example.android.apis.appwidget;

import android.app.Activity;
import android.appwidget.AppWidgetManager;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.VIEw;
import android.widget.EditText;

import Java.util.ArrayList;

import com.example.android.apis.R;

public class ExampleAppWidgetConfigure extends Activity {
static final String TAG = "ExampleAppWidgetConfigure";

private static final String PREFS_NAME
= "com.example.android.apis.appwidget.ExampleAppWidgetProvider";
private static final String PREF_PREFIX_KEY = "prefix_";

int mAppWidgetId = AppWidgetManager.INVALID_APPWIDGET_ID;
EditText mAppWidgetPrefix;

public ExampleAppWidgetConfigure() {
super();
}

@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);

setResult(RESULT_CANCELED);

setContentVIEw(R.layout.appwidget_configure);

mAppWidgetPrefix = (EditText)findVIEwById(R.id.appwidget_prefix);

findVIEwById(R.id.save_button).setOnClickListener(mOnClickListener);

Intent intent = getIntent();
Bundle extras = intent.getExtras();
if (extras != null) {
mAppWidgetId = extras.getInt(
AppWidgetManager.EXTRA_APPWIDGET_ID, AppWidgetManager.INVALID_APPWIDGET_ID);
}

if (mAppWidgetId == AppWidgetManager.INVALID_APPWIDGET_ID) {
finish();
}

mAppWidgetPrefix.setText(loadTitlePref(ExampleAppWidgetConfigure.this, mAppWidgetId));
}

View.OnClickListener mOnClickListener = new VIEw.OnClickListener() {
public void onClick(VIEw v) {
final Context context = ExampleAppWidgetConfigure.this;

String titlePrefix = mAppWidgetPrefix.getText().toString();
saveTitlePref(context, mAppWidgetId, titlePrefix);

AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
ExampleAppWidgetProvider.updateAppWidget(context, appWidgetManager,
mAppWidgetId, titlePrefix);

Intent resultValue = new Intent();
resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId);
setResult(RESULT_OK, resultValue);
finish();
}
};

static void saveTitlePref(Context context, int appWidgetId, String text) {
SharedPreferences.Editor prefs = context.getSharedPreferences(PREFS_NAME, 0).edit();
prefs.putString(PREF_PREFIX_KEY + appWidgetId, text);
prefs.commit();
}

static String loadTitlePref(Context context, int appWidgetId) {
SharedPreferences prefs = context.getSharedPreferences(PREFS_NAME, 0);
String prefix = prefs.getString(PREF_PREFIX_KEY + appWidgetId, null);
if (prefix != null) {
return prefix;
} else {
return context.getString(R.string.appwidget_prefix_default);
}
}

static void deleteTitlePref(Context context, int appWidgetId) {
}

static void loadAllTitlePrefs(Context context, ArrayList<Integer> appWidgetIds,
ArrayList<String> texts) {
}
}