ApiDemos中的Android Widget例子解析 Android开发技术

   今天继续我们的Android Widget开发之旅，看看Android SDK中ApiDemos上的Widget例子，下面的代码分为3个文件可以清楚的看到整个框架，主要是AppWidgetProvider类中的onUpdate、onDeleted、 onEnabled、onDisabled和updateAppWidget方法之间的状态改变，使用Logcat仔细分析一个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调试信息

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

        //   – 创建一个RemoteViews 对象
        //   – 设置RemoteViews 对象的文本
        //   – 告诉AppWidgetManager 显示 views对象给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");
        // 当用户删除Widget时触发该
        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");
        // 当widget创建时注册TIMEZONE_CHANGED 和 TIME_CHANGED改变的广播获取这些时间和区域的改变事件

        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) {
    }
}