Android-Widget桌面小组件

1，

掌握Widget的用：
Widget的用途，能够添加到手机桌面的程序

2，

Widget的特点和用法步骤：

特点：快捷，方便，个性化，可自定义功能，可及时控制更新Widget显示内容

3，

用法步骤流程图

1. 绘制Widget布局
2. 配置Widget的基本属性
3. 定义AppWidgetProvider
4. 提供Configuration Activity

4,

Android Widget实现一个基础的时钟功能

效果：

• 可以自动更新时间
• 可以添加和删除时钟Widget

5，

完整代码：

package com.example.widget;

import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.Context;
import android.content.Intent;
import android.widget.RemoteViews;

/**
 * 类似广播，是桌面小组件Widget的Provider
 */
public class widget extends AppWidgetProvider {

    static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                                int appWidgetId) {
        CharSequence widgetText = context.getString(R.string.appwidget_text);
        // Construct the RemoteViews object
        RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.widget);
        views.setTextViewText(R.id.tv, widgetText);
        // Instruct the widget manager to update the widget
        appWidgetManager.updateAppWidget(appWidgetId, views);
    }

    //刷新widget的时候执行，remoteView和AppWidgetManager
    @Override
    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
        // There may be multiple widgets active, so update all of them
        for (int appWidgetId : appWidgetIds) {
            updateAppWidget(context, appWidgetManager, appWidgetId);
        }
    }

    //第一个widget添加到屏幕上执行
    @Override
    public void onEnabled(Context context) {
        // Enter relevant functionality for when the first widget is created
        super.onEnabled(context);
        //启动Service
        context.startService(new Intent(context, TimerService.class));
    }

    //最后一个widget被从屏幕移除执行
    @Override
    public void onDisabled(Context context) {
        // Enter relevant functionality for when the last widget is disabled
        super.onDisabled(context);
        context.stopService(new Intent(context, TimerService.class));
    }

    //Widget被从屏幕移除
    @Override
    public void onDeleted(Context context, int[] appWidgetIds) {
        super.onDeleted(context, appWidgetIds);
    }

    //这个方法一般不会重写，无论操作中间（上面）的哪些方法，都会执行onReceive
    @Override
    public void onReceive(Context context, Intent intent) {
        super.onReceive(context, intent);
    }

}

　service:

package com.example.widget;

import android.app.Service;
import android.appwidget.AppWidgetManager;
import android.content.ComponentName;
import android.content.Intent;
import android.os.IBinder;
import android.widget.RemoteViews;

import androidx.annotation.Nullable;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;

public class TimerService extends Service {

    //java.util.Timer下的定时器
    private Timer timer;

    private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        timer = new Timer();
        timer.schedule(new TimerTask() {
            @Override
            public void run() {
                updateViews();
            }
        }, 0, 1000);
    }

    private void updateViews() {
        String time = sdf.format(new Date());
        RemoteViews rv = new RemoteViews(getPackageName(), R.layout.widget);
        rv.setTextViewText(R.id.tv, "黄朝阳666 ： " + time);
        AppWidgetManager manager = AppWidgetManager.getInstance(getApplicationContext());
        ComponentName cn = new ComponentName(getApplicationContext(), widget.class);
        manager.updateAppWidget(cn, rv);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        timer = null;
    }

}

6，

添加和删除天气Widget:

7，

8，