TeamProject/doc/精读代码（注释）/张嘉欣注释/ui/AlarmAlertActivity.java

/*
 * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.micode.notes.ui;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.DialogInterface.OnDismissListener;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.PowerManager;
import android.provider.Settings;
import android.view.Window;
import android.view.WindowManager;

import net.micode.notes.R;
import net.micode.notes.data.Notes;
import net.micode.notes.tool.DataUtils;

import java.io.IOException;


public class AlarmAlertActivity extends Activity implements OnClickListener, OnDismissListener {
    private long mNoteId;
    private String mSnippet;
    private static final int SNIPPET_PREW_MAX_LEN = 60;
    MediaPlayer mPlayer;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);//调用 super.onCreate(savedInstanceState) 方法来调用父类的 onCreate() 方法进行基本的活动初始化操作。
        requestWindowFeature(Window.FEATURE_NO_TITLE);//使用 requestWindowFeature(Window.FEATURE_NO_TITLE) 方法请求隐藏当前活动的标题栏。

        final Window win = getWindow();
        win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED);
        //通过 win.addFlags 方法添加标识，以在不打扰用户的情况下点亮屏幕和保持屏幕亮度。
        if (!isScreenOn()) {
            win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
                    | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON
                    | WindowManager.LayoutParams.FLAG_ALLOW_LOCK_WHILE_SCREEN_ON
                    | WindowManager.LayoutParams.FLAG_LAYOUT_INSET_DECOR);
        }

        Intent intent = getIntent();

        try {
            mNoteId = Long.valueOf(intent.getData().getPathSegments().get(1));
            mSnippet = DataUtils.getSnippetById(this.getContentResolver(), mNoteId);
            mSnippet = mSnippet.length() > SNIPPET_PREW_MAX_LEN ? mSnippet.substring(0,
                    SNIPPET_PREW_MAX_LEN) + getResources().getString(R.string.notelist_string_info)
                    : mSnippet;
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
            return;
        }
        /**
         * 然后，获取传入的 Intent 并通过 DataUtils.getSnippetById 方法获取传入笔记 ID 对应的摘要信息。如果摘要信息长度超过预设的最大长度，则截取前 SNIPPET_PREW_MAX_LEN 个字符，并添加 R.string.notelist_string_info 字符串信息。
         */

        mPlayer = new MediaPlayer();
        if (DataUtils.visibleInNoteDatabase(getContentResolver(), mNoteId, Notes.TYPE_NOTE)) {
            showActionDialog();
            playAlarmSound();
        } else {
            finish();
        }
        //创建一个 MediaPlayer 对象并调用 playAlarmSound 方法播放闹钟提醒铃声
    }
    /**
    *在创建活动时调用，用于执行初始化操作并显示AlertDialog对话框；
    */
    private boolean isScreenOn() {
        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        return pm.isScreenOn();
    }
    /**
     *用于检查屏幕是否开启；
     */
    private void playAlarmSound() {
        Uri url = RingtoneManager.getActualDefaultRingtoneUri(this, RingtoneManager.TYPE_ALARM);
    //默认的闹钟铃声 URI 地址。
        int silentModeStreams = Settings.System.getInt(getContentResolver(),
                Settings.System.MODE_RINGER_STREAMS_AFFECTED, 0);
        //获取当前静音模式下会受到影响的流类型，并将返回值赋值给 silentModeStreams 变量。
        if ((silentModeStreams & (1 << AudioManager.STREAM_ALARM)) != 0) {
            mPlayer.setAudioStreamType(silentModeStreams);
        } else {
            mPlayer.setAudioStreamType(AudioManager.STREAM_ALARM);
        }
        try {
            mPlayer.setDataSource(this, url);
            mPlayer.prepare();
            mPlayer.setLooping(true);
            mPlayer.start();
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        /**
         * 通过 mPlayer.setDataSource(this, url) 方法为 MediaPlayer 设置数据源，调用 mPlayer.prepare()方法进行准备操作，设置循环播放模式 mPlayer.setLooping(true) 并最终调用 mPlayer.start() 方法启动闹钟提醒铃声的播放。
         */
    }

    /**
     * 用于播放提醒铃声；
     */

    private void showActionDialog() {
        AlertDialog.Builder dialog = new AlertDialog.Builder(this);
        dialog.setTitle(R.string.app_name);
        dialog.setMessage(mSnippet);
        dialog.setPositiveButton(R.string.notealert_ok, this);
        if (isScreenOn()) {
            dialog.setNegativeButton(R.string.notealert_enter, this);
        }
        dialog.show().setOnDismissListener(this);
        //dialog.show().setOnDismissListener(this) 方法来显示该 AlertDialog 对话框，并将当前的 AlarmAlertActivity 对象作为监听器传入。当对话框被取消时，将会自动调用 onDismiss() 方法。
    }

    /**
     * 用于显示AlertDialog对话框；
     */

    public void onClick(DialogInterface dialog, int which) {
        switch (which) {
            case DialogInterface.BUTTON_NEGATIVE:
                Intent intent = new Intent(this, NoteEditActivity.class);
                intent.setAction(Intent.ACTION_VIEW);//使用 startActivity(intent) 方法启动 NoteEditActivity 活动，来编辑和查看该笔记。
                intent.putExtra(Intent.EXTRA_UID, mNoteId);
                startActivity(intent);
                break;
            default:
                break;
        }
    }

    /**
     * 处理AlertDialog中的按钮点击事件；
     */

    public void onDismiss(DialogInterface dialog) {
        stopAlarmSound();
        finish();
    }

    /**
     * 处理AlertDialog对话框取消事件；
     */

    private void stopAlarmSound() {
        if (mPlayer != null) {
            mPlayer.stop();
            mPlayer.release();
            mPlayer = null;
        }
    }
    /**
     * 用于停止播放提醒铃声。
     */
}