Android学习笔记_25_多媒体之在线播放器

一、布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#FFFFFF"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/filename" />

    <EditText
        android:id="@+id/filename"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="11.RMVB" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <ImageButton
            android:id="@+id/play"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/play" />

        <ImageButton
            android:id="@+id/pause"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/pause" />

        <ImageButton
            android:id="@+id/reset"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/reset" />

        <ImageButton
            android:id="@+id/stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/stop" />
    </LinearLayout>

    <SurfaceView
        android:id="@+id/surfaceView"
        android:layout_width="fill_parent"
        android:layout_height="240dip" />

</LinearLayout>

二、代码实现：

package com.example.video;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import android.R.integer;
import android.app.Activity;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.Toast;

public class MainActivity extends Activity {
    private static final String TAG = "VideoActivity";
    private EditText filenameText;
    private SurfaceView surfaceView;
    private MediaPlayer mediaPlayer;
    private String filename;// 当前播放文件的名称
    private int position;// 记录播放位置
    private boolean pause=false;//是否被暂停
    private  File file;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.mediaPlayer = new MediaPlayer();
        this.filenameText = (EditText) this.findViewById(R.id.filename);
        this.surfaceView = (SurfaceView) this.findViewById(R.id.surfaceView);
        ImageButton playButton = (ImageButton) this.findViewById(R.id.play);
        ImageButton pauseButton = (ImageButton) this.findViewById(R.id.pause);
        ImageButton resetButton = (ImageButton) this.findViewById(R.id.reset);
        ImageButton stopButton = (ImageButton) this.findViewById(R.id.stop);

        ButtonClickListener listener = new ButtonClickListener();
        playButton.setOnClickListener(listener);
        pauseButton.setOnClickListener(listener);
        resetButton.setOnClickListener(listener);
        stopButton.setOnClickListener(listener);

        /* 下面设置Surface不维护自己的缓冲区，而是等待屏幕的渲染引擎将内容推送到用户面前 */
        this.surfaceView.getHolder().setType(
                SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        this.surfaceView.getHolder().setFixedSize(176, 144);// 设置分辨率
        //让屏幕高亮，不要锁频
        this.surfaceView.getHolder().setKeepScreenOn(true);
        this.surfaceView.getHolder().addCallback(new SurfaceListener());
    }

    private class ButtonClickListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            try {
                switch (v.getId()) {
                case R.id.play:// 来自播放按钮
                    filename = filenameText.getText().toString();
                    file=new File("/storage/sdcard0/Music",filename);
                    if (file.exists()) {                        
                        play(0);
                    }else {
                        Toast.makeText(getApplicationContext(), "文件不存在", Toast.LENGTH_LONG).show();
                    }
                    break;

                case R.id.pause:// 来自暂停按钮
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.pause();
                        pause=true;
                    } else {
                        if (pause) {
                            mediaPlayer.start();
                            pause=false;
                        }
                    }
                    break;

                case R.id.reset:// 来自重新播放按钮
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.seekTo(0);
                    }else {
                        if(file!=null){
                            play(0);
                        }
                    }
                    break;
                case R.id.stop:// 来自停止按钮
                    if (mediaPlayer.isPlaying())
                        mediaPlayer.stop();
                    break;
                }
            } catch (Exception e) {
                Log.e(TAG, e.toString());
            }
        }
    }

    /**
     * 播放视频
     */
    private void play(int position) throws IOException {
        mediaPlayer.reset();
        //mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mediaPlayer.setDataSource(file.getAbsolutePath());// 设置需要播放的视频
        mediaPlayer.setDisplay(surfaceView.getHolder());// 把视频画面输出到SurfaceView
        mediaPlayer.prepare();//进行缓冲处理，完成之后播放
        mediaPlayer.setOnPreparedListener(new PrepareListener(position));
        
    }
    private final class PrepareListener implements OnPreparedListener{
        private int position;
        public PrepareListener(int position) {
            this.position=position;
        }

        //当缓冲完成之后就会调用onPrepared方法
        @Override
        public void onPrepared(MediaPlayer mp) {
            mediaPlayer.start();//播放
            if (position>0) {
                mediaPlayer.seekTo(position);
            }
        }
    }

    private class SurfaceListener implements SurfaceHolder.Callback {
        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width,
                int height) {
        }

        //当画面再次回到前台时调用
        @Override
        public void surfaceCreated(SurfaceHolder holder) {// 方法在onResume()后被调用
            Log.i(TAG, "surfaceCreated()");
            if (position > 0 && filename != null) {
                try {
                    play(position);
                    position = 0;
                } catch (Exception e) {
                    Log.e(TAG, e.toString());
                }
            }
        }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            if (mediaPlayer.isPlaying()) {
                position = mediaPlayer.getCurrentPosition();// 得到播放位置
                mediaPlayer.stop();
            }
            Log.i(TAG, "surfaceDestroyed()");
        }
    }

    @Override
    protected void onDestroy() {
        if (mediaPlayer.isPlaying())
            mediaPlayer.stop();
        mediaPlayer.release();
        super.onDestroy();
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}