阅读《Android 从入门到精通》（18）——拖动条

拖动条（SeekBar）

android.widget.ProgressBar;
android.widget.AbsSeekBar;
android.widget.SeekBar;

SeekBar 类方法

SeekBar 示例

完整工程：http://download.csdn.net/detail/sweetloveft/9419276

下面演示了 SeekBar 调节音量的功能，因为 SeekBar 继承于 ProgressBar，因此它也有 SetMax 等方法。

1.MainActivity.java

package com.sweetlover.activity;import com.sweetlover.audiorecord.R;import android.annotation.SuppressLint;import android.app.Activity;import android.media.AudioFormat;import android.media.AudioManager;import android.media.AudioRecord;import android.media.AudioTrack;import android.media.MediaRecorder;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.SeekBar;import android.widget.Toast;public class MainActivity extends Activity {Button recordButton, stopButton, exitButton;SeekBar skbVolume;boolean isRecording = false;static final int frequency = 44100;@SuppressWarnings("deprecation")static final int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;static final int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;int recBufSize, playBufSize;AudioRecord audioRecord;AudioTrack audioTrack;public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 用getMinBufferSize()方法得到采集数据所需要的最小缓冲区的大小recBufSize = AudioRecord.getMinBufferSize(frequency,channelConfiguration, audioEncoding);playBufSize = AudioTrack.getMinBufferSize(frequency,channelConfiguration, audioEncoding);// 实例化AudioRecord(声音来源，采样率，声道设置，采样声音编码，缓存大小）audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency,channelConfiguration, audioEncoding, recBufSize);audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, frequency,channelConfiguration, audioEncoding, playBufSize,AudioTrack.MODE_STREAM);recordButton = (Button) this.findViewById(R.id.recordbutton);stopButton = (Button) this.findViewById(R.id.stopbutton);exitButton = (Button) this.findViewById(R.id.exitbutton);recordButton.setOnClickListener(new ClickEvent());stopButton.setOnClickListener(new ClickEvent());exitButton.setOnClickListener(new ClickEvent());skbVolume = (SeekBar) this.findViewById(R.id.seekBarVolume);skbVolume.setMax(100);skbVolume.setProgress(70);// 设置声音大小audioTrack.setStereoVolume(0.7f, 0.7f);skbVolume.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {public void onStopTrackingTouch(SeekBar seekBar) {float vol = (float) (seekBar.getProgress())/ (float) (seekBar.getMax());audioTrack.setStereoVolume(vol, vol);}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}@Overridepublic void onProgressChanged(SeekBar seekBar,int progress, boolean fromUser) {// TODO Auto-generated method stub}});}protected void onDestroy() {super.onDestroy();// 杀死当前进程android.os.Process.killProcess(android.os.Process.myPid());}class ClickEvent implements View.OnClickListener {public void onClick(View v) {if (v == recordButton) {isRecording = true;new RecordPlayThread().start();} else if (v == stopButton) {isRecording = false;} else if (v == exitButton) {isRecording = false;MainActivity.this.finish();}}}class RecordPlayThread extends Thread {@SuppressLint("ShowToast")public void run() {try {// byte 文件来存储声音byte[] buffer = new byte[recBufSize];// 开始采集声音audioRecord.startRecording();// 播放声音audioTrack.play();while (isRecording) {// 从MIC存储到缓存区int bufferReadResult = audioRecord.read(buffer, 0,recBufSize);byte[] tmpBuf = new byte[bufferReadResult];System.arraycopy(buffer, 0, tmpBuf, 0, bufferReadResult);// 播放缓存区的数据audioTrack.write(tmpBuf, 0, tmpBuf.length);}audioTrack.stop();audioRecord.stop();} catch (Throwable t) {Toast.makeText(MainActivity.this, t.getMessage(), 1000);}}};}

2.activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/textViewOper"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/operator"        android:textAppearance="?android:attr/textAppearanceMedium" />    <Button        android:id="@+id/recordbutton"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/action" />    <Button        android:id="@+id/stopbutton"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/stop" />    <Button        android:id="@+id/exitbutton"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:text="@string/exit" />    <TextView        android:id="@+id/textViewAdjust"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/adjust"        android:textAppearance="?android:attr/textAppearanceMedium" />    <SeekBar        android:id="@+id/seekBarVolume"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

3.string.xml

<resources>    <string name="app_name">SeekBarDemo</string>    <string name="operator">录制操作</string>    <string name="action">开始边录边放</string>    <string name="stop">停止</string>    <string name="exit">退出</string>    <string name="adjust">音量调节</string></resources>

4.AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.sweetlover.audiorecord"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="19" />    <uses-permission android:name="android.permission.RECORD_AUDIO"/>    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity android:name="com.sweetlover.activity.MainActivity">            <intent-filter>                <action android:name="android.intent.action.MAIN"/>                <category android:name="android.intent.category.LAUNCHER"/>            </intent-filter>        </activity>    </application></manifest>