JNI在Android開發中的應用之--用AudioRecord錄音，用AudioTrack播放聲

[java]
下面是主Activity. 
 
package com.example.hellojni; 
 
import android.app.Activity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
 
import java.io.BufferedOutputStream; 
import java.io.File; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
 
 
public class HelloJni extends Activity 
{ 
 
    Button startRecord; 
    Button stopRecord; 
    Button play; 
    static BufferedOutputStream bos; 
 
    static { 
        System.loadLibrary("hello-jni"); 
    } 
 
 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) 
    { 
        super.onCreate(savedInstanceState); 
 
        setContentView(R.layout.main); 
 
        startRecord = (Button)findViewById(R.id.start); 
        stopRecord = (Button)findViewById(R.id.stop); 
        play  =(Button)findViewById(R.id.play); 
 
 
        startRecord.setOnClickListener(new OnClickListener() { 
            @Override 
            public void onClick(View v) { 
                new Thread(){ 
                    public void run(){ 
 
                        initOutputStream(); 
 
                        startRecord(); 
                    } 
                }.start(); 
 
            } 
        }); 
 
 
        stopRecord.setOnClickListener(new OnClickListener() { 
            @Override 
            public void onClick(View v) { 
                new Thread(){ 
                    public void run(){ 
                        stopRecord(); 
 
                        try{ 
                            Thread.sleep(1000*2); 
                            if(bos!=null){ 
                                try { 
                                    bos.close(); 
                                } catch (IOException e) { 
                                    // TODO Auto-generated catch block 
                                    e.printStackTrace(); 
                                } 
                            } 
                        }catch(Exception e){ 
 
                        } 
                    } 
                }.start(); 
 
            } 
        }); 
 
        play.setOnClickListener(new OnClickListener() { 
            @Override 
            public void onClick(View v) { 
                new Thread(){public void run(){play();}}.start(); 
            } 
        }); 
 
    } 
 
 
    public void initOutputStream(){ 
            File file = new File("/sdcard/temp.pcm"); 
            try { 
                bos = new BufferedOutputStream(new FileOutputStream(file)); 
            } catch (FileNotFoundException e) { 
                e.printStackTrace(); 
            } 
 
    } 
    public static void receiveAudioData(byte[] data,int size){ 
            try { 
                bos.write(data); 
                bos.flush(); 
            } catch (IOException e) { 
                e.printStackTrace(); 
            } 
    } 
 
    public native void startRecord(); 
    public native void stopRecord(); 
    public native void play(); 
 
 
} 

布局文件：

[html] 
<?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:orientation="vertical" > 
 
    <Button android:id="@+id/start" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="用AudioRecord錄音"/> 
 
    <Button android:id="@+id/stop" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="停止錄音"/> 
 
    <Button android:id="@+id/play" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="用AudioTrack播放"/> 
 
 
    <Button android:id="@+id/stop" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="底層在錄音哦，請點擊我，我反應很快的耶，沒有阻塞UI線程"/> 
 
</LinearLayout> 
接下來是hello-jni.c:

[cpp] 
#include <malloc.h> 
#include <string.h> 
#include <jni.h> 
#include <android/log.h> 
#include <stdio.h> 
 
static JNIEnv* (*jni_env); 
static jbyteArray buffer; 
static jobject audio_track; 
static jint buffer_size; 
static jmethodID method_write; 
 
#define AUDIO_SOURCE_VOICE_COMMUNICATION (7) 
#define AUDIO_SOURCE_MIC (1) 
#define SAMPLE_RATE_IN_HZ (11025) 
#define CHANNEL_CONFIGURATION_MONO (16) 
#define ENCODING_PCM_16BIT (2) 
 
#define LOG_TAG "test" 
#define LOGI(f,v)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,f,v) 
#define LOGI2(a)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,a) 
 
 
static int run= 1; 
void  Java_com_example_hellojni_HelloJni_stopRecord(JNIEnv* jni_env, 
        jobject thiz){ 
    run = 0; 
} 
void  Java_com_example_hellojni_HelloJni_startRecord(JNIEnv* jni_env, 
        jobject thiz){ 
 
    jclass audio_record_class =(*jni_env)->FindClass(jni_env,"android/media/AudioRecord"); 
 
    jmethodID constructor_id = (*jni_env)->GetMethodID(jni_env,audio_record_class, "<init>", 
                "(IIIII)V"); 
 
    jmethodID min_buff_size_id = (*jni_env)->GetStaticMethodID(jni_env,audio_record_class, 
                "getMinBufferSize", "(III)I"); 
 
    jint buff_size 
                = (*jni_env)->CallStaticIntMethod(jni_env,audio_record_class, 
                        min_buff_size_id, 
                        SAMPLE_RATE_IN_HZ, 
                        CHANNEL_CONFIGURATION_MONO, 
                        ENCODING_PCM_16BIT); 
 
    jobject audioRecord = (*jni_env)->NewObject(jni_env,audio_record_class, constructor_id, 
    //          AUDIO_SOURCE_MIC, 
                AUDIO_SOURCE_VOICE_COMMUNICATION, 
                SAMPLE_RATE_IN_HZ, 
                CHANNEL_CONFIGURATION_MONO, 
                ENCODING_PCM_16BIT, 
                buff_size); 
 
    LOGI2("startRecording"); 
    jmethodID record_id = (*jni_env)->GetMethodID(jni_env,audio_record_class, "startRecording", 
                "()V"); 
 
    //start recording 
    (*jni_env)->CallVoidMethod(jni_env,audioRecord, record_id); 
    LOGI2("after call startRecording"); 
    jmethodID read_id = (*jni_env)->GetMethodID(jni_env,audio_record_class, "read", "([BII)I"); 
 
 
    int nread = 0; 
    int blockSize = 100; 
    jbyteArray read_buff = (*jni_env)->NewByteArray(jni_env,blockSize); 
    jbyteArray aes_bytes = (*jni_env)->NewByteArray(jni_env,blockSize); 
 
    jbyte* audio_bytes; 
 
    FILE* fp = fopen("/sdcard/temp.pcm","ab"); 
    LOGI2("after fopen"); 
 
    // 
    jclass HelloJniCls =(*jni_env)->FindClass(jni_env,"com/example/hellojni/HelloJni"); 
    jmethodID receiveAudioData = (*jni_env)->GetStaticMethodID(jni_env,HelloJniCls,"receiveAudioData", 
            "([BI)V"); 
 
    while (run) { 
 
            nread = (*jni_env)->CallIntMethod(jni_env,audioRecord,read_id, read_buff, 0, blockSize); 
            if(nread<=0){ 
                break; 
            } 
 
            audio_bytes = (jbyte*)calloc(nread,1); 
 
            (*jni_env)->GetByteArrayRegion(jni_env,read_buff, 0, nread,audio_bytes); 
//          fwrite(audio_bytes, 1, nread, fp); 
 
            (*jni_env)->CallStaticVoidMethod(jni_env,HelloJniCls, receiveAudioData, read_buff,nread); 
            usleep(50); 
    } 
} 
 
void  Java_com_example_hellojni_HelloJni_play(JNIEnv* jni_env, 
        jobject thiz){ 
      LOGI2("after Java_com_example_hellojni_HelloJni_play"); 
 
//  (*jni_env) = jni_env; 
    jclass audio_track_cls = (*jni_env)->FindClass(jni_env,"android/media/AudioTrack"); 
    jmethodID min_buff_size_id = (*jni_env)->GetStaticMethodID( 
                                         jni_env, 
                                         audio_track_cls, 
                                        "getMinBufferSize", 
                                        "(III)I"); 
    buffer_size = (*jni_env)->CallStaticIntMethod(jni_env,audio_track_cls,min_buff_size_id, 
                11025, 
                2,          /*CHANNEL_CONFIGURATION_MONO*/ 
                2);         /*ENCODING_PCM_16BIT*/ 
    LOGI("buffer_size=%i",buffer_size); 
    buffer = (*jni_env)->NewByteArray(jni_env,buffer_size/4); 
 
    char buf[buffer_size/4]; 
 
    jmethodID constructor_id = (*jni_env)->GetMethodID(jni_env,audio_track_cls, "<init>", 
            "(IIIIII)V"); 
    audio_track = (*jni_env)->NewObject(jni_env,audio_track_cls, 
            constructor_id, 
            3,            /*AudioManager.STREAM_MUSIC*/ 
            11025,        /*sampleRateInHz*/ 
            2,            /*CHANNEL_CONFIGURATION_MONO*/ 
            2,            /*ENCODING_PCM_16BIT*/ 
            buffer_size,  /*bufferSizeInBytes*/ 
            1             /*AudioTrack.MODE_STREAM*/ 
    ); 
 
    //setvolume 
    LOGI2("setStereoVolume 1"); 
    jmethodID setStereoVolume = (*jni_env)->GetMethodID(jni_env,audio_track_cls,"setStereoVolume","(FF)I"); 
    (*jni_env)->CallIntMethod(jni_env,audio_track,setStereoVolume,1.0,1.0); 
    LOGI2("setStereoVolume 2"); 
    //play 
    jmethodID method_play = (*jni_env)->GetMethodID(jni_env,audio_track_cls, "play", 
            "()V"); 
    (*jni_env)->CallVoidMethod(jni_env,audio_track, method_play); 
 
    //write 
    method_write = (*jni_env)->GetMethodID(jni_env,audio_track_cls,"write","([BII)I"); 
 
   FILE* fp = fopen("/sdcard/temp.pcm","rb"); 
   LOGI2("after open"); 
   int i=0; 
   while(!feof(fp)){ 
       jint read= fread(buf,sizeof(char),200,fp); 
       (*jni_env)->SetByteArrayRegion(jni_env,buffer, 0,read, (jbyte *)buf); 
 
       (*jni_env)->CallVoidMethod(jni_env,audio_track,method_write,buffer,0,read); 
   } 
 
} 
編譯文件:Android.mk:
[html]
LOCAL_PATH := $(call my-dir) 
 
include $(CLEAR_VARS) 
 
LOCAL_MODULE    := hello-jni 
LOCAL_SRC_FILES := hello-jni.c 
LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog 
include $(BUILD_SHARED_LIBRARY) 

例子中的調用思路:   Activity->JNI API ->c    c->JNI API->Activity     
點擊"用AudioRecord錄音",啟動了一條線程，該線程調用native方法startRecord，開始在native層啟動錄音。在錄音的過程中，再將讀取到的音頻字節數組丟到java層。方法是：->(*jni_env)->CallStaticVoidMethod(jni_env,HelloJniCls, receiveAudioData, read_buff,nread);   然後在Activity中的靜態方法 public static void receiveAudioData(byte[] data,int size){
            try {
                bos.write(data);
                bos.flush();
            } catch (IOException e) {
                e.printStackTrace();
            }
    }

中將數據寫到文件.

至於用AudioTrack來播放的流程差不多，就不廢話了。

非常要注意的是在：

startRecord.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(){
                    public void run(){

                        initOutputStream();

                        startRecord();
                    }
                }.start();

            }www.2cto.com
        });

這裡要寫個線程，很重要！！！！ ，不然會阻塞UI線程的！！！

做這個例子是做一個遠程會議產品中要用到底層錄音，由於項目中開啟錄音導致界面很卡，所以通過這個例子找到了原因，那就是錄音模塊沒有在一個非UI線程中運行，導致阻塞UI.