JNI在Android开发中的应用之--用AudioRecord录音，用AudioTrack播放声音.

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：

<?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录音"/>

<Button android:id="@+id/stop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="停止录音"/>

<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="底层在录音哦，请点击我，我反应很快的耶，没有阻塞UI线程"/>

</LinearLayout>

接下来是hello-jni.c:

#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);
}

}

编译文件:Android.mk:

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)

贴上效果图:



例子中的调用思路: Activity->JNI API ->c c->JNI API->Activity

点击"用AudioRecord录音",启动了一条线程，该线程调用native方法startRecord，开始在native层启动录音。在录音的过程中，再将读取到的音频字节数组丢到java层。方法是：->(*jni_env)->CallStaticVoidMethod(jni_env,HelloJniCls, receiveAudioData, read_buff,nread); 然后在Activity中的静态方法 public static void receiveAudioData(byte[]
data,int size){

try {

bos.write(data);

bos.flush();

} catch (IOException e) {

e.printStackTrace();

}

}

中将数据写到文件.

至于用AudioTrack来播放的流程差不多，就不废话了。

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();

}

});

这里要写个线程，很重要！！！！ ，不然会阻塞UI线程的！！！

做这个例子是做一个远程会议产品中要用到底层录音，由于项目中开启录音导致界面很卡，所以通过这个例子找到了原因，那就是录音模块没有在一个非UI线程中运行，导致阻塞UI.

【代码全部已经全部贴上】