android native c java进行本地socket通信----java服务端 C客户端

方式一：java做服务器端，native做client端
1. 建立java应用程序，建立Server 类
* Copyright (C) 2009 The Android Open Source Project
*
* 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 com.example.hellojni;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.net.LocalServerSocket;
import android.net.LocalSocket;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

public class HelloJni extends Activity
{
public static final String SOCKET_NAME = "server_test";
private static final String TAG = "SocketService";
private LocalServerSocket mServerSocket = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

Log.v(TAG, "onCreate");
try {
mServerSocket = new LocalServerSocket(SOCKET_NAME);
} catch (IOException e) {
Log.v(TAG, "in onCreate, making server socket: " + e);
return;
}

Thread t = new Thread() {
@Override public void run() {
LocalSocket socket = null;
while (true) {
try {
Log.v(TAG, "Waiting for connection...");
socket = mServerSocket.accept();
Log.v(TAG, ".....Got socket: " + socket);
if (socket != null) {
startEchoThread(socket);
} else {
return; // socket shutdown?
}
} catch (IOException e) {
Log.v(TAG, "in accept: " + e);
}
}
}
};
t.start();

}

private void startEchoThread(final LocalSocket socket) {
Thread t = new Thread() {
@Override public void run() {
try {
InputStream is = socket.getInputStream();
OutputStream os = socket.getOutputStream();
InputStreamReader isr = new InputStreamReader(is);
while (true) {
char[] data = new char[128];

int ret = isr.read(data);
for(int i=0;i<ret;i++){
Log.d(TAG, "data["+i+"]="+data[i]);
}
byte[] values = TypeUtils.float2Byte(-1234567.122f);
float fd = -1234567.122f;
Log.d(TAG, " fd="+fd);
for(int i=0;i<values.length;i++){
Log.d(TAG, "values["+i+"]="+values[i]);
}
os.write(values);
os.flush();
Log.v(TAG, "after write: ");
}
} catch (IOException e) {
Log.v(TAG, "in echo thread loop: " + e.getMessage());
}
}
};
t.start();
}

}</PRE><BR>
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<P>2.将float转换成byte[]数组的工具类</P>
<P></P>
<PRE class=html name="code">import
java.nio.ByteBuffer;
import java.nio.FloatBuffer;

public class TypeUtils {

public static byte[] floatToByte(float v) {
ByteBuffer bb = ByteBuffer.allocate(4);
byte[] ret = new byte[4];
FloatBuffer fb = bb.asFloatBuffer();
fb.put(v);
bb.get(ret);
return ret;
}

public static byte[] float2Byte(float f) {
byte[] b = new byte[4];
int l = Float.floatToIntBits(f);
for (int i = 0; i < b.length;
i++) {
b[i] = new Integer(l).byteValue();
l = l >> 8;
}
return b;
}

public static byte[] doubleToByte(double d) {
byte[] b = new byte[8];
long l = Double.doubleToLongBits(d);
for (int i = 0; i < b.length;
i++) {
b[i] = new Long(l).byteValue();
l = l >> 8;
}
return b;
}

public static float byteToFloat(byte[] v) {
ByteBuffer bb = ByteBuffer.wrap(v);
FloatBuffer fb = bb.asFloatBuffer();
return fb.get();
}

public static float byte2Float(byte[] b) {
int l = 0;
l = b[0];
l &= 0xff;
l |= ((int) b[1] << 8);
l &= 0xffff;
l |= ((int) b[2] << 16);
l &= 0xffffff;
l |= ((int) b[3] << 24);
l &= 0xffffffffl;
return Float.intBitsToFloat(l);
}
}
3.在 native中建立client
#include <cutils/sockets.h>
static union FloatValue{
char val[4];
float f;
} mf_t;
static __inline__ int
qemud_fd_write(int fd, const void* buff, int len)
{
int len2;
do {
len2 = write(fd, buff, len);
} while (len2 < 0 && errno == EINTR);
return len2;
}

static __inline__ int
qemud_fd_read(int fd, void* buff, int len)
{
int len2;
do {
len2 = read(fd, buff, len);
} while (len2 < 0 && errno == EINTR);
return len2;
}

int main(int argc, char **argv)
{
int fd;
char answer[200];
char name[5]= "test!";
int namelen = 5;
/* connect to qemud control socket */
fd = socket_local_client( "server_test",
ANDROID_SOCKET_NAMESPACE_ABSTRACT,
SOCK_STREAM );
if (fd < 0) {
printf("no qemud control socket: %s \n", strerror(errno));
return -1;
}

/* send service name to connect */
if (qemud_fd_write(fd, name, namelen) != namelen) {
printf("can't send service name to qemud: %s \n",
strerror(errno));
close(fd);
return -1;
}
printf(".... before qemud_fd_read \n");
/* read answer from daemon */
int res =qemud_fd_read(fd, answer, 200);

printf(" .....after qemud_fd_read ");
if (res) {
printf("connect to service through qemud res =%d answer0 =%d ,answer1 =%d answer2 =%d
,answer3=%d \n",res,answer[0],answer[1],answer[2],answer[3]);
mf_t.val[0] = answer[0];
mf_t.val[1] = answer[1];
mf_t.val[2] = answer[2];
mf_t.val[3] = answer[3];
printf(" .....after convert f=%f \n",mf_t.f);
close(fd);
return -1;
}

return 0;
}
这样就实现了java和native进行通信的目的了，而且是本地socket哟