Android native c java for local socket communication

<Pre name = "code" class = "html"> Method 1: java is used as the server and native is used as the client.
1. Create a java application and a Server class
<Pre name = "code" class = "html"> /*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License ");
* You may not use this file before t in compliance with the License.
* You may obtain a copy of the License
*
* 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 ();
}
 
}

2. Tool class for converting float into byte [] Array

[Html]
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 ();
Ll = 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 ();
Ll = 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 & = 0 xffff;
L | = (int) B [2] <16 );
L & = 0 xffffff;
L | = (int) B [3] <24 );
L & = 0 xffffffffl;
Return Float. intBitsToFloat (l );
}
}

3. Create a client in native
[Html]
# 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;
}

In this way, java can communicate with native, and it is a local socket.

From weidawei0609