Android利用LocalSocket实现Java端进程与C端进程之间的IPC

来源：互联网发布：网络天才akinator很卡编辑：程序博客网时间：2024/04/30 01:23

　　Android是建立在Linux之上的OS，在涉及到安全、网络协议、文件加密等功能时，往往需要通过C语言调用底层API来实现，而如何发出指令让C端执行我们想要的功能，并且在执行之后有返回结果呢，这就需要打通Java端进程和C端进程，使之能高效地通信。这样，C端进程用于实现功能，Java端进程负责UI、功能的触发及结果处理就可以了。

　　对于*nix系统来说，“一切皆为文件”，Socket也不例外，Socket按照收发双方的媒介来说有三种类型：1，通过网络端口；2，通过文件系统；3，通过内存映射文件。具体说来，三种类型均可以用来作为IPC的Socket：1，通过本地回环接口(即LoopBack)127.0.0.1来收发数据；2，通过文件作为收发数据的中转站；3，在内存中开辟一块区域作为收发数据的中转站，此区域仍然使用文件读写API进行访问。LocalSocket支持方式2和方式3，从效率的角度来说，显然是方式3效率最高，那么下面我们就使用LocalSocket来演示如何实现Java端进程与C端进程之间的IPC。

　　以下的demo是Java端作为server，C端作为client；实际场景中可能更多的是Java端作为client，而C端作为server。

服务端代码如下：

  1 package main.activity;  2   3 import java.io.IOException;  4 import java.io.InputStream;  5 import java.io.InputStreamReader;  6   7 import android.app.Activity;  8 import android.net.LocalServerSocket;  9 import android.net.LocalSocket; 10 import android.os.Bundle; 11 import android.util.Log; 12  13 /** 14  * @author pengyiming 15  * @note 启动localSocketServer 16  * 17  */ 18  19 public class LocalSocketServerActivity extends Activity 20 { 21     /* 数据段begin */ 22     private final String TAG = "server"; 23      24     private ServerSocketThread mServerSocketThread; 25     /* 数据段end */ 26      27     /* 函数段begin */ 28     @Override 29     protected void onCreate(Bundle savedInstanceState) 30     { 31         super.onCreate(savedInstanceState); 32          33         mServerSocketThread = new ServerSocketThread(); 34         mServerSocketThread.start(); 35     } 36      37     @Override 38     protected void onDestroy() 39     { 40         super.onDestroy(); 41          42         mServerSocketThread.stopRun(); 43     } 44     /* 函数段end */ 45      46     /* 内部类begin */ 47     private class ServerSocketThread extends Thread 48     { 49         private boolean keepRunning = true; 50         private LocalServerSocket serverSocket; 51          52         private void stopRun() 53         { 54             keepRunning = false; 55         } 56          57         @Override 58         public void run() 59         { 60             try 61             { 62                 serverSocket = new LocalServerSocket("pym_local_socket"); 63             } 64             catch (IOException e) 65             { 66                 e.printStackTrace(); 67                  68                 keepRunning = false; 69             } 70              71             while(keepRunning) 72             { 73                 Log.d(TAG, "wait for new client coming !"); 74                  75                 try 76                 { 77                     LocalSocket interactClientSocket = serverSocket.accept(); 78                      79                     //由于accept()在阻塞时，可能Activity已经finish掉了，所以再次检查keepRunning 80                     if (keepRunning) 81                     { 82                         Log.d(TAG, "new client coming !"); 83                          84                         new InteractClientSocketThread(interactClientSocket).start(); 85                     } 86                 } 87                 catch (IOException e) 88                 { 89                     e.printStackTrace(); 90                      91                     keepRunning = false; 92                 } 93             } 94              95             if (serverSocket != null) 96             { 97                 try 98                 { 99                     serverSocket.close();100                 }101                 catch (IOException e)102                 {103                     e.printStackTrace();104                 }105             }106         }107     }108     109     private class InteractClientSocketThread extends Thread110     {111         private LocalSocket interactClientSocket;112         113         public InteractClientSocketThread(LocalSocket interactClientSocket)114         {115             this.interactClientSocket = interactClientSocket;116         }117         118         @Override119         public void run()120         {121             StringBuilder recvStrBuilder = new StringBuilder();122             InputStream inputStream = null;123             try124             {125                 inputStream = interactClientSocket.getInputStream();126                 InputStreamReader inputStreamReader = new InputStreamReader(inputStream);127                 char[] buf = new char[4096];128                 int readBytes = -1;129                 while ((readBytes = inputStreamReader.read(buf)) != -1)130                 {131                     String tempStr = new String(buf, 0, readBytes);132                     recvStrBuilder.append(tempStr);133                 }134             }135             catch (IOException e)136             {137                 e.printStackTrace();138                 139                 Log.d(TAG, "resolve data error !");140             }141             finally142             {143                 if (inputStream != null)144                 {145                     try146                     {147                         inputStream.close();148                     }149                     catch (IOException e)150                     {151                         e.printStackTrace();152                     }153                 }154             }155         }156     }157     /* 内部类end */158 }

客户端代码如下：

 1 package main.activity; 2  3 import android.app.Activity; 4 import android.os.Bundle; 5 import android.util.Log; 6  7 /** 8  * @author pengyiming 9  * @note 用于启动localSocketClient，向server发送心跳报文10  *11  */12 13 public class LocalSocketClientActivity extends Activity14 {15     /* 数据段begin */16     private final String TAG = "client";17     18     private HeartBeatThread mHeartBeatThread;19     20     public native int startHeartBeat();21     /* 数据段end */22     23     /* 函数段begin */24     static25     {26         System.loadLibrary("pymclient");27     }28     29     @Override30     protected void onCreate(Bundle savedInstanceState)31     {32         super.onCreate(savedInstanceState);33         34         mHeartBeatThread = new HeartBeatThread();35         mHeartBeatThread.start();36     }37     38     @Override39     protected void onDestroy()40     {41         super.onDestroy();42         43         mHeartBeatThread.stopRun();44     }45     /* 函数段end */46     47     /* 内部类begin */48     private class HeartBeatThread extends Thread49     {50         int ret;51         boolean keepRunning = true;52         53         public void stopRun()54         {55             keepRunning = false;56         }57         58         @Override59         public void run()60         {61             Log.d(TAG, "start heart beat!");62             63             while (keepRunning)64             {65                 ret = startHeartBeat();66                 67                 Log.d(TAG, "ret = " + ret);68                 69                 if (ret != 0)70                 {71                     break;72                 }73                 74                 try75                 {76                     sleep(1000);77                 }78                 catch (InterruptedException e)79                 {80                     e.printStackTrace();81                 }82             }83             84             Log.d(TAG, "stop heart beat!");85         }86     }87     /* 内部类end */88 }

上述客户端代码启动了一个线程用于发送“心跳”报文，每隔1s构建一个新的LocalSocket，连接服务端并发送流数据，其核心就在于native方法的实现。值得一提的是，我最初使用原生socket函数，没想connect总是返回错误；后来在同事的提醒下，我参考了Android源码rild.c中socket_local_client的使用，并从socket_local_client.c中抽取出相应代码改写而成。

客户端native方法头文件：

 1 /* DO NOT EDIT THIS FILE - it is machine generated */ 2 #include <jni.h> 3 /* Header for class main_activity_LocalSocketClientActivity */ 4  5 #ifndef _Included_main_activity_LocalSocketClientActivity 6 #define _Included_main_activity_LocalSocketClientActivity 7 #ifdef __cplusplus 8 extern "C" { 9 #endif10 11 /* socket命名空间(见cutils/sockets.h) */12 #define ANDROID_SOCKET_NAMESPACE_ABSTRACT 013 #define ANDROID_SOCKET_NAMESPACE_RESERVED 114 #define ANDROID_SOCKET_NAMESPACE_FILESYSTEM 215 16 /* socket类型 */17 #define SOCK_STREAM      118 #define SOCK_DGRAM       219 #define SOCK_RAW         320 #define SOCK_RDM         421 #define SOCK_SEQPACKET   522 #define SOCK_PACKET      1023 24 /* 清0宏 */25 #define MEM_ZERO(pDest, destSize) memset(pDest, 0, destSize)26 27 /* 错误码定义 */28 #define NO_ERR 029 #define CREATE_ERR -130 #define CONNECT_ERR -231 #define LINUX_MAKE_ADDRUN_ERROR -332 #define NO_LINUX_MAKE_ADDRUN_ERROR -433 #define CLOSE_ERR -534 35 /* 是否使用linux的本地socket命令空间 */36 #define HAVE_LINUX_LOCAL_SOCKET_NAMESPACE "linux_local_socket_namespace"37 38 #undef main_activity_LocalSocketClientActivity_MODE_PRIVATE39 #define main_activity_LocalSocketClientActivity_MODE_PRIVATE 0L40 #undef main_activity_LocalSocketClientActivity_MODE_WORLD_READABLE41 #define main_activity_LocalSocketClientActivity_MODE_WORLD_READABLE 1L42 #undef main_activity_LocalSocketClientActivity_MODE_WORLD_WRITEABLE43 #define main_activity_LocalSocketClientActivity_MODE_WORLD_WRITEABLE 2L44 #undef main_activity_LocalSocketClientActivity_MODE_APPEND45 #define main_activity_LocalSocketClientActivity_MODE_APPEND 32768L46 #undef main_activity_LocalSocketClientActivity_MODE_MULTI_PROCESS47 #define main_activity_LocalSocketClientActivity_MODE_MULTI_PROCESS 4L48 #undef main_activity_LocalSocketClientActivity_BIND_AUTO_CREATE49 #define main_activity_LocalSocketClientActivity_BIND_AUTO_CREATE 1L50 #undef main_activity_LocalSocketClientActivity_BIND_DEBUG_UNBIND51 #define main_activity_LocalSocketClientActivity_BIND_DEBUG_UNBIND 2L52 #undef main_activity_LocalSocketClientActivity_BIND_NOT_FOREGROUND53 #define main_activity_LocalSocketClientActivity_BIND_NOT_FOREGROUND 4L54 #undef main_activity_LocalSocketClientActivity_BIND_ABOVE_CLIENT55 #define main_activity_LocalSocketClientActivity_BIND_ABOVE_CLIENT 8L56 #undef main_activity_LocalSocketClientActivity_BIND_ALLOW_OOM_MANAGEMENT57 #define main_activity_LocalSocketClientActivity_BIND_ALLOW_OOM_MANAGEMENT 16L58 #undef main_activity_LocalSocketClientActivity_BIND_WAIVE_PRIORITY59 #define main_activity_LocalSocketClientActivity_BIND_WAIVE_PRIORITY 32L60 #undef main_activity_LocalSocketClientActivity_BIND_IMPORTANT61 #define main_activity_LocalSocketClientActivity_BIND_IMPORTANT 64L62 #undef main_activity_LocalSocketClientActivity_BIND_ADJUST_WITH_ACTIVITY63 #define main_activity_LocalSocketClientActivity_BIND_ADJUST_WITH_ACTIVITY 128L64 #undef main_activity_LocalSocketClientActivity_CONTEXT_INCLUDE_CODE65 #define main_activity_LocalSocketClientActivity_CONTEXT_INCLUDE_CODE 1L66 #undef main_activity_LocalSocketClientActivity_CONTEXT_IGNORE_SECURITY67 #define main_activity_LocalSocketClientActivity_CONTEXT_IGNORE_SECURITY 2L68 #undef main_activity_LocalSocketClientActivity_CONTEXT_RESTRICTED69 #define main_activity_LocalSocketClientActivity_CONTEXT_RESTRICTED 4L70 #undef main_activity_LocalSocketClientActivity_RESULT_CANCELED71 #define main_activity_LocalSocketClientActivity_RESULT_CANCELED 0L72 #undef main_activity_LocalSocketClientActivity_RESULT_OK73 #define main_activity_LocalSocketClientActivity_RESULT_OK -1L74 #undef main_activity_LocalSocketClientActivity_RESULT_FIRST_USER75 #define main_activity_LocalSocketClientActivity_RESULT_FIRST_USER 1L76 #undef main_activity_LocalSocketClientActivity_DEFAULT_KEYS_DISABLE77 #define main_activity_LocalSocketClientActivity_DEFAULT_KEYS_DISABLE 0L78 #undef main_activity_LocalSocketClientActivity_DEFAULT_KEYS_DIALER79 #define main_activity_LocalSocketClientActivity_DEFAULT_KEYS_DIALER 1L80 #undef main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SHORTCUT81 #define main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SHORTCUT 2L82 #undef main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SEARCH_LOCAL83 #define main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SEARCH_LOCAL 3L84 #undef main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SEARCH_GLOBAL85 #define main_activity_LocalSocketClientActivity_DEFAULT_KEYS_SEARCH_GLOBAL 4L86 /*87  * Class:     main_activity_LocalSocketClientActivity88  * Method:    startHeartBeat89  * Signature: ()I90  */91 JNIEXPORT jint JNICALL Java_main_activity_LocalSocketClientActivity_startHeartBeat92   (JNIEnv *, jobject);93 94 #ifdef __cplusplus95 }96 #endif97 #endif

客户端native方法实现：

  1 /* 头文件begin */  2 #include "main_activity_LocalSocketClientActivity.h"  3   4 #include <sys/socket.h>  5 #include <sys/un.h>  6 #include <stddef.h>  7 #include <string.h>  8 /* 头文件end */  9  10 #ifdef __cplusplus 11 extern "C" { 12 #endif 13  14 /* 15  * Class:     main_activity_LocalSocketClientActivity 16  * Method:    startHeartBeat 17  */ 18 JNIEXPORT jint JNICALL Java_main_activity_LocalSocketClientActivity_startHeartBeat(JNIEnv * env, jobject object) 19 { 20     int socketID; 21     struct sockaddr_un serverAddr; 22     char path[] = "pym_local_socket\0"; 23     int ret; 24  25     socketID = socket_local_client(path, ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM); 26     if (socketID < 0) 27     { 28         return socketID; 29     } 30  31     ret = close(socketID); 32     if (ret < 0) 33     { 34         return CLOSE_ERR; 35     } 36  37     return NO_ERR; 38 } 39  40 /* 创建本地socket客户端 */ 41 int socket_local_client(const char *name, int namespaceId, int type) 42 { 43     int socketID; 44     int ret; 45  46     socketID = socket(AF_LOCAL, type, 0); 47     if(socketID < 0) 48     { 49         return CREATE_ERR; 50     } 51  52     ret = socket_local_client_connect(socketID, name, namespaceId, type); 53     if (ret < 0) 54     { 55         close(socketID); 56  57         return ret; 58     } 59  60     return socketID; 61 } 62  63 /* 连接到相应的fileDescriptor上 */ 64 int socket_local_client_connect(int fd, const char *name, int namespaceId, int type) 65 { 66     struct sockaddr_un addr; 67     socklen_t socklen; 68     size_t namelen; 69     int ret; 70  71     ret = socket_make_sockaddr_un(name, namespaceId, &addr, &socklen); 72     if (ret < 0) 73     { 74         return ret; 75     } 76  77     if(connect(fd, (struct sockaddr *) &addr, socklen) < 0) 78     { 79         return CONNECT_ERR; 80     } 81  82     return fd; 83 } 84  85 /* 构造sockaddr_un */ 86 int socket_make_sockaddr_un(const char *name, int namespaceId, struct sockaddr_un *p_addr, socklen_t *socklen) 87 { 88     size_t namelen; 89  90     MEM_ZERO(p_addr, sizeof(*p_addr)); 91 #ifdef HAVE_LINUX_LOCAL_SOCKET_NAMESPACE 92  93     namelen  = strlen(name); 94  95     // Test with length +1 for the *initial* '\0'. 96     if ((namelen + 1) > sizeof(p_addr->sun_path)) 97     { 98         return LINUX_MAKE_ADDRUN_ERROR; 99     }100     p_addr->sun_path[0] = 0;101     memcpy(p_addr->sun_path + 1, name, namelen);102 103 #else104 105     namelen = strlen(name) + strlen(FILESYSTEM_SOCKET_PREFIX);106 107     /* unix_path_max appears to be missing on linux */108     if (namelen > (sizeof(*p_addr) - offsetof(struct sockaddr_un, sun_path) - 1))109     {110         return NO_LINUX_MAKE_ADDRUN_ERROR;111     }112 113     strcpy(p_addr->sun_path, FILESYSTEM_SOCKET_PREFIX);114     strcat(p_addr->sun_path, name);115 116 #endif117 118     p_addr->sun_family = AF_LOCAL;119     *socklen = namelen + offsetof(struct sockaddr_un, sun_path) + 1;120 121     return NO_ERR;122 }123 124 #ifdef __cplusplus125 }126 #endif

注意到100~101行比较特殊，是从p_addr->sun_path[1]开始拷贝本地域名，这就是之前为什么一直connect不上的原因，至于为什么偏移1个字节来拷贝本地域名，你可以在*nix系统下输入"man 7 unix"来找到原因。

　　先启动server，再启动client就可以看到结果了。对了，在成功创建并已自动连接后，我并未发送任何数据，其实发送数据就是写入文件，It's your trun now! 在close之前加入这段代码吧~

1 int ret;2 char buf[] = "hello";3 4 ret = write(socketID, buf, strlen(buf));

转自：http://www.cnblogs.com/zealotrouge/p/3152941.html

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