Question

我编写了以下代码来读取Android应用通过套接字接收的一些数据（特别是文件）：

    DataInputStream inputStream = new DataInputStream(socket.getInputStream());
    byte[] buffX = new byte[30054];
    int k = inputStream.read(buffX,0,30054);

我知道我从用C编写的代码发送的数据是一个30054字节的文件。

问题是变量k小于2000，即它不会读取所有已发送的文件或文件的某些部分被丢弃。我已经检查过接收器缓冲区的大小（在Android应用程序中）超过80kB。

我使用大小为1662字节的文件测试了相同的代码，正如我所料，变量k等于1662字节。

我做错了什么？我错过了什么？我是否需要关闭套接字？这是我在关闭应用时更喜欢做的事情，而不是在我展示的代码中。

ANDROID APP CODE：

    @SuppressLint("HandlerLeak")
    public class DisplayNewActivity extends Activity {
        ...
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.mainnewact);
            mHandler = new Handler() { // used to show the number of bytes that were read
                @Override
                public void handleMessage(Message msg) {
                    int d2 = (Integer)msg.obj;
                    commentS.setText(Integer.toString(d2));
                }
            }
            ...
            cThread = new Thread(new ClientThread()); // used to start socket connection 
            rThread = new Thread(new RcvThread()); // used to read incoming packages once the socket has been connected
            cThread.start();
        }

        public class ClientThread implements Runnable {
            public void run() {
                try {
                      ...
                      socket = new Socket(serverIpAddress, Integer.parseInt(serverPort));
                      rThread.start();
                      while (connected) { };
                      ...
                } catch (Exception e) { startActivity(intentback);}
            }
        }

        @SuppressLint("HandlerLeak")
        public class RcvThread implements Runnable {
            public void run() {
                while (connected) {
                    try {
                        DataInputStream inputStream = new DataInputStream(socket.getInputStream());
                        ByteArrayOutputStream baos = new ByteArrayOutputStream();
                        byte[] imBytes = new byte[31000];
                        int numRead = 0;
                        while ((numRead = inputStream.read(imBytes)) >= 0) {
                            baos.write(imBytes,0,numRead);
                        }
                        byte[] imageInBytes = baos.toByteArray();
                        int k = imageInBytes.length;
                        Message msg = new Message();
                        msg.obj = k;
                        mHandler.sendMessage(msg);
                    } catch (Exception e) {
                        Log.e("SocketConnectionv02Activity", "C: ErrorRCVD", e);
                    }
                }
            }
        }
    }

C代码：

    ...
    #include <sys/sendfile.h>
    ...
    int main(int argc, char *argv[]){
        int sockfd, newsockfd, portno;
        socklen_t clilen;
        struct sockaddr_in serv_addr, cli_addr;
        int fdfile;
        struct stat stat_buf;
        off_t offset = 0;
        int img2send = 1;
        char buffer[256];
        int closeSocket = 0;
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0) {error("ERROR opening socket"); exit(1);}
        bzero((char *) &serv_addr, sizeof(serv_addr));
        portno = 55000;
        serv_addr.sin_family = AF_INET;
        serv_addr.sin_addr.s_addr = INADDR_ANY;
        serv_addr.sin_port = htons(portno);
        if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) { 
            error("ERROR on binding");
            close(sockfd);
            exit(1);
        }
        listen(sockfd,1);
        clilen = sizeof(cli_addr);
        newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
        if (newsockfd < 0) {
            error("ERROR on accept");
            close(sockfd);
            exit(1);
        }
        while (closeSocket == 0) {
            if (img2send == 1) { // interchange the file that is sent through the socket
                 fdfile = open("/home/gachr/Desktop/CamaraTest/fig1bmp.bmp", O_RDONLY); 
                 img2send = 2;
            } else {
                 fdfile = open("/home/gachr/Desktop/CamaraTest/fig2bmp.bmp", O_RDONLY);
                 img2send = 1;
            }
            if (fdfile == -1) {
                 close(sockfd); 
                 close(newsockfd);
                 exit(1);
            } else {
                 fstat(fdfile, &stat_buf);
                 offset = 0;
                 n = sendfile(newsockfd, fdfile, &offset, stat_buf.st_size);
                 if (n == stat_buf.st_size) { printf("Complete transfering file\n"); }
                 close(fdfile);
            }
            sleep(5);
            bzero(buffer,256);
            n = recv(newsockfd,buffer,1,MSG_DONTWAIT); // to close the socket from the Android app, which is working
            if (n > 0) {
                  if (buffer[0] == 48){ closeSocket = 1;}
            }
        }
        close(newsockfd);
        close(sockfd);
        return 0;
    }

Answer 1

很难说你什么时候不在那里:) 但我会做以下事项：

一次逐步读取更少的字节并构建完整的字节来自这个较小块的字节数组
调试这些行并准确查看“bug”出现的时间

Answer 2

read方法不读取整个流。它只读取流缓冲区中当前可用的字节。

要从流中读取完整数据，您可以使用readFully() method或使用以下代码从流中读取完整数据：

ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] bytes = new byte[8192];

int numRead = 0;
while ((numRead = inputStream.read(bytes)) >= 0) {
    baos.write(bytes,0,numRead);
}

byte[] fileData = baos.toByteArray();

从android中的socket输入流中读取错误的字节数

2 个答案: