我一直在四处寻找,并且无法找到解决这一特定问题的方法.请原谅我,如果这是一个新手的错误,我刚刚离开学校,所以我正在阅读尽可能多的书籍,以便了解移动设备编程.
目标: 将基于PC的套接字服务器的数据无线传输到基于Android的客户端(802.11 b/g),然后处理所述数据以输出给用户.
问题: Android手机上的输入流缓冲区正在接收大量错误的垃圾数据.
程序: 我编写和/或修改了三段不同的代码.首先是我的笔记本电脑上运行的服务器端程序.原始源代码可以在这里找到:beej.us/guide/bgnet/examples/server.c(感谢Beej的源代码!).我修改了它以删除警告/错误,并添加了我自己的连续数据输入循环以进行测试.这是修改后的代码:
/* A simple server in the internet domain using TCP
The port number is passed as an argument */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
void error(char *msg)
{
perror(msg);
exit(1);
}
int main(int argc, char *argv[])
{
int sockfd, newsockfd, portno; //, clilen;
//Modified this fromt he original author's code, as
//the function is looking for clilen to be of type
//socklen_t, not int
socklen_t clilen;
char buffer[256];
struct sockaddr_in serv_addr, cli_addr;
int n;
if (argc < 2)
{
fprintf(stderr,"ERROR, no port provided\n");
exit(1);
}
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0)
error("ERROR opening socket");
bzero((char *) &serv_addr, sizeof(serv_addr));
portno = atoi(argv[1]);
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");
//Added this for some clarity
printf("Starting to listen on the socket now..\n");
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,
(struct sockaddr *) &cli_addr,
&clilen);
//Let me know a socket connection has been established
printf("Socket established!\n");
if (newsockfd < 0)
error("ERROR on accept");
bzero(buffer,256);
//Don't want this socket to block and read, only to write
//Modified from the original author
//n = read(newsockfd,buffer,255);
//if (n < 0) error("ERROR reading from socket");
//printf("Here is the message: %s\n",buffer);
//n = write(newsockfd,"Hello, socket!",18);
const int SIZE_OF_STRING = 30;
char string[SIZE_OF_STRING];
int i = 0;
for (i = 0; i < SIZE_OF_STRING; ++i)
{
string[i] = '\0';
}
//Ask input from the user until the word "quit" is seen
//then close the socket
while (!strstr(string, "quit"))
{
printf("Please enter something to send to the phone.\n");
scanf("%s", string);
strcat(string, "\n");
n = write(newsockfd, string, sizeof(string));
if (n < 0) error("ERROR writing to socket");
}
printf("\n\nexiting..\n");
close(newsockfd);
close(sockfd);
return 0;
}
这是Android代码:
public class SmartSawLineDrawSocketThread extends Thread
{
private Handler smartSawMainThreadCommunicationHandle_;
private Socket smartSawSocketHandle_;
private InputStream smartSawSocketInputStreamHandle_;
private BufferedReader smartSawSocketInputBuffer_;
private InputStreamReader smartSawSocketInputStreamReader_;
private boolean threadRunning_ = false;
private boolean isConnected_;
private char buffer[] = new char[50];
//Grab the thread's communication handle for use with sending messages to the UI
//Thread
public SmartSawLineDrawSocketThread(Handler handle)
{
smartSawMainThreadCommunicationHandle_ = handle;
threadRunning_ = true;
isConnected_ = false;
}
//Attempt a connection to the host
public int SmartSawLineDrawSocketThreadConnect(String hostIP, String hostPort)
{
int rval = 0;
Log.i("info", "hostIP = " + hostIP);
Log.i("info", "hostPort = " + Integer.parseInt(hostPort.trim()));
try
{
smartSawSocketHandle_ = new Socket(hostIP.trim(), Integer.parseInt(hostPort.trim()));
if (rval == 0)
{
smartSawSocketInputBuffer_ = new BufferedReader(new InputStreamReader(smartSawSocketHandle_.getInputStream()));
smartSawSocketInputStreamReader_ = new InputStreamReader(smartSawSocketHandle_.getInputStream());
if (smartSawSocketInputBuffer_ != null)
{
isConnected_ = true;
}
else
{
Log.e("error", "Input buffer pointer was null!");
}
}
}
catch (UnknownHostException e)
{
rval = 1;
Log.i("info", "unknown host message e when connecting:" + e);
e.printStackTrace();
isConnected_ = false;
}
catch (IOException e)
{
rval = 2;
Log.i("info", "unknown IOException e when connecting:" + e);
e.printStackTrace();
isConnected_ = false;
}
catch (SecurityException e)
{
rval = 3;
Log.i("info", "Need to set a security setting somewhere");
}
Log.i("info", "Rval returned with " + rval);
return rval;
}
//Disconnect from the server
public void SmartSawLineDrawSocketThreadDisconnect()
{
try
{
smartSawSocketHandle_.close();
isConnected_ = false;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//Once the thread has started running, make sure we're connected, and start
//trying to listen for messages
@Override
public void run()
{
Log.i("info", "Made it into the run() loop of the thread.");
while (threadRunning_)
{
if (isConnected_ == true)
{
try
{
if (smartSawSocketInputStreamReader_.ready() == true)
//(smartSawSocketInputBuffer_.ready() == true)
{
int numread = 0;
numread = smartSawSocketInputStreamReader_.read(buffer);
Log.i("info", "amount of characters read in: " + numread);
Message mainThreadMessage_ = Message.obtain();
Bundle mainThreadDataBundle_ = new Bundle();
mainThreadDataBundle_.putString("Zero", new String(buffer)); //smartSawSocketInputBuffer_.readLine());
mainThreadMessage_.setData(mainThreadDataBundle_);
mainThreadMessage_.setTarget(smartSawMainThreadCommunicationHandle_);
mainThreadMessage_.sendToTarget();
Log.i("info", "Received a string! Sent this to main thread: " + mainThreadDataBundle_.getString("Zero"));
}
}
catch (IOException e)
{
Log.i("info","IO Exception in thread main loop, e was: " + e);
}
}
}
}
}
家庭作业和测试: 我可以成功传输一个字符串,但之后的所有内容都是PC-Android连接中无法理解的垃圾.想要先做作业,我想消除服务器端代码.我使用了Beej的客户端代码(beej.us/guide/bgnet/examples/client.c)并将其修改为一个很好的倾听者.我能够在基于PC-PC的TCP连接上向客户端传输多个字符串.我将客户端的输出重定向到一个文件,并在十六进制编辑器下打开它.瞧,没有找到错误的数据.我用连接到作为服务器的802.11b/g路由器的笔记本电脑进行了测试,并且硬连线桌面是客户端.我已经消除了硬件问题,并在服务器端测试代码问题.它必须在我如何实现Android客户端代码的某个地方.我还尝试使用自动BufferedReader类来完成输入,以及使用InputStreamReader类手动处理输入.两者都在第一个字符串后收到相同的垃圾输出.这让我相信它在套接字输入流中的某个地方,但我该如何解决？有人有什么建议吗？
以下是基于PC的客户端测试的代码:
/*
** client.c -- a stream socket client demo
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#define PORT "27015" // the port client will be connecting to
#define MAXDATASIZE 100 // max number of bytes we can get at once
// get sockaddr, IPv4 or IPv6:
void *get_in_addr(struct sockaddr *sa)
{
if (sa->sa_family == AF_INET) {
return &(((struct sockaddr_in*)sa)->sin_addr);
}
return &(((struct sockaddr_in6*)sa)->sin6_addr);
}
int main(int argc, char *argv[])
{
int sockfd, numbytes;
char buf[MAXDATASIZE];
struct addrinfo hints, *servinfo, *p;
int rv;
char s[INET6_ADDRSTRLEN];
if (argc != 2) {
fprintf(stderr,"usage: client hostname\n");
exit(1);
}
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and connect to the first we can
for(p = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("client: socket");
continue;
}
if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
close(sockfd);
perror("client: connect");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "client: failed to connect\n");
return 2;
}
inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
s, sizeof s);
printf("client: connecting to %s\n", s);
freeaddrinfo(servinfo); // all done with this structure
//Modified from the original to spit out all strings transmitted from the server, then close the socket
//when finished.
while (!strstr(buf, "close"))
{
numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0);
if (numbytes)
{
printf("Received: \n");
printf("%s", buf);
printf("\n");
}
}
if ((numbytes = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
perror("recv");
exit(1);
}
buf[numbytes] = '\0';
printf("client: received '%s'\n",buf);
close(sockfd);
return 0;
}
谢谢您的帮助!Moscro
客户：
您应该使用创建字符串new String(buffer, 0, numread)，因为并非所有缓冲区都可能已被填充，因此未被覆盖的现有字符read()将出现在字符串中。
您还应该检查numread == -1，因为这表明连接已关闭。
服务器：
sizeof(some_array)返回整个数组的大小（以字节为单位），这意味着您的服务器每次发送 30 个字节。其中大部分将为 null ( \0)，这解释了为什么 C 客户端似乎可以工作，因为printf假设第一个空字节表示字符串的结尾。然而，Java 却没有，这可能就是为什么额外的字节在日志消息中显示为垃圾的原因。
一种解决方案可能是：
\n，这将是strlen(string) + 1BufferedReader方法readLine()，该方法读取下一个换行符| 归档时间： |
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