交叉编译器：arm-linux-gcc-4.5.4
Linux内核版本：Linux-3.0
主机操作系统：Centos 6.5
开发板：FL2440
温度传感器:ds18b20
注：此程序的客户端是在装有ds18b20模块并有ds18b20驱动的系统上跑的，本人写的ds18b20的驱动
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一、socket图解
socket是“open—write/read—close”模式的一种实现，而在socket编程里面，socket()就是open()函数了。socket编程的流程图示已经很清楚，各个函数的用法这里就懒得说了，也说不好，网上有一堆一堆的专业人士的解释，非专业人士还是直接上代码的比较好。
二、客户端代码：
1 /*********************************************************************************
2 * Copyright: (C) 2016 2013dianxin_3
3 * All rights reserved.
4 *
5 * Filename: mclient.c
6 * Description: This file
7 *
8 * Version: 1.0.0(08/16/2016)
9 * Author: xiaohexiansheng <1392195453@qq.com>
10 * ChangeLog: 1, Release initial version on "08/16/2016 07:16:44 PM"
11 *
12 ********************************************************************************/
13 #include <sys/types.h>
14 #include <sys/ioctl.h>
15 #include <termios.h>
16 #include <sys/stat.h>
17 #include <fcntl.h>
18 #include <sys/time.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <errno.h>
23 #include <sys/types.h>
24 #include <sys/socket.h>
25 #include <netinet/in.h>
26
27 #define MAXLINE 4096
28 /********************************************************************************
29 * Description:
30 * Input Args:
31 * Output Args:
32 * Return Value:
33 ********************************************************************************/
34 double get_tem(void) //获取温度的函数
35 {
36 int fd;
37 double result = 0;
38 unsigned char buff[2];
39 unsigned short temp = 0;
40 int flag = 0;
41
42 if ((fd=open("/dev/ds18b20",O_RDWR | O_NDELAY | O_NOCTTY)) < 0)
43 {
44 perror("open device ds18b20 failed.\r\n");
45 exit(1);
46 }
47
48 printf("open device ds18b20 success.\r\n");
49
50 read(fd, buff, sizeof(buff));
51 temp=((unsigned short)buff[1])<<8;
52 temp|=(unsigned short)buff[0];
53 result=0.0625*((double)temp);
54 close(fd);
55 printf("temperature is %4f \r\n", result);
56 return result;
57 }
58
59 int main (int argc, char **argv)
60 {
61 double temperature;
62 int sockfd;
63 char temp[25];
64 char sendline[MAXLINE];
65 struct sockaddr_in servaddr;
66
67 if(argc != 2) //主函数中需要获得服务器的地址作为第二参数
68 {
69 printf("usage: ./client <ipaddress>.\n");
70 return 0;
71 }
72
73 if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) //如果打开失败则打印错误并返回
74 {
75 printf("create socket error: %s(errno: %d).\n", strerror(errno), errno);
76 return 0;
77 }
78
79 memset(&servaddr, 0, sizeof(servaddr));
80 servaddr.sin_family = AF_INET;
81 servaddr.sin_port = htons(6666);
82 if(inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0) //将点分十进制ip转换为点分二进制ip
83 {
84 printf("inet_pton error for %s.\n", argv[1]);
85 return 0;
86 }
87
88 if(connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0) //建立连接
89 {
90 printf("connect error: %s(errno: %d)\n", strerror(errno), errno);
91 return 0;
92 }
93
94 temperature = get_tem(); //获取温度
95 gcvt(temperature, 4, temp); //将浮点型数转换为字符串
96 memset(sendline, 0, sizeof(sendline));
97 strcpy(sendline, temp);
98 if(send(sockfd, sendline, strlen(sendline), 0) < 0)
99 {
100 printf("send msg error: %s(errno: %d)\n", strerror(errno), errno);
101 return 0;
102 }
103
104 close(sockfd);
105 return 0;
106 } /* ----- End of main() ----- */
三、服务器端代码
1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<string.h>
4 #include<errno.h>
5 #include<sys/types.h>
6 #include<sys/socket.h>
7 #include<netinet/in.h>
8 #include <sys/time.h>
9 #include<time.h>
10
11 #define MAXLINE 4096
12
13 int main(int argc, char** argv)
14 {
15 int n;
16 int listenfd;
17 int connfd;
18 char buff[4096];
19 struct sockaddr_in servaddr;
20
21 if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1 ) //打开socket，若失败则打印失败信息并返回
22 {
23 printf("create socket error: %s(errno: %d)\n",strerror(errno),errno);
24 exit(0);
25 }
26
27 memset(&servaddr, 0, sizeof(servaddr));
28 servaddr.sin_family = AF_INET;
29 servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
30 servaddr.sin_port = htons(6666);
31
32 if(bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) == -1)
33 {
34 printf("bind socket error: %s(errno: %d)\n",strerror(errno),errno);
35 exit(0);
36 }
37
38 if(listen(listenfd, 10) == -1) //监听串口
39 {
40 printf("listen socket error: %s(errno: %d)\n",strerror(errno),errno);
41 exit(0);
42 }
43
44 printf("======waiting for client's request======\n");
45 while(1)
46 {
47 memset(buff, 0, sizeof(buff));
48 time_t rawtime;
49 struct tm* timeinfo;
50 char timE[80];
51 time(&rawtime);
52 timeinfo=localtime(&rawtime);
53 strftime(timE,80,"%y-%m-%d %I:%M:%S",timeinfo); //获取系统时间
54
55 if((connfd = accept(listenfd, (struct sockaddr*)NULL, NULL)) == -1)
56 {
57 printf("accept socket error: %s(errno: %d)",strerror(errno),errno);
58 continue;
59 }
60 n = recv(connfd, buff, MAXLINE, 0); //从客户端获取数据，并返回数据大小
61 strcat(buff, "℃\0");
62 printf("the degrees is: %s %s\n", buff, timE);
63 close(connfd);
64 }
65 close(listenfd);
66 }