CGI介绍

CGI（Common Gateway Interface）是一种常见的Web编程技术，可以让Web服务器调用外部程序实现动态网页。本文将介绍如何使用C语言实现一个简单的通讯录管理系统。 首先，需要在Web服务器上配置好CGI环境。这里以Apache服务器为例，可以在httpd.conf文件中添加如下配置： ``` ScriptAlias /cgi-bin/ "/usr/local/apache2/cgi-bin/" <Directory "/usr/local/apache2/cgi-bin"> AllowOverride None Options None Require all granted </Directory> ``` 这样，可以将CGI程序存放在/usr/local/apache2/cgi-bin目录下，并在Web页面中通过访问http://localhost/cgi-bin/program.cgi的方式调用程序。 接下来，编写C语言代码实现通讯录管理系统。这里使用了文件存储数据，因此需要先创建一个contacts.txt文件存放通讯录信息。 程序主要分为两部分：解析HTTP请求和处理通讯录操作。在解析HTTP请求时，需要读取请求方法、请求路径和请求参数等信息，然后根据请求路径调用相应的处理函数。在处理通讯录操作时，需要读取contacts.txt文件中的数据，并根据请求参数进行增删改查等操作。 以下是示例代码： ```c #include <stdio.h> #include <stdlib.h> #include <string.h> #define MAX_LINE 1024 // 解析HTTP请求 void parse_request(char *request_method, char *request_path, char *request_params) { char *request_body = getenv("QUERY_STRING"); if (request_body == NULL) { request_method[0] = '\0'; request_path[0] = '\0'; request_params[0] = '\0'; return; } sscanf(request_body, "%[^&]&%[^&]&%s", request_method, request_path, request_params); } // 处理添加联系人操作 void add_contact(char *params) { FILE *fp; char line[MAX_LINE]; fp = fopen("contacts.txt", "a"); if (fp == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); return; } sprintf(line, "%s\n", params); fputs(line, fp); fclose(fp); printf("Content-type: text/plain\n\n"); printf("Success"); } // 处理删除联系人操作 void delete_contact(char *params) { FILE *fp1, *fp2; char line[MAX_LINE]; int found = 0; fp1 = fopen("contacts.txt", "r"); if (fp1 == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); return; } fp2 = fopen("temp.txt", "w"); if (fp2 == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); fclose(fp1); return; } while (fgets(line, MAX_LINE, fp1) != NULL) { if (strstr(line, params) == NULL) { fputs(line, fp2); } else { found = 1; } } fclose(fp1); fclose(fp2); if (found) { remove("contacts.txt"); rename("temp.txt", "contacts.txt"); printf("Content-type: text/plain\n\n"); printf("Success"); } else { remove("temp.txt"); printf("Content-type: text/plain\n\n"); printf("Contact not found"); } } // 处理修改联系人操作 void update_contact(char *params) { FILE *fp1, *fp2; char line[MAX_LINE]; int found = 0; fp1 = fopen("contacts.txt", "r"); if (fp1 == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); return; } fp2 = fopen("temp.txt", "w"); if (fp2 == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); fclose(fp1); return; } while (fgets(line, MAX_LINE, fp1) != NULL) { if (strstr(line, params) == NULL) { fputs(line, fp2); } else { found = 1; sprintf(line, "%s\n", params); fputs(line, fp2); } } fclose(fp1); fclose(fp2); if (found) { remove("contacts.txt"); rename("temp.txt", "contacts.txt"); printf("Content-type: text/plain\n\n"); printf("Success"); } else { remove("temp.txt"); printf("Content-type: text/plain\n\n"); printf("Contact not found"); } } // 处理查询联系人操作 void query_contact(char *params) { FILE *fp; char line[MAX_LINE]; int found = 0; fp = fopen("contacts.txt", "r"); if (fp == NULL) { printf("Content-type: text/plain\n\n"); printf("Failed to open file\n"); return; } while (fgets(line, MAX_LINE, fp) != NULL) { if (strstr(line, params) != NULL) { printf("Content-type: text/plain\n\n"); printf("%s", line); found = 1; break; } } fclose(fp); if (!found) { printf("Content-type: text/plain\n\n"); printf("Contact not found"); } } int main() { char request_method[MAX_LINE], request_path[MAX_LINE], request_params[MAX_LINE]; parse_request(request_method, request_path, request_params); // 根据请求路径调用相应的处理函数 if (strcmp(request_path, "/add") == 0) { add_contact(request_params); } else if (strcmp(request_path, "/delete") == 0) { delete_contact(request_params); } else if (strcmp(request_path, "/update") == 0) { update_contact(request_params); } else if (strcmp(request_path, "/query") == 0) { query_contact(request_params); } else { printf("Content-type: text/plain\n\n"); printf("Invalid request"); } return 0; } ``` 编译并将程序命名为program.cgi，然后将其存放在/usr/local/apache2/cgi-bin目录下。此时，在Web页面中访问http://localhost/cgi-bin/program.cgi/add?name=John&phone=123456789即可添加联系人，访问http://localhost/cgi-bin/program.cgi/query?name=John即可查询联系人信息，以此类推。