【RequestContext】关于RequestContext的一些小心得;

本文介绍如何利用RequestContext在Web应用中传递参数,并重点讲解了globalData()方法的应用,包括存放和取出参数的具体步骤。

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后台传参,一直是一个比较重要的地方,如果涉及Web,我们可以用RequestContext来帮我们传递参数,即使在不同的页面,不用的方法,只要没有新的请求产生,我们都可以用RequestContext;但是,大前提是:
没有新的请求,
没有新的请求,
没有新的请求;
重要的事情说三遍~

1、RequestContext;

我们只有通过登录,才能获取从页面拿过来的请求上下文(RequestContext):

RequestContext requestContext = securityLogin.login(info);

info是我们登录需要传递的参数,这里的Info是一个对象,包括账户和密码;你也可以自己写一个方法,把账户和密码分别传进去,然后做模拟登录;这样,登录过的requestContext才能有实质性的东西;
否则:
我们也可以创建一个新的RequestContext,来装载我们的请求参数;

RequestContext requestContext = new RequestContext();

但是,这里的requestContext里面都是null;

2、globalData();

requestContext里面有一个非常重要的方法,就是globalData(),这里我们可以通过它来传递参数,这个也是本帖子的核心;顾名思义,globalData,全局数据,就是同一个请求中的数据,都可以互通往来;

①放数据:

requestContext.globalData("name",name);

通过键值对的方式来存入数据,key-value键值对的形式来存入数据;前面是key,后面是值;
②取数据:
如果别的页面存入了数据,我这个页面要拿过来调用怎么办,这时候就直接通过键(key)来取值;

requestContext.globalData("name");

很方便;(别忘了大前提,没有新的请求产生)
一般情况,如果在requestContext.globalData();附近报null的错,或者对象的size,length不能为null,那么很有可能就是没有存值,取出来的值是null,进而数据类型不匹配;要么就是取值的时候,key跟原来要取值的key对不上,不是单词拼写错误,就是大小写错误,要么就是压根忘了存值,直接取值;这个都要避免;还要注意,取出来的数据是Object类型,取出来之后,还要进行数据类型转换;

3、基本内容简介

requestContext有8个基本的内容,分别是:
①url:请求的地址,到底去哪里获取请求的上下文;
②timeout:超时链接的上限,默认是30000ms;
③method:请求的方法,到底是GET请求,还是POST请求,到底是做自行车,还是做卡车,看具体情况定;
例如:

.method(Connection.Method.POST)

④requestBody():可以把其它的一些参数以字符串等的形式放入请求体中;
⑤cookies:这个是最重要的参数之一
可以用Jsoup.connect再接下面的代码:
例如:

.cookies(requestContext.cookies())

也可以独立写:
例如:

Map<String,String> cookies = response.cookies();
requestContext.cookies(cookies);

⑥header:请求头,可以设置上下文的类型,请求携带的其它信息等,可以类比html中的

<head>
    <meta charset="utf-8">
    <title>标题</title>
</head>

例如:

.header("Content-Type","application/x-www-form-urlencoded")
.header("X-Requested-With","XMLHttpRequest")

⑦globalData():最重要的方法之一,用来传递参数,上面讲了好多,这里参照上面即可;
⑧requestDatas():自己百度下;

/*! * ************************************************************************************************* * @copyright(c) 2008-2025 Shenzhen TP-LINK Technologies Co.Ltd. * * @file http.c * @brief * * @author huyushuai * @version 1.0.0 * @date 2025-08-08 * ************************************************************************************************* */ /**************************************************************************************************/ /* INCLUDE_FILES */ /**************************************************************************************************/ #include <stdio.h> #include <stdbool.h> #include <sys/socket.h> #include <sys/types.h> #include <netinet/in.h> #include <arpa/inet.h> #include <unistd.h> #include <ctype.h> #include <strings.h> #include <string.h> #include <sys/stat.h> #include <pthread.h> #include <sys/wait.h> #include <stdlib.h> #include <errno.h> #include <signal.h> #include <stdatomic.h> /**************************************************************************************************/ /* DEFINES */ /**************************************************************************************************/ #define ISspace(x) isspace((int)(x)) #define SERVER_STRING "Server: jdbhttpd/0.1.0\r\n" #define MAX_THREADS 100 #define DOCUMENT_ROOT "htdocs" /**************************************************************************************************/ /* TYPES */ /**************************************************************************************************/ typedef struct { pthread_t *threads; int count; atomic_int active_count; pthread_mutex_t mutex; pthread_cond_t cond; } ThreadPool; typedef struct { int client_sock; struct sockaddr_in client_addr; } RequestContext; ThreadPool *thread_pool = NULL; /**************************************************************************************************/ /* LOCAL_PROTOTYPES */ /**************************************************************************************************/ void *worker_thread(void *arg); void accept_request(RequestContext *ctx); void bad_request(int client); void cat(int, FILE *); void cannot_execute(int); void error_die(const char *); void execute_cgi(int, const char *, const char *, const char *); int get_line(int, char *, int); void headers(int, const char *); void not_found(int); void serve_file(int, const char *); int startup(u_short *); void unimplemented(int); void normalize_path(char *path); const char *get_content_type(const char *path); void handle_sigpipe(int sig); ThreadPool* create_thread_pool(int size); void destroy_thread_pool(ThreadPool *pool); void submit_request(ThreadPool *pool, RequestContext *ctx); /**************************************************************************************************/ /* LOCAL_FUNCTIONS */ /**************************************************************************************************/ /*! * @brief 路径规范函数 * * @param[in] path 文件路径 */ void normalize_path(char *path) { char *p = path; char *q = path; while (*p) { if (strncmp(p, "/../", 4) == 0) { p += 3; while (q > path && *--q != '/') { ; } } else if (strncmp(p, "/./", 3) == 0) { p += 2; } else if (strncmp(p, "//", 2) == 0) { p += 1; } else { *q++ = *p++; } } *q = '\0'; } /*! * @brief 忽略SIGPIPE信号处理 * * @param[in] sig SIGPIPE信号 */ void handle_sigpipe(int sig) { } /*! * @brief 创建线程池 * * @param[in] size 大小 * @return ThreadPool* */ ThreadPool* create_thread_pool(int size) { ThreadPool *pool = malloc(sizeof(ThreadPool)); if (!pool) { return NULL; } pool->threads = malloc(sizeof(pthread_t) * size); if (!pool->threads) { free(pool); return NULL; } pool->count = size; pool->active_count = 0; pthread_mutex_init(&pool->mutex, NULL); pthread_cond_init(&pool->cond, NULL); for (int i = 0; i < size; i++) { if (pthread_create(&pool->threads[i], NULL, worker_thread, pool) != 0) { perror("Failed to create thread"); destroy_thread_pool(pool); return NULL; } } return pool; } // 销毁线程池 void destroy_thread_pool(ThreadPool *pool) { if (!pool) { return; } // 通知所有线程退出 for (int i = 0; i < pool->count; i++) { pthread_cancel(pool->threads[i]); } // 等待所有线程结束 for (int i = 0; i < pool->count; i++) { pthread_join(pool->threads[i], NULL); } free(pool->threads); pthread_mutex_destroy(&pool->mutex); pthread_cond_destroy(&pool->cond); free(pool); } /*! * @brief 提交请求到线程池 * * @param[in] pool 线程池 * @param[in] ctx 请求 */ void submit_request(ThreadPool *pool, RequestContext *ctx) { pthread_mutex_lock(&pool->mutex); while (pool->active_count >= pool->count) { pthread_cond_wait(&pool->cond, &pool->mutex); } atomic_fetch_add(&pool->active_count, 1); pthread_mutex_unlock(&pool->mutex); pthread_t thread; if (pthread_create(&thread, NULL, (void *(*)(void *))accept_request, ctx) != 0) { perror("Failed to create request thread"); close(ctx->client_sock); free(ctx); atomic_fetch_sub(&pool->active_count, 1); pthread_cond_signal(&pool->cond); } else { pthread_detach(thread); } } // 工作线程函数 void *worker_thread(void *arg) { ThreadPool *pool = (ThreadPool *)arg; while (1) { // 线程池管理逻辑 sleep(1); // 简化实现,实际应有任务队列 } return NULL; } /**********************************************************************/ /* A request has caused a call to accept() on the server port to * return. Process the request appropriately. * Parameters: the socket connected to the client */ /**********************************************************************/ void accept_request(RequestContext *ctx) { int client = ctx->client_sock; char buf[1024]; char method[255]; char url[255]; char path[512]; struct stat st; int cgi = 0; char *query_string = NULL; int numchars = get_line(client, buf, sizeof(buf)); size_t i = 0; size_t j = 0; while (!ISspace(buf[j]) && (i < sizeof(method) - 1)) { method[i] = buf[j]; i++; j++; } method[i] = '\0'; // 只支持GET和POST方法 if (strcasecmp(method, "GET") && strcasecmp(method, "POST")) { unimplemented(client); close(client); free(ctx); return; } // POST请求启用CGI if (strcasecmp(method, "POST") == 0) { cgi = 1; } i = 0; while (ISspace(buf[j]) && (j < sizeof(buf))) { j++; } while (!ISspace(buf[j]) && (i < sizeof(url) - 1) && (j < sizeof(buf))) { url[i] = buf[j]; i++; j++; } url[i] = '\0'; // 处理GET查询参数 if (strcasecmp(method, "GET") == 0) { query_string = url; while ((*query_string != '?') && (*query_string != '\0')) query_string++; if (*query_string == '?') { cgi = 1; *query_string = '\0'; query_string++; } } // 构建安全路径 if (strlen(url) == 0 || strstr(url, "..") != NULL) { bad_request(client); close(client); free(ctx); return; } snprintf(path, sizeof(path), "%s%s", DOCUMENT_ROOT, url); normalize_path(path); // 确保路径在文档根目录内 if (strncmp(path, DOCUMENT_ROOT, strlen(DOCUMENT_ROOT)) != 0) { not_found(client); close(client); free(ctx); return; } // 默认索引文件 if (path[strlen(path) - 1] == '/') { strncat(path, "index.html", sizeof(path) - strlen(path) - 1); } // 检查文件状态 if (stat(path, &st) == -1) { // 丢弃剩余头部 while ((numchars > 0) && strcmp("\n", buf) != 0) { numchars = get_line(client, buf, sizeof(buf)); } not_found(client); } else { if (S_ISDIR(st.st_mode)) { strncat(path, "/index.html", sizeof(path) - strlen(path) - 1); stat(path, &st); // 重新获取状态 } if ((st.st_mode & S_IXUSR) || (st.st_mode & S_IXGRP) || (st.st_mode & S_IXOTH)) { cgi = 1; } if (!cgi) { serve_file(client, path); } else { execute_cgi(client, path, method, query_string); } } /* 清理资源 */ close(client); free(ctx); /* 更新线程池状态 */ if (thread_pool) { atomic_fetch_sub(&thread_pool->active_count, 1); pthread_cond_signal(&thread_pool->cond); } } /**********************************************************************/ /* Inform the client that a request it has made has a problem. * Parameters: client socket */ /**********************************************************************/ void bad_request(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 400 BAD REQUEST\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "\r\n"); send(client, buf, sizeof(buf), 0); sprintf(buf, "<P>Your browser sent a bad request, "); send(client, buf, sizeof(buf), 0); sprintf(buf, "such as a POST without a Content-Length.\r\n"); send(client, buf, sizeof(buf), 0); } /*! * @brief 将文件内容发送到网络客户端 * * @param[in] client 客户端套接字描述符 * @param[in] resource 文件指针(指向要发送的文件) */ void cat(int client, FILE *resource) { char buf[1024]; size_t bytes_read; while ((bytes_read = fread(buf, 1, sizeof(buf), resource)) > 0) { if (send(client, buf, bytes_read, 0) < bytes_read) { perror("send"); break; } } } /**********************************************************************/ /* Inform the client that a CGI script could not be executed. * Parameter: the client socket descriptor. */ /**********************************************************************/ void cannot_execute(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 500 Internal Server Error\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<P>Error prohibited CGI execution.\r\n"); send(client, buf, strlen(buf), 0); } /**********************************************************************/ /* Print out an error message with perror() (for system errors; based * on value of errno, which indicates system call errors) and exit the * program indicating an error. */ /**********************************************************************/ void error_die(const char *sc) { perror(sc); exit(1); } /**********************************************************************/ /* Execute a CGI script. Will need to set environment variables as * appropriate. * Parameters: client socket descriptor * path to the CGI script */ /**********************************************************************/ void execute_cgi(int client, const char *path, const char *method, const char *query_string) { // 缓冲区 char buf[1024]; int cgi_output[2]; int cgi_input[2]; pid_t pid; int status; int i = 0; char c; int numchars = 1; int content_length = -1; // 默认字符 buf[0] = 'A'; buf[1] = '\0'; // 忽略大小写比较字符串 if (strcasecmp(method, "GET") == 0) { while ((numchars > 0) && strcmp("\n", buf)) /* read & discard headers */ { numchars = get_line(client, buf, sizeof(buf)); } } else /* POST */ { numchars = get_line(client, buf, sizeof(buf)); while ((numchars > 0) && strcmp("\n", buf)) { buf[15] = '\0'; if (strcasecmp(buf, "Content-Length:") == 0) { content_length = atoi(&(buf[16])); } numchars = get_line(client, buf, sizeof(buf)); } if (content_length == -1) { bad_request(client); return; } } sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); /* 建立output管道 */ if (pipe(cgi_output) < 0) { cannot_execute(client); return; } /* 建立input管道 */ if (pipe(cgi_input) < 0) { cannot_execute(client); return; } if ((pid = fork()) < 0) { cannot_execute(client); return; } if (pid == 0) /* child: CGI script */ { char meth_env[255]; char query_env[255]; char length_env[255]; // 子进程输出重定向到output管道的1端 dup2(cgi_output[1], 1); // 子进程输入重定向到input管道的0端 dup2(cgi_input[0], 0); // 关闭无用管道口 close(cgi_output[0]); close(cgi_input[1]); // CGI环境变量 sprintf(meth_env, "REQUEST_METHOD=%s", method); putenv(meth_env); if (strcasecmp(method, "GET") == 0) { sprintf(query_env, "QUERY_STRING=%s", query_string); putenv(query_env); } else { /* POST */ sprintf(length_env, "CONTENT_LENGTH=%d", content_length); putenv(length_env); } // 替换执行path execl(path, path, NULL); // int m = execl(path, path, NULL); // 如果path有问题,例如将html网页改成可执行的,但是执行后m为-1 // 退出子进程,管道被破坏,但是父进程还在往里面写东西,触发Program received signal SIGPIPE, Broken pipe. exit(0); } else { /* parent */ close(cgi_output[1]); close(cgi_input[0]); if (strcasecmp(method, "POST") == 0) { for (i = 0; i < content_length; i++) { recv(client, &c, 1, 0); ssize_t bytes_written = write(cgi_input[1], &c, 1); if (bytes_written <= 0) { perror("Failed to write to CGI"); close(cgi_input[1]); close(cgi_input[0]); break; } } } while (read(cgi_output[0], &c, 1) > 0) { send(client, &c, 1, 0); } close(cgi_output[0]); close(cgi_input[1]); waitpid(pid, &status, 0); } } /**********************************************************************/ /* Get a line from a socket, whether the line ends in a newline, * carriage return, or a CRLF combination. Terminates the string read * with a null character. If no newline indicator is found before the * end of the buffer, the string is terminated with a null. If any of * the above three line terminators is read, the last character of the * string will be a linefeed and the string will be terminated with a * null character. * Parameters: the socket descriptor * the buffer to save the data in * the size of the buffer * Returns: the number of bytes stored (excluding null) */ /**********************************************************************/ // 得到一行数据,只要发现c为\n,就认为是一行结束,如果读到\r,再用MSG_PEEK的方式读入一个字符,如果是\n,从socket用读出 // 如果是下个字符则不处理,将c置为\n,结束。如果读到的数据为0中断,或者小于0,也视为结束,c置为\n /*! * @brief 从socket中获取一行数据 * * @param[in] sock socket * @param[in] buf 用于保存数据的缓冲区 * @param[in] size 缓冲区的大小 * @return int 存储的字节数 */ int get_line(int sock, char *buf, int size) { int i = 0; char c = '\0'; int n; while ((i < size - 1) && (c != '\n')) { n = recv(sock, &c, 1, 0); if (n > 0) { if (c == '\r') { n = recv(sock, &c, 1, MSG_PEEK); if ((n > 0) && (c == '\n')) { recv(sock, &c, 1, 0); } else { c = '\n'; } } buf[i] = c; i++; } else c = '\n'; } buf[i] = '\0'; return (i); } /*! * @brief 根据文件路径的扩展名返回对应的 MIME 类型 * * @param[in] path 路径字符串 * @return const char* */ const char *get_content_type(const char *path) { const char *ext = strrchr(path, '.'); if (ext) { if (strcasecmp(ext, ".css") == 0) { return "text/css"; } if (strcasecmp(ext, ".js") == 0) { return "application/javascript"; } if (strcasecmp(ext, ".png") == 0) { return "image/png"; } if (strcasecmp(ext, ".jpg") == 0 || strcasecmp(ext, ".jpeg") == 0) { return "image/jpeg"; } if (strcasecmp(ext, ".gif") == 0) { return "image/gif"; } if (strcasecmp(ext, ".ico") == 0) { return "image/x-icon"; } if (strcasecmp(ext, ".svg") == 0) { return "image/svg+xml"; } if (strcasecmp(ext, ".woff") == 0) { return "font/woff"; } if (strcasecmp(ext, ".woff2") == 0) { return "font/woff2"; } } return "text/html"; } /*! * @brief 发送HTTP响应头 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void headers(int client, const char *filename) { char buf[1024]; const char *content_type = get_content_type(filename); sprintf(buf, "HTTP/1.0 200 OK\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: %s\r\n", content_type); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 404 * * @param[in] client 客户端 */ void not_found(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 404 NOT FOUND\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><TITLE>Not Found</TITLE>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY><P>The server could not fulfill\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "your request because the resource specified\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "is unavailable or nonexistent.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } /*! * @brief 如果不是CGI文件,直接读取文件返回给请求的http客户端 * * @param[in] client 客户端 * @param[in] filename 文件名 */ void serve_file(int client, const char *filename) { FILE *resource = NULL; int numchars = 1; char buf[1024]; buf[0] = 'A'; buf[1] = '\0'; while ((numchars > 0) && strcmp("\n", buf)) { numchars = get_line(client, buf, sizeof(buf)); } resource = fopen(filename, "rb"); if (resource == NULL) { not_found(client); } else { headers(client, filename); cat(client, resource); } fclose(resource); } /**********************************************************************/ /* This function starts the process of listening for web connections * on a specified port. If the port is 0, then dynamically allocate a * port and modify the original port variable to reflect the actual * port. * Parameters: pointer to variable containing the port to connect on * Returns: the socket */ /**********************************************************************/ int startup(u_short *port) { int httpd = 0; struct sockaddr_in name; httpd = socket(PF_INET, SOCK_STREAM, 0); if (httpd == -1) { error_die("socket"); } memset(&name, 0, sizeof(name)); name.sin_family = AF_INET; name.sin_port = htons(*port); name.sin_addr.s_addr = htonl(INADDR_ANY); if (bind(httpd, (struct sockaddr *)&name, sizeof(name)) < 0) { error_die("bind"); } if (*port == 0) { socklen_t namelen = sizeof(name); if (getsockname(httpd, (struct sockaddr *)&name, &namelen) == -1) { error_die("getsockname"); } *port = ntohs(name.sin_port); } if (listen(httpd, 5) < 0) { error_die("listen"); } return (httpd); } /*! * @brief 没有实现请求 * * @param[in] client 客户端 */ void unimplemented(int client) { char buf[1024]; sprintf(buf, "HTTP/1.0 501 Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, SERVER_STRING); send(client, buf, strlen(buf), 0); sprintf(buf, "Content-Type: text/html\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<HTML><HEAD><TITLE>Method Not Implemented\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</TITLE></HEAD>\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "<BODY><P>HTTP request method not supported.\r\n"); send(client, buf, strlen(buf), 0); sprintf(buf, "</BODY></HTML>\r\n"); send(client, buf, strlen(buf), 0); } int main(void) { int server_sock = -1; u_short port = 80; // 使用8080端口避免权限问题 struct sockaddr_in client_name; socklen_t client_name_len = sizeof(client_name); // 设置信号处理 signal(SIGPIPE, handle_sigpipe); // 创建线程池 thread_pool = create_thread_pool(MAX_THREADS); if (!thread_pool) { fprintf(stderr, "Failed to create thread pool\n"); exit(EXIT_FAILURE); } server_sock = startup(&port); printf("HTTP server running on port %d\n", port); while (1) { RequestContext *ctx = malloc(sizeof(RequestContext)); if (!ctx) { perror("malloc failed"); continue; } ctx->client_sock = accept(server_sock, (struct sockaddr *)&ctx->client_addr, &client_name_len); if (ctx->client_sock == -1) { perror("accept failed"); free(ctx); continue; } submit_request(thread_pool, ctx); } close(server_sock); destroy_thread_pool(thread_pool); return 0; } 阅读上面代码,提炼出多线程实现web_server的核心部分,(关键点在于和多进程,io多路复用的对比实现,要列出可能不同的地方)
最新发布
08-09
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