一、簡介

Apache HTTP服務器是一個模塊化的軟件，使管理者可以選擇核心中包含的模塊以裁剪功能。可以在編譯時選擇被靜態包含進httpd二進制映象的模塊，也可以編譯成獨立于主httpd二進制映象的動態共享對象DSO，DSO模塊可以在編譯服務器之后編譯，也可以用Apache擴展工具(apxs)編譯并增加。

Apache模塊開發主要采用掛鉤子的方法來實現模塊開發的，這和linux內核模塊開發有點像，說白了就是加一個回調函數。

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二、安裝Apache的apxs

apxs是一個為Apache HTTP服務器編譯和安裝擴展模塊的工具，用于編譯一個或多個源程序或目標代碼文件為動態共享對象，使之可以用由mod_so提供的LoadModule指令在運行時加載到Apache服務器中。
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apxs參考文檔：http://lamp.linux.gov.cn/Apache/ApacheMenu/programs/apxs.html
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查看是否有httpd-devel這個包，如果沒有需要安裝

#rpm -qa | grep httpd #查看 #yum -y install httpd-devel #安裝

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三、開發實例

程序1：apache模塊開發之內容生成器

執行以下命令，將生成helloworld的模板

apxs -g -n helloworld

生成的代碼如下：

/* ** mod_helloworld.c -- Apache sample helloworld module ** [Autogenerated via ``apxs -n helloworld -g''] ** ** To play with this sample module first compile it into a ** DSO file and install it into Apache's modules directory ** by running: ** ** $ apxs -c -i mod_helloworld.c ** ** Then activate it in Apache's httpd.conf file for instance ** for the URL /helloworld in as follows: ** ** # httpd.conf ** LoadModule helloworld_module modules/mod_helloworld.so ** <Location /helloworld> ** SetHandler helloworld ** </Location> ** ** Then after restarting Apache via ** ** $ apachectl restart ** ** you immediately can request the URL /helloworld and watch for the ** output of this module. This can be achieved for instance via: ** ** $ lynx -mime_header http://localhost/helloworld ** ** The output should be similar to the following one: ** ** HTTP/1.1 200 OK ** Date: Tue, 31 Mar 1998 14:42:22 GMT ** Server: Apache/1.3.4 (Unix) ** Connection: close ** Content-Type: text/html ** ** The sample page from mod_helloworld.c */ #include "httpd.h" #include "http_config.h" #include "http_protocol.h" #include "ap_config.h"/* The sample content handler */ static int helloworld_handler(request_rec *r) {if (strcmp(r->handler, "helloworld")) {return DECLINED;}r->content_type = "text/html"; if (!r->header_only)ap_rputs("The sample page from mod_helloworld.c\n", r);return OK; }static void helloworld_register_hooks(apr_pool_t *p) {ap_hook_handler(helloworld_handler, NULL, NULL, APR_HOOK_MIDDLE); }/* Dispatch list for API hooks */ module AP_MODULE_DECLARE_DATA helloworld_module = {STANDARD20_MODULE_STUFF, NULL, /* create per-dir config structures */NULL, /* merge per-dir config structures */NULL, /* create per-server config structures */NULL, /* merge per-server config structures */NULL, /* table of config file commands */helloworld_register_hooks /* register hooks */ };

編譯

apxs -c mod_helloworld.c

安裝

apxs -i mod_helloworld.la

修改配置文件httpd.conf，以加載模塊，主要添加如下內容

LoadModule helloworld_module modules/mod_helloworld.so <Location /helloworld>SetHandler helloworld </Location>

重啟服務器，進行測試

apachectl -k stop #停止apachectl -k start #啟動

在瀏覽器中輸入url,即可看到效果

http://127.0.0.1/helloworld

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程序2：apache模塊開發之輸出過濾器

對于過濾器，有輸入過濾器與輸出過濾器兩種，有下面的順序：

請求－－輸入過濾器－－內容生成器－－輸出過濾器－－響應
所有的請求都會經過我們的過濾器，所以我們可以對這些進行操作，比如統計流量、數據壓縮等。下面示例可把頁面中所有的小寫字母變成大寫字母。

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/** * @file: mod_casefilter.c * @brief: 把頁面中所有的小寫字母變成大寫字母 */?#include "httpd.h" #include "http_config.h" #include "apr_buckets.h" #include "apr_general.h" #include "apr_lib.h" #include "util_filter.h" #include "http_request.h"#include <ctype.h>static const char s_szCaseFilterName[]="CaseFilter"; module AP_MODULE_DECLARE_DATA case_filter_module;typedef struct {int bEnabled; } CaseFilterConfig;static void *CaseFilterCreateServerConfig(apr_pool_t *p,server_rec *s) {CaseFilterConfig *pConfig=apr_pcalloc(p,sizeof *pConfig);pConfig->bEnabled=0;return pConfig; }static void CaseFilterInsertFilter(request_rec *r) {CaseFilterConfig *pConfig=ap_get_module_config(r->server->module_config,&case_filter_module);if (!pConfig->bEnabled)return;ap_add_output_filter(s_szCaseFilterName,NULL,r,r->connection); }static apr_status_t CaseFilterOutFilter(ap_filter_t *f,apr_bucket_brigade *pbbIn) {request_rec *r = f->r;conn_rec *c = r->connection;apr_bucket *pbktIn;apr_bucket_brigade *pbbOut;pbbOut=apr_brigade_create(r->pool, c->bucket_alloc);for (pbktIn = APR_BRIGADE_FIRST(pbbIn);pbktIn != APR_BRIGADE_SENTINEL(pbbIn);pbktIn = APR_BUCKET_NEXT(pbktIn)){const char *data;apr_size_t len;char *buf;apr_size_t n;apr_bucket *pbktOut;if (APR_BUCKET_IS_EOS(pbktIn)){apr_bucket *pbktEOS=apr_bucket_eos_create(c->bucket_alloc);APR_BRIGADE_INSERT_TAIL(pbbOut,pbktEOS);continue;}/* read */apr_bucket_read(pbktIn,&data,&len,APR_BLOCK_READ);/* write */buf = apr_bucket_alloc(len, c->bucket_alloc);for (n=0 ; n < len ; ++n)buf[n] = apr_toupper(data[n]);pbktOut = apr_bucket_heap_create(buf, len, apr_bucket_free,c->bucket_alloc);APR_BRIGADE_INSERT_TAIL(pbbOut,pbktOut);}apr_brigade_cleanup(pbbIn);return ap_pass_brigade(f->next,pbbOut); }static const char *CaseFilterEnable(cmd_parms *cmd, void *dummy, int arg) {CaseFilterConfig *pConfig=ap_get_module_config(cmd->server->module_config,&case_filter_module);pConfig->bEnabled=arg;return NULL; }static const command_rec CaseFilterCmds[] = {AP_INIT_FLAG("CaseFilter", CaseFilterEnable, NULL, RSRC_CONF,"Run a case filter on this host"),{ NULL } };static void CaseFilterRegisterHooks(apr_pool_t *p) {ap_hook_insert_filter(CaseFilterInsertFilter,NULL,NULL,APR_HOOK_MIDDLE);ap_register_output_filter(s_szCaseFilterName,CaseFilterOutFilter,NULL,AP_FTYPE_RESOURCE); }module AP_MODULE_DECLARE_DATA case_filter_module = {STANDARD20_MODULE_STUFF,NULL,NULL,CaseFilterCreateServerConfig,NULL,CaseFilterCmds,CaseFilterRegisterHooks };

編譯

apxs -c mod_filter.c

安裝

apxs -i mod_filter.la

配置httpd.conf，添加如下內容：

LoadModule case_filter_module modules/mod_casefilter.soCaseFilter on

測試

總結

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