在本文中，将探讨如何在Apache模块中添加第一个C++类，从而从Apache C的世界迈向C++领域。
C++
EXTERN_C_FUNC
int
foo_handler( request_rec* inpRequest )
{
int
nReturnVal = DECLINED;
if
( inpRequest-
>
handler != NULL && strcmp( inpRequest-
>
handler,
"
foo"
) ==
0
{
ap_rputs(
"
Hello World from FOO"
, inpRequest );
nReturnVal = OK;
}
return
nReturnVal;
}
首先要注意的是，处理器是通过指向ApacheAPI请求记录的指针request_rec* inpRequest来调用的。反过来，该指针用于获取一些数据（处理器名称，“foo”）并用于输出（在ap_rputs()函数中）。现在让介绍第一个类CApplication。在Netbeans项目中创建以下两个文件：
头文件 > 应用程序 > CApplication.hpp
源文件 > 应用程序 > CApplication.cpp
现在在这些文件中，代码如下：
CApplication.hpp
C++
#ifndef CAPPLICATION_HPP
#define CAPPLICATION_HPP
#include
"
mod_foo.hpp"
class
CApplication
{
private:
request_rec* m_pRequestRec;
public:
CApplication( request_rec* inpRequestRec ) :
m_pRequestRec( inpRequestRec )
{}
int
RunHandler();
};
#endif /* CAPPLICATION_HPP */
CApplication.cpp
C++
#include
"
CApplication.hpp"
int
CApplication::RunHandler()
{
int
nReturnVal = DECLINED;
if
( inpRequest-
>
handler != NULL && strcmp( inpRequest-
>
handler,
"
foo"
) ==
0
{
ap_rputs(
"
Hello World from FOO"
, inpRequest );
nReturnVal = OK;
}
return
nReturnVal;
}
如所见，核心功能已从foo_handler()转移到CApplication::RunHandler()。现在所要做的就是回到mod_foo.cpp并更改它以创建应用程序实例并调用它的CApplication::RunHandler()方法（注意，添加了注释来描述每个部分的作用）：
C++
#include
"
mod_foo.hpp"
#include
"
CApplication.hpp"
/*
Custom definition to hold any configuration data we may need.
At this stage we just use it to keep a copy of the CApplication
object pointer. Later we will add more when we need specific custom
configuration information. */
EXTERN_C_BLOCK_BEGIN
typedef
struct
{
void
* vpCApplication;
}
FOOCONFIG_t;
EXTERN_C_BLOCK_END
/*
Forward reference to our custom function to save the FOOCONFIG_t*
configuration pointer with Apache. */
EXTERN_C_FUNC
void
foo_register_config_ptr( request_rec* inpRequest, FOOCONFIG_t* inpFooConfig );
/*
Forward reference to our custom function to get the FOOCONFIG_t*
configuration pointer when we need it. */
EXTERN_C_FUNC
FOOCONFIG_t* foo_get_config_ptr( request_rec* inpRequest );
/*
Custom function to ensure our CApplication get's deleted at the
end of the request cycle. */
EXTERN_C_FUNC
apr_status_t foo_delete_capplication_object(
void
* inPtr )
{
if
( inPtr )
delete
( CApplication* )inPtr;
return
OK;
}
/*
Our custom handler (content generator)
*/
EXTERN_C_FUNC
int
foo_handler( request_rec* inpRequest )
{
/*
Create an instance of our application. */
CApplication* pApp =
new
CApplication( inpRequest );
if
( pApp == NULL )
return
HTTP_SERVICE_UNAVAILABLE;
/*
Register a C function to delete pApp
at the end of the request cycle. */
apr_pool_cleanup_register(
inpRequest-
>
pool,
(
void
* )pApp,
foo_delete_capplication_object,
apr_pool_cleanup_null
);
/*
Reserve a temporary memory block from the
request pool to store data between hooks. */
FOOCONFIG_t* pFooConfig =
( FOOCONFIG_t* ) apr_palloc(
inpRequest-
>
pool,
sizeof
( FOOCONFIG_t ) );
/*
Remember our application pointer for future calls. */
pFooConfig-
>
vpCApplication = (
void
* )pApp;
/*
Register our config data structure for our module. */
foo_register_config_ptr( inpRequest, pFooConfig );
/*
Run our application handler. */
return
pApp-
>
RunHandler();
}
/*
Apache callback to register our hooks.
*/
EXTERN_C_FUNC
void
foo_hooks( apr_pool_t* inpPool )
{
ap_hook_handler( foo_handler, NULL, NULL, APR_HOOK_MIDDLE );
}
/*
Our standard module definition.
*/
EXTERN_C_BLOCK_BEGIN
module AP_MODULE_DECLARE_DATA foo_module =
{
STANDARD20_MODULE_STUFF,
NULL,
NULL,
NULL,
NULL,
NULL,
foo_hooks
};
EXTERN_C_BLOCK_END
/*
Custom function to register our FOOCONFIG_t* pointer with Apache
for retrieval later as required. */
EXTERN_C_FUNC
void
foo_register_capplication_ptr( request_rec* inpRequest, FOOCONFIG_t* inpPtr )
{
ap_set_module_config( inpRequest-
>
request_config, &foo_module, (
void
* )inpPtr );
}
/*
Custom function to retrieve our FOOCONFIG_t* pointer previously
registered with Apache on this request cycle. */
EXTERN_C_FUNC
FOOCONFIG_t* foo_get_capplication_ptr( request_rec* inpRequest )
{
FOOCONFIG_t* pReturnValue = NULL;
if
( inpRequest != NULL )
{
pReturnValue =
( FOOCONFIG_t* )ap_get_module_config(
inpRequest-
>
request_config, &foo_module );
}
return
pReturnValue;
}
如所见，已经从C函数foo_handler()过渡到C++的CApplication::RunHandler()，并且已经进入了C++的世界。在处理器中，创建了应用程序的新实例。
为了确保应用程序不会泄漏内存，一个C清理函数已注册到request_rec->pool垃圾收集系统，该系统负责在请求周期结束时调用delete应用程序指针pApp。