[zz]使用 Google gflags 简化命令行参数处理

（本文章仅适用于C++程序）
写服务程序时，如果需要提供命令行参数。传统的方法是手工解析argv参数，或者使用getopt函数。两种方法都比较费劲。使用Google gflags可以大大简化命令行参数处理。

安装gflag

从官方地址 http://code.google.com/p/google-gflags/下载gflags并安装。比如我下载的是1.5版本。

[yichi@yichi tmp]$ wget  http://google-gflags.googlecode.com/files/gflags-1.5.tar.gz

[yichi@yichi tmp]$ tar zxvf gflags-1.5.tar.gz

[yichi@yichi tmp]$ cd gflags

[yichi@yichi gflags-1.5]$ ./configure –prefix=$HOME/google-library

[yichi@yichi gflags-1.5]$ make j=4 & make install

使用gflags

示例代码下载地址： http://www.faithbee.com/wp-content/uploads/2011/05/gflags-sample.tar.bz2

main.cc

// Copyright (c) 2011, D-Media Communication Technology Inc.
// All rights reserved.
//
//
// ---
// Author: Yichi Zhang <[email protected]>
//
// File content description here

#include "server.h"

#include <google/gflags.h>

#include <string>

#include <stdio.h>

DEFINE_bool(memory_pool, false , "If use memory pool" );
DEFINE_bool(daemon, true , "If started as daemon" );
DEFINE_string(module_id, "" , "Server module id" );

DEFINE_int32(http_port, 80, "HTTP listen port" );
DEFINE_int32(https_port, 443, "HTTPS listen port" );

int
main( int argc, char ** argv)
{
  ::google::ParseCommandLineFlags(&argc, &argv, true );

  // XXX NOTE: Should add 'FLAGS_' prefix.
  printf ( "Server module id: %s\n" , FLAGS_module_id.c_str());

  if (FLAGS_daemon) {
    printf ( "Run as daemon: %d\n" , FLAGS_daemon);
  }
  if (FLAGS_memory_pool) {
    printf ( "Use memory pool: %d\n" , FLAGS_daemon);
  }

  Server server;

  return 0;
}

server.h

// Copyright (c) 2011, D-Media Communication Technology Inc.
// All rights reserved.
//
//
// ---
// Author: Yichi Zhang <[email protected]>
//
// File content description here

#include <google/gflags.h>

#include <stdio.h>

// Declare, defined in 'main.cc'.
DECLARE_int32(http_port);
DECLARE_int32(https_port);

class Server {
 public :
  Server() {
    // XXX NOTE: Should add 'FLAGS_' prefix.
    printf ( "HTTP listen port: %d\n" , FLAGS_http_port);
    printf ( "HTTPS listen port: %d\n" , FLAGS_https_port);
  }
  virtual ~Server() {}

 private :
  ;
};

编译示例程序

[yichi@yichi gflags-sample]$ g++ -o gflags-sample main.cc -I $HOME/google-library/include -L $HOME/google-library/lib -lgflags

运行示例程序

带参数运行

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample

Server module id:

Run as daemon: 1

HTTP listen port: 80

HTTPS listen port: 443

带参数运行，使用等号赋值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id="server_007" -daemon=true -http_port=8080 -https_port=4443

Server module id: server_007

Run as daemon: 1

HTTP listen port: 8080

HTTPS listen port: 4443

带参数运行，使用空格分割参数和值

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample -module_id "server_007" -daemon true -http_port 8080 -https_port 4443

Server module id: server_007

Run as daemon: 1

HTTP listen port: 8080

HTTPS listen port: 4443

显示帮助

[yichi@yichi gflags-sample]$ LD_LIBRARY_PATH=$HOME/google-library/lib:$LD_LIBRARY_PATH ./gflags-sample –help

gflags-sample: Warning: SetUsageMessage() never called

Flags from main.cc:

-daemon (If started as daemon) type: bool default: true

-http_port (HTTP listen port) type: int32 default: 80

-https_port (HTTPS listen port) type: int32 default: 443

-memory_pool (If use memory pool) type: bool default: false

-module_id (Server module id) type: string default: ""

参考资料

Google gflags官方文档： http://google-gflags.googlecode.com/svn/trunk/doc/gflags.html