linux读取字符设备-键盘、扫码枪、二维码设备
原理：
1.扫描/proc/bus/input/devices看你的设备是否在系统中
2.解析cat /proc/bus/input/devices输出的信息，查看event的id
3.根据event id去组装/dev/input/event你的id
4.用open和read去读取event里面的输入
5.将二进制数据翻译成字符，翻译方法：input-event-codes.h中的宏定义去匹配
代码见下：
#ifndef CQRDEVICE_H
#define CQRDEVICE_H
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
using namespace std;
#define ERR printf
#define RTM printf
#define MAXSSDPSIZE 1024
class CQRDevice
{
public:
CQRDevice();
void FindQRUsb();
void ReadQRUsb();
bool TransKey( bool bShift,unsigned short k,char & c );
bool m_bQuit;
bool m_bOpenSerial;
bool m_bInitSerial;
bool m_bFindQRUsb;
string m_strData;
string m_strEvent;
std::mutex m_mx;
list m_list;
};
#endif // CQRDEVICE_H
#include "cqrdevice.h"
CQRDevice::CQRDevice()
{
}
void CQRDevice::ReadQRUsb()
{
int keys_fd=open(m_strEvent.c_str(),O_RDONLY);
if(keys_fd<=0)
{
ERR("open %s failed",m_strEvent.c_str());
return ;
}
else
{
RTM("Open %s success",m_strEvent.c_str());
}
bool bShift=false;
m_bQuit=false;
while(!m_bQuit)
{
struct input_event ev_temp;
// ev_temp.time.tv_sec=time(0);
// ev_temp.time.tv_usec=0;
ev_temp.type=EV_KEY;
//this_thread::sleep_for(chrono::milliseconds(1));
int nRet = read(keys_fd, &ev_temp, sizeof(struct input_event));
if( nRet <=0 )
{
this_thread::sleep_for(chrono::milliseconds(1));
continue;
}
if( ev_temp.type != EV_KEY )
{
this_thread::sleep_for(chrono::milliseconds(1));
continue;
}
//printf("ret=%d,t=%d,v=%d,c=%d\n",nRet,ev_temp.type,ev_temp.value,ev_temp.code);
if( ev_temp.code== KEY_LEFTSHIFT )
{
if( ev_temp.value == 1)
bShift=true;
else
bShift=false;
}
if( ev_temp.value== 1 &&ev_temp.code != KEY_LEFTSHIFT )
{
char c;
if( TransKey( bShift,ev_temp.code,c ) )
{
//printf("trans key=%c\n",c);
m_strData += c;
}
//RTM("key=0x%d,trans=%c",ev_temp.code,c);
}
if( ev_temp.value==1 && ev_temp.code== KEY_ENTER )//回车
{
if( m_strData.size()>10 )
{
m_mx.lock();
m_list.push_back(m_strData );
RTM("data =%s,list=%d",m_strData.c_str(),m_list.size());
m_mx.unlock();
}
m_strData.clear();
}
}
close(keys_fd);
}
void CQRDevice::FindQRUsb()
{
FILE *fp;
char path[1035];
string strDevice;
/* Open the command for reading. */
fp = popen("/bin/cat /proc/bus/input/devices", "r");
if (fp == NULL)
{
ERR("Failed to run command\n" );
return;
}
/* Read the output a line at a time - output it. */
bool bGet1=false;
while (fgets(path, sizeof(path)-1, fp) != NULL)
{
strDevice += path;
RTM( path );
if( strstr(path,"N: Name=") )
{
if( strstr(path,"dwc2-gadget HID Gadget") )
{
RTM("have wc2-gadget HID Gadget str");
bGet1=true;
}
else
{
RTM("no wc2-gadget HID Gadget str");
bGet1=false;
}
}
else
{
}
if( bGet1 )
{
char *p1=strstr(path,"kbd");
char *p2=strstr(path,"leds");
if( p1&&p2 )
{
string str;
str.assign(path);
int nPos3 = str.find("event");
if( nPos3 >=0 )
{
str = str.substr(nPos3);
int nPos4 = str.find(" ");
if( nPos4 >=0 )
{
str = str.substr(0,nPos4);
m_strEvent="/dev/input/";
m_strEvent+=str;
m_bFindQRUsb=true;
}
}
}
else
{
}
}
//printf("%s", path);
}
/* close */
pclose(fp);
}
bool CQRDevice::TransKey( bool bShift,unsigned short k,char & c )
{
//printf("bshift=%d,k=%d\n",bShift,k);
switch( k )
{
case KEY_1:
if( bShift ) c='!';else c='1';
break;
case KEY_2:
if( bShift ) c='@';else c='2';
break;
case KEY_3:
if( bShift ) c='#';else c='3';
break;
case KEY_4:
if( bShift ) c='$';else c='4';
break;
case KEY_5:
if( bShift ) c='%';else c='5';
break;
case KEY_6:
if( bShift ) c='^';else c='6';
break;
case KEY_7:
if( bShift ) c='&';else c='7';
break;
case KEY_8:
if( bShift ) c='*';else c='8';
break;
case KEY_9:
if( bShift ) c='(';else c='9';
break;
case KEY_0:
if( bShift ) c=')';else c='0';
break;
case KEY_MINUS:
if( bShift ) c='_';else c='-';
break;
case KEY_EQUAL:
if( bShift ) c='+'; else c='=';
break;
case KEY_Q:
c='q';
if( bShift ) c -=32;
break;
case KEY_W:
c='w';
if( bShift ) c -=32;
break;
case KEY_E:
c='e';
if( bShift ) c -=32;
break;
case KEY_R:
c='r';
if( bShift ) c -=32;
break;
case KEY_T:
c='t';
if( bShift ) c -=32;
break;
case KEY_Y:
c='y';
if( bShift ) c -=32;
break;
case KEY_U:
c='u';
if( bShift ) c -=32;
break;
case KEY_I:
c='i';
if( bShift ) c -=32;
break;
case KEY_O:
c='o';
if( bShift ) c -=32;
break;
case KEY_P:
c='p';
if( bShift ) c -=32;
break;
case KEY_A:
c='a';
if( bShift ) c -=32;
break;
case KEY_S:
c='s';
if( bShift ) c -=32;
break;
case KEY_D:
c='d';
if( bShift ) c -=32;
break;
case KEY_F:
c='f';
if( bShift ) c -=32;
break;
case KEY_G:
c='g';
if( bShift ) c -=32;
break;
case KEY_H:
c='h';
if( bShift ) c -=32;
break;
case KEY_J:
c='j';
if( bShift ) c -=32;
break;
case KEY_K:
c='k';
if( bShift ) c -=32;
break;
case KEY_L:
c='l';
if( bShift ) c -=32;
break;
case KEY_SEMICOLON:
if( bShift ) c=':';else c=';';
break;
case KEY_APOSTROPHE:
if( bShift ) c='\＂';else c='\'';
break;
case KEY_BACKSLASH:
if( bShift ) c='|';else c='\\';
break;
case KEY_Z:
c='z';
if( bShift ) c -=32;
break;
case KEY_X:
c='x';
if( bShift ) c -=32;
break;
case KEY_C:
c='c';
if( bShift ) c -=32;
break;
case KEY_V:
c='v';
if( bShift ) c -=32;
break;
case KEY_B:
c='b';
if( bShift ) c -=32;
break;
case KEY_N:
c='n';
if( bShift ) c -=32;
break;
case KEY_M:
c='m';
if( bShift ) c -=32;
break;
case KEY_COMMA:
if( bShift ) c='<';c=',';
break;
case KEY_DOT:
if( bShift ) c='>';c='.';
break;
case KEY_SLASH:
if( bShift ) c='?';c='/';
break;
default:
//printf("######################error key code=%d##########################\n",k);
return false;
}
return true;
}