为什么编写本函数库？
目前好多电力方面的抄表器由于其RAM内存及FLASH闪存的空间都比较小，没有办法象java那样调用各种基于各种大型数据库的外界jar包进行数据采集工作。为此，dbf这种简单的结构型数据库成为手选。另外，因为抄表器要求的数据格式也比较简单，选用这种结构型的最贴合实际。
基于以上两点，本人上网搜了些这方面的资料，想down一个.dbf驱动，但水平有限没找着，只好自己编写了。
直接贴代码吧：
１：HT_DBF.H，定义了.dbf的几个数据结构。
/**************************************************************
** c语言操作dbf文件
**
** 目前只支持int--N,char--C
**************************************************************/
#define MAX_INT_LENTH 20
#define MAX_FLOAT_LENTH 20
#define MAX_CHAR_LENTH 254
/***************************************************************
* 数据库表中的列声明，包含一些列属性
***************************************************************/
typedef struct field
{
char FIELD_NAME[11];
char FIELD_TYPE;
int FIELD_X;
int FIELD_Y;
unsigned char FIELD_LENTH;
unsigned char FIELD_FLOAT_LENTH;
int index;
struct field * next;
}DBF_FIELD;
/***************************************************************
* 数据库表的配置信息，包含 文件开始标志，最后更新日期，记录总数，文件头大小，记录大小，列属性链表
* 数据库文件句柄，当前记录
***************************************************************/
typedef struct {
unsigned char BEGIN_FLAG;
unsigned char LAST_UPPDATE_TIME[3];
long RECORD_COUNT;
int HEAD_SIZE;
int RECORD_SIZE;
DBF_FIELD *head;
int DBF_HANDLE;
long current;
}DBF_CONFIG;
/***************************************************************
* 数据表中的一条记录
* 为了通用性，仅用一个 void *指示
* 其中的具体内容，可以参照DBF_CONFIG中的DBF_FIELD *head进行解析
***************************************************************/
typedef struct record
{
void * value;
}DBF_RECORD;
２:HT_DBF.C，操作函数库
#define __ASM asm
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <io.h>
#include <dos.h>
#include <share.h>
#include <fcntl.h>
#include <string.h>
#include <mem.h>
#include "..\project\ht_dbf.h"
DBF_CONFIG * dbfopen(char *fname,DBF_CONFIG * db_con);
int dbfclose(DBF_CONFIG * con);
int dbfread(DBF_CONFIG * con,DBF_RECORD * record);
int dbfgetFieldByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value);
int dbfgetFieldByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value);
int dbfgetFloatByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value);
int dbfgetFloatByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value);
int dbfgetCharByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value);
int dbfgetCharByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value);
int dbfsetFieldByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value);
int dbfsetFieldByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * value);
int dbfsetFloatByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value);
int dbfsetFloatByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * value);
int dbfsetCharByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value);
int dbfsetCharByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * value);
char *ccstr( char *str);
void dbf_info();
void dbf_info()
{
char column_name[12];
DBF_FIELD *cur=NULL;
DBF_RECORD record;
float b=0.0;
float c;
char *record_value;
char ret_val[MAX_CHAR_LENTH+1];
/*打开数据库*/
DBF_CONFIG *con=dbfopen("..\\project\\CBDATA.DBF",NULL);
/*数据库配置信息*/
printf("BEGIN_FLAG:%d\n",con->BEGIN_FLAG);
printf("LAST_UPPDATE_TIME:%d",con->LAST_UPPDATE_TIME[0]);
printf(" - %d",con->LAST_UPPDATE_TIME[1]);
printf(" - %d\n",con->LAST_UPPDATE_TIME[2]);
printf("RECORD_COUNT:%d\n",con->RECORD_COUNT);
printf("HEAD_SIZE:%d\n",con->HEAD_SIZE);
printf("RECORD_SIZE:%d\n",con->RECORD_SIZE);
printf("DBF_HANDLE:%d\n",con->DBF_HANDLE);
printf("current:%d\n",con->current);
/*列信息*/
cur=con->head;
while(cur!=NULL){
strncpy(column_name,cur->FIELD_NAME,11);
column_name[11]='\0';
printf("FIELD-INFO-->NAME:%s,TYPE:%c,X:%d,Y:%d,LENTH:%d,FLOAT_LENTH:%d,index:%d\n",column_name,
cur->FIELD_TYPE,cur->FIELD_X,cur->FIELD_Y,cur->FIELD_LENTH,cur->FIELD_FLOAT_LENTH,cur->index);
cur=cur->next;
}
/*读取第2条记录*/
con->current=1;
dbfread(con,&record);
record_value=(char *)malloc(con->RECORD_SIZE+1);
memcpy(record_value,record.value,con->RECORD_SIZE);
*(record_value+con->RECORD_SIZE)='\0';
printf(record_value);
printf("\n");
dbfgetFloatByName(con,&record,"cs1",&b);
printf("A:%f\n",b);
dbfgetFloatByIndex(con,&record,2,&c);
printf("c:%f\n",c);
printf("\n");
dbfgetCharByName(con,&record,"HM",ret_val);
memset(ret_val,'\0',sizeof(ret_val));
dbfgetCharByIndex(con,&record,1,ret_val);
printf("ret_val:%s\n",ret_val);
printf("\ncurrent:%d\n",con->current);
/*改写数据库记录*/
con->current=1;
b=41.01;
//dbfsetFieldByIndex(con,&record,7,&b);
dbfsetFloatByIndex(con,&record,7,&b);
sprintf(ret_val,"%-254s","01-001-01");
dbfsetCharByName(con,&record,"bh",ret_val);
sprintf(ret_val,"%-254s","太平路1号");
dbfsetCharByName(con,&record,"dz",ret_val);
/*关闭数据库*/
dbfclose(con);
getch();
}
/**********************************************************************************************************/
/******************************************
* 打开指定文件名的文件，并初始化DBF_CONFIG。
******************************************/
DBF_CONFIG * dbfopen(char *fname,DBF_CONFIG * db_con)
{
unsigned tmp,field_x;
int fhandle;
char fhead[12];
char field_desc[32];
long pos=0;
DBF_FIELD *field=NULL;
DBF_FIELD *cur=NULL;
if(_dos_open(fname, O_RDWR, &fhandle)!=0)
{
printf("不能打开文件:%s\n",fname);
return NULL;
}
db_con = (DBF_CONFIG *)malloc(sizeof(DBF_CONFIG));
_dos_read(fhandle, fhead, 12, &tmp);
/*基本信息*/
db_con->BEGIN_FLAG=(unsigned char)fhead[0];
memcpy(db_con->LAST_UPPDATE_TIME,fhead+1,3);
db_con->RECORD_COUNT=*(long*)&fhead[4];
db_con->HEAD_SIZE=*(unsigned *)&fhead[8];
db_con->RECORD_SIZE=*(unsigned *)&fhead[10];
/*状态信息*/
db_con->DBF_HANDLE=fhandle;
db_con->current=1;
/*数据库表属性列表,Delphi3.0创建的数据库表，没有FIELD_X,FIELD_Y字段，Visial FoxPro中有。*/
/*Delphi3.0的BEGIN_FLAG=03H,Visial FoxPro的BEGIN_FLAG=30H,可据此进行以下的初始化*/
lseek(fhandle, 0L, SEEK_SET);
lseek(fhandle, 32L, SEEK_SET);
pos=1;
field_x=1;
while((++pos*32)<db_con->HEAD_SIZE)
{
_dos_read(fhandle, field_desc, 32, &tmp);
field=(DBF_FIELD *)malloc(sizeof(DBF_FIELD));
memcpy(field->FIELD_NAME,field_desc,11);
field->FIELD_TYPE=field_desc[11];
field->FIELD_LENTH=(unsigned char)field_desc[16];
field->FIELD_FLOAT_LENTH=(unsigned char)field_desc[17];
if(db_con->BEGIN_FLAG==0x30)
{
field->FIELD_X=*(unsigned *)&field_desc[12];
field->FIELD_Y=*(unsigned *)&field_desc[14];
}
else
{
field->FIELD_X=field_x;
field->FIELD_Y=0;
field_x+=(unsigned)field->FIELD_LENTH;
}
field->index=pos-1;
field->next=NULL;
if(pos*32==64)
{
cur=field;
db_con->head=field;
}
else
{
cur->next=field;
cur=field;
}
}
return db_con;
}
/******************************************
* 关闭数据库，并且释放DBF_CONFIG内存。
******************************************/
int dbfclose(DBF_CONFIG * con)
{
DBF_FIELD *cur=NULL;
DBF_FIELD *deleted=NULL;
if(con==NULL) return 0;
/*释放DBF_FIELD所占内存*/
cur=con->head;
while(cur!=NULL)
{
deleted=cur;
cur=deleted->next;
free(deleted);
}
/*关闭文件句柄*/
_dos_close(con->DBF_HANDLE);
/*释放DBF_CONFIG所占内存*/
free(con);
return 0;
}
/******************************************
* 得到DBF_CONFIG中current所指示的记录
******************************************/
int dbfread(DBF_CONFIG * con,DBF_RECORD * record)
{
unsigned tmp;
if(con==NULL)
{
printf("您没有初始化DBF_CONFIG！\n");
return -1;
}
if(record==NULL)
{
record=(DBF_RECORD *)malloc(sizeof(DBF_RECORD));
}
if(record->value==NULL)
{
record->value=(void *)malloc(con->RECORD_SIZE+1);
}
lseek(con->DBF_HANDLE, (long)(con->HEAD_SIZE+(con->RECORD_SIZE+1)*(con->current-1)), SEEK_SET);
_dos_read(con->DBF_HANDLE, record->value, con->RECORD_SIZE+1, &tmp);
if(con->current<con->RECORD_COUNT)
con->current++;
return 0;
}
/******************************************
* 写入DBF_CONFIG中current所指示的记录
******************************************/
int dbfwrite(DBF_CONFIG * con,DBF_RECORD * record)
{
unsigned tmp;
lseek(con->DBF_HANDLE, (long)(con->HEAD_SIZE+(con->RECORD_SIZE+1)*(con->current-1)), SEEK_SET);
_dos_write(con->DBF_HANDLE, record->value, con->RECORD_SIZE+1, &tmp);
return 0;
}
/******************************************
* 读取DBF_RECORD相应的FIELD
* 目前仅支持C-char,N-float,F-float
* return 0:正确
* -1：没有此索引
* -2：没有此列名称
******************************************/
int dbfgetFieldByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value)
{
DBF_FIELD* field=con->head;
char field_type;
float rfloat;
unsigned char * temp;
char float_buf[MAX_FLOAT_LENTH+1];
while(field!=NULL)
{
if(field->index==index)
{
/*根据field的类型进行判断，并生成合适的值返回*/
switch(field->FIELD_TYPE)
{
case 'F':
case 'N':
temp=(unsigned char *)record->value;
memcpy(float_buf,temp+field->FIELD_X,field->FIELD_LENTH);
float_buf[MAX_FLOAT_LENTH]='\0';
printf("float_buf:%0x\n",float_buf);
rfloat=atof(float_buf);
memcpy(return_value,(void *)&rfloat,4);
printf("rfloat:%f\n",rfloat);
break;
case 'C':
default:
if(return_value==NULL)
{
printf("return_value需要预先分配空间！\n");
return -1;
}
temp=(unsigned char *)record->value;
memcpy(return_value,temp+field->FIELD_X,field->FIELD_LENTH);
break;
}
return 0;
}
field=field->next;
}
printf("没有此索引index=%d\n",index);
return -1;
}
int dbfgetFieldByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value)
{
DBF_FIELD* field=con->head;
char field_type;
int index=0;
while(field!=NULL)
{
if((field->FIELD_LENTH>0)&&(strncmpi(field->FIELD_NAME,name,strlen(name)<field->FIELD_LENTH?strlen(name):field->FIELD_LENTH)==0))
{
index=field->index;
break;
}
field=field->next;
}
if(index==0)
{
printf("没有此列名称name=%s\n",name);
return -2;
}
return dbfgetFieldByIndex(con,record,index,return_value);
}
/*特殊的针对Float-N,Float-F的读取操作*/
/******************************************
*return 0:正确
* -1：没有此索引
* -2：没有此列名称
* -3：类型不匹配！您试图读取非Float或int型字段
******************************************/
int dbfgetFloatByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value)
{
DBF_FIELD* field=con->head;
char field_type;
while(field!=NULL)
{
if(field->index==index)
{
if(field->FIELD_TYPE=='N'||field->FIELD_TYPE=='F')
return dbfgetFieldByIndex(con,record,index,return_value);
else
{
printf("类型不匹配！您试图用dbfgetFloatByIndex去读取非Float或int型字段\n");
return -3;
}
}
field=field->next;
}
printf("没有此索引index=%d\n",index);
return -1;
}
int dbfgetFloatByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value)
{
DBF_FIELD* field=con->head;
char field_type;
int index=0;
while(field!=NULL)
{
if((field->FIELD_LENTH>0)&&(strncmpi(field->FIELD_NAME,name,strlen(name)<field->FIELD_LENTH?strlen(name):field->FIELD_LENTH)==0))
{
if(field->FIELD_TYPE=='N'||field->FIELD_TYPE=='F')
{
index=field->index;
break;
}
else
{
printf("类型不匹配！您试图用dbfgetFloatByName去读取非Float或int型字段\n");
return -3;
}
}
field=field->next;
}
if(index==0)
{
printf("没有此列名称name=%s\n",name);
return -2;
}
return dbfgetFieldByIndex(con,record,index,return_value);
}
/*特殊的针对char-C或其他小于等于"MAX_CHAR_LENTH"个字符的串的读取操作*/
/******************************************
*@return_value:必须在调用此函数前已经声明并分配空间，一般可以定义为unsigned char ret[MAX_CHAR_LENTH+1];
* return 0:正确
* -1：没有此索引
* -2：没有此列名称
******************************************/
int dbfgetCharByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * return_value)
{
return dbfgetFieldByIndex(con,record,index,return_value);
}
int dbfgetCharByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * return_value)
{
return dbfgetFieldByName(con,record,name,return_value);
}
/******************************************
* 写入DBF_RECORD相应的FIELD
* 目前仅支持C-char,N-float,F-float
* value 指向一个float或一个char型数组，若为数组则此数组一般为MAX_CHAR_LENTH长
* 但一定要大于等于field->FIELD_LENTH，可在数组末尾补齐空格0x20。
* return 0:正确
* -1：没有此索引
* -2：没有此列名称
******************************************/
int dbfsetFieldByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value)
{
DBF_FIELD* field=con->head;
char field_type;
unsigned char * temp;
/*以下用于float和int*/
float rfloat;
char f_length[3],f_f_length[3],f_format[10]={"%"};
char float_buf[MAX_FLOAT_LENTH+1];
/*以下用于char*/
unsigned char *temp2;
while(field!=NULL)
{
if(field->index==index)
{
/*根据field的类型进行判断，并生成合适的值返回*/
switch(field->FIELD_TYPE)
{
case 'F':
case 'N':
rfloat=*(float *)value;
itoa(field->FIELD_LENTH,f_length,10);
itoa(field->FIELD_FLOAT_LENTH,f_f_length,10);
strcat(f_format,f_length);
strcat(f_format,".");
strcat(f_format,f_f_length);
strcat(f_format,"f");
sprintf(float_buf,f_format,rfloat);
temp=(unsigned char *)record->value;
memcpy(temp+field->FIELD_X,float_buf,field->FIELD_LENTH);
dbfwrite(con,record);
break;
case 'C':
default:
if(value==NULL)
{
printf("value未设定！\n");
return -1;
}
temp=(unsigned char *)record->value;
temp2=(unsigned char *)value;
memcpy(temp+field->FIELD_X,temp2,field->FIELD_LENTH);
dbfwrite(con,record);
break;
}
return 0;
}
field=field->next;
}
printf("没有此索引index=%d\n",index);
return -1;
}
int dbfsetFieldByName(DBF_CONFIG * con,DBF_RECORD * record,char * name,void * value)
{
DBF_FIELD* field=con->head;
char field_type;
int index=0;
while(field!=NULL)
{
if((field->FIELD_LENTH>0)&&(strncmpi(field->FIELD_NAME,name,strlen(name)<field->FIELD_LENTH?strlen(name):field->FIELD_LENTH)==0))
{
index=field->index;
break;
}
field=field->next;
}
if(index==0)
{
printf("没有此列名称name=%s\n",name);
return -2;
}
return dbfsetFieldByIndex(con,record,index,value);
}
int dbfsetFloatByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value)
{
DBF_FIELD* field=con->head;
char field_type;
while(field!=NULL)
{
if(field->index==index)
{
if(field->FIELD_TYPE=='N'||field->FIELD_TYPE=='F')
return dbfsetFieldByIndex(con,record,index,value);
else
{
printf("类型不匹配！您试图用dbfgetFloatByIndex去写入非Float或int型字段\n");
return -3;
}
}
field=field->next;
}
printf("没有此索引index=%d\n",index);
return -1;
}
int dbfsetFloatByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * value)
{
DBF_FIELD* field=con->head;
char field_type;
int index=0;
while(field!=NULL)
{
if((field->FIELD_LENTH>0)&&(strncmpi(field->FIELD_NAME,name,strlen(name)<field->FIELD_LENTH?strlen(name):field->FIELD_LENTH)==0))
{
if(field->FIELD_TYPE=='N'||field->FIELD_TYPE=='F')
{
index=field->index;
break;
}
else
{
printf("类型不匹配！您试图用dbfgetFloatByName去写入非Float或int型字段\n");
return -3;
}
}
field=field->next;
}
if(index==0)
{
printf("没有此列名称name=%s\n",name);
return -2;
}
return dbfsetFieldByIndex(con,record,index,value);
}
int dbfsetCharByIndex(DBF_CONFIG * con,DBF_RECORD * record,int index,void * value)
{
return dbfsetFieldByIndex(con,record,index,value);
}
int dbfsetCharByName(DBF_CONFIG * con,DBF_RECORD * record,char* name,void * value)
{
return dbfsetFieldByName(con,record,name,value);
}
void main()
{
dbf_info();
}
/************************************工具函数**********************************************/
char *ccstr( char *str)
{
char *tok = " ", *p;
p = strtok( str, tok );
while( p != NULL)
{
if( p != str )
strcat( str, p );
p = strtok( NULL, tok );
}
return( str );
}
３：结束
