用PHP实现将GB编码转换为UTF8

functionGB2UTF8($InStr="")
{
$this->gb=$InStr;
$this->SetGb2312();
($this->gb=="")?0:$this->Convert();
}

functionSetGb2312($InStr="gb2312.txt")
{//设置gb2312代码文件，默认为gb2312.txt
$this->ErrorMsg="";
$tmp=@file($InStr);
if(!$tmp){
$this->ErrorMsg="NoGB2312";
returnfalse;
}
$this->CodeTable=array();
while(list($key,$value)=each($tmp)){
$this->CodeTable[hexdec(substr($value,0,6))]=substr($value,7,6);
}
}

functionConvert()
{//转换GB2312字符串到UTF8字符串，需预先设置$gb
$this->utf8="";
if(!trim($this->gb)||$this->ErrorMsg!=""){
return($this->utf8=$this->ErrorMsg);
}
$str=$this->gb;

while($str){
if(ord(substr($str,0,1))>127)
{
$tmp=substr($str,0,2);
$str=substr($str,2,strlen($str));
$tmp=$this->U2UTF8(hexdec($this->CodeTable[hexdec(bin2hex($tmp))-0x8080]));
for($i=0;$i$this->utf8.=chr(substr($tmp,$i,3));
}
else
{
$tmp=substr($str,0,1);
$str=substr($str,1,strlen($str));
$this->utf8.=$tmp;
}
}
return$this->utf8;
}

functionU2UTF8($InStr)
{
for($i=0;$i<count($InStr);$i++)
$str="";
if($InStr<0x80){
$str.=ord($InStr);
}
elseif($InStr<0x800){
$str.=(0xC0|$InStr>>6);
$str.=(0x80|$InStr&0x3F);
}
elseif($InStr<0x10000){
$str.=(0xE0|$InStr>>12);
$str.=(0x80|$InStr>>6&0x3F);
$str.=(0x80|$InStr&0x3F);
}
elseif($InStr<0x200000){
$str.=(0xF0|$InStr>>18);
$str.=(0x80|$InStr>>12&0x3F);
$str.=(0x80|$InStr>>6&0x3F);
$str.=(0x80|$InStr&0x3F);
}
return$str;
}
}
?>

测试文件如下：
复制代码 代码如下:
Header("Content-type:image/png");
$im=imagecreate(400,300);
$black=ImageColorAllocate($im,0,0,0);
$white=ImageColorAllocate($im,184,44,6);
include("gb2utf8.php");
$obj=newgb2utf8();
$obj->gb="123abc中国456def测试正确";
$obj->Convert();
ImageTTFText($im,20,0,5,50,$white,"SIMKAI.TTF",$obj->utf8);
ImagePNG($im);
ImageDestroy($im);
?>

说明：
需要正确设置font文件，请先确认可以使用font直接（不使用gb2utf8）输出英文。