PHP上传大文件和处理大数据

        /* 以1.5M/秒的速度写入文件，防止一次过写入文件过大导致服务器出错(chy/20150327) */
        $is_large_file = false;
        if( strlen($xml_str)>=2097152 ){ //当文件大于2M
            $is_large_file = true;
            
            fwrite($fp, $pre, strlen($pre)); //写入头部
            $start = 0;
            while( $content=mb_strcut($xml_str,$start,1572864) ){
                $start = $start + 1572864;
                $writeResult = fwrite($fp, $content, strlen($content));
                if( !$writeResult ){
                    unlink($filename);
                    break;
                }
                sleep(1);
                unset($content);
            }
            unset($xml_str);
            fwrite($fp, $end, strlen($end)); //写入尾部
        }else{
            $content = $pre.$xml_str.$end;
            fwrite($fp, $content, strlen($content));
        }

    //aes加密
    public function aesEncode_large($info) {
        //.....(省略部分代码)

　　　　if(mcrypt_generic_init($cipher, $this->aesKey, $this->aesIv) != -1){
            //$cipherText = mcrypt_generic($cipher, $beianInfo); //原普通的加密方式(chy/20150327)
            
            //处理大字符串加密。temp.text主要用于文件缓存(chy/20150327)
            $filename = B_ROOT."/admin/temp/temp.txt";
            file_put_contents($filename,‘‘); //将文件清空
            $fp = fopen($filename, ‘wb‘);
            
            while( $content=mb_strcut($info,$start,104800) ){
                $start = $start + 104800;
                $cipherTextCut = mcrypt_generic($cipher, $content);
                fwrite($fp, $cipherTextCut, strlen($cipherTextCut));
                unset($cipherTextCut);
                unset($content);
            }
            
            mcrypt_generic_deinit($cipher);
            mcrypt_module_close($cipher);
            fclose($fp);
            return true;
        } else {
            return false;
        }
    }