nodejs实现日志读取、日志查找及日志刷新的方法分析

function readLog(date,type，operation){//函数接受3个参数，日期、精度(天时分秒)和操作（查找、刷新或者默认）    if(date){    //如果有时间参数则对时间参数进行处理（一般日志名称都是时间加类型）      var dataStr = arguments[0];      var date = dataStr.slice(0,10);      var hour = dataStr.slice(11,13);      var minute = dataStr.slice(11,16);      var second =dataStr.slice(11,19);      var type = arguments[1];      //获取精度    }else{    //若无时间参数则获取当前时间，然后精度默认      var date = new Date(+new Date()+8*3600*1000).toISOString().replace(/T/g,' ').replace(//.[/d]{3}Z/,'').slice(0,10);      var type=null;    }    var op = arguments[2];    var countResult = 0;    //对日志结果进行统计    var logPath = appDirName.slice(0,-3)+'log//'+'ivsvr_'+date+'.log';    //拼接日志文件名称    var logStr = '';    fs.stat(logPath, function (err, stats) {    //获取对应的日志文件状态    if(err){    //日志不存在或者异常处理信息      $('#logTipInfo tr td').html('无日志信息可供查看');      console.log(err);    }else{      var lineCount = 0;      var readline = require('readline');      var fReadName = logPath;      var fRead = fs.createReadStream(fReadName);      var objReadline = readline.createInterface({        input: fRead,      });      //按行读取日志      objReadline.on('line', (line)=>{        var itemStr = $.trim(line);        var time = itemStr.slice(0,19);        var content = itemStr.substr(20);        if(!time || !content){return;}        ++ lineCount;        //计数行数        var matched = true;        var itemStr = $.trim(line);        var itemArr = itemStr.split(' ');        var logDate = itemArr[0];        var logTime = itemArr[1];        var time = logDate+' '+logTime;        switch(type){        //进度查找过滤          case '0':          case null:            matched = true;            break;          case '1':            var timeSplit = logTime.slice(0,2);            if(timeSplit == hour){              matched = true;              break;            }            matched = false;            break;          case '2':            var timeSplit = logTime.slice(0,5);            if(timeSplit == minute){              matched = true;              break;            }            matched = false;            break;          case '3':            var timeSplit = logTime.slice(0,8);            if(timeSplit == second){              matched = true;              break;            }            matched = false;            break;          default:            console.log('unkonw type!');            break;        }        if(matched === true &&(lineCount>logReadFlag)){        //日志结果格式化输出呈现          countResult ++;          var result = itemArr[2];          if(result == 'err'){            var operation = itemArr[4];            result = '失败：'+itemArr[5]+' '+(itemArr[6]?itemArr[6]:'');          }else{            var operation = itemArr[4]+' '+itemArr[5]+(itemArr[6]?itemArr[6]:'');            result = '成功';          }          logStr += '<tr><td>'+time+'</td><td>'+operation+'</td><td>'+result+'</td></tr>'        }        logStr += '<tr><td>'+time+'</td><td>'+content+'</td></tr>'      });      objReadline.on('close', ()=>{        if(logReadFlag == 0 && (logStr == '')){          var info = '无日志信息可供查看';        }        if(logReadFlag >0 && (logStr != '')){          var newLogNum = lineCount - logReadFlag;          var info = '刷新成功,更新'+newLogNum+'条日志!';          $('#logInfoTable').prepend(logStr);        }else if(logReadFlag >0 && (logStr == '')){          var info = '刷新成功,无日志更新!';        }else{          $('#logInfoTable').html(logStr);        }        if(op == 'search'){          var info = '查找到'+countResult+'条日志';        }        $('#logTipInfo tr td').html(info);        if((op == 'search' || op == 'refresh') &&(logReadFlag != 0 || newLogNum >0 || countResult >0)){          setTimeout(function() {$('#logTipInfo').fadeOut(567);}, 2000);          //操作结束后给出信息反馈，反馈自动淡出消失        }        else{          $('#logTipInfo').hide();        }        logReadFlag = lineCount;        console.log('closed');      });    }  });}