Nodejs处理异常操作示例

module.exports = {
  expfun: function(flag) {
    if(flag == 0) {
      throw '我是error';
    }
    return "suess";
  }
}

//-------------optfile.js-------------------------
var fs = require('fs');
module.exports = {
  readfile: function (path, recall) { //异步执行
    fs.readFile(path, function (err, data) {
      if (err) {
        console.log("异步执行error" + err);
        recall("文件不存在，异步执行error" + err);//异步处理异常
      } else {
        //console.log(data.toString());
        recall(data);
      }
    });
    console.log("===异步方法执行完毕===");
  },
  readImg: function (path, res) {
    fs.readFile(path, 'binary', function (err, filedata) {
      if (err) {
        console.log(err);
        return;
      } else {
        console.log("输出文件");
        res.write(filedata, 'binary');
        res.end();
      }
    });
  }
}

var optfile = require('../model/optfile2.js');
function getRecall(req, res) {
  res.writeHead(200, {
    'Content-Type': 'text/html; charset=utf-8'
  });
  function recall(data) {
    res.write(data);
    res.end(''); //不写则没有http协议尾
  }
  return recall;
}
module.exports = {
  login: function (req, res) {
    recall = getRecall(req, res);
    optfile.readfile('./view/login.html', recall);
  },
  showimg: function (req, res) {
    res.writeHead(200, {
      'Content-Type': 'image/jpeg'
    });
    optfile.readImg("./view/pig.png", res);
  }
}