hello.js

/**
 * node.js的入口文件.
 * 必须的参数：file - 文件名称； callback - jsonp形式调用
 * 返回jsonp形式
 */
var http = require('http');
var url=require('url');
var querystring = require('querystring');
var fs=require('fs');
var path=require('path');

function writeMsg(response,msg){
    response.writeHead(200, {'Content-Type': 'text/plain;charset=utf-8;'});
    response.write(msg);
    response.end();
}


http.createServer(function(request, response){
    //获取url的query
    var arg = url.parse(request.url).query;
    //转换为json形式
    var arg_json = querystring.parse(arg);
    //输出的内容
    var content = '';
    var filepath = arg_json.file;
    var callback =arg_json.callback;

    if(filepath){
       //file -- 本地的json文件路径
        filepath = path.resolve('./json/'+filepath);
       //判断文件是否存在
       if(!fs.existsSync(filepath)){
            content='error:文件不存在';
            writeMsg(response,content);
       }else{
           fs.readFile(filepath,'utf-8',function(err,data){
               if(err){
                   console.log(err);
                   content='error:文件读取失败';
                   writeMsg(response,content);
               }else{
                   //读取成功
                   if(callback){
                       //callback -- jsonp形式
                       response.writeHead(200, {'Content-Type': 'application/javascript;charset=utf-8;'});
                       content = callback+'('+data+');';
                       response.write(content);
                       response.end();
                       return false;
                   }
                   else{
                       //callback -- jsonp形式
                       response.writeHead(200, {'Content-Type': 'text/json;charset=utf-8;'});
                       response.write(data);
                       response.end();
                       return false;
                   }
               }
           });
       }
    }else{
        content='error:参数错误';
        writeMsg(response,content);
    }


}).listen(3001);