爬取网站的图片

    var http = require('http');  
    var fs = require('fs');
    var request = require('request');
    var CryptoJS = require('crypto-js');

function decode(code) { 
    code = code.replace(/^eval/, ''); 
    return eval(code); 
} 

function encode(code){
    code = code.replace(/[\r\n]+/g, ''); 
    code = code.replace(/'/g, "\\'"); 
    var tmp = code.match(/\b(\w+)\b/g); 
    tmp.sort(); 
    var dict = []; 
    var i, t = ''; 
    for(var i=0; i<tmp.length; i++) { 
    if(tmp[i] != t) dict.push(t = tmp[i]); 
    } 
    var len = dict.length; 
    var ch; 
    for(i=0; i<len; i++) { 
    ch = num(i); 
    code = code.replace(new RegExp('\\b'+dict[i]+'\\b','g'), ch); 
    if(ch == dict[i]) dict[i] = ''; 
    } 
    return "eval(function(p,a,c,k,e,d){e=function(c){return(c<a?'':e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))};if(!''.replace(/^/,String)){while(c--)d[e(c)]=k[c]||e(c);k=[function(e){return d[e]}];e=function(){return'\\\\w+'};c=1};while(c--)if(k[c])p=p.replace(new RegExp('\\\\b'+e(c)+'\\\\b','g'),k[c]);return p}(" + "'"+code+"',"+a+","+len+",'"+ dict.join('|')+"'.split('|'),0,{}))"; 
}


function downloadPic(url,filePath,fn){
    var r = request(url).pipe(fs.createWriteStream(filePath));
    r.on('close', function(){
        fn();
    }).on('error',function(){
        log('download pic error!');
        if(nextChapterPath && chapterNow < chapterNum){
            downloadChapter(nextChapterPath);
        }else{
            chapterNow++;
        }
    });
}

function downloadFiles(arr,baseDir){
    var length = arr.length;
    var i = 0;
    function loadNext(index){
        downloadPic(encodeURI(picDomain + jsonData.path + arr[i]), baseDir + '/' + index + '.jpg',function(){
            i++;
            if(i < length){
                console.log('Pictrure ' + (index + 1 +  '/' + jsonData.len) + ' done!');
                loadNext(i);
            }else{
                console.log('Chapter ' + jsonData.cname + ' All done!');

                chapterNum++;
                if(chapterNum < maxChapterNum){
                    downloadChapter(chapterNum + '.html');
                }
            }
        });
    }
    loadNext(i);
}



var baseDir = 'F:/node_test/Pictures/';
var picDomain = 'http://somedomain.pic.com';

var dataReg = new RegExp("decryptDES\\(\\'([\\w+/=]+)\\'\\)");
var jsonData = null;

var chapterNum = 154731;
var maxChapterNum = 154743;

function log(data){
    fs.appendFile(baseDir + 'log.txt',data + '\r\n','utf8',function(err){
        if(err)
        {
            console.log(err);
        }
    });
}

function decryptDES(t) {
    var a = CryptoJS.DES.decrypt({
        ciphertext: CryptoJS.enc.Base64.parse(t.substring(8))
    }, CryptoJS.enc.Utf8.parse(t.substring(0, 8)), {
        mode: CryptoJS.mode.ECB,
        padding: CryptoJS.pad.Pkcs7
    });
    return a.toString(CryptoJS.enc.Utf8);
}

function downloadChapter(path){
    log('//------------------------------------------------------------------//');

    var page = 'http://somepage.url.com/' + path;
    log('正在读取页面:' + page);

    var html = '';  
    http.get(page , function(res) {  
        res.setEncoding('utf-8');  
        res.on('data', function(data) {  
            // collect the data chunks to the variable named "html"  
            html += data;  
        }).on('end', function() {

            var dir = baseDir;
            if(dataReg.test(html)){
                var str = decryptDES(RegExp.$1);
                
                str = str.replace(/^eval/,'');
                str = eval(str);

                log('页面数据：\r\n' + str);
                str = str.replace('var cInfo=','return ');
                //字符串转对象
                jsonData = (new Function(str))();

                dir += jsonData["cname"];
                if (!fs.existsSync(dir)) {
                    fs.mkdirSync(dir);
                    log('文件存放目录：' + dir);
                }else{
                    console.log(dir + ' 已存在!');
                    return;
                }
                downloadFiles(jsonData["files"],dir);

            }else{
                return;
            }
        });  
    });  
}

downloadChapter( chapterNum + '.html');