详解用node-images 打造简易图片服务器

var http = require('http'); 
var url = require('url'); 
var siteUrl = url.parse('http://img1.gtimg.com/view/pics/hv1/42/80/2065/134297067.jpg'); 
 
request = http.request({ 
  method : 'HEAD', 
  port: siteUrl.port || 80, 
  host: siteUrl.host, 
  path : siteUrl.pathname 
}); 
request.on('response', function (response) { 
  response.setEncoding('utf8'); 
  console.log(response.headers['content-length']); 
}); 
request.end(); 

npm install images 

// 配置对象。 
var staticFileServer_CONFIG = { 
  'host': '127.0.0.1',      // 服务器地址 
  'port': 3000,        // 端口 
  'site_base': 'C:/project/bigfoot',   // 根目录，虚拟目录的根目录 
  'file_expiry_time': 480,    // 缓存期限 HTTP cache expiry time, minutes 
  'directory_listing': true    // 是否打开 文件 列表 
}; 

const 
  HTTP = require('http'), PATH = require('path'), fs = require('fs'), CRYPTO = require('crypto'), 
  url = require("url"), querystring = require("querystring"), 
  Step = require('./step'), images = require("images"); 
 
// 配置对象。 
var staticFileServer_CONFIG = { 
  'host': '127.0.0.1',      // 服务器地址 
  'port': 3001,            // 端口 
  'site_base': 'C:/project/bigfoot',     // 根目录，虚拟目录的根目录 
  'file_expiry_time': 480,    // 缓存期限 HTTP cache expiry time, minutes 
  'directory_listing': true    // 是否打开 文件 列表 
}; 
 
const server = HTTP.createServer((req, res) => { 
  init(req, res, staticFileServer_CONFIG); 
}); 
 
server.listen(staticFileServer_CONFIG.port, staticFileServer_CONFIG.host, () => { 
  console.log(`Image Server running at http://${staticFileServer_CONFIG.host}:${staticFileServer_CONFIG.port}/`); 
}); 
 
// 当前支持的 文件类型，你可以不断扩充。 
var MIME_TYPES = { 
  '.txt': 'text/plain', 
  '.md': 'text/plain', 
  '': 'text/plain', 
  '.html': 'text/html', 
  '.css': 'text/css', 
  '.js': 'application/javascript', 
  '.json': 'application/json', 
  '.jpg': 'image/jpeg', 
  '.png': 'image/png', 
  '.gif': 'image/gif' 
}; 
 
MIME_TYPES['.htm'] = MIME_TYPES['.html']; 
 
var httpEntity = { 
  contentType: null, 
  data: null, 
  getHeaders: function (EXPIRY_TIME) { 
    // 返回 HTTP Meta 的 Etag。可以了解 md5 加密方法 
    var hash = CRYPTO.createHash('md5'); 
    //hash.update(this.data); 
    //var etag = hash.digest('hex'); 
 
    return { 
      'Content-Type': this.contentType, 
      'Content-Length': this.data.length, 
      //'Cache-Control': 'max-age='   EXPIRY_TIME, 
      //'ETag': etag 
    }; 
  } 
}; 
 
function init(request, response) { 
  var args = url.parse(request.url).query,     //arg => name=a&id=5  
    params = querystring.parse(args); 
 
  if (params.url) { 
    getRemoteImg(request, response, params); 
  } else { 
    load_local_img(request, response, params); 
  } 
} 
 
// 加载远程图片 
function getRemoteImg(request, response, params) { 
  var imgData = ""; // 字符串 
  var size = 0; 
  var chunks = []; 
 
  Step(function () { 
      HTTP.get(params.url, this); 
    }, 
    function (res) { 
      var maxLength = 10; // 10mb 
      var imgData = ""; 
      if (res.headers['content-length'] > maxLength * 1024 * 1024) { 
        server500(response, new Error('Image too large.')); 
      } else if (!~[200, 304].indexOf(res.statusCode)) { 
        server500(response, new Error('Received an invalid status code.')); 
      } else if (!res.headers['content-type'].match(/image/)) { 
        server500(response, new Error('Not an image.')); 
      } else { 
        // res.setEncoding("binary"); //一定要设置response的编码为binary否则会下载下来的图片打不开 
        res.on("data", function (chunk) { 
          // imgData =chunk; 
          size  = chunk.length; 
          chunks.push(chunk); 
        }); 
 
        res.on("end", this); 
      } 
       
    }, 
    function () {  
      imgData = Buffer.concat(chunks, size); 
     
      var _httpEntity = Object.create(httpEntity); 
      _httpEntity.contentType = MIME_TYPES['.png']; 
      _httpEntity.data = imgData; 
      // console.log('imgData.length:::'   imgData.length) 
      // 缓存过期时限 
      var EXPIRY_TIME = (staticFileServer_CONFIG.file_expiry_time * 60).toString(); 
      response.writeHead(200); 
      response.end(_httpEntity.data); 
    } 
  ); 
   
} 
 
 
// 获取本地图片 
function load_local_img(request, response, params) { 
  if (PATH.extname(request.url) === '') { 
    // connect.directory('C:/project/bigfoot')(request, response, function(){}); 
    // 如果 url 只是 目录 的，则列出目录 
    console.log('如果 url 只是 目录 的，则列出目录'); 
    server500(response, '如果 url 只是 目录 的，则列出目录@todo'); 
  } else { 
    var pathname = require('url').parse(request.url).pathname; 
    // 如果 url 是 目录   文件名 的，则返回那个文件 
    var path = staticFileServer_CONFIG.site_base   pathname; 
 
    Step(function () { 
      console.log('请求 url :'   request.url   ', path : '   pathname); 
      fs.exists(path, this); 
    }, function (path_exists, err) { 
      if (err) { 
        server500(response, '查找文件失败！'); 
        return; 
      } 
      if (path_exists) { 
        fs.readFile(path, this); 
      } else { 
        response.writeHead(404, { 'Content-Type': 'text/plain;charset=utf-8' }); 
        response.end('找不到 '   path   '\n'); 
      } 
    }, function (err, data) { 
      if (err) { 
        server500(response, '读取文件失败！'); 
        return; 
      } 
      var extName = '.'   path.split('.').pop(); 
      var extName = MIME_TYPES[extName] || 'text/plain'; 
 
      var _httpEntity = Object.create(httpEntity); 
      _httpEntity.contentType = extName; 
      var buData = new Buffer(data); 
      //images(buData).height(100); 
 
      var newImage; 
 
      if (params.w && params.h) { 
        newImage = images(buData).resize(Number(params.w), Number(params.h)).encode("jpg", { operation: 50 }); 
      } else if (params.w) { 
        newImage = images(buData).resize(Number(params.w)).encode("jpg", { operation: 50 }); 
      } else if (params.h) { 
        newImage = images(buData).resize(null, Number(params.h)).encode("jpg", { operation: 50 }); 
      } else { 
        newImage = buData; // 原图 
      } 
 
      _httpEntity.data = newImage; 
 
      // 命中缓存，Not Modified返回 304 
      if (request.headers.hasOwnProperty('if-none-match') && request.headers['if-none-match'] === _httpEntity.ETag) { 
        response.writeHead(304); 
        response.end(); 
      } else { 
        // 缓存过期时限 
        var EXPIRY_TIME = (staticFileServer_CONFIG.file_expiry_time * 60).toString(); 
 
        response.writeHead(200, _httpEntity.getHeaders(EXPIRY_TIME)); 
        response.end(_httpEntity.data); 
      } 
    }); 
  } 
} 
function server500(response, msg) { 
  console.log(msg); 
  response.writeHead(404, { 'Content-Type': 'text/plain;charset=utf-8' }); 
  response.end(msg   '\n'); 
} 
加水印也是可以的。例子如下。
var images = require('images'); 
var path = require('path'); 
var watermarkImg = images(path.join(__dirname, 'path/to/watermark.ext')); 
var sourceImg = images(path.join(__dirname, 'path/to/sourceImg.ext')); 
var savePath = path.join(__dirname, 'path/to/saveImg.jpg'); 
 
// 比如放置在右下角，先获取原图的尺寸和水印图片尺寸 
var sWidth = sourceImg.width(); 
var sHeight = sourceImg.height(); 
var wmWidth = watermarkImg.width(); 
var wmWidth = watermarkImg.height(); 
 
images(sourceImg) 
 // 设置绘制的坐标位置，右下角距离 10px 
 .draw(watermarkImg, sWidth - wmWidth - 10, sHeight - wmHeight - 10) 
 // 保存格式会自动识别 
 .save(savePath);