我正在尝试使用HttpUrlConnection将图像发送到服务器,因为它是Google推荐的。我决定将图像转换为Base64字符串,然后将其发送到服务器,然后将其解码为.jpg文件。但是这种方法仅适用于小尺寸缩略图,而我无法发送全尺寸图像。
这是android客户端代码:
public static void postData(Bitmap imageToSend) { try { URL url = new URL("http://"); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("POST"); conn.setDoInput(true); conn.setDoOutput(true); conn.setRequestProperty("Connection", "Keep-Alive"); conn.setRequestProperty("Cache-Control", "no-cache"); conn.setReadTimeout(35000); conn.setConnectTimeout(35000); ByteArrayOutputStream bos = new ByteArrayOutputStream(); // writes a compress version of Bitmap to a specified outputstream imageToSend.compress(Bitmap.CompressFormat.JPEG, 100, bos); byte[] byteArray = bos.toByteArray(); String imageEncoded = Base64.encodeToString(byteArray, Base64.DEFAULT); List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("image", imageEncoded)); OutputStream os = conn.getOutputStream(); BufferedWriter writer = new BufferedWriter( new OutputStreamWriter(os, "UTF-8")); // getQuery is function for creating a URL encoded string writer.write(getQuery(params)); System.out.println("Response Code: " + conn.getResponseCode()); InputStream in = new BufferedInputStream(conn.getInputStream()); Log.d("sdfs", "sfsd"); BufferedReader responseStreamReader = new BufferedReader(new InputStreamReader(in)); String line = ""; StringBuilder stringBuilder = new StringBuilder(); while ((line = responseStreamReader.readLine()) != null) stringBuilder.append(line).append("\n"); responseStreamReader.close(); String response = stringBuilder.toString(); System.out.println(response); bos.flush(); bos.close(); in.close(); conn.disconnect(); } catch(MalformedURLException e) { e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } }
Node.js服务器代码:
function base64_decode(base64str,file) { var bitmap = new Buffer(base64str,'base64'); //writing into an image file fs.writeFile(file, bitmap); //write a text file console.log('File created from base64 encoded string'); } app.post("/", function (req,res,next) { //requesting the value of the image key which is urlencoded base 64 string var image = req.body.image; console.log(req.body.image); base64_decode(image,'newImage.jpg'); res.writeHead(200, {'Content-Type':'text/plain'}); res.write('the image is saved'); res.end(); if (req.url != "/") next();
由于BufferedWriter的大小限制,我无法对完整尺寸的图像使用相同的方法-base64编码的字符串太长了。
另一种方法是使用HttpPost和MultipartEntity,但是API22中已弃用了这两种方法,而且我不知道如何在服务器端处理请求。在其他示例中,使用了一些包装,例如两个连字符,border,crlf,但我找不到原因。
我需要一个带有HttpUrlConnection的示例
感谢您的帮助,因为我是Android和node.js的新手
我建议上传二进制数据。您可以将图像元数据(例如名称,类型,用户ID等)放置为url参数或自定义HTTP标头(X -…)。
Android客户端代码(未经测试!):
public static void postData(Bitmap imageToSend) { try { URL url = new URL("http://myserver/myapp/upload-image"); HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.setRequestMethod("POST"); conn.setDoInput(true); conn.setDoOutput(true); conn.setRequestProperty("Connection", "Keep-Alive"); conn.setRequestProperty("Cache-Control", "no-cache"); conn.setReadTimeout(35000); conn.setConnectTimeout(35000); // directly let .compress write binary image data // to the output-stream OutputStream os = conn.getOutputStream(); imageToSend.compress(Bitmap.CompressFormat.JPEG, 100, os); os.flush(); os.close(); System.out.println("Response Code: " + conn.getResponseCode()); InputStream in = new BufferedInputStream(conn.getInputStream()); Log.d("sdfs", "sfsd"); BufferedReader responseStreamReader = new BufferedReader(new InputStreamReader(in)); String line = ""; StringBuilder stringBuilder = new StringBuilder(); while ((line = responseStreamReader.readLine()) != null) stringBuilder.append(line).append("\n"); responseStreamReader.close(); String response = stringBuilder.toString(); System.out.println(response); conn.disconnect(); } catch(MalformedURLException e) { e.printStackTrace(); } catch(IOException e) { e.printStackTrace(); } }
Node.js,快速代码:
function rawBody(req, res, next) { var chunks = []; req.on('data', function(chunk) { chunks.push(chunk); }); req.on('end', function() { var buffer = Buffer.concat(chunks); req.bodyLength = buffer.length; req.rawBody = buffer; next(); }); req.on('error', function (err) { console.log(err); res.status(500); }); } app.post('/upload-image', rawBody, function (req, res) { if (req.rawBody && req.bodyLength > 0) { // TODO save image (req.rawBody) somewhere // send some content as JSON res.send(200, {status: 'OK'}); } else { res.send(500); } });
我将尝试解释node.js部分:该函数rawBody充当Express中间件。发出POST请求时,该函数将与请求对象一起调用。它注册了听众data,end和error事件。这些data事件将所有传入的数据块追加到缓冲区。当end火灾,该属性rawBody在请求对象被创建并包含二进制数据(图像斑点)。rawBody()然后将控制权转移到下一个处理程序,该处理程序现在可以将blob保存到您的数据库或文件系统中。
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当处理真正的大数据斑点时,这种处理方法不是最佳方法。最好将数据流传输到文件或数据库以节省内存。