通过HttpURLConnection使用POST发送文件
通过HttpURLConnection使用POST发送文件
提问于 2012-08-02 04:13:43
由于Android开发人员recommend使用了HttpURLConnection类，我想知道是否有人可以提供一个很好的示例，告诉我如何通过POST将位图“文件”(实际上是内存流)发送到Apache HTTP服务器。我对cookie或身份验证或任何复杂的东西不感兴趣，但我只想有一个可靠的和逻辑的实现。我在这里看到的所有例子看起来更像是“让我们尝试一下，也许它会起作用”。
现在，我有这样的代码：
URL url;
HttpURLConnection urlConnection = null;
try {
url = new URL("http://example.com/server.cgi");
urlConnection = (HttpURLConnection) url.openConnection();
} catch (Exception e) {
this.showDialog(getApplicationContext(), e.getMessage());
}
finally {
if (urlConnection != null)
{
urlConnection.disconnect();
}
}其中showDialog应该只显示一个AlertDialog (如果是无效的URL?)。
现在，假设我生成了一个位图，如下所示:从View派生的控件中的Bitmap image = this.getBitmap()，我想通过POST发送它。实现这一目标的正确程序是什么？我需要使用哪些类？我可以像在this example中一样使用HttpPost吗？如果是这样，我该如何为我的位图构造InputStreamEntity呢？我会发现要求首先将位图存储在设备上的文件中是一件令人反感的事情。
我还应该提到，我真的需要将原始位图的每个未更改的像素发送到服务器，所以我不能将其转换为JPEG。
回答 8
Stack Overflow用户
回答已采纳
发布于 2012-08-06 18:15:19
我不知道为什么HttpURLConnection类不提供任何发送文件的方法，而不必手动编写文件包装器。这就是我最终要做的，但如果有人知道更好的解决方案，请让我知道。
输入数据：
Bitmap bitmap = myView.getBitmap();静态内容：
String attachmentName = "bitmap";
String attachmentFileName = "bitmap.bmp";
String crlf = "\r\n";
String twoHyphens = "--";
String boundary = "*****";设置请求：
HttpURLConnection httpUrlConnection = null;
URL url = new URL("http://example.com/server.cgi");
httpUrlConnection = (HttpURLConnection) url.openConnection();
httpUrlConnection.setUseCaches(false);
httpUrlConnection.setDoOutput(true);
httpUrlConnection.setRequestMethod("POST");
httpUrlConnection.setRequestProperty("Connection", "Keep-Alive");
httpUrlConnection.setRequestProperty("Cache-Control", "no-cache");
httpUrlConnection.setRequestProperty(
"Content-Type", "multipart/form-data;boundary=" + this.boundary);启动内容包装：
DataOutputStream request = new DataOutputStream(
httpUrlConnection.getOutputStream());
request.writeBytes(this.twoHyphens + this.boundary + this.crlf);
request.writeBytes("Content-Disposition: form-data; name=\"" +
this.attachmentName + "\";filename=\"" +
this.attachmentFileName + "\"" + this.crlf);
request.writeBytes(this.crlf);将Bitmap转换为ByteBuffer
//I want to send only 8 bit black & white bitmaps
byte[] pixels = new byte[bitmap.getWidth() * bitmap.getHeight()];
for (int i = 0; i < bitmap.getWidth(); ++i) {
for (int j = 0; j < bitmap.getHeight(); ++j) {
//we're interested only in the MSB of the first byte,
//since the other 3 bytes are identical for B&W images
pixels[i + j] = (byte) ((bitmap.getPixel(i, j) & 0x80) >> 7);
}
}
request.write(pixels);结束内容包装器：
request.writeBytes(this.crlf);
request.writeBytes(this.twoHyphens + this.boundary +
this.twoHyphens + this.crlf);刷新输出缓冲区：
request.flush();
request.close();获取响应：
InputStream responseStream = new
BufferedInputStream(httpUrlConnection.getInputStream());
BufferedReader responseStreamReader =
new BufferedReader(new InputStreamReader(responseStream));
String line = "";
StringBuilder stringBuilder = new StringBuilder();
while ((line = responseStreamReader.readLine()) != null) {
stringBuilder.append(line).append("\n");
}
responseStreamReader.close();
String response = stringBuilder.toString();关闭响应流：
responseStream.close();关闭连接：
httpUrlConnection.disconnect();PS:当然，为了让安卓平台高兴，我不得不将请求包装在private class AsyncUploadBitmaps extends AsyncTask<Bitmap, Void, String>中，因为它不喜欢在主线程上有网络请求。
Stack Overflow用户
发布于 2013-05-12 20:46:05
实际上，我发现了一种更好的方法，可以使用MultipartEntity通过HttpURLConnection发送文件
private static String multipost(String urlString, MultipartEntity reqEntity) {
try {
URL url = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("POST");
conn.setUseCaches(false);
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setRequestProperty("Connection", "Keep-Alive");
conn.addRequestProperty("Content-length", reqEntity.getContentLength()+"");
conn.addRequestProperty(reqEntity.getContentType().getName(), reqEntity.getContentType().getValue());
OutputStream os = conn.getOutputStream();
reqEntity.writeTo(conn.getOutputStream());
os.close();
conn.connect();
if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
return readStream(conn.getInputStream());
}
} catch (Exception e) {
Log.e(TAG, "multipart post error " + e + "(" + urlString + ")");
}
return null;
}
private static String readStream(InputStream in) {
BufferedReader reader = null;
StringBuilder builder = new StringBuilder();
try {
reader = new BufferedReader(new InputStreamReader(in));
String line = "";
while ((line = reader.readLine()) != null) {
builder.append(line);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return builder.toString();
} 假设您上传的是包含位图数据的图像：
Bitmap bitmap = ...;
String filename = "filename.png";
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);
ContentBody contentPart = new ByteArrayBody(bos.toByteArray(), filename);
MultipartEntity reqEntity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
reqEntity.addPart("picture", contentPart);
String response = multipost("http://server.com", reqEntity);瞧！您的帖子数据将包含图片字段以及服务器上的文件名和路径。
Stack Overflow用户
发布于 2015-10-15 21:07:00
简单的使用MultipartUtility上传一些参数的文件到服务器上。
MultipartUtility.java
public class MultipartUtility {
private final String boundary;
private static final String LINE_FEED = "\r\n";
private HttpURLConnection httpConn;
private String charset;
private OutputStream outputStream;
private PrintWriter writer;
/**
* This constructor initializes a new HTTP POST request with content type
* is set to multipart/form-data
*
* @param requestURL
* @param charset
* @throws IOException
*/
public MultipartUtility(String requestURL, String charset)
throws IOException {
this.charset = charset;
// creates a unique boundary based on time stamp
boundary = "===" + System.currentTimeMillis() + "===";
URL url = new URL(requestURL);
Log.e("URL", "URL : " + requestURL.toString());
httpConn = (HttpURLConnection) url.openConnection();
httpConn.setUseCaches(false);
httpConn.setDoOutput(true); // indicates POST method
httpConn.setDoInput(true);
httpConn.setRequestProperty("Content-Type",
"multipart/form-data; boundary=" + boundary);
httpConn.setRequestProperty("User-Agent", "CodeJava Agent");
httpConn.setRequestProperty("Test", "Bonjour");
outputStream = httpConn.getOutputStream();
writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
true);
}
/**
* Adds a form field to the request
*
* @param name field name
* @param value field value
*/
public void addFormField(String name, String value) {
writer.append("--" + boundary).append(LINE_FEED);
writer.append("Content-Disposition: form-data; name=\"" + name + "\"")
.append(LINE_FEED);
writer.append("Content-Type: text/plain; charset=" + charset).append(
LINE_FEED);
writer.append(LINE_FEED);
writer.append(value).append(LINE_FEED);
writer.flush();
}
/**
* Adds a upload file section to the request
*
* @param fieldName name attribute in <input type="file" name="..." />
* @param uploadFile a File to be uploaded
* @throws IOException
*/
public void addFilePart(String fieldName, File uploadFile)
throws IOException {
String fileName = uploadFile.getName();
writer.append("--" + boundary).append(LINE_FEED);
writer.append(
"Content-Disposition: form-data; name=\"" + fieldName
+ "\"; filename=\"" + fileName + "\"")
.append(LINE_FEED);
writer.append(
"Content-Type: "
+ URLConnection.guessContentTypeFromName(fileName))
.append(LINE_FEED);
writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
writer.append(LINE_FEED);
writer.flush();
FileInputStream inputStream = new FileInputStream(uploadFile);
byte[] buffer = new byte[4096];
int bytesRead = -1;
while ((bytesRead = inputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
outputStream.flush();
inputStream.close();
writer.append(LINE_FEED);
writer.flush();
}
/**
* Adds a header field to the request.
*
* @param name - name of the header field
* @param value - value of the header field
*/
public void addHeaderField(String name, String value) {
writer.append(name + ": " + value).append(LINE_FEED);
writer.flush();
}
/**
* Completes the request and receives response from the server.
*
* @return a list of Strings as response in case the server returned
* status OK, otherwise an exception is thrown.
* @throws IOException
*/
public String finish() throws IOException {
StringBuffer response = new StringBuffer();
writer.append(LINE_FEED).flush();
writer.append("--" + boundary + "--").append(LINE_FEED);
writer.close();
// checks server's status code first
int status = httpConn.getResponseCode();
if (status == HttpURLConnection.HTTP_OK) {
BufferedReader reader = new BufferedReader(new InputStreamReader(
httpConn.getInputStream()));
String line = null;
while ((line = reader.readLine()) != null) {
response.append(line);
}
reader.close();
httpConn.disconnect();
} else {
throw new IOException("Server returned non-OK status: " + status);
}
return response.toString();
}
}将你的file与参数一起使用。
注意:将下面的代码放在非ui线程中以获取响应。
String charset = "UTF-8";
String requestURL = "YOUR_URL";
MultipartUtility multipart = new MultipartUtility(requestURL, charset);
multipart.addFormField("param_name_1", "param_value");
multipart.addFormField("param_name_2", "param_value");
multipart.addFormField("param_name_3", "param_value");
multipart.addFilePart("file_param_1", new File(file_path));
String response = multipart.finish(); // response from server.页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/11766878
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