我正在尝试实现一个HTTP客户端,该客户端发出多部分请求以将文件上载到HTTP服务器. HTML表单有三个输入字段：一个用于用户名,一个用于密码,一个用于文件.服务器端如下所示.
我的实现如下.
public class MultipartUploader {
private static final String CHARSET = "UTF-8";
private static final String CRLF = "rn";
public String httpUpload(String url,String filename,byte[] byteStream)
throws MalformedURLException,IOException {
HttpURLConnection connection = (HttpURLConnection) new URL(url).openConnection();
final String boundary = Strings.repeat("-",15) + Long.toHexString(System.currentTimeMillis());
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setUseCaches(false);
connection.setRequestMethod("POST");
connection.setRequestProperty("Connection","Keep-Alive");
connection.setRequestProperty("Cache-Control","no-cache");
connection.setRequestProperty("Content-Type","multipart/form-data; boundary=" + boundary);
OutputStream directOutput = connection.getOutputStream();
PrintWriter body = new PrintWriter(new OutputStreamWriter(directOutput,CHARSET),true);
body.append(CRLF);
addSimpleFormData("myuser","myUserName",body,boundary);
addSimpleFormData("mypassword","mySecretPassword",boundary);
addFileData("myfile",filename,byteStream,directOutput,boundary);
addCloseDelimiter(body,boundary);
int responseCode = connection.getResponseCode();
String responseMessage = connection.getResponseMessage();
String payload = CharStreams.toString(new InputStreamReader(connection.getInputStream()));
return payload;
}
private static void addSimpleFormData(String paramName,String wert,PrintWriter body,final String boundary) {
body.append(boundary).append(CRLF);
body.append("Content-Disposition: form-data; name="" + paramName + """).append(CRLF);
body.append("Content-Type: text/plain; charset=" + CHARSET).append(CRLF);
body.append(CRLF);
body.append(wert).append(CRLF);
body.flush();
}
private static void addFileData(String paramName,byte[] byteStream,OutputStream directOutput,final String boundary) throws IOException {
body.append(boundary).append(CRLF);
body.append("Content-Disposition: form-data; name="" + paramName + ""; filename="" + filename + """)
.append(CRLF);
body.append("Content-Type: application/octed-stream").append(CRLF);
body.append("Content-Transfer-Encoding: binary").append(CRLF);
body.append(CRLF);
body.flush();
directOutput.write(byteStream);
directOutput.flush();
body.append(CRLF);
body.flush();
}
private static void addCloseDelimiter(PrintWriter body,final String boundary) {
body.append(boundary).append("--").append(CRLF);
body.flush();
}
}
服务器响应200 OK.我遇到的问题是,不正确地创建了HTTP正文,以便我从服务器获得的响应表明并非所有表单字段都已设置.服务器没有说明它是哪个字段.
所以我的问题是你看到这个代码有什么问题吗？我是否正确创建了多部分请求？
我还尝试使用cURL上传一个文件,并使用以下命令.
cURL -F "myuser=myUserName" -F "mypassword=mySecretPassword" -F "myfile=@/path/to/my/file.zip" "http://abcdef.gh:1234/path/to/uploader"
您在数据部分之间的界限在开头缺少额外的两个破折号： –
我通过捕获通过程序制作的http://httpbin.org/post请求并卷曲并通过diff工具进行比较来找到这个.我使用Wireshark来捕获请求.
以下是解决此问题的方法：
private static void addSimpleFormData(String paramName,final String boundary) {
body.append("--").append(boundary).append(CRLF);
body.append("Content-Disposition: form-data; name="" + paramName + """).append(CRLF);
body.append("Content-Type: text/plain; charset=" + CHARSET).append(CRLF);
body.append(CRLF);
body.append(wert).append(CRLF);
body.flush();
}
private static void addFileData(String paramName,final String boundary) throws IOException {
body.append("--").append(boundary).append(CRLF);
body.append("Content-Disposition: form-data; name="" + paramName + ""; filename="" + filename + """)
.append(CRLF);
body.append("Content-Type: application/octed-stream").append(CRLF);
body.append("Content-Transfer-Encoding: binary").append(CRLF);
body.append(CRLF);
body.flush();
directOutput.write(byteStream);
directOutput.flush();
body.append(CRLF);
body.flush();
}
private static void addCloseDelimiter(PrintWriter body,final String boundary) {
body.append("--").append(boundary).append("--").append(CRLF);
body.flush();
}
注意每个方法开头的额外.append(“ – ”).
有关完整的工作代码,请参阅https://gist.github.com/shtratos/8e9570a4a5591b2bcecd55ca60b3f24f
