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java - 使用 HTTPHandler 上传文件

转载 作者：行者123 更新时间：2023-12-01 19:34:10 25 4
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我正在尝试使用 HTTPHandler 上传文件(多部分表单数据)。

WebKit Boundary 正在写入目标文件，从而损坏文件。

输入文件可以是任何类型的文件，包括文本、zip、apk 等。

代码:

    public void handle(HttpExchange httpExchange) throws IOException {

    URI uri = httpExchange.getRequestURI();
    String httpReqMethod = httpExchange.getRequestMethod();
    Headers headers = httpExchange.getRequestHeaders();
    InputStream  inputStrm = null;
    FileOutputStream destFile = null;
    String contentType = ((headers.get("Content-type") != null) ? (headers.get("Content-type").toString()) : (null));
    httpExchange.getRequestURI().getQuery());

    Map<String, String> queryParams = queryToMap(httpExchange.getRequestURI().getQuery());
    Set<String> keys= headers.keySet();
    Iterator<String> itr = keys.iterator();
    while(itr.hasNext())
    {
      String key = (String)itr.next();
    }

    File file = new File(ACEConstants.WEB_SERVER_CTX_ROOT + uri.getPath()).getCanonicalFile();
    String resource = uri.getPath().substring(
              uri.getPath().indexOf(ACEConstants.WEB_SERVER_CTX_ROOT)+ACEConstants.WEB_SERVER_CTX_ROOT.length()+1);

      if(httpReqMethod.equals(ACEConstants.HTTP_REQUEST_METHOD_POST) )
      {
        if(contentType != null && contentType.contains("multipart/form-data"))
        {
          if(resource.equals("fileUpload"))
          {
            inputStrm = httpExchange.getRequestBody();
            destFile = new FileOutputStream(new File("D:\\"+queryParams.get("fileName")));
            String contentLength = headers.get("Content-length").toString();
            long fileSize = (Long.parseLong(contentLength.substring(1, contentLength.length()-1)));
            int iteration = 1;
            long bytesToBeRead = (fileSize > 1024) ? ((iteration * 1024)) : (inputStrm.available());
            long bytesRemaining = (fileSize) - (iteration * 1024);
              byte[] bytes = new byte[1024];

            if(fileSize <= 1024) 
            {
              bytes = new byte[inputStrm.available()];
              inputStrm.read(bytes);
              destFile.write(bytes);
            }
            else {

              while (inputStrm.read(bytes) != -1) {
                iteration++;
                destFile.write(bytes);
                bytesRemaining =  ( fileSize - ((iteration-1) * 1024));
                if (bytesRemaining >= 1024) {
                  bytesToBeRead = 1024;
                  bytes = new byte[1024];
                }
                else {
                  bytes = new byte[inputStrm.available()];

                  inputStrm.read(bytes);
                  destFile.write(bytes);
                  break;
                }
              }
            }
            destFile.close();
          }
        } 
      }
    }

这是 HTML 代码

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script type="text/javascript">

        function processForm(frm)
        {
            var fu1 = document.getElementsByName("datafile");
            var filename = fu1[0].value;
            filename = filename.substring(filename.lastIndexOf("\\")+1);
            alert("You selected " + filename);
            frm.action = "http://localhost:64444/ACE/fileUpload?fileName="+filename;
            return true;
        }

    </script>
</head>
<body>

<form name="myForm" enctype="multipart/form-data" method="post" acceptcharset="UTF-8" onsubmit="processForm(this);">
    <p>
        Please specify a file, or a set of files:<br>
        <input type="file" name="datafile" size="40">
    </p>
    <div>
        <input type="submit" value="Send">
    </div>
</form>

</body>
</html>

这里出了什么问题？非常感谢您的帮助。

编辑1:

如果输入文件是包含文本的文本文件:1234567890
输出文件有内容:

 ------WebKitFormBoundaryKBRUiUWrIpW9wq2j
Content-Disposition: form-data; name="textline"


------WebKitFormBoundaryKBRUiUWrIpW9wq2j
Content-Disposition: form-data; name="datafile"; filename="test.txt"
Content-Type: text/plain

1234567890
------WebKitFormBoundaryKBRUiUWrIpW9wq2j--

最佳答案

如何使用HttpHandler上传文件

文件上传到 HttpHandler 会导致边界和其他 MIME 信息写入请求内容。由于解析此信息非常复杂且容易出错，因此可以求助于使用 Commons FileUpload事实证明，它在经典的 Servlet 环境中非常有效。

考虑这个带有自定义ContextRequest的示例。这将处理通过 multipart/form-data 添加到请求正文中的所有边界解析，同时仍然允许您保留 HttpHandler 接口(interface)。

主要思想包括实现自己版本的 ContextRequest 来处理 HttpHandler 中提供的数据:

   public HttpHandlerRequestContext implements RequestContext {

          private HttpExchange http;

          public HttpHandlerRequestContext(HttpExchange http) {
                this.http = http;
          }

          @Override
          public String getCharacterEncoding() {
                //Need to figure this out yet
                return "UTF-8"; 
          }

          @Override
          public int getContentLength() {
                //tested to work with 0 as return. Deprecated anyways
                return 0; 
          }

          @Override
          public String getContentType() {
                //Content-Type includes the boundary needed for parsing
                return http.getRequestHeaders().getFirst("Content-type");
          }

          @Override
          public InputStream getInputStream() throws IOException {
                 //pass on input stream
                return http.getRequestBody();
          }
 }

供引用:这是一个列出收到的文件的工作示例。

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.List;
import java.util.Map.Entry;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.RequestContext;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.sun.net.httpserver.HttpExchange;
import com.sun.net.httpserver.HttpHandler;
import com.sun.net.httpserver.HttpServer;

public class HttpServerTest {

    public static void main(String[] args) throws Exception {
        HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
        server.createContext("/fileupload", new MyHandler());
        server.setExecutor(null); // creates a default executor
        server.start();
    }

    static class MyHandler implements HttpHandler {
        @Override
        public void handle(final HttpExchange t) throws IOException {
            for(Entry<String, List<String>> header : t.getRequestHeaders().entrySet()) {
                System.out.println(header.getKey() + ": " + header.getValue().get(0));
            }
            DiskFileItemFactory d = new DiskFileItemFactory();      

            try {
                ServletFileUpload up = new ServletFileUpload(d);
                List<FileItem> result = up.parseRequest(new RequestContext() {

                    @Override
                    public String getCharacterEncoding() {
                        return "UTF-8";
                    }

                    @Override
                    public int getContentLength() {
                        return 0; //tested to work with 0 as return
                    }

                    @Override
                    public String getContentType() {
                        return t.getRequestHeaders().getFirst("Content-type");
                    }

                    @Override
                    public InputStream getInputStream() throws IOException {
                        return t.getRequestBody();
                    }

                });
                t.getResponseHeaders().add("Content-type", "text/plain");
                t.sendResponseHeaders(200, 0);
                OutputStream os = t.getResponseBody();               
                for(FileItem fi : result) {
                    os.write(fi.getName().getBytes());
                    os.write("\r\n".getBytes());
                    System.out.println("File-Item: " + fi.getFieldName() + " = " + fi.getName());
                }
                os.close();

            } catch (Exception e) {
                e.printStackTrace();
            }            
        }
    }
}

关于java - 使用 HTTPHandler 上传文件，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/59237193/

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