java – 使用HTTPHandler上传文件

文件上传到HttpHandler导致边界和其他MIME信息被写入请求内容.由于解析这些信息非常复杂且容易出错,因此可以使用Commons FileUpload,这被证明在经典的Servlet环境中非常有用.

考虑使用自定义ContextRequest的此示例.这将处理由multipart / form-data添加到请求体中的边界的所有解析,同时仍允许您保留HttpHandler接口.

主要思想包括实现一个自己的ContextRequest版本来处理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();
          }
 }

供参考：这是列出接收文件的工作示例.

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("rn".getBytes());
                    System.out.println("File-Item: " + fi.getFieldName() + " = " + fi.getName());
                }
                os.close();

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