构造HTTP消息体采用HttpConnection实现文件上传

自己构造http消息体，用HttpConnection实现文件上传，后台用的是Sinatra框架搞定服务端，很简洁，几行代码，比起servlet快捷不少

package com.hoot.regx;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

public class Regx {
private static final String BOUNDARY = "-----------------7d4a6d158c9";
private static final String TWO_HYPHENS = "--";
private static final String END = "\r\n";

/**
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
URL url = new URL("http://localhost:4567/upload");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

  conn.setDoOutput(true);
  conn.setDoInput(true);
  conn.setRequestMethod("POST");
  conn.setRequestProperty("Connection", "Keep-Alive");
  conn.setRequestProperty("Charset", "UTF-8");
  conn.setRequestProperty("Content-Type",
    "multipart/form-data;boundary=" + BOUNDARY);

  StringBuffer sb = new StringBuffer();
  //分解符
  sb.append(TWO_HYPHENS + BOUNDARY + END);

  //设置与上次文件相关信息
  sb.append("Content-Disposition: form-data; name=\"myfile\"; filename=\"test.txt\""
    + END);
  //上传文件信息和文件的内容间必须有一个空行
  sb.append(END);

//  Map<String, List<String>> props = conn.getRequestProperties();
//  for(Entry<String, List<String>> prop : props.entrySet()){
//   System.out.println(prop.getKey() + ":" );
//   for(String str : prop.getValue()){
//    System.out.print(str);
//   }
//   System.out.println();
//  }
  System.out.println(sb.toString());

  byte[] data = sb.toString().getBytes();
  OutputStream os = conn.getOutputStream();
  os.write(data);

  //一下是文件数据
  FileInputStream fis = new FileInputStream(new File("test.txt"));
  byte[] buf = new byte[1024];
  int len = 0;
  while ((len = fis.read(buf)) > 0) {
   os.write(buf, 0, len);
  }
  String endStr = END + TWO_HYPHENS + BOUNDARY + TWO_HYPHENS + END;
  byte[] end_data = endStr.getBytes();
  System.out.println("<this is file content>");
  System.out.println(endStr);

  os.write(end_data);
  os.flush();
  os.close();
  fis.close();

  InputStream is = conn.getInputStream();
  while ((len = is.read(buf)) > 0) {
   System.out.write(buf, 0, len);
  }
  is.close();
}
}
服务器端：
需要安装几个gem
sinatra haml

require 'rubygems'
require 'sinatra'
require 'haml'

get '/' do
'Hello world'
end

# Handle GET-request (Show the upload form)
get "/upload" do
haml :upload
end

# Handle POST-request (Receive and save the uploaded file)
post "/upload" do
logger.info "#{params}"
unless   params[:myfile] &&
           (tmpfile = params[:myfile][:tempfile]) &&
           (name = params[:myfile][:filename])
      @error = "No file selected"
   logger.info "params #{@error} file: #{tmpfile} name: #{name} #{params}"
      return haml(:error)
end
directory = 'uploads'
path = File.join(directory, name)

File.open(path, "wb") do |f|
f.write(tmpfile.read)
end
#File.copy(tempfile.path, path)
@msg = "#{name}The file was successfully uploaded!"
end够简洁吧，下面我吧两个haml文件也贴一下（haml文件放在在同级目录的views目录下）
upload.haml

%html
%body
    %h1 File uploader!
    %form(method="post" enctype='multipart/form-data')
      %input(type='file' name='myfile')
      %br
      %input(type='submit' value='Upload!')error.haml

%html
%body
%h1 File uploader error!

总结：自己构造Post请求有些繁琐，分隔符间空格很重要，如过看不明白可以用抓包工具传两个小文件然后看看浏览器构造的请求体是什么格式，然后我们用字符串片接方式构造相同的结构，发送给服务器。

补充：综合编程 , 其他综合 ,