[置顶] 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。

参考资料http://my.oschina.net/u/226973/blog/48897 sinatrarb.comhaml.info