java map转Multipart/form-data类型body实例

public static string maptotxt(map<string,string> fieldmap, map<string,file> filemap,string filename) throws exception{
		random random = new random();
		int j;
		string getline = "\r\n";
		string filetype = "content-type: application/octet-stream";
		string doublebar = "--";
		biaoshi = "----webkitformboundary";
		stringbuffer sb = new stringbuffer();
		for(int i = 0; i < 16;i++){
			j = random.nextint(multipart_chars.length-2)+2;
			sb.append(multipart_chars[j]);
		}
		biaoshi = biaoshi + sb.tostring();
		stringbuffer stringbuffer = new stringbuffer();
 
 
 
		for (map.entry<string,string> entity:fieldmap.entryset()) {
			string name = "content-disposition: form-data; name=\""+entity.getkey()+"\"";
			stringbuffer.append(doublebar+biaoshi);
			stringbuffer.append(getline);
			stringbuffer.append(name);
			stringbuffer.append(getline);
			stringbuffer.append(getline);
			stringbuffer.append(entity.getvalue());
			stringbuffer.append(getline);
		}
 
		for (map.entry<string,file> entity:filemap.entryset()) {
			string name = "content-disposition: form-data; name=\""+filename+"\"; filename=\""+entity.getvalue().getname()+"\"";
			stringbuffer.append(doublebar+biaoshi);
			stringbuffer.append(getline);
			stringbuffer.append(name);
			stringbuffer.append(getline);
			stringbuffer.append(filetype);
			stringbuffer.append(getline);
			stringbuffer.append(getline);
			file f = entity.getvalue();
			fileinputstream fileinputstream = new fileinputstream(f);
			bytearrayoutputstream bytearrayoutputstream = new bytearrayoutputstream();
			byte by[] = new byte[1024];
			int k = 0;
			while ((k=fileinputstream.read(by))!=-1){
				bytearrayoutputstream.write(by,0,k);
			}
			by = bytearrayoutputstream.tobytearray();
			for(int i = 0; i < by.length; i++){
				stringbuffer.append(by[i]);
			}
			stringbuffer.append(getline);
		}
		stringbuffer.append(doublebar+biaoshi+doublebar);
		return stringbuffer.tostring();
	}

 public map<string, object> test(httpservletrequest request,httpservletrequest response) throws exception {
     map<string, string> returnmap = new hashmap<string, string>();
    string a=request.getparameter("a");//取出form-data中a的值
    string b=request.getparameter("b");//取出form-data中a的值
    //取出form-data中的二进制字段
    multiparthttpservletrequest multipartrequest=(multiparthttpservletrequest) request; 
    multipartfile multipartfile = multipartrequest.getfile("file");//file是form-data中二进制字段对应的name
    system.out.println(multipartfile.getsize());  
    map<string, object> resultmapsreturn = new hashmap<>();
    string imagepath="c:\\users\\win\\desktop\\1.jpg"//把取出来的二进制保存图片到本地
    if(multipartfile.getsize()<=0){
      resultmapsreturn.put("resultcode", "0");
      resultmapsreturn.put("msg", diswebconst.error_title);
    }else{
      inputstream is = multipartfile.getinputstream();

      outputstream out = new fileoutputstream(imagepath);
      ioutils.copy(is, out);
      is.close();
      out.close();
    }