java通过模拟post方式提交表单实现图片上传功能实例

<form action="up_result.jsp" method="post" enctype="multipart/form-data" name="form1" id="form1">
 <label>
 <input type="text" name="name" value="" />
 </label>
 <label>
 <input type="file" name="userfile" />
 </label>
 <label>
 <input type="submit" value="上传" />
 </label>
</form>

package com.yanek.util; 
import java.io.bufferedreader; 
import java.io.datainputstream; 
import java.io.dataoutputstream; 
import java.io.file; 
import java.io.fileinputstream; 
import java.io.inputstreamreader; 
import java.io.outputstream; 
import java.net.httpurlconnection; 
import java.net.url; 
import java.util.hashmap; 
import java.util.iterator; 
import java.util.map; 
import javax.activation.mimetypesfiletypemap; 
import net.sf.json.jsonarray; 
import net.sf.json.jsonobject; 
public class httppostuploadutil { 
 /** 
  * @param args 
  */ 
 public static void main(string[] args) { 
  string filepath="e:\\ziliao\\0.jpg"; 
  string urlstr = "http://127.0.0.1:8080/minicms/up/up_result.jsp"; 
  map<string, string> textmap = new hashmap<string, string>(); 
  textmap.put("name", "testname"); 
  map<string, string> filemap = new hashmap<string, string>(); 
  filemap.put("userfile", filepath); 
  string ret = formupload(urlstr, textmap, filemap); 
  system.out.println(ret); 
 } 
 /** 
  * 上传图片 
  * 
  * @param urlstr 
  * @param textmap 
  * @param filemap 
  * @return 
  */ 
 public static string formupload(string urlstr, map<string, string> textmap,
   map<string, string> filemap) { 
  string res = ""; 
  httpurlconnection conn = null; 
  string boundary = "---------------------------123821742118716"; //boundary就是request头和上传文件内容的分隔符 
  try { 
   url url = new url(urlstr); 
   conn = (httpurlconnection) url.openconnection(); 
   conn.setconnecttimeout(5000); 
   conn.setreadtimeout(30000); 
   conn.setdooutput(true); 
   conn.setdoinput(true); 
   conn.setusecaches(false); 
   conn.setrequestmethod("post"); 
   conn.setrequestproperty("connection", "keep-alive"); 
   conn 
     .setrequestproperty("user-agent", 
       "mozilla/5.0 (windows; u; windows nt 6.1; zh-cn; rv:1.9.2.6)"); 
   conn.setrequestproperty("content-type", 
     "multipart/form-data; boundary=" + boundary); 
   outputstream out = new dataoutputstream(conn.getoutputstream()); 
   // text 
   if (textmap != null) { 
    stringbuffer strbuf = new stringbuffer(); 
    iterator iter = textmap.entryset().iterator(); 
    while (iter.hasnext()) { 
     map.entry entry = (map.entry) iter.next(); 
     string inputname = (string) entry.getkey(); 
     string inputvalue = (string) entry.getvalue(); 
     if (inputvalue == null) { 
      continue; 
     } 
     strbuf.append("\r\n").append("--").append(boundary).append( 
       "\r\n"); 
     strbuf.append("content-disposition: form-data; name=\"" 
       + inputname + "\"\r\n\r\n"); 
     strbuf.append(inputvalue); 
    } 
    out.write(strbuf.tostring().getbytes()); 
   } 
   // file 
   if (filemap != null) { 
    iterator iter = filemap.entryset().iterator(); 
    while (iter.hasnext()) { 
     map.entry entry = (map.entry) iter.next(); 
     string inputname = (string) entry.getkey(); 
     string inputvalue = (string) entry.getvalue(); 
     if (inputvalue == null) { 
      continue; 
     } 
     file file = new file(inputvalue); 
     string filename = file.getname(); 
     string contenttype = new mimetypesfiletypemap() 
       .getcontenttype(file); 
     if (filename.endswith(".png")) { 
      contenttype = "image/png"; 
     } 
     if (contenttype == null || contenttype.equals("")) { 
      contenttype = "application/octet-stream"; 
     } 
     stringbuffer strbuf = new stringbuffer(); 
     strbuf.append("\r\n").append("--").append(boundary).append( 
       "\r\n"); 
     strbuf.append("content-disposition: form-data; name=\"" 
       + inputname + "\"; filename=\"" + filename 
       + "\"\r\n"); 
     strbuf.append("content-type:" + contenttype + "\r\n\r\n"); 
     out.write(strbuf.tostring().getbytes()); 
     datainputstream in = new datainputstream( 
       new fileinputstream(file)); 
     int bytes = 0; 
     byte[] bufferout = new byte[1024]; 
     while ((bytes = in.read(bufferout)) != -1) { 
      out.write(bufferout, 0, bytes); 
     } 
     in.close(); 
    } 
   } 
   byte[] enddata = ("\r\n--" + boundary + "--\r\n").getbytes(); 
   out.write(enddata); 
   out.flush(); 
   out.close(); 
   // 读取返回数据 
   stringbuffer strbuf = new stringbuffer(); 
   bufferedreader reader = new bufferedreader(new inputstreamreader( 
     conn.getinputstream())); 
   string line = null; 
   while ((line = reader.readline()) != null) { 
    strbuf.append(line).append("\n"); 
   } 
   res = strbuf.tostring(); 
   reader.close(); 
   reader = null; 
  } catch (exception e) { 
   system.out.println("发送post请求出错。" + urlstr); 
   e.printstacktrace(); 
  } finally { 
   if (conn != null) { 
    conn.disconnect(); 
    conn = null; 
   } 
  } 
  return res; 
 } 
}