java通过模拟post方式提交表单实现图片上传功能实例

本文实例讲述了java通过模拟post方式提交表单实现图片上传功能。分享给大家供大家参考，具体如下：

模拟表单html如下:

<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>

java代码如下:

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;
 }
}

希望本文所述对大家Java程序设计有所帮助。