This article describes the image upload function of Java by imitating post to submit forms. Share it for your reference, as follows:
The mock form html is as follows:
<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="upload" /> </label >/form>
The java code is as follows:
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 jav a.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>(); te xtMap.put ("name", "testname"); Map<String, String> fileMap = new HashMap<String, String>(); fileMap.put("userfile", filepath); String ret = formUpload(ur lStr, textMap, fileMap) ; System.out.println(ret); } /** * Upload image* * @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 is the delimiter of the request header and upload file content 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")) { conten tType = "image/png"; } if (contentType == null || contentType.equals("")) { contentType = "application/octet-stream"; } StringBuffer strBuf = new StringBuffer(); strBuf.append("/r/n").ap pend("--") .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) { ou t.write( bufferOut, 0, bytes); } in.close(); } } byte[] endData = ("/r/n--" + BOUNDARY + "--/r/n").getBytes(); out.write (endData); out.flush(); out.close(); // Read the return data StringBuffer strBuf = new StringBuffer(); BufferedReader reader = new BufferedReader(new InputStream Reader( 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("An error occurred sending a POST request. " + urlStr); e.printStackTrace(); } finally { if (conn != null) { conn.disconnect(); conn = null; } } return res; } }I hope this article will be helpful to everyone's Java programming.