Servlet实现文件上传的三种方法总结
1. 通过getInputStream()取得上传文件。
/** * To change this template, choose Tools | Templates * and open the template in the editor. */ package net.individuals.web.servlet; import java.io.DataInputStream; import java.io.FileOutputStream; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * * @author Barudisshu */ @WebServlet(name = "UploadServlet", urlPatterns = {"/UploadServlet"}) public class UploadServlet extends HttpServlet { /** * Processes requests for both HTTP * <code>GET</code> and * <code>POST</code> methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); //读取请求Body byte[] body = readBody(request); //取得所有Body内容的字符串表示 String textBody = new String(body, "ISO-8859-1"); //取得上传的文件名称 String fileName = getFileName(textBody); //取得文件开始与结束位置 Position p = getFilePosition(request, textBody); //输出至文件 writeTo(fileName, body, p); } //构造类 class Position { int begin; int end; public Position(int begin, int end) { this.begin = begin; this.end = end; } } private byte[] readBody(HttpServletRequest request) throws IOException { //获取请求文本字节长度 int formDataLength = request.getContentLength(); //取得ServletInputStream输入流对象 DataInputStream dataStream = new DataInputStream(request.getInputStream()); byte body[] = new byte[formDataLength]; int totalBytes = 0; while (totalBytes < formDataLength) { int bytes = dataStream.read(body, totalBytes, formDataLength); totalBytes += bytes; } return body; } private Position getFilePosition(HttpServletRequest request, String textBody) throws IOException { //取得文件区段边界信息 String contentType = request.getContentType(); String boundaryText = contentType.substring(contentType.lastIndexOf("=") + 1, contentType.length()); //取得实际上传文件的气势与结束位置 int pos = textBody.indexOf("filename=\""); pos = textBody.indexOf("\n", pos) + 1; pos = textBody.indexOf("\n", pos) + 1; pos = textBody.indexOf("\n", pos) + 1; int boundaryLoc = textBody.indexOf(boundaryText, pos) - 4; int begin = ((textBody.substring(0, pos)).getBytes("ISO-8859-1")).length; int end = ((textBody.substring(0, boundaryLoc)).getBytes("ISO-8859-1")).length; return new Position(begin, end); } private String getFileName(String requestBody) { String fileName = requestBody.substring(requestBody.indexOf("filename=\"") + 10); fileName = fileName.substring(0, fileName.indexOf("\n")); fileName = fileName.substring(fileName.indexOf("\n") + 1, fileName.indexOf("\"")); return fileName; } private void writeTo(String fileName, byte[] body, Position p) throws IOException { FileOutputStream fileOutputStream = new FileOutputStream("e:/workspace/" + fileName); fileOutputStream.write(body, p.begin, (p.end - p.begin)); fileOutputStream.flush(); fileOutputStream.close(); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP * <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Handles the HTTP * <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> }
2. 通过getPart()、getParts()取得上传文件。
body格式：
POST HTTP/1.1 Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryrGKCBY7qhFd3TrwA ------WebKitFormBoundaryrGKCBY7qhFd3TrwA Content-Disposition: form-data; title ------WebKitFormBoundaryrGKCBY7qhFd3TrwA Content-Disposition: form-data;; filename="chrome.png" Content-Type: image/png PNG ... content of chrome.png ... ------WebKitFormBoundaryrGKCBY7qhFd3TrwA-- [html] view plain copy /** * To change this template, choose Tools | Templates * and open the template in the editor. */ package net.individuals.web.servlet; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import javax.servlet.ServletException; import javax.servlet.annotation.MultipartConfig; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.Part; /** * * @author Barudisshu */ @MultipartConfig @WebServlet(name = "UploadServlet", urlPatterns = {"/UploadServlet"}) public class UploadServlet extends HttpServlet { /** * Processes requests for both HTTP * <code>GET</code> and * <code>POST</code> methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Part part = request.getPart("photo"); String fileName = getFileName(part); writeTo(fileName, part); } //取得上传文件名 private String getFileName(Part part) { String header = part.getHeader("Content-Disposition"); String fileName = header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\"")); return fileName; } //存储文件 private void writeTo(String fileName, Part part) throws IOException, FileNotFoundException { InputStream in = part.getInputStream(); OutputStream out = new FileOutputStream("e:/workspace/" + fileName); byte[] buffer = new byte[1024]; int length = -1; while ((length = in.read(buffer)) != -1) { out.write(buffer, 0, length); } in.close(); out.close(); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP * <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Handles the HTTP * <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; } }
3、另一种较为简单的方法：采用part的wirte(String fileName)上传，浏览器将产生临时TMP文件