Servlet实现文件上传的几种方法

1. 通过getInputStream()取得上传文件。

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/**

* 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：

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POST http://www.example.com HTTP/1.1

Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryrGKCBY7qhFd3TrwA

------WebKitFormBoundaryrGKCBY7qhFd3TrwA

Content-Disposition: form-data; name="text"

title

------WebKitFormBoundaryrGKCBY7qhFd3TrwA

Content-Disposition: form-data; name="file"; filename="chrome.png"

Content-Type: image/png

PNG ... content of chrome.png ...

------WebKitFormBoundaryrGKCBY7qhFd3TrwA--

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/**

* 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

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/**

* To change this template, choose Tools | Templates

* and open the template in the editor.

*/

package net.individuals.web.servlet;

import java.io.IOException;

import java.io.PrintWriter;

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;

/**

*采用part的wirte(String fileName)上传，浏览器将产生临时TMP文件。

* @author Barudisshu

*/

@MultipartConfig(location = "e:/workspace")

@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 {

//处理中文文件名

request.setCharacterEncoding("UTF-8");

Part part = request.getPart("photo");

String fileName = getFileName(part);

//将文件写入location指定的目录

part.write(fileName);

}

private String getFileName(Part part) {

String header = part.getHeader("Content-Disposition");

String fileName = header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\""));

return fileName;

}

// <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>

}