文件上傳的方法主要目前有兩個常用的，一個是SmartUpload，一個是Apache的Commons fileupload.

　　我們這里主要介紹下第二個的用法，首先要上傳文件，注意幾個問題：

　　1 form表單內，要添加空間<input type="file" name="myfile">

　　2 form表單的內容格式要定義成multipart/form-data格式

　　3 需要類庫：1 commons-io.jar 2commons-fileupload-1.3.1.jar

　　接下來我們看下他的用法。

　　首先閱讀Apache commons fileupload的官方文檔可以發現下面幾個常用的函數：

　　1 創建文件解析對象

DiskFileUpload diskFileUpload = new DiskFileUpload();

　　2 進行文件解析后放在List中，因為這個類庫支持多個文件上傳，因此把結果會存在List中。

List<FileItem> list = diskFileUpload.parseRequest(request);

　　3 獲取上傳文件，進行分析（不是必須）

File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));

　　4 創建新對象，進行流拷貝

file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());file1.getParentFile().mkdirs();file1.createNewFile();InputStream ins = fileItem.getInputStream();OutputStream ous = new FileOutputStream(file1);try{byte[] buffer = new byte[1024];int len = 0;while((len = ins.read(buffer)) > -1)ous.write(buffer,0,len);out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");}finally{ous.close();ins.close();}

　　這樣我們就完成了文件的上傳。

fileUpload.html

<form action="servlet/UploadServlet" method="post" enctype="multipart/form-data"><div align="center"><fieldset style="width:80%"><legend>上傳文件</legend><br/><div align="left">上傳文件1</div><div align="left"><input type="file" name="file1"/></div><div align="left">上傳文件2</div><div align="left"><input type="file" name="file2"/></div><div><div align='left'>上傳文件說明1</div><div align='left'><input type="text" name="description1"/></div></div><div><div align='left'>上傳文件說明2</div><div align='left'><input type="text" name="description2"/></div></div><div><div align='left'><input type='submit' value="上傳文件"/></div></div></fieldset></div></form>

web.xml

<servlet><servlet-name>UploadServlet</servlet-name><servlet-class>com.test.hello.UploadServlet</servlet-class></servlet> <servlet-mapping><servlet-name>UploadServlet</servlet-name><url-pattern>/servlet/UploadServlet</url-pattern></servlet-mapping>

UploadServlet.java

package com.test.hello;import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintWriter; import java.util.List;import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.DiskFileUpload; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileUploadException;public class UploadServlet extends HttpServlet {/*** Constructor of the object.*/public UploadServlet() {super();}/*** Destruction of the servlet. <br>*/public void destroy() {super.destroy(); // Just puts "destroy" string in log// Put your code here }/*** The doGet method of the servlet. <br>** This method is called when a form has its tag value method equals to get.* * @param request the request send by the client to the server* @param response the response send by the server to the client* @throws ServletException if an error occurred* @throws IOException if an error occurred*/public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setCharacterEncoding("UTF-8");response.getWriter().println("請以POST方式上傳文件");}/*** The doPost method of the servlet. <br>** This method is called when a form has its tag value method equals to post.* * @param request the request send by the client to the server* @param response the response send by the server to the client* @throws ServletException if an error occurred* @throws IOException if an error occurred*/@SuppressWarnings({ "unchecked", "deprecation" })public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {File file1 = null,file2=null;String description1 = null,description2 = null;response.setCharacterEncoding("UTF-8");request.setCharacterEncoding("UTF-8");response.setContentType("text/html");PrintWriter out = response.getWriter();DiskFileUpload diskFileUpload = new DiskFileUpload();try{List<FileItem> list = diskFileUpload.parseRequest(request);out.println("遍歷所有的FileItem...<br/>");for(FileItem fileItem : list){if(fileItem.isFormField()){if("description1".equals(fileItem.getFieldName())){out.println("遍歷到description1 ... <br/>");description1 = new String(fileItem.getString().getBytes(),"UTF-8");}if("description2".equals(fileItem.getFieldName())){out.println("遍歷到description2 ... <br/>");description2 = new String(fileItem.getString().getBytes(),"UTF-8");}}else{if("file1".equals(fileItem.getFieldName())){File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));out.println("遍歷到file1...<br/>");out.println("客戶端文件位置："+remoteFile.getAbsolutePath()+"<br/>");file1 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());file1.getParentFile().mkdirs();file1.createNewFile();InputStream ins = fileItem.getInputStream();OutputStream ous = new FileOutputStream(file1);try{byte[] buffer = new byte[1024];int len = 0;while((len = ins.read(buffer)) > -1)ous.write(buffer,0,len);out.println("以保存文件"+file1.getAbsolutePath()+"<br/>");}finally{ous.close();ins.close();}}if("file2".equals(fileItem.getFieldName())){File remoteFile = new File(new String(fileItem.getName().getBytes(),"UTF-8"));out.println("遍歷到file2...<br/>");out.println("客戶端文件位置："+remoteFile.getAbsolutePath()+"<br/>");file2 = new File(this.getServletContext().getRealPath("attachment"),remoteFile.getName());file2.getParentFile().mkdirs();file2.createNewFile();InputStream ins = fileItem.getInputStream();OutputStream ous = new FileOutputStream(file2);try{byte[] buffer = new byte[1024];int len = 0;while((len = ins.read(buffer)) > -1)ous.write(buffer,0,len);out.println("以保存文件"+file2.getAbsolutePath()+"<br/>");}finally{ous.close();ins.close();}}}out.println("Request 解析完畢<br/><br/>");}}catch(FileUploadException e){}out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");out.println("<HTML>");out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");out.println(" <BODY>");if(file1 != null){out.println("<div>");out.println(" <div align='left'>file1;</div>");out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+file1.getName()+"'target=_blank>"+file1.getName()+"</a>");out.println("</div>");out.println("</div>");}if(file2 != null){out.println("<div>");out.println(" <div align='left'>file2;</div>");out.println(" <div align='left'><a href='"+request.getContextPath()+"/attachment/"+file2.getName()+"'target=_blank>"+file2.getName()+"</a>");out.println("</div>");out.println("</div>");}out.println("<div>");out.println(" <div align='left'>description1:</div>");out.println(" <div align='left'>");out.println(description1);out.println("</div>");out.println("</div>");out.println("<div>");out.println(" <div align='left'>description2:</div>");out.println(" <div align='left'>");out.println(description2);out.println("</div>");out.println("</div>");out.println(" </BODY>");out.println("</HTML>");out.flush();out.close();}/*** Initialization of the servlet. <br>** @throws ServletException if an error occurs*/public void init() throws ServletException {// Put your code here }} View Code

運行示例

總結

以上是生活随笔為你收集整理的文件上传之Apache commons fileupload使用的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。