文件上傳之Apache commons fileupload使用

　　文件上傳的方法主要目前有兩個經常使用的，一個是SmartUpload，一個是Apache的Commons fileupload.

　　咱們這裏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 須要類庫：1 commons-io.jar 2commons-fileupload-1.3.1.jar

　　接下來咱們看下他的用法。

　　首先閱讀Apache commons fileupload的官方文檔能夠發現下面幾個經常使用的函數：

　　1 建立文件解析對象

DiskFileUpload diskFileUpload = new DiskFileUpload();

　　2 進行文件解析後放在List中，由於這個類庫支持多個文件上傳，所以把結果會存在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 建立新對象，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(); }

　　這樣咱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("遍歷全部的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