利用 commons-fileupload 组件进行文件上传

 <wbr> </wbr><wbr>  </wbr><wbr>今天做JSP的网页，遇到一下传文件的问题，从网上搜了搜，可以实现文件上传，但是没有办法将File表单和其它表单的信息同时获取，但这是经常遇到的问题，所以，自己研究一下，其实挺简单的。
 </wbr><wbr>我们利用的是Common-fileupload组件，需要两个包：commons-fileupload-1.2.jar和commons-io-1.3.2.jar这两个包，可以从它的官方去下载（里面有doc和src）。
 </wbr><wbr>另外，我们还需要在WebRoot目录下，新建两个文件夹，ImagesUploadTemp 和upload。其中，我们将上传的文件放到upload目录下边。
 </wbr><wbr>下面就开始进行操作吧：
 </wbr><wbr>首先呢，得有个上传页面吧，文件如下：
 </wbr><wbr><form name="form1" method="post" action="FileUploadServlet" enctype="multipart/form-data">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <table width="619" height="562" border="1" >
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <tr>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <td width="146" height="35">用户名：</td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <td width="454">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <input name="name" type="text" id="name">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </tr>
<tr>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <td width="146" height="35">密码：</td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <td width="454">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> <input name="password" type="password" id="name">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </tr></wbr>

 <wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>  </wbr><wbr><tr>
 </wbr><wbr> </wbr><wbr><td width="140" height="38">图片：</td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr><td width="447">
 </wbr><wbr> </wbr><wbr> </wbr><wbr><input type="file" size="30" name="test" /> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr><input type="submit" name="Submit" value="上传">
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr></td>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr></tr>
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </table>
 </wbr><wbr> </wbr><wbr></form>
 </wbr><wbr>利用JSP文件操作，记得一定要在头上写这两个语句：
<%@ page contentType="text/html;charset=gb2312" language="java" import="java.util.*" pageEncoding="gb2312"%>
<%request.setCharacterEncoding("gb2312"); %>
这是设置页面的编码格式。
 </wbr><wbr>通过上面的页面，我们发现，form的表单地址是一个servlet，我的servlet如下所示：
 </wbr><wbr> </wbr><wbr>public void doPost(HttpServletRequest request, HttpServletResponse response)
 </wbr><wbr> </wbr><wbr> </wbr><wbr>throws ServletException, IOException {
 </wbr><wbr> </wbr><wbr>ArrayList<String> others = new ArrayList<String>(); // 这是所有的表单元素的列表。</wbr>

 <wbr> </wbr><wbr>String prefix = null; // 文件名
 </wbr><wbr> </wbr><wbr>String t_ext = null; // 后缀
 </wbr><wbr> </wbr><wbr>String fullname = null;
 </wbr><wbr> </wbr><wbr>request.setCharacterEncoding("gb2312");
 </wbr><wbr> </wbr><wbr>final long MAX_SIZE = 3 * 1024 * 1024;// 设置上传文件最大为 3M
 </wbr><wbr> </wbr><wbr>// 允许上传的文件格式的列表
 </wbr><wbr> </wbr><wbr>final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>"doc", "docx", "mp3", "wma", "m4a" };
 </wbr><wbr> </wbr><wbr>response.setContentType("text/html;charset=gb2312");
 </wbr><wbr> </wbr><wbr>// 设置字符编码为UTF-8, 这样支持汉字显示
 </wbr><wbr> </wbr><wbr>response.setCharacterEncoding("gb2312");</wbr>

 <wbr> </wbr><wbr>// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
 </wbr><wbr> </wbr><wbr>DiskFileItemFactory dfif = new DiskFileItemFactory();
 </wbr><wbr> </wbr><wbr>dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
 </wbr><wbr> </wbr><wbr>dfif.setRepository(new File(request.getRealPath("/")
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>+ "ImagesUploadTemp"));// 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录</wbr>

 <wbr> </wbr><wbr>// 用以上工厂实例化上传组件
 </wbr><wbr> </wbr><wbr>ServletFileUpload sfu = new ServletFileUpload(dfif);
 </wbr><wbr> </wbr><wbr>// 设置最大上传尺寸
 </wbr><wbr> </wbr><wbr>sfu.setSizeMax(MAX_SIZE);</wbr>

 <wbr> </wbr><wbr>PrintWriter out = response.getWriter();
 </wbr><wbr> </wbr><wbr>// 从request得到 所有 上传域的列表
 </wbr><wbr> </wbr><wbr>List fileList = null;
 </wbr><wbr> </wbr><wbr>try {
 </wbr><wbr> </wbr><wbr> </wbr><wbr>fileList = sfu.parseRequest(request);
 </wbr><wbr> </wbr><wbr>} catch (FileUploadException e) {// 处理文件尺寸过大异常
 </wbr><wbr> </wbr><wbr> </wbr><wbr>if (e instanceof SizeLimitExceededExcepti</wbr><wbr>on) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>return;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr> </wbr><wbr>e.printStackTrace();
 </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr>// 没有文件上传
 </wbr><wbr> </wbr><wbr>if (fileList == null || fileList.size() == 0) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("请选择上传文件<p />");
 </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
 </wbr><wbr> </wbr><wbr> </wbr><wbr>return;
 </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr>// 得到所有上传的文件
 </wbr><wbr> </wbr><wbr>Iterator fileItr = fileList.iterator();
 </wbr><wbr> </wbr><wbr>// 循环处理所有文件
 </wbr><wbr> </wbr><wbr>int i = fileList.size();
 </wbr><wbr> </wbr><wbr>System.out.println(i);
 </wbr><wbr> </wbr><wbr>String o[];//这是存放所有其它表单值的数组。
 </wbr><wbr> </wbr><wbr>o = new String[i];
 </wbr><wbr> </wbr><wbr>System.out.println("总共：" + i + "个字段");
 </wbr><wbr> </wbr><wbr>int j = 0;
 </wbr><wbr> </wbr><wbr>while (fileItr.hasNext()) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr>FileItem fileItem = null;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>String path = null;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>long size = 0;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 得到当前文件
 </wbr><wbr> </wbr><wbr> </wbr><wbr>fileItem = (FileItem) fileItr.next();
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 忽略简单form字段而不是上传域的文件域(<input type="text" />等)
 </wbr><wbr> </wbr><wbr> </wbr><wbr>if (fileItem == null || fileItem.isFormField()) {</wbr>

 <wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>String name = fileItem.getFieldName();
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>// if (name.equals("name")) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>String namea = fileItem.getString("gb2312");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>String a = new String(namea.getBytes(), "gb2312");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>o[j] = a;
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>System.out.println(o[j]);
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>// }
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>j++;
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>continue;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr> </wbr><wbr>System.out.println(j);</wbr>

 <wbr> </wbr><wbr> </wbr><wbr>// 得到文件的完整路径
 </wbr><wbr> </wbr><wbr> </wbr><wbr>path = fileItem.getName();
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 得到文件的大小
 </wbr><wbr> </wbr><wbr> </wbr><wbr>size = fileItem.getSize();
 </wbr><wbr> </wbr><wbr> </wbr><wbr>if ("".equals(path) || size == 0) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("请选择上传文件<p />");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("<a href=\"upload.html\" target=\"_top\">返回</a>");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>return;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}</wbr>

 <wbr> </wbr><wbr> </wbr><wbr>// 得到去除路径的文件名
 </wbr><wbr> </wbr><wbr> </wbr><wbr>String t_name = path.substring(path.lastIndexOf("\\") + 1);
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 得到文件的扩展名(无扩展名时将得到全名)
 </wbr><wbr> </wbr><wbr> </wbr><wbr>t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 拒绝接受规定文件格式之外的文件类型
 </wbr><wbr> </wbr><wbr> </wbr><wbr>int allowFlag = 0;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>int allowedExtCount = allowedExt.length;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>for (; allowFlag < allowedExtCount; allowFlag++) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>if (allowedExt[allowFlag].equals(t_ext))
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>break;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr> </wbr><wbr>if (allowFlag == allowedExtCount) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("请上传以下类型的文件<p />");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("*." + allowedExt[allowFlag]
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>+ "&nbsp;&nbsp;&nbsp;");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>.println("<p /><a href=\"upload.html\" target=\"_top\">返回</a>");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>return;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}</wbr>

 <wbr> </wbr><wbr> </wbr><wbr>long now = System.currentTimeMillis();
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 根据系统时间生成上传后保存的文件名
 </wbr><wbr> </wbr><wbr> </wbr><wbr>prefix = String.valueOf(now);
 </wbr><wbr> </wbr><wbr> </wbr><wbr>// 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
 </wbr><wbr> </wbr><wbr> </wbr><wbr>String u_name = request.getRealPath("/") + "upload/" + prefix + "."
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>+ t_ext;
 </wbr><wbr> </wbr><wbr> </wbr><wbr>try {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>// 保存文件
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>fileItem.write(new File(u_name));
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>System.out.println(prefix + "." + t_ext);
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>+ " &nbsp;&nbsp;文件大小: " + size + "字节<p />");
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("<a href=\"upload.html\" target=\"_top\">继续上传</a>");
 </wbr><wbr> </wbr><wbr> </wbr><wbr>} catch (Exception e) {
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>e.printStackTrace();
 </wbr><wbr> </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr>fullname = "upload/" + prefix + "." + t_ext;
 </wbr><wbr> </wbr><wbr>System.out.println(fullname);</wbr>

 <wbr> </wbr><wbr>String sql =””;
 </wbr><wbr> </wbr><wbr>System.out.println(sql);
 </wbr><wbr> </wbr><wbr>CarDAO dao = new CarDAO();//这里是操作数据库的代码。</wbr>

 <wbr> </wbr><wbr>if(dao.addCar(sql)){
 </wbr><wbr> </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("添加用户成功！！"); </wbr><wbr> </wbr><wbr>
 </wbr><wbr> </wbr><wbr>}else{
 </wbr><wbr> </wbr><wbr> </wbr><wbr>out.println("添加用户失败！！！");
 </wbr><wbr> </wbr><wbr>}
 </wbr><wbr> </wbr><wbr>
 </wbr><wbr>}</wbr>

这时，我们就可以在上传文件的同时，将文件的路径信息及其它表单信息存入到数据库中，
另外在web.xml中， 添加如下代码：
 <wbr><servlet>
 </wbr><wbr> </wbr><wbr><servlet-name>FileUploadServlet</servlet-name>
 </wbr><wbr> </wbr><wbr><servlet-class>servlet.FileUploadServlet</servlet-class>
 </wbr><wbr></servlet></wbr>

 <wbr><servlet-mapping>
 </wbr><wbr> </wbr><wbr><servlet-name>FileUploadServlet</servlet-name>
 </wbr><wbr> </wbr><wbr><url-pattern>/FileUploadServlet</url-pattern>
 </wbr><wbr></servlet-mapping>
这时，就可以完成操作了、
本例在Tomcat 6.0 和Resin3.0.25 下边测试成功。本人第一次写，有不对的地请大家指教。</wbr>