FileUpload下载地址：
http://commons.apache.org/fileupload/
下载：commons-fileupload-1.2.2-bin.zip 得到：commons-fileupload-1.2.2.jar
http://commons.apache.org/io/
下载：commons-io-1.4-bin.zip 得到：commons-io-1.4.jar
思路:
1.上传的文件通过http协议指定格式传输到后台
method="post" action="upload.action" enctype="multipart/form-data"
2.后台获取文件数据 (可以限制上传文件大小upload.setSizeMax())
DiskFileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> items = upload.parseRequest(req);
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> items = upload.parseRequest(req);
3.在指定目录下创建相同名称的文件然后将数据内容写入
String path = request.getServletContetxt().getRealPath("upload").getPath()+"\"+
+item.getName().substring(item.getName().lastIndexOf("/")+1);
item.write(new File(path));
<!--将文件作为一种数据格式;-->
<!--注意:1.method="post" 2.enctype="multipart/form-data"-->
<html>
<form id="form" name="form" method="post" action="upload.action" enctype="multipart/form-data">
<table >
<tr>
<td >
<input type="file" style="font-size:14px" name="filename" />
</td>
</tr>
<tr>
<td >
<input type="submit" style="font-size:14px" value="上传文件" />
</td>
</tr>
</table>
</form>
</html>
import java.io.File;
import java.io.IOException;
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.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
req.setCharacterEncoding("gbk");
resp.setContentType("text/html;charset=gbk");
PrintWriter out = resp.getWriter();
//磁盘文件工厂类;
DiskFileItemFactory factory = new DiskFileItemFactory();
//关联关系创建ServletFileUpload类;
ServletFileUpload upload = new ServletFileUpload(factory);
List<FileItem> items;
try {
//将req中的数据放入表单域;
items = upload.parseRequest(req);
for(FileItem item : items){
//判断是否是文件
if(!item.isFormField()) {
//文件名称;
String filename = item.getName();
//前缀路径;
//某些浏览器会将文件的绝对路径全部提交;（ie）Y (chrome)N
filename = filename.substring(filename.lastIndexOf("\\")+1);
//在WebRoot下创建一个uploads文件夹;
//找到服务器上的路径upload文件夹;
File file = new File(req.getServletContext().getRealPath("uploads")+File.separator+filename);
//文件的二进制已经在item对象中,导入file文件;
item.write(file);
out.print("<html><center >上传成功,3秒后跳转!</center></html>");
return ;
}
}
} catch (Exception e) {
e.printStackTrace();
}
out.print("<html><center>上传失败!</center></html>");
}
}
web.xml
web.xml <servlet> <servlet-name>upload</servlet-name> <servlet-class>cn.lh.web.UploadServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>upload</servlet-name> <url-pattern>/upload.action</url-pattern> </servlet-mapping>