Servlet实现简单文件上传功能

本文实例为大家分享了Servlet文件上传的具体代码，供大家参考，具体内容如下

两点要素：

表单提交方式必须是post
2.enctype一定要是multipart/fORM-data。
enctype的默认值是application/x-www-form-urlencoded，
这种编码格式只支持键值对的数据，?键=值&键=值，只能是字符串，无法传输文件。
multipart/form-data这种编码可以上传文件

需要的jar包：

实现：

import java.io.BufferedInputStream;import java.io.File;import java.io.FileOutputStream;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 {  //文件夹路径常量  private static String TEMP_PATH = "E:/Learning/temp/170926";  private static final long serialVersionUID = 3364746345428715093L;  public void doGet(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    doPost(request, response);  }  public void doPost(HttpServletRequest request, HttpServletResponse response)      throws ServletException, IOException {    response.setContentType("text/html;charset=UTF-8");    PrintWriter out = response.getWriter();    // 接收文件    boolean isMultipart = ServletFileUpload.isMultipartContent(request);    // 判断是否是文件上传请求    if (!isMultipart) {      out.println("Error : 表单必须包含 enctype=multipart/form-data");      return;    }    // 用于创建解析文件上传的工厂类    DiskFileItemFactory factory = new DiskFileItemFactory();    // 用于从请求中解析出文件    ServletFileUpload upload = new ServletFileUpload(factory);    try {      // 获取所有提交过来的文件(包含表单内容) 这个FileItem叫做一个项，这个项有可能是文件也有可能是表单参数       List<FileItem> items = upload.parseRequest(request);      // 定义一个输出流      FileOutputStream fos = null;      //缓冲区      byte [] buf = new byte[8192];      if (items != null && items.size() > 0) { // 不为空且长度大于0则遍历之        for (FileItem item : items) {          if (item.isFormField()) { // isFormField = true 文本框的值            out.println("用户名: " + item.getString() + "<br />");          } else {            //获取输入流            BufferedInputStream bis = new BufferedInputStream(item.getInputStream());            //初始化本地输出流            fos = new FileOutputStream(new File(TEMP_PATH + "/" + item.getName()));            int len = -1;            while ((len = bis.read(buf)) != -1) {              fos.write(buf , 0 , len);              fos.flush();            }            out.println("文件: " + item.getName() + "已上传 <br />");          }        }      }    } catch (FileUploadException e) {      out.println("Error: 文件解析异常");    }  }}