Servlet實現(xiàn)簡單文件上傳功能

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 {

  //文件夾路徑常量
  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);

    // 判斷是否是文件上傳請求
    if (!isMultipart) {
      out.println("Error : 表單必須包含 enctype=multipart/form-data");
      return;
    }

    // 用于創(chuàng)建解析文件上傳的工廠類
    DiskFileItemFactory factory = new DiskFileItemFactory();

    // 用于從請求中解析出文件
    ServletFileUpload upload = new ServletFileUpload(factory);

    try {

      // 獲取所有提交過來的文件(包含表單內(nèi)容) 這個FileItem叫做一個項，這個項有可能是文件也有可能是表單參數(shù) 
      List<FileItem> items = upload.parseRequest(request);

      // 定義一個輸出流
      FileOutputStream fos = null;

      //緩沖區(qū)
      byte [] buf = new byte[8192];

      if (items != null && items.size() > 0) { // 不為空且長度大于0則遍歷之
        for (FileItem item : items) {
          if (item.isFormField()) { // isFormField = true 文本框的值
            out.println("用戶名: " + item.getString() + "<br />");
          } else {
            //獲取輸入流
            BufferedInputStream bis = new BufferedInputStream(item.getInputStream());

            //初始化本地輸出流
            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() + "已上傳 <br />");
          }
        }
      }
    } catch (FileUploadException e) {
      out.println("Error: 文件解析異常");
    }

  }

}