java servlet 文件上传

package ren.minions.com;

import java.io.File;
import java.io.IOException;
//import java.io.UncheckedIOException;

import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.tomcat.util.http.fileupload.FileItem;
import org.apache.tomcat.util.http.fileupload.disk.DiskFileItemFactory;
import org.apache.tomcat.util.http.fileupload.servlet.ServletFileUpload;
import org.apache.tomcat.util.http.fileupload.servlet.ServletRequestContext;

/**
 * Servlet implementation class UploadFile
 */
@WebServlet("/UploadFile")
public class UploadFile extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	
	// 上传文件存储目录
    private static final String UPLOAD_DIRECTORY = "upload";
    // 上传配置
    private static final int MEMORY_THRESHOLD   = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB
    
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public UploadFile() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		
		if (!ServletFileUpload.isMultipartContent(request)) {/*错误识别*/
			response.getWriter().println("Error: 表单未包含 enctype=multipart/form-data");
			response.getWriter().flush();
		}

        DiskFileItemFactory factory = new DiskFileItemFactory();// 配置上传参数
        factory.setSizeThreshold(MEMORY_THRESHOLD); // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));// 设置临时存储目录
        ServletFileUpload upload = new ServletFileUpload(factory);
        
        upload.setFileSizeMax(MAX_FILE_SIZE);// 设置最大文件上传值
        upload.setSizeMax(MAX_REQUEST_SIZE); // 设置最大请求值 (包含文件和表单数据)
        upload.setHeaderEncoding("UTF-8"); // 中文处理
        
        // 构造临时路径来存储上传的文件
        // 这个路径相对当前应用的目录
        String uploadPath = request.getServletContext().getRealPath("./") + File.separator + UPLOAD_DIRECTORY;
        File uploadDir = new File(uploadPath);// 如果目录不存在则创建
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }
        
        
        try {
        	
			List
 
   formItems = (List
  
   )upload.parseRequest(new ServletRequestContext(request)); System.out.println(formItems.size());/*注意： 在表单的input元素中的name属性一定要有名字。否则元素将无法被检索到，造成数组为空*/ if (formItems != null && formItems.size() > 0) { for (FileItem fileItem : formItems) { if (!fileItem.isFormField()) { String fileName = new File(fileItem.getName()).getName(); String filePath = uploadPath + File.separator + fileName; File storeFile = new File(filePath); System.out.println("文件保存到:"+filePath); fileItem.write(storeFile); request.setAttribute("message", "文件上传成功！"); } } } } catch (Exception e) { // TODO: handle exception request.setAttribute("message", "错误信息：" + e.getMessage()); } // 跳转到 message.jsp request.getServletContext().getRequestDispatcher("/message.jsp").forward(request, response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }