使用FileUpload上传文件的主要Java代码详解编程语言

import java.io.File; 
import java.io.IOException; 
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.disk.DiskFileItemFactory; 
import org.apache.commons.fileupload.servlet.ServletFileUpload; 
  
public class UploadServlet extends HttpServlet { 
  
    @SuppressWarnings("unchecked") 
    public void doPost(HttpServletRequest request, HttpServletResponse response) 
            throws ServletException, IOException { 
        System.out.println("--------------upload-----------"); 
  
        DiskFileItemFactory factory = new DiskFileItemFactory(); 
        factory.setSizeThreshold(1024 * 1024); // 设置缓存大小，单位KB 
        String path = request.getRealPath("/upload"); // 得到当前项目upload目录的绝对路径 
        factory.setRepository(new File(path)); // 设置文件临时存储路径为path 
        ServletFileUpload upload = new ServletFileUpload(factory); 
        try { 
            List<FileItem> list = upload.parseRequest(request); 
            for (FileItem item : list) { 
                // 如果item是普通表单字段 
                if (item.isFormField()) { 
                    String name = item.getFieldName(); // 得到表单字段的name属性值 
                    String value = item.getString("gbk"); // 得到表单字段值，编码采用gbk 
                    request.setAttribute(name, value); 
                } else { 
                    String name = item.getFieldName(); 
                    String value = item.getName(); // 得到上传文件的路径(根据浏览器不同可能会有所差异) 
                    int start = value.lastIndexOf("//"); 
                    String fileName = value.substring(start + 1); // 截取最后一个/之后的字符，即行到上传文件名 
                    request.setAttribute(name, fileName); 
  
                    item.write(new File(path, fileName)); // 在硬盘上写入文件 
  
                    // 自己用流写的方法 
                    // OutputStream os = new FileOutputStream(new 
                    // File(path,fileName)); 
                    // InputStream is = item.getInputStream(); 
                    // byte[] buffer = new byte[500]; 
                    // int length = 0; 
                    // while((length = is.read(buffer))>0){ 
                    // os.write(buffer, 0, length); 
                    // } 
                    // os.close(); 
                    // is.close(); 
                } 
            } 
        } catch (Exception e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
        } 
        request.getRequestDispatcher("upload/result.jsp").forward(request, 
                response); 
    } 
}