文件上传处理-优快云博客

本文链接：https://blog.youkuaiyun.com/jike_yl/article/details/77774184

环境准备

– 在项目中引入 commons-fileupload-1.2.2.jar 和 commons-io-2.4.jar 文件

设置表单的enctype属性

        <form action="UploadServlet" method="post" enctype="multipart/form-data">

注意：上传文件时 form 标签的 method 属性必须取值为“ post” ，不能取值为“ get”

编写上传文件处理页的实现步骤

//创建FileItemFactory对象
//创建ServletFileUpload对象	
//解析form表单中所有文件
if (普通表单字段){  
    //获取表单字段的name属性值
    if (此属性是“user”)){ 
	//输出XXX上传了文件
    }
}else{   //文件表单字段
    //获取上传文件的名字
    if (名字不为空) {
    //保存此文件并输出保存成功		
    }
}

实例

1. index.jsp

<body>
  	<form action="UploadServlet" method="post"
		enctype="multipart/form-data">
		用户名 <input type="text" name="username" /> <br> 上传文件<input
			type="file" name="file" /> <br> <input type="submit" value="提交" />
	</form>
</body>

2. UploadServlet

package com.servlet;

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 {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		doPost(request, response);
		
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//实例化一个硬盘文件工厂，用来配置上传组件ServletFileUpload
		DiskFileItemFactory factory = new DiskFileItemFactory();
		//使用工厂对象实例化上传组件ServletFileUpload
		ServletFileUpload upload = new ServletFileUpload(factory);
		
		try {
			//使用集合获取表单的所有数据
			List<FileItem> items = upload.parseRequest(request);
			for (int i =0;i<items.size();i++){
					FileItem item = items.get(i);
					//普通表单域
					if(item.isFormField()){
						//获得表单元素的name
						String name = item.getFieldName();
						if(name.equals("username")){
							//获得表单元素的值
							String value =item.getString("utf-8");
							System.out.println("name:"+name+"\tvalue:"+value);
						}
					}else{
						//上传文件
						//获得文件在Apache的保存路径
						String filepath = getServletContext().getRealPath("/");//根目录
						String filename = item.getName();//文件名称，上传文件的真实名称
						String path = filepath +"upload\\"+filename;
						//创建一个文件对象
						File file = new File(path);
						//生成一个文件(复制)
						item.write(file);
					}
				}
		} catch (FileUploadException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		out.print("文件上传成功");
		out.flush();
		out.close();
	}

}

测试

JSP的文件上传方法