最简单的文件上传

最简单的文件上传
1、在做之前需要导入的jar包组件：

commons-fileupload-1.2.1.jar、commons-io-2.0.jar（依赖包）

2、页面代码html>
```
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form action="simpleFileupload" method="post" enctype="multipart/form-data">
	最简单的文件上传：<input type="file" name="fileupload"/>
	描述：<input type="text" name="desc"/>
	<input type="submit" value="submit"/>
	</form>
</body>
</html>
```
注意：这里的enctype(编码类型)是“multipart/form-data”
3、servlet代码
package com.xiaojie.simpleFileupload;



import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

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.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;



/**

* Servlet implementation class SimpleFileupload

*/

@WebServlet("/simpleFileupload")

public class SimpleFileupload extends HttpServlet {

    private static final long serialVersionUID = 1L;



    /**

     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

     */

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("utf-8");

        response.setCharacterEncoding("utf-8");

        //1、创建一个DiskFileItemFactory工厂

        DiskFileItemFactory factory = new DiskFileItemFactory();

        //2、创建一个文件上传解析器

        ServletFileUpload upload = new ServletFileUpload(factory);

        //解决上传文件名的中文乱码

        upload.setHeaderEncoding("UTF-8");

        factory.setSizeThreshold(1024 * 500);//设置内存的临界值为500K

        File linshi = new File("E:\linshi");//当超过500K的时候，存到一个临时文件夹中

        factory.setRepository(linshi);

        upload.setSizeMax(1024 * 1024 * 5);//设置上传的文件总的大小不能超过5M

        try {

            // 1. 得到 FileItem 的集合 items

            List<FileItem> /* FileItem */items = upload.parseRequest(request);



            // 2. 遍历 items:

            for (FileItem item : items) {

                // 若是一个一般的表单域, 打印信息

                if (item.isFormField()) {

                    String name = item.getFieldName();

                    String value = item.getString("utf-8");



                    System.out.println(name + ": " + value);





                }

                // 若是文件域则把文件保存到 e:\files 目录下.

                else {

                    String fileName = item.getName();

                    long sizeInBytes = item.getSize();

                    System.out.println(fileName);

                    System.out.println(sizeInBytes);



                    InputStream in = item.getInputStream();

                    byte[] buffer = new byte[1024];

                    int len = 0;



                    fileName = "e:\files\" + fileName;//文件最终上传的位置

                    System.out.println(fileName);

                    OutputStream out = new FileOutputStream(fileName);



                    while ((len = in.read(buffer)) != -1) {

                        out.write(buffer, 0, len);

                    }



                    out.close();

                    in.close();

                }

            }



        } catch (FileUploadException e) {

            e.printStackTrace();

        }



    }

}
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原文地址：https://www.cnblogs.com/HHR-SUN/p/6816969.html

最简单的文件上传

1、在做之前需要导入的jar包组件：

2、页面代码html>

3、servlet代码