Javaweb文件上传

文件上传

【 https://github.com/Davis-Samuel/File-Upload/blob/master/JavaWeb功能扩展.md 】

导入pom依赖：

<!--文件上传-->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.3</version>
</dependency>
<!--servlet-api导入高版本的-->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>4.0.1</version>
</dependency>

FileServlet.java：

package com.it.servlet;

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;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.List;
import java.util.UUID;

public class FileServlet extends HttpServlet  {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException {

//        判断上传的文件是普通表单还是带文件的表单
        if (!ServletFileUpload.isMultipartContent(req)) {
            return; //终止方法运行，如果是一个普通文件直接返回；
        }
//            创建文件上传的保存路径，最好在WEB-INF下，用户无法直接访问
        String uploadPath = this.getServletContext().getRealPath("/WEB-INF/upload");
        File uploadFile = new File(uploadPath);
        if (!uploadFile.exists()) {
            uploadFile.mkdir(); //如国文件不存在就创建一个。
        }

        //消息提示
        String msg = "";


//        缓存临时文件，如果文件大小超过了限至，就转到缓存中，过一段时间后删除，或者提醒用户永久删除
        String tempPath = this.getServletContext().getRealPath("/WEB-INF/upload");
        File temp = new File(tempPath);
        if (!temp.exists()) {
            temp.mkdir(); //如国文件不存在就创建一个。
        }
//        使用commons-fileupload上传组件实现上传
//        1.创建DiskFileItemFactory对象，处理文件上传l路径或者大小的限至
        DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();

        /*
//        通过这个工厂的设置一个缓冲区，当文件上传大于这个缓冲区的时候就将它放到临时文件中
        diskFileItemFactory.setSizeThreshold(1024*1024); //缓存区大小
        diskFileItemFactory.setRepository(temp);  //临时文件的保存目录
        */

//        2.获取ServletFileUpload
        ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);
        //解决上传文件名的中文乱码
        servletFileUpload.setHeaderEncoding("UTF-8");
//      3.处理上传文件
        List<FileItem> fileItems = null;
        try {
            fileItems = servletFileUpload.parseRequest(req);
        } catch (FileUploadException e) {
            e.printStackTrace();
        }
        //fileItem每一个表单对象
        for (FileItem fileItem : fileItems) {
            //如果fileitem中封装的是普通输入项的数据
            if (fileItem.isFormField()) {
                String name = fileItem.getFieldName(); //getFieldName()表单对象的name
                //解决普通输入项的数据的中文乱码问题
                String value = fileItem.getString("UTF-8");
                //value = new String(value.getBytes("iso8859-1"),"UTF-8");
                System.out.println(name + "=" + value);
            }else {

                //======================处理文件==========================//
                String uploadFileName = fileItem.getName();
                System.out.println(uploadFileName);
                if(uploadFileName==null || uploadFileName.trim().equals("")){
                    continue;
                }
                //处理获取到的上传文件的文件名的路径部分，只保留文件名部分
                uploadFileName = uploadFileName.substring(uploadFileName.lastIndexOf("\")+1);
                //处理获取到的上传文件的后缀名例如.jpg
                uploadFileName = uploadFileName.substring(uploadFileName.lastIndexOf(".")+1);
                //生成为一个一个识别的通用码
                String uuidPath = UUID.randomUUID().toString();
                //======================存放地址==========================//
                //文件存在的真实路径
                String realPath = uploadPath + "/" + uuidPath;
                //给每个文件创建一个文件夹
                File realFile = new File(realPath);
                if (!realFile.exists()){
                    realFile.mkdir();
                }
                //======================文件输出==========================//
                InputStream inputStream = fileItem.getInputStream();
                FileOutputStream fileOutputStream = new FileOutputStream(realPath + "/" + uploadFileName);
                byte[] bytes = new byte[1024 * 1024];
                int len = 0;
                while ((len=inputStream.read(bytes))>0){
                    fileOutputStream.write(bytes,0,len);
                }
                fileOutputStream.close();
                inputStream.close();
                msg = "文件上传成功";
                fileItem.delete();
            }
                msg="文件上传失败";

        }

        req.setAttribute("msg",msg);
        req.getRequestDispatcher("/info.jsp").forward(req, resp);


    }
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

web.xml注册servlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
         version="3.0"
         metadata-complete="true">

<servlet>
  <servlet-name>FileServlet</servlet-name>
  <servlet-class>com.it.servlet.FileServlet</servlet-class>
</servlet>
  <servlet-mapping>
    <servlet-name>FileServlet</servlet-name>
    <url-pattern>/upload.do</url-pattern>
  </servlet-mapping>

</web-app>

index.jsp:

<%@ page contentType="text/html; charset=UTF-8" language="java" %>
<html>
<body>

<%--get上传文件大小有限制，post没有大小限制.文件上传加一个enctype--%>
<form action="${PageContext.request.contextPath}/upload" enctype="multipart/form-data" method="post">
    <input type="text"name="text">
    <input type="file" name="file1">
    <input type="file" name="file1">
    <input type="submit">
</form>

</body>
</html>

info.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

${msg}

</body>
</html>