javaWeb中文件的上传与下载及乱码问题解决

墨蓝 2022-06-06 01:24 139阅读 0赞

前端代码：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
    
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
    <html>
     <head>
        <title>文件上传页面</title>   
     </head>
    
      <body>
        <form action="${pageContext.request.contextPath }/servlet/UploadServlet" enctype="multipart/form-data" method="post">
            上传用户：<input type="text" name="username"><br/>    
            上传文件1：<input type="file" name="file1"><br/>    
            上传文件2：<input type="file" name="file2"><br/>
    
            <input type="submit" value="提交">    
        </form>
      </body>
    </html>

文件下载的后台servlet处理

package he.junhua.web.controller;
    
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    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 { 
    
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
    
            try {
                //1.得到解析器工厂
                DiskFileItemFactory factory = new DiskFileItemFactory();
                //2.得到解析器
                ServletFileUpload upload = new ServletFileUpload(factory);
    
                //3.判断上传表单的类型
                if (!upload.isMultipartContent(request)) {
                    //上传表单为普通表单，则按照传统方式获取数据即可
                    return;
                }
    
                //为上传表单，则调用解析器解析上传数据
                List<FileItem> list =    upload.parseRequest(request);
    
                for (FileItem item : list) {
                    //如果是普通输入项，则得到输入项的名称和值        username="xxx"
                    if(item.isFormField()){
                        String name =    item.getFieldName();
                        String value =    item.getString();
                        System.out.println(name+":"+value);
                    }else{
                        //得到上传文件的文件名
                        String filename =    item.getName();
                        filename =    filename.substring(filename.lastIndexOf("\\")+1);
                        //得到上传数据
                        InputStream in =    item.getInputStream();
    
                        int len=0;
                        byte buffer[] =    new byte[1024];
    
                        //设置保存路径,注意安全问题，即保存路径不能被外界直接访问到
                        String savepath =    this.getServletContext().getRealPath("/WEB-INF/upload");
    
                        //向保存路径中写入数据
                        FileOutputStream out =    new FileOutputStream(savepath+"\\"+filename);
                        while((len=in.read(buffer))>0){
                            out.write(buffer, 0, len);
                        }
    
                        out.close();
                        in.close();
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            doGet(request, response);
        }
    
    }
    
    /*
    文件下载
    文件下载时要注意文件名为中文时产生乱码的问题，在网上查询得如下解决方案：
    先在页面做下判断，判断是什么浏览器，然后传一个参数到servlet，进行用不同的编码方式。
    //判断当前使用浏览器版本类
    var SysBrowser = function(){
    this.ua = navigator.userAgent.toLowerCase();
    this.browserAndVersion;
    this.verIE ;
    this.verFirefox;
    this.verChrome;
    this.verOpera;
    this.verSafari;
    this.getBrowser = function(){
    (this.browserAndVersion = this.ua.match(/msie ([\d.]+)/)) ? this.verIE = parseInt(this.browserAndVersion[1],10) :
        (this.browserAndVersion = this.ua.match(/firefox\/([\d.]+)/)) ? this.verFirefox = this.browserAndVersion[1] :
        (this.browserAndVersion = this.ua.match(/chrome\/([\d.]+)/)) ? this.verChrome = this.browserAndVersion[1] :
        (this.browserAndVersion = this.ua.match(/opera.([\d.]+)/)) ? this.verOpera = this.browserAndVersion[1] :
        (this.browserAndVersion = this.ua.match(/version\/([\d.]+).*safari/)) ? this.verSafari = this.browserAndVersion[1] : 0;
        //以下进行测试 
        if (this.verIE) return "IE"+this.verIE; 
        if (this.verFirefox) return "Firefox";
        if (this.verChrome) return "Chrome";
        if (this.verOpera) return "Opera";
        if (this.verSafari) return "Safari";
        }
    }; 
    // 设置Content-Disposition
    String agent = request.getHeader("user-agent");
    System.out.println(agent);
    if (agent.contains("MSIE")) {
    // IE浏览器 --- URL编码
    filename = URLEncoder.encode(filename, "utf-8");
    } else if (agent.contains("Firefox")) {
    // 火狐浏览器 --- Base64编码
    filename = base64EncodeFileName(filename);
    } else {
    filename = URLEncoder.encode(filename, "utf-8");
    }
    */
    package he.junhua.web.controller;
    
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.net.URLEncoder;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class DownloadServlet extends HttpServlet { 
    
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
    
            String path =    this.getServletContext().getRealPath("/WEB-INF/upload/花菇.txt");
            String filename =    path.substring(path.lastIndexOf("\\")+1);
    
    //        response.setHeader("content-disposition", "attachment;filename="+filename);
            response.setHeader("content-disposition", "attachment;filename="+URLEncoder.encode(filename,"utf-8"));
    
            InputStream in = null;
            OutputStream out = null;
            try {
                in = new FileInputStream(path);
                int len = 0;
                byte buffer[] = new byte[1024];
                out = response.getOutputStream();
                while ((len = in.read(buffer)) > 0) {
                    out.write(buffer, 0, len);
                }
            } finally {
                if (in != null) {
                    try {
                        in.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                if (out != null) {
                    try {
                        out.close();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            doGet(request, response);
        }
    }