• java servlet中上传文件的简单实现(基于第三方jar)


    这里的案例使用了两种文件上传的组件、分别介绍

    1、使用JSPSmartUpload完成上传

     1 package test_servlet_package;
     2 
     3 import java.io.File;
     4 import java.io.IOException;
     5 import java.util.Calendar;
     6 import java.util.Random;
     7 import javax.servlet.ServletException;
     8 import javax.servlet.http.HttpServlet;
     9 import javax.servlet.http.HttpServletRequest;
    10 import javax.servlet.http.HttpServletResponse;
    11 import com.jspsmart.upload.SmartUpload;
    12 
    13 public class test_servlet_SmartUpload extends HttpServlet {
    14 
    15     String tempPath = "D:\test";
    16     String filePath = "D:\filePath";
    17     @Override
    18     protected void doPost(HttpServletRequest request, HttpServletResponse response)
    19             throws ServletException, IOException {
    20         response.setCharacterEncoding("GBK");
    21         SmartUpload mySmartUpload = new SmartUpload();
    22         // 初始化
    23         mySmartUpload.initialize(getServletConfig(), request, response);
    24         long file_size_max = 4000000;
    25         String ext = "";
    26         try {
    27             mySmartUpload.setAllowedFilesList("jpg,gif,png");
    28             mySmartUpload.upload();// 上载文件
    29         } catch (Exception e) {
    30             response.getWriter().write("<script> alert('只允许上传.jpg和.gif类型图片文件');</script>");
    31         }
    32         try {
    33             com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
    34             if (!myFile.isMissing()) {
    35                 ext = myFile.getFileExt(); // 取得后缀名
    36                 int file_size = myFile.getSize(); // 取得文件的大小
    37                 String saveurl = "";
    38                 if (file_size < file_size_max) {
    39                     // 更改文件名,取得当前上传时间的毫秒数值
    40                     Calendar calendar = Calendar.getInstance();
    41                     String filename = String.valueOf(calendar.getTimeInMillis());
    42                     Random r = new Random();
    43                     String ram = String.valueOf(r.nextInt(1241241241));
    44                     filename = filename + ram;
    45                     filename = filename.substring(0, (filename.length() - ext.length() - 1));
    46                     //saveurl = this.getServletContext().getRealPath("/") + "/uploadFile/" + filename + "." + ext;
    47                     //System.out.println(saveurl);
    48                     File uploadFile2 = new File(filePath);
    49                     if(!uploadFile2.exists()){
    50                         uploadFile2.mkdirs();
    51                     }
    52                     myFile.saveAs(filePath+"/"+filename+"." + ext);
    53                 }
    54             }
    55             String name = mySmartUpload.getRequest().getParameter("name");
    56             request.setAttribute("name", "name");
    57             request.getSession().setAttribute("name", "name");
    58             request.getSession().getId();
    59             System.out.println(name);
    60         } catch (Exception e) {
    61             e.printStackTrace();
    62         }
    63         request.getRequestDispatcher("/uploadsuccess.jsp").forward(request, response);
    64     }
    65 }

    2、使用commons-fileupload完成文件上传

     1 package test_servlet_package;
     2 
     3 import java.io.File;
     4 import java.io.IOException;
     5 import java.io.PrintWriter;
     6 import java.util.Iterator;
     7 import java.util.List;
     8 import javax.servlet.ServletException;
     9 import javax.servlet.http.HttpServlet;
    10 import javax.servlet.http.HttpServletRequest;
    11 import javax.servlet.http.HttpServletResponse;
    12 import org.apache.commons.fileupload.FileItem;
    13 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
    14 import org.apache.commons.fileupload.servlet.ServletFileUpload;
    15 
    16 public class test_servlet extends HttpServlet {
    17 
    18     String tempPath = "D:\test";
    19     String filePath = "D:\filePath";
    20     @Override
    21     protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
    22         res.setContentType("text/plain;charset=gbk");
    23         PrintWriter pw = res.getWriter();
    24         try {
    25             DiskFileItemFactory diskFactory = new DiskFileItemFactory();
    26             // threshold 极限、临界值,即硬盘缓存 1M
    27             diskFactory.setSizeThreshold(4 * 1024);
    28             // repository 贮藏室,即临时文件目录
    29             diskFactory.setRepository(new File(tempPath));
    30             ServletFileUpload upload = new ServletFileUpload(diskFactory);
    31             // 设置允许上传的最大文件大小 4M
    32             upload.setSizeMax(4 * 1024 * 1024);
    33             // 解析HTTP请求消息头
    34             List<FileItem> fileItems = upload.parseRequest(req);
    35             Iterator<FileItem> iter = fileItems.iterator();
    36             while (iter.hasNext()) {
    37                 FileItem item = (FileItem) iter.next();
    38                 if (item.isFormField()) {
    39                     System.out.println("处理表单内容 ...");
    40                     processFormField(item, pw);
    41                 } else {
    42                     System.out.println("处理上传的文件 ...");
    43                     processUploadFile(item, pw);
    44                 }
    45             }
    46             pw.close();
    47         } catch (Exception e) {
    48             System.out.println("使用 fileupload 包时发生异常 ...");
    49             e.printStackTrace();
    50         }
    51     }
    52 
    53     // 处理表单内容
    54     private void processFormField(FileItem item, PrintWriter pw) throws Exception {
    55         String name = item.getFieldName();
    56         String value = item.getString();
    57         pw.println(name + " : " + value + "
    ");
    58     }
    59 
    60     // 处理上传的文件
    61     private void processUploadFile(FileItem item, PrintWriter pw) throws Exception {
    62         // 此时的文件名包含了完整的路径,得注意加工一下
    63         String filename = item.getName();
    64         System.out.println("完整的文件名:" + filename);
    65         int index = filename.lastIndexOf("\");
    66         filename = filename.substring(index + 1, filename.length());
    67         long fileSize = item.getSize();
    68         if ("".equals(filename) && fileSize == 0) {
    69             System.out.println("文件名为空 ...");
    70             return;
    71         }
    72         File uploadFile = new File(filePath + "/" + filename);
    73         File uploadFile2 = new File(filePath);
    74         if(!uploadFile2.exists()){
    75             uploadFile2.mkdirs();
    76         }
    77         item.write(uploadFile);
    78         pw.println(filename + " 文件保存完毕 ...");
    79         pw.println("文件大小为 :" + fileSize + "
    ");
    80     }
    81 }

    3、依赖的jar:

     1 <classpath>
     2     <classpathentry kind="lib" path="base/WEB-INF/lib/commons-fileupload-1.2.2.jar"/>
     3     <classpathentry kind="lib" path="base/WEB-INF/lib/commons-io-2.0.1.jar"/>
     4     <classpathentry kind="lib" path="base/WEB-INF/lib/jsmartcom_zh_CN.jar"/>
     5     <classpathentry kind="lib" path="base/WEB-INF/lib/mysql-connector-java-5.1.21-bin.jar"/>
     6     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-compat-1.2.1.jar"/>
     7     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-impl-1.2.1.jar"/>
     8     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-jstlel-1.2.1.jar"/>
     9     <classpathentry kind="lib" path="base/WEB-INF/lib/taglibs-standard-spec-1.2.1.jar"/>
    10     <classpathentry kind="output" path="base/WEB-INF/classes"/>
    11 </classpath>
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  • 原文地址:https://www.cnblogs.com/kongxianghao/p/6961785.html
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