文件上传(File upload)

导包


<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>

前端

<form action="${pageContext.request.contextPath}/upload.do" enctype="multipart/form-data" method="post">
用户名:  <input type="text" name="username"><br>
  <input type="file" name="file1"><br>
  <input type="file" name="file2"><br>
  <input type="submit" value="提交"> | <input type="reset" value="重置">
  

注意这里的enctype=”multipart/form-data”一定要写(加密类型),还有请求方式要为POST

servlet


package com.Google.FileUp;


import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ProgressListener;
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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.UUID;

public class FileupServlet extends HttpServlet {

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

    }


    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            //1,判断前端传过来的表单是普通表单还是文件表单
            if (!ServletFileUpload.isMultipartContent(req)) {
                return;//这里表达的是,如果是普通表单直接返回
            }
        /*2,通过了if,就表明是文件表单,给文件表单创建个目录,
        建议放在WEB-INF目录下,这样用户不能访问*/
            String uploadPath = this.getServletContext().getRealPath("/WEB-INF/upload");
            File uploadFile = new File(uploadPath);
            if (!uploadFile.exists()) {//如果文件夹不存在
                uploadFile.mkdir();//就创建一个目录
            }
            /*
             * 3,缓存,临时文件
             * 临时目录,如果文件超过了预期的大小,我们就把他放进临时目录中,过几天会自动清除,或者提醒用户存为永久
             * */
            //创建缓存目录
            String temPath = this.getServletContext().getRealPath("/WEB-INF/tem");
            File temFlie = new File(temPath);
            if (!temFlie.exists()) {
                temFlie.mkdir();
            }
            //处理上传文件
            //1.创建DiskFileItemfactory对象,设置文件上传路径和文件大小
            DiskFileItemFactory factory = new DiskFileItemFactory();
            //通过设置临界点(Threshold),当上传文件大于这个临界点时,会把文件放到缓冲区目录中
            factory.setSizeThreshold(1024 * 1024);
            //设置临时文件的缓冲目录
            factory.setRepository(temFlie);
            //2.创建ServletfileupLoad对象
            ServletFileUpload fileUpload = new ServletFileUpload(factory);
            //监听文件上传进度
            fileUpload.getProgressListener(/*new ProgressListener() {
            @Override
            public void update(long pBytesRead, long pContentLength, int pIteams) {
                System.out.println("总大小:" + pContentLength + "已上传:" + pBytesRead);
            }
        }*/);
            //处理乱码问题
            fileUpload.setHeaderEncoding("UTF-8");
            //设置单个文件的最大值
            fileUpload.setFileSizeMax(1024 * 1024 * 10);
            //设置总共能上传文件的最大值
            fileUpload.setSizeMax(1024 * 1024 * 10);

            //处理上传文件
            //把前端请求解析,封装成一个Fileiteam对象
            List<FileItem> fileItems = fileUpload.parseRequest(req);
            for (FileItem fileItem : fileItems) {
                //判断上传的表单是普通表单还是文件表单
                if(fileItem.isFormField()){//判断是普通表单
                    String name = fileItem.getFieldName();
                    String value = fileItem.getString("UTF-8");
                    System.out.println(name+value);
                }else{//文件的情况

                    //=========处理文件===============//
                    //拿到上传文件的名字
                    String upLoadName = fileItem.getFieldName();
                    System.out.println("fileName:"+upLoadName);
                    //可能存在文件不合法的情况
                    if(upLoadName.trim().equals("")||upLoadName==null){//trim()返回本身的字符串
                        continue;//如果不合法,继续下面的程序
                    }
                    //获得文件的上传名
                    String fileName = upLoadName.substring(upLoadName.lastIndexOf("/") + 1);
                    //获得文件的后缀名
                    String fileExtName = upLoadName.substring(upLoadName.lastIndexOf(".") + 1);
                    /*
                    如果,文件后缀名不是我想要的,直接return 告诉作者,文件类型有误

                     */
                    //使用UUID保证文件名唯一
                    String uuidPath = UUID.randomUUID().toString();

                    //=========存放地址===============//
                    String realPath = uploadPath+"/"+uuidPath;
                    File realPathFile = new File(realPath);
                    //给每个文件创建一个文件夹
                    if(!realPathFile.exists()){
                        realPathFile.mkdir();
                    }

                    //======上传文件====//
                    InputStream inputStream = fileItem.getInputStream();
                    //创建一个文件输出流,也就是文件最后到达的地方
                    FileOutputStream fos = new FileOutputStream(realPath + "/" + fileName);
                    //创建一个缓冲区
                    byte[] buffer = new byte[1024 * 1024];
                    //判断是否读取完璧
                    int i =0;
                    while((i=inputStream.read(buffer))>0){
                        fos.write(buffer,0,i);
                    }
                    fos.close();
                    inputStream.close();
                }
            }

        } catch (FileUploadException e) {
            e.printStackTrace();
        }
    }

}
————————

Guide Package


<dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>

front end

<form action="${pageContext.request.contextPath}/upload.do" enctype="multipart/form-data" method="post">
用户名:  <input type="text" name="username"><br>
  <input type="file" name="file1"><br>
  <input type="file" name="file2"><br>
  <input type="submit" value="提交"> | <input type="reset" value="重置">
  

Note that the enctype = “multipart / form data” here must be written (encryption type), and the request method must be post

servlet


package com.Google.FileUp;


import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ProgressListener;
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.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.UUID;

public class FileupServlet extends HttpServlet {

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

    }


    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        try {
            //1,判断前端传过来的表单是普通表单还是文件表单
            if (!ServletFileUpload.isMultipartContent(req)) {
                return;//这里表达的是,如果是普通表单直接返回
            }
        /*2,通过了if,就表明是文件表单,给文件表单创建个目录,
        建议放在WEB-INF目录下,这样用户不能访问*/
            String uploadPath = this.getServletContext().getRealPath("/WEB-INF/upload");
            File uploadFile = new File(uploadPath);
            if (!uploadFile.exists()) {//如果文件夹不存在
                uploadFile.mkdir();//就创建一个目录
            }
            /*
             * 3,缓存,临时文件
             * 临时目录,如果文件超过了预期的大小,我们就把他放进临时目录中,过几天会自动清除,或者提醒用户存为永久
             * */
            //创建缓存目录
            String temPath = this.getServletContext().getRealPath("/WEB-INF/tem");
            File temFlie = new File(temPath);
            if (!temFlie.exists()) {
                temFlie.mkdir();
            }
            //处理上传文件
            //1.创建DiskFileItemfactory对象,设置文件上传路径和文件大小
            DiskFileItemFactory factory = new DiskFileItemFactory();
            //通过设置临界点(Threshold),当上传文件大于这个临界点时,会把文件放到缓冲区目录中
            factory.setSizeThreshold(1024 * 1024);
            //设置临时文件的缓冲目录
            factory.setRepository(temFlie);
            //2.创建ServletfileupLoad对象
            ServletFileUpload fileUpload = new ServletFileUpload(factory);
            //监听文件上传进度
            fileUpload.getProgressListener(/*new ProgressListener() {
            @Override
            public void update(long pBytesRead, long pContentLength, int pIteams) {
                System.out.println("总大小:" + pContentLength + "已上传:" + pBytesRead);
            }
        }*/);
            //处理乱码问题
            fileUpload.setHeaderEncoding("UTF-8");
            //设置单个文件的最大值
            fileUpload.setFileSizeMax(1024 * 1024 * 10);
            //设置总共能上传文件的最大值
            fileUpload.setSizeMax(1024 * 1024 * 10);

            //处理上传文件
            //把前端请求解析,封装成一个Fileiteam对象
            List<FileItem> fileItems = fileUpload.parseRequest(req);
            for (FileItem fileItem : fileItems) {
                //判断上传的表单是普通表单还是文件表单
                if(fileItem.isFormField()){//判断是普通表单
                    String name = fileItem.getFieldName();
                    String value = fileItem.getString("UTF-8");
                    System.out.println(name+value);
                }else{//文件的情况

                    //=========处理文件===============//
                    //拿到上传文件的名字
                    String upLoadName = fileItem.getFieldName();
                    System.out.println("fileName:"+upLoadName);
                    //可能存在文件不合法的情况
                    if(upLoadName.trim().equals("")||upLoadName==null){//trim()返回本身的字符串
                        continue;//如果不合法,继续下面的程序
                    }
                    //获得文件的上传名
                    String fileName = upLoadName.substring(upLoadName.lastIndexOf("/") + 1);
                    //获得文件的后缀名
                    String fileExtName = upLoadName.substring(upLoadName.lastIndexOf(".") + 1);
                    /*
                    如果,文件后缀名不是我想要的,直接return 告诉作者,文件类型有误

                     */
                    //使用UUID保证文件名唯一
                    String uuidPath = UUID.randomUUID().toString();

                    //=========存放地址===============//
                    String realPath = uploadPath+"/"+uuidPath;
                    File realPathFile = new File(realPath);
                    //给每个文件创建一个文件夹
                    if(!realPathFile.exists()){
                        realPathFile.mkdir();
                    }

                    //======上传文件====//
                    InputStream inputStream = fileItem.getInputStream();
                    //创建一个文件输出流,也就是文件最后到达的地方
                    FileOutputStream fos = new FileOutputStream(realPath + "/" + fileName);
                    //创建一个缓冲区
                    byte[] buffer = new byte[1024 * 1024];
                    //判断是否读取完璧
                    int i =0;
                    while((i=inputStream.read(buffer))>0){
                        fos.write(buffer,0,i);
                    }
                    fos.close();
                    inputStream.close();
                }
            }

        } catch (FileUploadException e) {
            e.printStackTrace();
        }
    }

}