关于文件上传

1.最主要两个jar包

  commons-fileupload
  commons-fileupload
  1.4



  commons-io
  commons-io
  2.11.0


其中两个类，

（1）DiskFileItemFactory factory = new DiskFileItemFactory();

其中磁盘文件工厂，是最底层存储东西的，可以设置临时目录，临时目录临界值

（2）ServletFileUpload upload = new ServletFileUpload(factory);

可以设置文件上传最大值，文件监听
　　

　　　　List fileItems = upload.parseRequest(request);
方法可以将所有表单传递过来的数据读取出来，可用循环判断是不是文件

for (FileItem fileItem : fileItems) {}，然后分别执行操作




做到此处发现问题：路径，
关于此处IO流中，路径“/”代表的是tomcat目录所在的磁盘根目录





案例：

package Com.Ren.Servlet;

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.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.*;
import java.util.List;
import java.util.UUID;

@WebServlet("/UploadServlet")
public class UploadServlet extends HttpServlet {
    // 上传配置
    private static final int MEMORY_THRESHOLD   = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB


    private String msg;


    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //判断是不是文件上传表单
        if (!ServletFileUpload.isMultipartContent(request)){
            response.getWriter().print("不是文件上传的表单");
            return;
        }
        //得到磁盘文件工厂
        DiskFileItemFactory factory = new DiskFileItemFactory();

        factory.setSizeThreshold(MEMORY_THRESHOLD);
        // 设置临时存储目录

        String uploadPath = request.getServletContext().getRealPath("/WEB-INF/upload") ;
        String tempPath = request.getServletContext().getRealPath("/WEB-INF/temp")  ;
        File tempFile = new File(uploadPath);
        //判断文件夹是否存在，如果不存在就创建
        if (!tempFile.exists()){
            tempFile.mkdir();
        }

        factory.setRepository(tempFile);
        //临时目录产生，临界值
        factory.setSizeThreshold(MEMORY_THRESHOLD);
        ServletFileUpload upload = new ServletFileUpload(factory);
        //设置文件上传最大值
        upload.setSizeMax(MAX_FILE_SIZE);
        //设置请求最大值
        upload.setSizeMax(MAX_REQUEST_SIZE);
        //中文处理
        upload.setHeaderEncoding("utf-8");
        //文件监听
        upload.setProgressListener(new ProgressListener() {
            @Override
            public void update(long l, long l1, int i) {
                System.out.println("总大小：" + l1 + ",已上传：" + l);
            }
        });

        //取出提交的每一项
        try {
            List fileItems = upload.parseRequest(request);
            for (FileItem fileItem : fileItems) {
                if (fileItem.isFormField()){ //是普通的表单数据
                    String name = fileItem.getFieldName();
                    String value = fileItem.getString("utf-8");
                    System.out.println(name + ":" + value);


                }else {//是文件数据
                    //处理文件
                    String upLoadFileName = fileItem.getName();
                    System.out.println(upLoadFileName);

                    //判断改文件名字是否为空
                    if (upLoadFileName.trim().equals("") || upLoadFileName == null){
                        continue;
                    }

                    //如果不为空，获得文件名
                    String fileName = upLoadFileName.substring(upLoadFileName.lastIndexOf("/") + 1);
                    //获得文件后缀
                    String fileEXTName = upLoadFileName.substring(upLoadFileName.lastIndexOf(".") + 1);

                    System.out.println("文件名：" + fileName);
                    System.out.println("后缀名：" + fileEXTName);

                    //文件存放地址
                    String uuidPath = UUID.randomUUID().toString();
                    String realPaht =  uploadPath + "/" + uuidPath;
                    File file = new File(realPaht);
                    if (!file.exists()){
                        file.mkdir();
                    }
                    //获取当前文件上传流
                    InputStream inputStream = fileItem.getInputStream();
                    //获取要输出位置的流
                    BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(realPaht + "/" + fileName));

                    System.out.println(realPaht);
                    byte bytes[] = new byte[1024 * 2];
                    int len = 0;
                    while((len = inputStream.read(bytes)) > 0){
                        bufferedOutputStream.write(bytes,0,len);
                    }
                    bufferedOutputStream.close();
                    inputStream.close();

                    msg = "文件上传成功";
                    System.out.println(msg);
                }
            }


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


    }
}