JAVA文件上传基本操作

天祈
2021-06-05 / 0 评论 / 163 阅读 / 正在检测是否收录...
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最近在学习文件上传部署的一些操作,以此记录做备忘之用.
一共两种方式:
1> 标准上传方式,可通过form表单action属性请求或者ajax方式进行请求,返回服务器上的存储路径.
2> 在前端将文件转换为Base64,然后将文件名和Base64字符串后端,经过解析之后,以输出流的方式写入到指定文件路径之中.
项目绝对路径基本可通过servletContext和类加载器.getPath的方式得到,不做赘述.

获取项目绝对路径:

//类加载器方式
ClassLoader classLoader = this.getClass().getClassLoader();
URL resource = classLoader.getResource(".");
String path = resource.getPath();

//通过ServletContext
ServletContext servletContext = request.getServletContext();
String realPath = servletContext.getRealPath("");


<!--文件上传导包-->
<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
    <dependency>
      <groupId>commons-fileupload</groupId>
      <artifactId>commons-fileupload</artifactId>
      <version>1.3.1<ersion>
    </dependency>

    <!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.5<ersion>
    </dependency>

两种文件上传方式:


import com.alibaba.fastjson.JSON;
import com.sakura.Common.ResponseCode;
import com.sakura.Common.ServerResponse;
import com.sakura.Const.Const;
import com.sakura.Pojo.User;
import com.sakura.Utils.Random;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.springframework.stereotype.Service;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.*;
import java.util.ArrayList;
import java.util.Base64;
import java.util.List;

@Service
public class UploadFileService {

    // 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 ResponseCode data=new ResponseCode();
    //基本文件上传
    public ServerResponse loadFile(HttpSession session,
       HttpServletRequest request, HttpServletResponse response) {
        try {
            request.setCharacterEncoding("UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        response.setContentType("textml;charset=UTF-8");
        // 检测是否为多媒体上传
        if (!ServletFileUpload.isMultipartContent(request)) {
            // 如果不是则停止
            PrintWriter writer = null;
            try {
                writer = response.getWriter();
            } catch (IOException e) {
                e.printStackTrace();
            }
            writer.println("Error: 表单必须包含 enctype=multipart/form-data");
            writer.flush();
            return ServerResponse.DefaultResponse(Const.OPERATION_DEFAULE, Const.DEFAULT_FILE);
        }
        // 配置上传参数
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
        factory.setSizeThreshold(MEMORY_THRESHOLD);
        // 设置临时存储目录
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
        ServletFileUpload upload = new ServletFileUpload(factory);
        // 设置最大文件上传值
        upload.setFileSizeMax(MAX_FILE_SIZE);
        // 设置最大请求值 (包含文件和表单数据)
        upload.setSizeMax(MAX_REQUEST_SIZE);
        // 中文处理
        upload.setHeaderEncoding("UTF-8");

        // 构造临时路径来存储上传的文件
        // 这个路径相对当前应用的目录
        String UPLOAD_DIRECTORY = "upload";
        //存储文件目录
        ServletContext servletContext = request.getServletContext();
        String realPath = servletContext.getRealPath("");
        String uploadPath = realPath + File.separator + UPLOAD_DIRECTORY;
        System.out.println("uploadPath:" + uploadPath);
        // 如果目录不存在则创建
        File uploadDir = new File(uploadPath);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }

        try {
            // 解析请求的内容提取文件数据
            @SuppressWarnings("unchecked")
            List<FileItem> formItems = upload.parseRequest(request);
            if (formItems != null && formItems.size() > 0) {
                int size = formItems.size();
                List<String> UrlList = new ArrayList();
                // 迭代表单数据
                for (FileItem item : formItems) {   // 处理不在表单中的字段
                    if (!item.isFormField()) {
                        String fileName = new File(item.getName()).getName();
                        //时间 UUID随机串以避免重复
                        String uuid =Random.RandUUIDAndDate()+"_"+fileName;
                        String filePath = uploadPath + File.separator + uuid;
                        File storeFile = new File(filePath);
                        // 在控制台输出文件的上传路径
                        System.out.println("filePath:" + filePath);
                        // 保存文件到硬盘
                        item.write(storeFile);
                        UrlList.add(UPLOAD_DIRECTORY + "/" + uuid);
                    }
                }
                data.setMsg(JSON.toJSONString(UrlList));
                data.setStatus(200);
            }
        } catch (Exception ex) {
            String error = "错误信息: " + ex.getMessage();
            data.setMsg(error);
            data.setStatus(100);
        }
        return  ServerResponse.SuccessResponse(data);
    }

     /**
     * Base64方式存储文件 此法不通 需配置tomcat文件 同时Base64解码会出错,待研 
     * 究,不可用!
     * @param name
     * @param base64String
     * @param session
     * @param request
     * @param response
     * @return
     */
public ServerResponse loadFileBase64(String name, String base64String, 
  HttpSession session, HttpServletRequest request,
  HttpServletResponse response) {
        ServerResponse res=null;
        String UPLOAD_DIRECTORY = "upload";
        byte[] decode = Base64.getDecoder().decode(base64String);
        //存储文件目录
        ServletContext servletContext = request.getServletContext();
        String realPath = servletContext.getRealPath("");
        String uploadPath = realPath + File.separator + UPLOAD_DIRECTORY +
        File.separator + Random.RandUUIDAndDate()
                +"_"+name;
        String path=File.separator + UPLOAD_DIRECTORY + File.separator
        +Random.RandUUIDAndDate()+"_"+name;
        File file = new File(uploadPath);
        FileOutputStream fileOutputStream =null;
        BufferedOutputStream bufferedOutputStream =null;
        try {
            fileOutputStream = new FileOutputStream(file);
            bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
            bufferedOutputStream.write(decode);
            bufferedOutputStream.flush();
            res.setMsg("上传成功");
            res.setStatus(200);
            res.setData(path);
        } catch (IOException e) {
            res.setMsg("上传失败");
            res.setStatus(100);
            path=null;
        } finally {
            if (bufferedOutputStream != null) {
                try {
                    bufferedOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fileOutputStream != null) {
                try {
                    fileOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        }
        return  res;
     }
}


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