Linux创建软链接导致文件无法下载的问题处理

Linux里可以创建软链接，如同Windows系统的快捷方式。如图：

Linux里创建软链接的语法：

ln  -s  源文件  链接目录

ln -s /app/tomcat_file/uploadfiles uploadfiles

创建链接目录后，如图所示：

在一个SpringBoot项目里，如果把下载的文件存到 /usr/local/tomcat/webapps/ROOT/WEB-INF/uploadfiles里，这时若下载该链接目录里的文件时，可能会找不到文件。

解决方式在下载的Controller里，进行下述处理：

package cn.lzy;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLDecoder;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

@Controller
@RequestMapping("/attachment/accept")
public class AttachmentDownloadController extends CommonAttachmentController {
    @Autowired
    private ICommonAttachmentService commonAttachmentService;

    @RequestMapping(value = "/downloadByAttachmentId.action", method = {RequestMethod.POST, RequestMethod.GET})
    public void downloadByIdDo(HttpServletResponse response, String id) throws IOException {
        ServletOutputStream out = null;
        try {
            CommonAttachment attachment = new CommonAttachment();
            attachment.setId(id);
            attachment = commonAttachmentService.queryOne(attachment);
            String path = URLDecoder.decode(attachment.getAttachmentPath(), "utf-8");
            path = UtilAttachmentPath.getDiskBaseFilePath(path);
            String fileName = URLDecoder.decode(attachment.getAttachmentName(), "utf-8");
            response.setContentType("application/octet-stream");
            response.setHeader("Content-Disposition", "filename=" + new String(fileName.getBytes("gb2312"), "iso8859-1"));
            out = response.getOutputStream();
            /*判断是否软链接文件，并区分软链接与普通文件进行读取.*/
            Path target = FileSystems.getDefault().getPath(path.trim());
            boolean isSoftLink = Files.isSymbolicLink(target);
            if(isSoftLink){
                Files.copy(Files.readSymbolicLink(target), out);
            }else {
                Files.copy(Paths.get(path.trim()), out);
            }
        } catch (Exception e) {
            log.error(e.getMessage(), e);
            throw e;
        }finally {
            if(out != null){
                out.close();
            }
        }
    }
}

 通过上述方式，可以判断文件路径是普通路径还是链接路径，从而顺利下载文件。