思路：把要下载的文件放到exportExcel目录下，利用url查找是否有改文件，有的话下载，没有的话报错。
import io.swagger.annotations.ApiOperation;
import org.apache.commons.io.IOUtils;
import org.springframework.stereotype.Controller;
import org.springframework.util.ClassUtils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.io.OutputStream;@Controller
@RequestMapping("templatedownload")
public class TemplateDownload {@GetMapping("{filename}")@ApiOperation(value = "获取Excel模板",notes = "获取Excel模板")public ResultVO downExcel(@PathVariable("filename") String filename, HttpServletResponse response)throws Exception{InputStream in = ClassUtils.class.getClassLoader().getResourceAsStream("exportexcel/"+filename+".xls");if (in == null) {throw new AppcationException(ExceptionEnum.NOTFOUNTVALUE);}response.setHeader("content-type", "application/vnd.ms-excel");response.addHeader("Content-Disposition","attachment;filename=" +filename+".xls");OutputStream fileOut= response.getOutputStream();IOUtils.copy(in, fileOut);in.close();fileOut.close();return ResultVOUtil.success();}
}
