@GetMapping(value = "/downfile")
    public void download(HttpServletResponse response) throws IOException {
        String fileName = "template.xlsx";
        // 設(shè)置信息給客戶端不解析
        String type = new MimetypesFileTypeMap().getContentType(fileName);
        // 設(shè)置contenttype，即告訴客戶端所發(fā)送的數(shù)據(jù)屬于什么類型
        response.setHeader("Content-type",type);
        // 設(shè)置編碼
        String code = new String(fileName.getBytes("utf-8"), "iso-8859-1");
        // 設(shè)置擴(kuò)展頭，當(dāng)Content-Type 的類型為要下載的類型時(shí) , 這個(gè)信息頭會(huì)告訴瀏覽器這個(gè)文件的名字和類型。
        response.setHeader("Content-Disposition", "attachment;filename=" + code);
        response.setContentType("application/octet-stream;charset=ISO8859-1");
        response.addHeader("Pargam", "no-cache");
        response.addHeader("Cache-Control", "no-cache");
        DownLoadUtils.download(fileName, response);
    }

public class DownLoadUtils { 
    public static void download(String filename, HttpServletResponse res) throws IOException {
        // 發(fā)送給客戶端的數(shù)據(jù)
        // 讀取filename
        ClassPathResource classPathResource = new ClassPathResource("templates/"+filename);
        long length = classPathResource.getFile().length();
        res.addHeader("Content-Length",String.valueOf(length));
        OutputStream outputStream = res.getOutputStream();
        byte[] buff = new byte[1024];
        BufferedInputStream bis = null;
        InputStream inputStream =classPathResource.getInputStream();
        bis = new BufferedInputStream(inputStream);
        int i = bis.read(buff);
        while (i != -1) {
            outputStream.write(buff, 0, buff.length);
            outputStream.flush();
            i = bis.read(buff);
        }
        bis.close();
        outputStream.close();
    }
}

response.addHeader("Content-Length",String.valueOf(file.length()));

import java.io.FileReader;
import java.io.InputStream;
import java.util.Properties;
/*
 */
public class Reflect {
    public static void main(String[] args) throws Exception{
       //獲取一個(gè)文件的絕對(duì)路徑！??！
        // 這種是先獲得絕對(duì)路徑然后在轉(zhuǎn)換成流。
//        String path = Thread.currentThread().getContextClassLoader()
//                .getResource("classinfo2.properties").getPath();
//        FileReader reader = new FileReader(path);
        //下面這種是直接用流的方式返回。
        InputStream reader = Thread.currentThread().getContextClassLoader()
                .getResourceAsStream("classinfo2.properties");
        Properties pro = new Properties();
        pro.load(reader);
        reader.close();
        //通過key獲取value。
        String className = pro.getProperty("className");
        System.out.println(className);
    }
}