Java如何获取相对路径文件

class.getResourceAsStream(“”)获得的是相对路径
class.getClassLoader().getResourceAsStream(“”)加载器获得是绝对路径

InputStream in = new BufferedInputStream(new FileInputStream("./test/aaa.txt"));

/**
     * 文件大小--路径
     *
     * @return
     */
    public static long getFileLength(String downloadUrl) {
        if(downloadUrl == null || "".equals(downloadUrl)){
            return 0L ;
        }
        URL url = null;
        try {
            url = new URL(downloadUrl);
        } catch (MalformedURLException e) {
            e.printStackTrace();
            return 0L;
        }
        HttpURLConnection conn = null;
        try {
            conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("HEAD");
            conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows 7; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/47.0.2526.73 Safari/537.36 YNoteCef/5.8.0.1 (Windows)");
            return (long) conn.getContentLength();
        } catch (IOException e) {
            return 0L;
        } finally {
            conn.disconnect();
        }
    }

/**
     * 文件大小--文件
     *
     * @return
     */
    public static int getFileSize(File file) {
        int fileSize = 0;
        FileInputStream fis = null;
        try {
            if (file.exists() && file.isFile()) {
                String fileName = file.getName();
                fis = new FileInputStream(file);
                fileSize = fis.available();
                System.out.println("文件" + fileName + "的大小是：" + fis.available() + "\n");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (null != fis) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return fileSize;
    }

public static void main(String[] args) {
       File file = new File("C:\\Users\\xuzh\\Desktop\\6f3c0052d684451a92e7fb5b55eda9fd.jpg");
        getFileSize(file);
    }