apollo-core/src/main/java/com/ctrip/framework/foundation/internals/io/ProxyInputStream.java/ProxyInputStream/read
class ProxyInputStream:  @Override
  public int read(final byte[] bts) throws IOException {
    try {
      beforeRead(bts != null ? bts.length : 0);
      final int n = in.read(bts);
      afterRead(n);
      return n;
    } catch (final IOException e) {
      handleIOException(e);
      return EOF;
    }
  }