- [x] I have searched the [issues](https://github.com/apache/incubator-dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/incubator-dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: xxx
* Operating System version: xxx
* Java version: xxx

### Steps to reproduce this issue

1. xxx
2. xxx
3. xxx

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

if (size <= showLogLength) {
                            bb = ByteBuffer.allocate((int) size);
                            filechannel.read(bb, 0);
                        } else {
                            int pos = (int) (size - showLogLength);
                            bb = ByteBuffer.allocate(showLogLength);
                            filechannel.read(bb, pos);
                        }
                        bb.flip();
                        String content = new String(bb.array()).replace("<", "&lt;")
                                .replace(">", "&gt;").replace("\n", "<br/><br/>");
                        buf.append("\r\ncontent:" + content);
                        buf.append("\r\nmodified:" + (new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")
                                .format(new Date(file.lastModified()))));
                        buf.append("\r\nsize:" + size + "\r\n");
                    } catch (Exception e) {
                        buf.append(e.getMessage());
                    }
                } else {
                    size = 0;
                    buf.append("\r\nMESSAGE: log file not exists or log appender is console .");
                }
            }
        }
        buf.append("\r\nCURRENT LOG LEVEL:" + LoggerFactory.getLevel())
                .append("\r\nCURRENT LOG APPENDER:" + (file == null ? "console" : file.getAbsolutePath()));
        return buf.toString();
    }
}