Log4j的ConversionPattern无缝适配到Logback

为了能将log4j的ConversionPattern无缝应用到logback上来，需要对两个Conversion做适配，具体可以参考：Log4j 与 Logback的ConversionPattern对比

ch.qos.logback.classic.PatternLayout

static代码块新增：

// adapter for log4j
defaultConverterMap.put("l", LocationConverter.class.getName());
defaultConverterMap.put("x", NDCConverter.class.getName());

其中：

public class LocationConverter extends ClassicConverter {

    @Override
    public String convert(ILoggingEvent le) {
        StringBuilder buf = new StringBuilder();

        StackTraceElement[] cda = le.getCallerData();
        if (cda != null && cda.length > 0) {

            buf.append(cda[0]);
            return buf.toString();
        } else {
            return CallerData.CALLER_DATA_NA;
        }
    }

}

public class NDCConverter extends ClassicConverter {

    @Override
    public String convert(ILoggingEvent event) {
        Map<String, String> mdcPropertyMap = event.getMDCPropertyMap();
        return outputMDCForAllKeys(mdcPropertyMap);
    }

    private String outputMDCForAllKeys(Map<String, String> mdcPropertyMap) {
        StringBuilder buf = new StringBuilder();

        Map<Integer, String> ndcMap = new HashMap<Integer, String>();

        for (Map.Entry<String, String> entry : mdcPropertyMap.entrySet()) {
            if (entry.getKey().startsWith("NDC") && entry.getKey().length() > 3) {
                String index = entry.getKey().substring(3);
                try {
                    int idx = Integer.parseInt(index);
                    ndcMap.put(idx, entry.getValue());
                } catch (Exception e) {
                    // ignore
                }
            }
        }

        boolean first = true;
        for (int i = 0; i < ndcMap.size(); i++) {
            if (first) {
                first = false;
            } else {
                buf.append(" ");
            }
            buf.append(ndcMap.get(i));
        }
        return buf.toString();
    }
}

NDCConverter只是兼容了输出，因为在logback里，NDC是通过MDC来实现的，其key为NDC + index(from 0)，因此可以通过key来实现顺序输出，但是这个是基于用户的 MDC 不能以 "NDC"开头，再加上数字来命令，否则NDC的输出会出现MDC的内容；