refactor

Author: JoeWang1127

java-sdk-logging/logback-extension/src/main/java/com/google/api/logging/LoggingMdcJsonProvider.java

@@ -0,0 +1,53 @@
+package com.google.api.logging;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.IOException;
+import java.util.Map;
+import net.logstash.logback.composite.loggingevent.MdcJsonProvider;
+
+public class SDKLoggingMdcJsonProvider extends MdcJsonProvider {
+
+  private final ObjectMapper objectMapper = new ObjectMapper();
+
+  @Override
+  public void writeTo(JsonGenerator generator, ILoggingEvent event) throws IOException {
+    Map<String, String> mdcProperties = event.getMDCPropertyMap();
+    if (mdcProperties == null || mdcProperties.isEmpty()) {
+      return;
+    }
+
+    boolean hasWrittenStart = false;
+    for (Map.Entry<String, String> entry : mdcProperties.entrySet()) {
+      String fieldName = entry.getKey();
+
+      if (!hasWrittenStart && getFieldName() != null) {
+        generator.writeObjectFieldStart(getFieldName());
+        hasWrittenStart = true;
+      }
+      generator.writeFieldName(fieldName);
+      String entryValueString = entry.getValue();
+      try {
+        JsonNode jsonNode = convertToTreeNode(entryValueString);
+        if (jsonNode != null) {
+          generator.writeTree(jsonNode);
+        } else {
+          generator.writeObject(entryValueString);
+        }
+      } catch (JsonProcessingException e) {
+        // in case of conversion exception, just use String
+        generator.writeObject(entryValueString);
+      }
+    }
+    if (hasWrittenStart) {
+      generator.writeEndObject();
+    }
+  }
+
+  private JsonNode convertToTreeNode(String jsonString) throws JsonProcessingException {
+    return objectMapper.readTree(jsonString);
+  }
+}