chore(java): Improve javadoc for logging module. (#1509)

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## What does this PR do?

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Improve javadoc for logging module.

## Related issues

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- #xxxx1
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#1497

## Does this PR introduce any user-facing change?

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- [ ] Does this PR introduce any binary protocol compatibility change?

- [ ] Does this PR introduce any public API change?

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---------

Signed-off-by: LiangliangSui <[email protected]>

java/fury-core/src/main/java/org/apache/fury/logging/LogLevel.java

@@ -19,6 +19,7 @@
 
 package org.apache.fury.logging;
 
+/** Defines a series of log levels. */
 public class LogLevel {
   public static final int ERROR_LEVEL = 0;
 

java/fury-core/src/main/java/org/apache/fury/logging/LoggerFactory.java

@@ -26,30 +26,54 @@
  */
 public class LoggerFactory {
   private static volatile boolean disableLogging;
-  private static volatile boolean useSlf4jlogger;
-  private static volatile int logLevel = 2;
+  private static volatile boolean useSlf4jLogger;
+  private static volatile int logLevel = LogLevel.INFO_LEVEL;
 
+  /** Disable Logger, there will be no log output. */
   public static void disableLogging() {
     disableLogging = true;
   }
 
+  /**
+   * Enable Logger. {@link FuryLogger} is used by default. You can configure whether to use {@link
+   * Slf4jLogger} through {@link LoggerFactory#createSlf4jLogger(Class)}.
+   */
   public static void enableLogging() {
     disableLogging = false;
   }
 
+  /**
+   * Set the {@link FuryLogger} log output control level, the default is {@link
+   * LogLevel#INFO_LEVEL}.
+   *
+   * @param level The log control level to be set, see {@link LogLevel}.
+   */
   public static void setLogLevel(int level) {
     logLevel = level;
   }
 
+  /**
+   * Set whether to use Slf4jLogging.
+   *
+   * @param useSlf4jLogging {@code true} means using {@link Slf4jLogger}, {@code false} means not
+   *     using it.
+   */
   public static void useSlf4jLogging(boolean useSlf4jLogging) {
-    LoggerFactory.useSlf4jlogger = useSlf4jLogging;
+    LoggerFactory.useSlf4jLogger = useSlf4jLogging;
   }
 
+  /**
+   * Get a Logger for log output.
+   *
+   * @param clazz Class of output Log.
+   * @return If the logger is disabled, {@link NilLogger} will be returned, otherwise {@link
+   *     FuryLogger} or {@link Slf4jLogger} will be returned.
+   */
   public static Logger getLogger(Class<?> clazz) {
     if (disableLogging) {
       return new FuryLogger(clazz, logLevel);
     } else {
-      if (GraalvmSupport.IN_GRAALVM_NATIVE_IMAGE || !useSlf4jlogger) {
+      if (GraalvmSupport.IN_GRAALVM_NATIVE_IMAGE || !useSlf4jLogger) {
         return new FuryLogger(clazz, logLevel);
       } else {
         return createSlf4jLogger(clazz);