src/android/src/com/google/android/inputmethod/japanese/session/MozcJNI.java

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package org.mozc.android.inputmethod.japanese.session;

import org.mozc.android.inputmethod.japanese.MozcLog;
import com.google.common.base.Preconditions;

import java.nio.Buffer;

/**
 * The wrapper for JNI Mozc server.
 *
 */
class MozcJNI {
  /**
   * Load the mozc native library. This method must be invoked before {@code evalCommand}.
   */
  private static volatile boolean isLoaded = false;

  /**
   * Loads and initializes the JNI library.
   *
   * @param dictionaryBuffer the buffer pointing the system dictionary
   * @param connectionDataBuffer the buffer pointing the connection data
   * @param expectedVersion expected version name of .so
   */
  static void load(
      String userProfileDirectoryPath, Buffer dictionaryBuffer, Buffer connectionDataBuffer,
      String expectedVersion) {
    Preconditions.checkNotNull(userProfileDirectoryPath);
    Preconditions.checkNotNull(dictionaryBuffer);
    Preconditions.checkNotNull(connectionDataBuffer);
    Preconditions.checkNotNull(expectedVersion);

    if (isLoaded) {
      return;
    }
    synchronized (MozcJNI.class) {
      if (isLoaded) {
        return;
      }
      MozcLog.d("start MozcJNI#load " + System.nanoTime());
      try {
        System.loadLibrary("mozc");
        MozcLog.v("loadLibrary succeeded");
      } catch (Throwable e) {
        MozcLog.e("loadLibrary failed", e);
        throw new RuntimeException(e);
      }
      String nativeVersion = getVersion();
      if (!nativeVersion.equals(expectedVersion)) {
        StringBuilder message = new StringBuilder("Version conflicts;");
        message.append(" Client:").append(expectedVersion);
        message.append(" Server:").append(nativeVersion);
        throw new UnsatisfiedLinkError(message.toString());
      }
      onPostLoad(userProfileDirectoryPath, dictionaryBuffer, connectionDataBuffer);
      isLoaded = true;
      MozcLog.d("end MozcJNI#load " + System.nanoTime());
    }
  }

  /**
   * Sends Command message to Mozc server and get a result.
   *
   * A caller has to interpret Command instance to and from blob.
   *
   * @param command blob of Command message.
   * @return blob of Command message.
   */
  static synchronized native byte[] evalCommand(byte[] command);

  /**
   * This method initializes the internal state of mozc server, especially dictionary data
   * and session related stuff. We cannot do this in JNI_OnLoad, which is the callback API
   * for JNI called when the shared object is loaded, because we need to pass the pointers
   * of dictionary data from Java as only Java knows where the data is in our context.
   */
  private static synchronized native void onPostLoad(
      String userProfileDirectoryPath, Buffer dictionaryData, Buffer connectionData);

  /**
   * @return Version string of shared object
   */
  private static native String getVersion();
}