Add a java api for rocksdb::Options, currently only supports create_if_missing.

Summary:
* [java] Add a java api for rocksdb::Options, currently only supports create_if_missing.
* [java] Add a test for RocksDBException in RocksDBSample.

Test Plan: make jtest

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D17385

java/org/rocksdb/Options.java

@@ -0,0 +1,69 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb;
+
+/**
+ * Options to control the behavior of a database.  It will be used
+ * during the creation of a RocksDB (i.e., RocksDB::Open()).
+ *
+ * Note that dispose() must be called before an Options instance
+ * become out-of-scope to release the allocated memory in c++.
+ */
+public class Options {
+  /**
+   * Construct options for opening a RocksDB.
+   *
+   * This constructor will create (by allocating a block of memory)
+   * an rocksdb::Options in the c++ side.
+   */
+  public Options() {
+    nativeHandle_ = 0;
+    newOptions();
+  }
+
+  /**
+   * If this value is set to true, then the database will be created
+   * if it is missing during RocksDB::Open().
+   * Default: false
+   *
+   * @param flag a flag indicating whether to create a database the
+   *     specified database in RocksDB::Open() operation is missing.
+   * @see RocksDB::Open()
+   */
+  public void setCreateIfMissing(boolean flag) {
+    assert(nativeHandle_ != 0);
+    setCreateIfMissing(nativeHandle_, flag);
+  }
+
+  /**
+   * Return true if the create_if_missing flag is set to true.
+   * If true, the database will be created if it is missing.
+   *
+   * @return return true if the create_if_missing flag is set to true.
+   * @see setCreateIfMissing()
+   */
+  public boolean craeteIfMissing() {
+    assert(nativeHandle_ != 0);
+    return createIfMissing(nativeHandle_);
+  }
+
+  /**
+   * Release the memory allocated for the current instance
+   * in the c++ side.
+   */
+  public synchronized void dispose() {
+    if (nativeHandle_ != 0) {
+      dispose0();
+    }
+  }
+
+  private native void newOptions();
+  private native void dispose0();
+  private native void setCreateIfMissing(long handle, boolean flag);
+  private native boolean createIfMissing(long handle);
+
+  long nativeHandle_;
+}

java/org/rocksdb/RocksDB.java

@@ -20,12 +20,16 @@ public class RocksDB {
   public static final int NOT_FOUND = -1;
   /**
    * The factory constructor of RocksDB that opens a RocksDB instance given
-   * the path to the database.
+   * the path to the database using the default options w/ createIfMissing
+   * set to true.
    *
    * @param path the path to the rocksdb.
    * @param status an out value indicating the status of the Open().
    * @return a rocksdb instance on success, null if the specified rocksdb can
    *     not be opened.
+   *
+   * @see Options.setCreateIfMissing()
+   * @see Options.createIfMissing()
    */
   public static RocksDB open(String path) throws RocksDBException {
     RocksDB db = new RocksDB();
@@ -33,6 +37,17 @@ public class RocksDB {
     return db;
   }
 
+  /**
+   * The factory constructor of RocksDB that opens a RocksDB instance given
+   * the path to the database using the specified options and db path.
+   */
+  public static RocksDB open(Options options, String path)
+      throws RocksDBException {
+    RocksDB db = new RocksDB();
+    db.open(options.nativeHandle_, path);
+    return db;
+  }
+
   public synchronized void close() {
     if (nativeHandle_ != 0) {
       close0();
@@ -93,6 +108,7 @@ public class RocksDB {
 
   // native methods
   private native void open0(String path) throws RocksDBException;
+  private native void open(long optionsHandle, String path) throws RocksDBException;
   private native void put(
       byte[] key, int keyLen,
       byte[] value, int valueLen) throws RocksDBException;