Refactor ScopedJavaRef

base/android/scoped_java_global_reference.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_ANDROID_SCOPED_JAVA_GLOBAL_REFERENCE_H_
-#define BASE_ANDROID_SCOPED_JAVA_GLOBAL_REFERENCE_H_
-
-#include <jni.h>
-#include <stddef.h>
-
-#include "base/android/scoped_java_reference.h"
-#include "base/basictypes.h"
-
-namespace base {
-namespace android {
-
-// Holds a global reference to a Java object. The global reference is scoped
-// to the lifetime of this object. Note that since a JNI Env is only suitable
-// for use on a single thread, objects of this class must be created, used and
-// destroyed on the same thread.
-template<typename T>
-class ScopedJavaGlobalReference {
- public:
-  // Holds a NULL reference.
-  ScopedJavaGlobalReference()
-      : env_(NULL),
-        obj_(NULL) {
-  }
-  // Takes a new global reference to the Java object held by obj.
-  explicit ScopedJavaGlobalReference(const ScopedJavaReference<T>& obj)
-      : env_(obj.env()),
-        obj_(static_cast<T>(obj.env()->NewGlobalRef(obj.obj()))) {
-  }
-  ~ScopedJavaGlobalReference() {
-    Reset();
-  }
-
-  void Reset() {
-    if (env_ && obj_)
-      env_->DeleteGlobalRef(obj_);
-    env_ = NULL;
-    obj_ = NULL;
-  }
-  void Reset(const ScopedJavaGlobalReference& other) {
-    Reset();
-    env_ = other.env_;
-    obj_ = other.env_ ? static_cast<T>(other.env_->NewGlobalRef(other.obj_)) :
-        NULL;
-  }
-
-  T obj() const { return obj_; }
-
- private:
-  JNIEnv* env_;
-  T obj_;
-
-  DISALLOW_COPY_AND_ASSIGN(ScopedJavaGlobalReference);
-};
-
-}  // namespace android
-}  // namespace base
-
-#endif  // BASE_ANDROID_SCOPED_JAVA_GLOBAL_REFERENCE_H_