Home | History | Annotate | Download | only in nativehelper 
      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef SCOPED_BYTES_H_
     18 #define SCOPED_BYTES_H_
     19 
     20 #include "jni.h"
     21 #include "nativehelper_utils.h"
     22 
     23 /**
     24  * ScopedBytesRO and ScopedBytesRW attempt to paper over the differences between byte[]s and
     25  * ByteBuffers. This in turn helps paper over the differences between non-direct ByteBuffers backed
     26  * by byte[]s, direct ByteBuffers backed by bytes[]s, and direct ByteBuffers not backed by byte[]s.
     27  * (On Android, this last group only contains MappedByteBuffers.)
     28  */
     29 template<bool readOnly>
     30 class ScopedBytes {
     31 public:
     32     ScopedBytes(JNIEnv* env, jobject object)
     33     : mEnv(env), mObject(object), mByteArray(NULL), mPtr(NULL)
     34     {
     35         if (mObject == NULL) {
     36             jniThrowNullPointerException(mEnv, NULL);
     37         } else if (mEnv->IsInstanceOf(mObject, JniConstants::byteArrayClass)) {
     38             mByteArray = reinterpret_cast<jbyteArray>(mObject);
     39             mPtr = mEnv->GetByteArrayElements(mByteArray, NULL);
     40         } else {
     41             mPtr = reinterpret_cast<jbyte*>(mEnv->GetDirectBufferAddress(mObject));
     42         }
     43     }
     44 
     45     ~ScopedBytes() {
     46         if (mByteArray != NULL) {
     47             mEnv->ReleaseByteArrayElements(mByteArray, mPtr, readOnly ? JNI_ABORT : 0);
     48         }
     49     }
     50 
     51 private:
     52     JNIEnv* const mEnv;
     53     const jobject mObject;
     54     jbyteArray mByteArray;
     55 
     56 protected:
     57     jbyte* mPtr;
     58 
     59 private:
     60     DISALLOW_COPY_AND_ASSIGN(ScopedBytes);
     61 };
     62 
     63 class ScopedBytesRO : public ScopedBytes<true> {
     64 public:
     65     ScopedBytesRO(JNIEnv* env, jobject object) : ScopedBytes<true>(env, object) {}
     66     const jbyte* get() const {
     67         return mPtr;
     68     }
     69 };
     70 
     71 class ScopedBytesRW : public ScopedBytes<false> {
     72 public:
     73     ScopedBytesRW(JNIEnv* env, jobject object) : ScopedBytes<false>(env, object) {}
     74     jbyte* get() {
     75         return mPtr;
     76     }
     77 };
     78 
     79 #endif  // SCOPED_BYTES_H_
     80