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* Copyright (C) 2008 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "android_nio_utils.h"
struct NioJNIData {
jclass nioAccessClass;
jmethodID getBasePointerID;
jmethodID getBaseArrayID;
jmethodID getBaseArrayOffsetID;
static NioJNIData gNioJNI;
void* android::nio_getPointer(JNIEnv *_env, jobject buffer, jarray *array) {
jlong pointer;
jint offset;
void *data;
pointer = _env->CallStaticLongMethod(gNioJNI.nioAccessClass,
gNioJNI.getBasePointerID, buffer);
if (pointer != 0L) {
*array = NULL;
return reinterpret_cast<void *>(pointer);
*array = (jarray) _env->CallStaticObjectMethod(gNioJNI.nioAccessClass,
gNioJNI.getBaseArrayID, buffer);
offset = _env->CallStaticIntMethod(gNioJNI.nioAccessClass,
gNioJNI.getBaseArrayOffsetID, buffer);
data = _env->GetPrimitiveArrayCritical(*array, (jboolean *) 0);
return (void *) ((char *) data + offset);
void android::nio_releasePointer(JNIEnv *_env, jarray array, void *data,
jboolean commit) {
_env->ReleasePrimitiveArrayCritical(array, data,
commit ? 0 : JNI_ABORT);
android::AutoBufferPointer::AutoBufferPointer(JNIEnv* env, jobject nioBuffer,
jboolean commit) {
fEnv = env;
fCommit = commit;
fPointer = android::nio_getPointer(env, nioBuffer, &fArray);
android::AutoBufferPointer::~AutoBufferPointer() {
if (NULL != fArray) {
android::nio_releasePointer(fEnv, fArray, fPointer, fCommit);
static jclass findClass(JNIEnv* env, const char name[]) {
jclass c = env->FindClass(name);
LOG_FATAL_IF(!c, "Unable to find class %s", name);
return c;
static jmethodID findStaticMethod(JNIEnv* env, jclass c, const char method[],
const char params[]) {
jmethodID m = env->GetStaticMethodID(c, method, params);
LOG_FATAL_IF(!m, "Unable to find method %s", method);
return m;
static jfieldID getFieldID(JNIEnv* env, jclass c, const char name[],
const char type[]) {
jfieldID f = env->GetFieldID(c, name, type);
LOG_FATAL_IF(!f, "Unable to find field %s", name);
return f;
namespace android {
int register_android_nio_utils(JNIEnv* env) {
jclass localClass = findClass(env, "java/nio/NIOAccess");
gNioJNI.getBasePointerID = findStaticMethod(env, localClass,
"getBasePointer", "(Ljava/nio/Buffer;)J");
gNioJNI.getBaseArrayID = findStaticMethod(env, localClass,
"getBaseArray", "(Ljava/nio/Buffer;)Ljava/lang/Object;");
gNioJNI.getBaseArrayOffsetID = findStaticMethod(env, localClass,
"getBaseArrayOffset", "(Ljava/nio/Buffer;)I");
// now record a permanent version of the class ID
gNioJNI.nioAccessClass = (jclass) env->NewGlobalRef(localClass);
return 0;