1 /* 2 * Copyright (C) 2011 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_STRING_CHARS_H_included 18 #define SCOPED_STRING_CHARS_H_included 19 20 #include "JNIHelp.h" 21 22 // A smart pointer that provides access to a jchar* given a JNI jstring. 23 // Unlike GetStringChars, we throw NullPointerException rather than abort if 24 // passed a null jstring, and get will return NULL. 25 // This makes the correct idiom very simple: 26 // 27 // ScopedStringChars name(env, java_name); 28 // if (name.get() == NULL) { 29 // return NULL; 30 // } 31 class ScopedStringChars { 32 public: ScopedStringChars(JNIEnv * env,jstring s)33 ScopedStringChars(JNIEnv* env, jstring s) : env_(env), string_(s), size_(0) { 34 if (s == NULL) { 35 chars_ = NULL; 36 jniThrowNullPointerException(env, NULL); 37 } else { 38 chars_ = env->GetStringChars(string_, NULL); 39 if (chars_ != NULL) { 40 size_ = env->GetStringLength(string_); 41 } 42 } 43 } 44 ~ScopedStringChars()45 ~ScopedStringChars() { 46 if (chars_ != NULL) { 47 env_->ReleaseStringChars(string_, chars_); 48 } 49 } 50 get()51 const jchar* get() const { 52 return chars_; 53 } 54 size()55 size_t size() const { 56 return size_; 57 } 58 59 const jchar& operator[](size_t n) const { 60 return chars_[n]; 61 } 62 63 private: 64 JNIEnv* const env_; 65 const jstring string_; 66 const jchar* chars_; 67 size_t size_; 68 69 DISALLOW_COPY_AND_ASSIGN(ScopedStringChars); 70 }; 71 72 #endif // SCOPED_STRING_CHARS_H_included 73