1 /* 2 * libjingle 3 * Copyright 2015 Google Inc. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright notice, 9 * this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 // This file contain convenience functions and classes for JNI. 30 // Before using any of the methods, InitGlobalJniVariables must be called. 31 32 #ifndef TALK_APP_WEBRTC_JAVA_JNI_JNI_HELPERS_H_ 33 #define TALK_APP_WEBRTC_JAVA_JNI_JNI_HELPERS_H_ 34 35 #include <jni.h> 36 #include <string> 37 38 #include "webrtc/base/checks.h" 39 40 // Abort the process if |jni| has a Java exception pending. 41 // This macros uses the comma operator to execute ExceptionDescribe 42 // and ExceptionClear ignoring their return values and sending "" 43 // to the error stream. 44 #define CHECK_EXCEPTION(jni) \ 45 RTC_CHECK(!jni->ExceptionCheck()) \ 46 << (jni->ExceptionDescribe(), jni->ExceptionClear(), "") 47 48 // Helper that calls ptr->Release() and aborts the process with a useful 49 // message if that didn't actually delete *ptr because of extra refcounts. 50 #define CHECK_RELEASE(ptr) \ 51 RTC_CHECK_EQ(0, (ptr)->Release()) << "Unexpected refcount." 52 53 namespace webrtc_jni { 54 55 jint InitGlobalJniVariables(JavaVM *jvm); 56 57 // Return a |JNIEnv*| usable on this thread or NULL if this thread is detached. 58 JNIEnv* GetEnv(); 59 60 JavaVM *GetJVM(); 61 62 // Return a |JNIEnv*| usable on this thread. Attaches to |g_jvm| if necessary. 63 JNIEnv* AttachCurrentThreadIfNeeded(); 64 65 // Return a |jlong| that will correctly convert back to |ptr|. This is needed 66 // because the alternative (of silently passing a 32-bit pointer to a vararg 67 // function expecting a 64-bit param) picks up garbage in the high 32 bits. 68 jlong jlongFromPointer(void* ptr); 69 70 // JNIEnv-helper methods that RTC_CHECK success: no Java exception thrown and 71 // found object/class/method/field is non-null. 72 jmethodID GetMethodID( 73 JNIEnv* jni, jclass c, const std::string& name, const char* signature); 74 75 jmethodID GetStaticMethodID( 76 JNIEnv* jni, jclass c, const char* name, const char* signature); 77 78 jfieldID GetFieldID(JNIEnv* jni, jclass c, const char* name, 79 const char* signature); 80 81 jclass GetObjectClass(JNIEnv* jni, jobject object); 82 83 jobject GetObjectField(JNIEnv* jni, jobject object, jfieldID id); 84 85 jstring GetStringField(JNIEnv* jni, jobject object, jfieldID id); 86 87 jlong GetLongField(JNIEnv* jni, jobject object, jfieldID id); 88 89 jint GetIntField(JNIEnv* jni, jobject object, jfieldID id); 90 91 bool GetBooleanField(JNIEnv* jni, jobject object, jfieldID id); 92 93 // Java references to "null" can only be distinguished as such in C++ by 94 // creating a local reference, so this helper wraps that logic. 95 bool IsNull(JNIEnv* jni, jobject obj); 96 97 // Given a UTF-8 encoded |native| string return a new (UTF-16) jstring. 98 jstring JavaStringFromStdString(JNIEnv* jni, const std::string& native); 99 100 // Given a (UTF-16) jstring return a new UTF-8 native string. 101 std::string JavaToStdString(JNIEnv* jni, const jstring& j_string); 102 103 // Return the (singleton) Java Enum object corresponding to |index|; 104 jobject JavaEnumFromIndex(JNIEnv* jni, jclass state_class, 105 const std::string& state_class_name, int index); 106 107 jobject NewGlobalRef(JNIEnv* jni, jobject o); 108 109 void DeleteGlobalRef(JNIEnv* jni, jobject o); 110 111 // Scope Java local references to the lifetime of this object. Use in all C++ 112 // callbacks (i.e. entry points that don't originate in a Java callstack 113 // through a "native" method call). 114 class ScopedLocalRefFrame { 115 public: 116 explicit ScopedLocalRefFrame(JNIEnv* jni); 117 ~ScopedLocalRefFrame(); 118 119 private: 120 JNIEnv* jni_; 121 }; 122 123 // Scoped holder for global Java refs. 124 template<class T> // T is jclass, jobject, jintArray, etc. 125 class ScopedGlobalRef { 126 public: ScopedGlobalRef(JNIEnv * jni,T obj)127 ScopedGlobalRef(JNIEnv* jni, T obj) 128 : obj_(static_cast<T>(jni->NewGlobalRef(obj))) {} ~ScopedGlobalRef()129 ~ScopedGlobalRef() { 130 DeleteGlobalRef(AttachCurrentThreadIfNeeded(), obj_); 131 } 132 T operator*() const { 133 return obj_; 134 } 135 private: 136 T obj_; 137 }; 138 139 } // namespace webrtc_jni 140 141 #endif // TALK_APP_WEBRTC_JAVA_JNI_JNI_HELPERS_H_ 142