base/android/jni_android.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_ANDROID_JNI_ANDROID_H_
   6 #define BASE_ANDROID_JNI_ANDROID_H_
   7
   8 #include <jni.h>
   9 #include <sys/types.h>
  10
  11 #include "base/android/scoped_java_ref.h"
  12 #include "base/atomicops.h"
  13 #include "base/base_export.h"
  14 #include "base/compiler_specific.h"
  15
  16 namespace base {
  17 namespace android {
  18
  19 // Used to mark symbols to be exported in a shared library's symbol table.
  20 #define JNI_EXPORT __attribute__ ((visibility("default")))
  21
  22 // Contains the registration method information for initializing JNI bindings.
  23 struct RegistrationMethod {
  24   const char* name;
  25   bool (*func)(JNIEnv* env);
  26 };
  27
  28 // Attach the current thread to the VM (if necessary) and return the JNIEnv*.
  29 BASE_EXPORT JNIEnv* AttachCurrentThread();
  30
  31 // Detach the current thread from VM if it is attached.
  32 BASE_EXPORT void DetachFromVM();
  33
  34 // Initializes the global JVM. It is not necessarily called before
  35 // InitApplicationContext().
  36 BASE_EXPORT void InitVM(JavaVM* vm);
  37
  38 // Returns true if the global JVM has been initialized.
  39 BASE_EXPORT bool IsVMInitialized();
  40
  41 // Initializes the global application context object. The |context| can be any
  42 // valid reference to the application context. Internally holds a global ref to
  43 // the context. InitVM and InitApplicationContext maybe called in either order.
  44 BASE_EXPORT void InitApplicationContext(JNIEnv* env,
  45                                         const JavaRef<jobject>& context);
  46
  47 // Gets a global ref to the application context set with
  48 // InitApplicationContext(). Ownership is retained by the function - the caller
  49 // must NOT release it.
  50 const BASE_EXPORT jobject GetApplicationContext();
  51
  52 // Finds the class named |class_name| and returns it.
  53 // Use this method instead of invoking directly the JNI FindClass method (to
  54 // prevent leaking local references).
  55 // This method triggers a fatal assertion if the class could not be found.
  56 // Use HasClass if you need to check whether the class exists.
  57 BASE_EXPORT ScopedJavaLocalRef<jclass> GetClass(JNIEnv* env,
  58                                                 const char* class_name);
  59
  60 // This class is a wrapper for JNIEnv Get(Static)MethodID.
  61 class BASE_EXPORT MethodID {
  62  public:
  63   enum Type {
  64     TYPE_STATIC,
  65     TYPE_INSTANCE,
  66   };
  67
  68   // Returns the method ID for the method with the specified name and signature.
  69   // This method triggers a fatal assertion if the method could not be found.
  70   template<Type type>
  71   static jmethodID Get(JNIEnv* env,
  72                        jclass clazz,
  73                        const char* method_name,
  74                        const char* jni_signature);
  75
  76   // The caller is responsible to zero-initialize |atomic_method_id|.
  77   // It's fine to simultaneously call this on multiple threads referencing the
  78   // same |atomic_method_id|.
  79   template<Type type>
  80   static jmethodID LazyGet(JNIEnv* env,
  81                            jclass clazz,
  82                            const char* method_name,
  83                            const char* jni_signature,
  84                            base::subtle::AtomicWord* atomic_method_id);
  85 };
  86
  87 // Returns true if an exception is pending in the provided JNIEnv*.
  88 BASE_EXPORT bool HasException(JNIEnv* env);
  89
  90 // If an exception is pending in the provided JNIEnv*, this function clears it
  91 // and returns true.
  92 BASE_EXPORT bool ClearException(JNIEnv* env);
  93
  94 // This function will call CHECK() macro if there's any pending exception.
  95 BASE_EXPORT void CheckException(JNIEnv* env);
  96
  97 }  // namespace android
  98 }  // namespace base
  99
 100 #endif  // BASE_ANDROID_JNI_ANDROID_H_