| // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| package org.chromium.example.jni_generator; |
| |
| import android.graphics.Rect; |
| |
| // This class serves as a reference test for the bindings generator, and as example documentation |
| // for how to use the jni generator. |
| // The C++ counter-part is sample_for_tests.cc. |
| // jni_generator.gyp has a jni_generator_tests target that will: |
| // * Generate a header file for the JNI bindings based on this file. |
| // * Compile sample_for_tests.cc using the generated header file. |
| // * link a native executable to prove the generated header + cc file are self-contained. |
| // All comments are informational only, and are ignored by the jni generator. |
| // |
| // This JNINamespace annotation indicates that all native methods should be |
| // generated inside this namespace, including the native class that this |
| // object binds to. |
| @JNINamespace("base::android") |
| class SampleForTests { |
| // Classes can store their C++ pointer counter part as an int that is normally initialized by |
| // calling out a nativeInit() function. |
| int nativePtr; |
| |
| // You can define methods and attributes on the java class just like any other. |
| // Methods without the @CalledByNative annotation won't be exposed to JNI. |
| public SampleForTests() { |
| } |
| |
| public void startExample() { |
| // Calls native code and holds a pointer to the C++ class. |
| nativePtr = nativeInit("myParam"); |
| } |
| |
| public void doStuff() { |
| // This will call CPPClass::Method() using nativePtr as a pointer to the object. This must be |
| // done to: |
| // * avoid leaks. |
| // * using finalizers are not allowed to destroy the cpp class. |
| nativeMethod(nativePtr); |
| } |
| |
| public void finishExample() { |
| // We're done, so let's destroy nativePtr object. |
| nativeDestroy(nativePtr); |
| } |
| |
| // ----------------------------------------------------------------------------------------------- |
| // The following methods demonstrate exporting Java methods for invocation from C++ code. |
| // Java functions are mapping into C global functions by prefixing the method name with |
| // "Java_<Class>_" |
| // This is triggered by the @CalledByNative annotation; the methods may be named as you wish. |
| |
| // Exported to C++ as: |
| // Java_Example_javaMethod(JNIEnv* env, jobject obj, jint foo, jint bar) |
| // Typically the C++ code would have obtained the jobject via the Init() call described above. |
| @CalledByNative |
| public int javaMethod(int foo, |
| int bar) { |
| return 0; |
| } |
| |
| // Exported to C++ as Java_Example_staticJavaMethod(JNIEnv* env) |
| // Note no jobject argument, as it is static. |
| @CalledByNative |
| public static boolean staticJavaMethod() { |
| return true; |
| } |
| |
| // No prefix, so this method is package private. It will still be exported. |
| @CalledByNative |
| void packagePrivateJavaMethod() {} |
| |
| // Note the "Unchecked" suffix. By default, @CalledByNative will always generate bindings that |
| // call CheckException(). With "@CalledByNativeUnchecked", the client C++ code is responsible to |
| // call ClearException() and act as appropriate. |
| // See more details at the "@CalledByNativeUnchecked" annotation. |
| @CalledByNativeUnchecked |
| void methodThatThrowsException() throws Exception {} |
| |
| // The generator is not confused by inline comments: |
| // @CalledByNative void thisShouldNotAppearInTheOutput(); |
| // @CalledByNativeUnchecked public static void neitherShouldThis(int foo); |
| |
| /** |
| * The generator is not confused by block comments: |
| * @CalledByNative void thisShouldNotAppearInTheOutputEither(); |
| * @CalledByNativeUnchecked public static void andDefinitelyNotThis(int foo); |
| */ |
| |
| // String constants that look like comments don't confuse the generator: |
| private String arrgh = "*/*"; |
| |
| //------------------------------------------------------------------------------------------------ |
| // Java fields which are accessed from C++ code only must be annotated with @AccessedByNative to |
| // prevent them being eliminated when unreferenced code is stripped. |
| @AccessedByNative |
| private int javaField; |
| |
| //------------------------------------------------------------------------------------------------ |
| // The following methods demonstrate declaring methods to call into C++ from Java. |
| // The generator detects the "native" and "static" keywords, the type and name of the first |
| // parameter, and the "native" prefix to the function name to determine the C++ function |
| // signatures. Besides these constraints the methods can be freely named. |
| |
| // This declares a C++ function which the application code must implement: |
| // static jint Init(JNIEnv* env, jobject obj); |
| // The jobject parameter refers back to this java side object instance. |
| // The implementation must return the pointer to the C++ object cast to jint. |
| // The caller of this method should store it, and supply it as a the nativeCPPClass param to |
| // subsequent native method calls (see the methods below that take an "int native..." as first |
| // param). |
| private native int nativeInit(); |
| |
| // This defines a function binding to the associated C++ class member function. The name is |
| // derived from |nativeDestroy| and |nativeCPPClass| to arrive at CPPClass::Destroy() (i.e. native |
| // prefixes stripped). |
| // The |nativeCPPClass| is automatically cast to type CPPClass* in order to obtain the object on |
| // which to invoke the member function. |
| private native void nativeDestroy(int nativeCPPClass); |
| |
| // This declares a C++ function which the application code must implement: |
| // static jdouble GetDoubleFunction(JNIEnv* env, jobject obj); |
| // The jobject parameter refers back to this java side object instance. |
| private native double nativeGetDoubleFunction(); |
| |
| // Similar to nativeGetDoubleFunction(), but here the C++ side will receive a jclass rather than |
| // jobject param, as the function is declared static. |
| private static native float nativeGetFloatFunction(); |
| |
| // This function takes a non-POD datatype. We have a list mapping them to their full classpath in |
| // jni_generator.py JavaParamToJni. If you require a new datatype, make sure you add to that |
| // function. |
| private native void nativeSetNonPODDatatype(Rect rect); |
| |
| // This declares a C++ function which the application code must implement: |
| // static ScopedJavaLocalRef<jobject> GetNonPODDatatype(JNIEnv* env, jobject obj); |
| // The jobject parameter refers back to this java side object instance. |
| // Note that it returns a ScopedJavaLocalRef<jobject> so that you don' have to worry about |
| // deleting the JNI local reference. This is similar with Strings and arrays. |
| private native Object nativeGetNonPODDatatype(); |
| |
| // Similar to nativeDestroy above, this will cast nativeCPPClass into pointer of CPPClass type and |
| // call its Method member function. |
| private native int nativeMethod(int nativeCPPClass); |
| |
| // Similar to nativeMethod above, but here the C++ fully qualified class name is taken from the |
| // annotation rather than parameter name, which can thus be chosen freely. |
| @NativeClassQualifiedName("CPPClass::InnerClass") |
| private native double nativeMethodOtherP0(int nativePtr); |
| |
| // An inner class has some special attributes for annotation. |
| class InnerClass { |
| @CalledByNative("InnerClass") |
| public float JavaInnerMethod() { |
| } |
| |
| @CalledByNative("InnerClass") |
| public static void javaInnerFunction() { |
| } |
| |
| @NativeCall("InnerClass") |
| private static native int nativeInnerFunction(); |
| |
| @NativeCall("InnerClass") |
| private static native String nativeInnerMethod(int nativeCPPClass); |
| |
| } |
| } |