[Android] Java Bridge with Gin: implement Java bound object

content/browser/renderer_host/java/gin_java_bound_object.cc

+// Copyright 2014 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.
+
+#include "content/browser/renderer_host/java/gin_java_bound_object.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/strings/utf_string_conversions.h"
+#include "content/browser/renderer_host/java/jni_helper.h"
+
+using base::android::AttachCurrentThread;
+using base::android::ScopedJavaLocalRef;
+
+namespace content {
+
+namespace {
+
+const char kJavaLangClass[] = "java/lang/Class";
+const char kJavaLangObject[] = "java/lang/Object";
+const char kJavaLangReflectMethod[] = "java/lang/reflect/Method";
+const char kGetClass[] = "getClass";
+const char kGetMethods[] = "getMethods";
+const char kIsAnnotationPresent[] = "isAnnotationPresent";
+const char kReturningJavaLangClass[] = "()Ljava/lang/Class;";
+const char kReturningJavaLangReflectMethodArray[] =
+    "()[Ljava/lang/reflect/Method;";
+const char kTakesJavaLangClassReturningBoolean[] = "(Ljava/lang/Class;)Z";
+
+}  // namespace
+
+
+// static
+GinJavaBoundObject* GinJavaBoundObject::CreateNamed(
+    const JavaObjectWeakGlobalRef& ref,
+    const base::android::JavaRef<jclass>& safe_annotation_clazz) {
+  return new GinJavaBoundObject(ref, safe_annotation_clazz);
+}
+
+// static
+GinJavaBoundObject* GinJavaBoundObject::CreateTransient(
+    const JavaObjectWeakGlobalRef& ref,
+    const base::android::JavaRef<jclass>& safe_annotation_clazz,
+    RenderFrameHost* holder) {
+  std::set<RenderFrameHost*> holders;
+  holders.insert(holder);
+  return new GinJavaBoundObject(ref, safe_annotation_clazz, holders);
+}
+
+GinJavaBoundObject::GinJavaBoundObject(
+    const JavaObjectWeakGlobalRef& ref,
+    const base::android::JavaRef<jclass>& safe_annotation_clazz)
+    : ref_(ref),
+      names_count_(1),
+      object_get_class_method_id_(NULL),
+      are_methods_set_up_(false),
+      safe_annotation_clazz_(safe_annotation_clazz) {
+}
+
+GinJavaBoundObject::GinJavaBoundObject(
+    const JavaObjectWeakGlobalRef& ref,
+    const base::android::JavaRef<jclass>& safe_annotation_clazz,
+    const std::set<RenderFrameHost*> holders)
+    : ref_(ref),
+      names_count_(0),
+      holders_(holders),
+      object_get_class_method_id_(NULL),
+      are_methods_set_up_(false),
+      safe_annotation_clazz_(safe_annotation_clazz) {
+}
+
+GinJavaBoundObject::~GinJavaBoundObject() {
+}
+
+std::set<std::string> GinJavaBoundObject::GetMethodNames() {
+  EnsureMethodsAreSetUp();
+  std::set<std::string> result;
+  for (JavaMethodMap::const_iterator it = methods_.begin();
+       it != methods_.end();
+       ++it) {
+    result.insert(it->first);
+  }
+  return result;
+}
+
+bool GinJavaBoundObject::HasMethod(const std::string& method_name) {
+  EnsureMethodsAreSetUp();
+  return methods_.find(method_name) != methods_.end();
+}
+
+const JavaMethod* GinJavaBoundObject::FindMethod(
+    const std::string& method_name,
+    size_t num_parameters) {
+  EnsureMethodsAreSetUp();
+
+  // Get all methods with the correct name.
+  std::pair<JavaMethodMap::const_iterator, JavaMethodMap::const_iterator>
+      iters = methods_.equal_range(method_name);
+  if (iters.first == iters.second) {
+    return NULL;
+  }
+
+  // LIVECONNECT_COMPLIANCE: We just take the first method with the correct
+  // number of arguments, while the spec proposes using cost-based algorithm:
+  // https://jdk6.java.net/plugin2/liveconnect/#OVERLOADED_METHODS
+  for (JavaMethodMap::const_iterator iter = iters.first; iter != iters.second;
+       ++iter) {
+    if (iter->second->num_parameters() == num_parameters) {
+      return iter->second.get();
+    }
+  }
+
+  return NULL;
+}
+
+bool GinJavaBoundObject::IsObjectGetClassMethod(const JavaMethod* method) {
+  EnsureMethodsAreSetUp();
+  // As java.lang.Object.getClass is declared to be final, it is sufficient to
+  // compare methodIDs.
+  return method->id() == object_get_class_method_id_;
+}
+
+const base::android::JavaRef<jclass>&
+GinJavaBoundObject::GetSafeAnnotationClass() {
+  return safe_annotation_clazz_;
+}
+
+base::android::ScopedJavaLocalRef<jclass> GinJavaBoundObject::GetLocalClassRef(
+    JNIEnv* env) {
+  if (!object_get_class_method_id_) {
+    object_get_class_method_id_ = GetMethodIDFromClassName(
+        env, kJavaLangObject, kGetClass, kReturningJavaLangClass);
+  }
+  ScopedJavaLocalRef<jobject> obj = GetLocalRef(env);
+  if (obj.obj()) {
+    return base::android::ScopedJavaLocalRef<jclass>(
+        env,
+        static_cast<jclass>(
+            env->CallObjectMethod(obj.obj(), object_get_class_method_id_)));
+  } else {
+    return base::android::ScopedJavaLocalRef<jclass>();
+  }
+}
+
+void GinJavaBoundObject::EnsureMethodsAreSetUp() {
+  if (are_methods_set_up_)
+    return;
+  are_methods_set_up_ = true;
+
+  JNIEnv* env = AttachCurrentThread();
+
+  ScopedJavaLocalRef<jclass> clazz = GetLocalClassRef(env);
+  if (clazz.is_null()) {
+    return;
+  }
+
+  ScopedJavaLocalRef<jobjectArray> methods(env, static_cast<jobjectArray>(
+      env->CallObjectMethod(clazz.obj(), GetMethodIDFromClassName(
+          env,
+          kJavaLangClass,
+          kGetMethods,
+          kReturningJavaLangReflectMethodArray))));
+
+  size_t num_methods = env->GetArrayLength(methods.obj());
+  // Java objects always have public methods.
+  DCHECK(num_methods);
+
+  for (size_t i = 0; i < num_methods; ++i) {
+    ScopedJavaLocalRef<jobject> java_method(
+        env,
+        env->GetObjectArrayElement(methods.obj(), i));
+
+    if (!safe_annotation_clazz_.is_null()) {
+      jboolean safe = env->CallBooleanMethod(java_method.obj(),
+          GetMethodIDFromClassName(
+              env,
+              kJavaLangReflectMethod,
+              kIsAnnotationPresent,
+              kTakesJavaLangClassReturningBoolean),
+          safe_annotation_clazz_.obj());
+
+      if (!safe)
+        continue;
+    }
+
+    JavaMethod* method = new JavaMethod(java_method);
+    methods_.insert(std::make_pair(method->name(), method));
+  }
+}
+
+}  // namespace content