Dart/JNI: reflection-based wrapper for the raw JNI API

Example:
  JavaClass dateFormatClass = Java.getClass('java.text.SimpleDateFormat');
  JavaObject format = dateFormatClass.newInstance('yyyy.MM.dd');
  print(format.parse('2016.01.01').getYear());

sky/engine/bindings/BUILD.gn

@@ -63,6 +63,8 @@ action("generate_snapshot_bin") {
     "//dart/runtime/tools/create_snapshot_bin.py",
     "//sky/engine/bindings/internals.dart",
     "//sky/engine/bindings/jni/jni.dart",
+    "//sky/engine/bindings/jni/jni_raw.dart",
+    "//sky/engine/bindings/jni/jni_helper.dart",
     "snapshot.dart",
   ] + rebase_path(dart_mojo_internal_sdk_sources,
                   "",

sky/engine/bindings/jni/BUILD.gn

@@ -6,6 +6,8 @@ source_set("jni") {
   sources = [
     "dart_jni.cc",
     "dart_jni.h",
+    "jni_api.cc",
+    "jni_api.h",
     "jni_array.cc",
     "jni_array.h",
     "jni_class.cc",

sky/engine/bindings/jni/dart_jni.cc

@@ -7,6 +7,7 @@
 #include "base/logging.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
+#include "sky/engine/bindings/jni/jni_api.h"
 #include "sky/engine/bindings/jni/jni_array.h"
 #include "sky/engine/bindings/jni/jni_class.h"
 #include "sky/engine/bindings/jni/jni_object.h"
@@ -93,6 +94,10 @@ bool CheckDartException(Dart_Handle result, Dart_Handle* exception) {
   return true;
 }
 
+DART_NATIVE_CALLBACK_STATIC(JniApi, FromReflectedField);
+DART_NATIVE_CALLBACK_STATIC(JniApi, FromReflectedMethod);
+DART_NATIVE_CALLBACK_STATIC(JniApi, GetApplicationContext);
+DART_NATIVE_CALLBACK_STATIC(JniApi, GetClassLoader);
 DART_NATIVE_CALLBACK_STATIC(JniBooleanArray, Create);
 DART_NATIVE_CALLBACK_STATIC(JniByteArray, Create);
 DART_NATIVE_CALLBACK_STATIC(JniCharArray, Create);
@@ -196,6 +201,10 @@ void DartJni::InitForGlobal() {
     g_natives = new DartLibraryNatives();
 
     g_natives->Register({
+      DART_REGISTER_NATIVE_STATIC(JniApi, FromReflectedField)
+      DART_REGISTER_NATIVE_STATIC(JniApi, FromReflectedMethod)
+      DART_REGISTER_NATIVE_STATIC(JniApi, GetApplicationContext)
+      DART_REGISTER_NATIVE_STATIC(JniApi, GetClassLoader)
       DART_REGISTER_NATIVE_STATIC(JniBooleanArray, Create)
       DART_REGISTER_NATIVE_STATIC(JniByteArray, Create)
       DART_REGISTER_NATIVE_STATIC(JniCharArray, Create)
@@ -306,6 +315,10 @@ jstring DartJni::DartToJavaString(JNIEnv* env, Dart_Handle dart_string,
   return java_string;
 }
 
+jobject DartJni::class_loader() {
+  return g_jvm_data->class_loader.obj();
+}
+
 jclass DartJni::class_clazz() {
   return g_jvm_data->class_clazz.obj();
 }

sky/engine/bindings/jni/dart_jni.h

@@ -37,6 +37,7 @@ class DartJni {
   static jstring DartToJavaString(JNIEnv* env, Dart_Handle dart_string,
                                   Dart_Handle* exception);
 
+  static jobject class_loader();
   static jclass class_clazz();
   static Dart_Handle jni_object_type();
   static Dart_Handle jni_float_type();

sky/engine/bindings/jni/jni.dart

@@ -7,262 +7,5 @@ library dart_jni;
 import 'dart:collection';
 import 'dart:nativewrappers';
 
-/// Wrapper for a Java class accessed via JNI.
-class JniClass extends NativeFieldWrapperClass2 {
-  static JniClass fromName(String name)
-      native 'JniClass_FromName';
-  static JniClass fromClassObject(JniObject classObject)
-      native 'JniClass_FromClassObject';
-
-  int getFieldId(String name, String sig)
-      native 'JniClass_GetFieldId';
-  int getStaticFieldId(String name, String sig)
-      native 'JniClass_GetStaticFieldId';
-  int getMethodId(String name, String sig)
-      native 'JniClass_GetMethodId';
-  int getStaticMethodId(String name, String sig)
-      native 'JniClass_GetStaticMethodId';
-
-  JniObject newObject(int methodId, List args)
-      native 'JniClass_NewObject';
-
-  JniObject getStaticObjectField(int fieldId)
-      native 'JniClass_GetStaticObjectField';
-  bool getStaticBooleanField(int fieldId)
-      native 'JniClass_GetStaticBooleanField';
-  int getStaticByteField(int fieldId)
-      native 'JniClass_GetStaticByteField';
-  int getStaticCharField(int fieldId)
-      native 'JniClass_GetStaticCharField';
-  int getStaticShortField(int fieldId)
-      native 'JniClass_GetStaticShortField';
-  int getStaticIntField(int fieldId)
-      native 'JniClass_GetStaticIntField';
-  int getStaticLongField(int fieldId)
-      native 'JniClass_GetStaticLongField';
-  double getStaticFloatField(int fieldId)
-      native 'JniClass_GetStaticFloatField';
-  double getStaticDoubleField(int fieldId)
-      native 'JniClass_GetStaticDoubleField';
-
-  void setStaticObjectField(int fieldId, JniObject value)
-      native 'JniClass_SetStaticObjectField';
-  void setStaticBooleanField(int fieldId, bool value)
-      native 'JniClass_SetStaticBooleanField';
-  void setStaticByteField(int fieldId, int value)
-      native 'JniClass_SetStaticByteField';
-  void setStaticCharField(int fieldId, int value)
-      native 'JniClass_SetStaticCharField';
-  void setStaticShortField(int fieldId, int value)
-      native 'JniClass_SetStaticShortField';
-  void setStaticIntField(int fieldId, int value)
-      native 'JniClass_SetStaticIntField';
-  void setStaticLongField(int fieldId, int value)
-      native 'JniClass_SetStaticLongField';
-  void setStaticFloatField(int fieldId, double value)
-      native 'JniClass_SetStaticFloatField';
-  void setStaticDoubleField(int fieldId, double value)
-      native 'JniClass_SetStaticDoubleField';
-
-  JniObject callStaticObjectMethod(int methodId, List args)
-      native 'JniClass_CallStaticObjectMethod';
-  bool callStaticBooleanMethod(int methodId, List args)
-      native 'JniClass_CallStaticBooleanMethod';
-  int callStaticByteMethod(int methodId, List args)
-      native 'JniClass_CallStaticByteMethod';
-  int callStaticCharMethod(int methodId, List args)
-      native 'JniClass_CallStaticCharMethod';
-  int callStaticShortMethod(int methodId, List args)
-      native 'JniClass_CallStaticShortMethod';
-  int callStaticIntMethod(int methodId, List args)
-      native 'JniClass_CallStaticIntMethod';
-  int callStaticLongMethod(int methodId, List args)
-      native 'JniClass_CallStaticLongMethod';
-  double callStaticFloatMethod(int methodId, List args)
-      native 'JniClass_CallStaticFloatMethod';
-  double callStaticDoubleMethod(int methodId, List args)
-      native 'JniClass_CallStaticDoubleMethod';
-  void callStaticVoidMethod(int methodId, List args)
-      native 'JniClass_CallStaticVoidMethod';
-}
-
-/// Wrapper for a Java object accessed via JNI.
-class JniObject extends NativeFieldWrapperClass2 {
-  JniObject getObjectField(int fieldId)
-      native 'JniObject_GetObjectField';
-  bool getBooleanField(int fieldId)
-      native 'JniObject_GetBooleanField';
-  int getByteField(int fieldId)
-      native 'JniObject_GetByteField';
-  int getCharField(int fieldId)
-      native 'JniObject_GetCharField';
-  int getShortField(int fieldId)
-      native 'JniObject_GetShortField';
-  int getIntField(int fieldId)
-      native 'JniObject_GetIntField';
-  int getLongField(int fieldId)
-      native 'JniObject_GetLongField';
-  double getFloatField(int fieldId)
-      native 'JniObject_GetFloatField';
-  double getDoubleField(int fieldId)
-      native 'JniObject_GetDoubleField';
-
-  void setObjectField(int fieldId, JniObject value)
-      native 'JniObject_SetObjectField';
-  void setBooleanField(int fieldId, bool value)
-      native 'JniObject_SetBooleanField';
-  void setByteField(int fieldId, int value)
-      native 'JniObject_SetByteField';
-  void setCharField(int fieldId, int value)
-      native 'JniObject_SetCharField';
-  void setShortField(int fieldId, int value)
-      native 'JniObject_SetShortField';
-  void setIntField(int fieldId, int value)
-      native 'JniObject_SetIntField';
-  void setLongField(int fieldId, int value)
-      native 'JniObject_SetLongField';
-  void setFloatField(int fieldId, double value)
-      native 'JniObject_SetFloatField';
-  void setDoubleField(int fieldId, double value)
-      native 'JniObject_SetDoubleField';
-
-  JniObject callObjectMethod(int methodId, List args)
-      native 'JniObject_CallObjectMethod';
-  bool callBooleanMethod(int methodId, List args)
-      native 'JniObject_CallBooleanMethod';
-  int callByteMethod(int methodId, List args)
-      native 'JniObject_CallByteMethod';
-  int callCharMethod(int methodId, List args)
-      native 'JniObject_CallCharMethod';
-  int callShortMethod(int methodId, List args)
-      native 'JniObject_CallShortMethod';
-  int callIntMethod(int methodId, List args)
-      native 'JniObject_CallIntMethod';
-  int callLongMethod(int methodId, List args)
-      native 'JniObject_CallLongMethod';
-  double callFloatMethod(int methodId, List args)
-      native 'JniObject_CallFloatMethod';
-  double callDoubleMethod(int methodId, List args)
-      native 'JniObject_CallDoubleMethod';
-  void callVoidMethod(int methodId, List args)
-      native 'JniObject_CallVoidMethod';
-}
-
-/// Wrapper for a Java string.
-class JniString extends JniObject {
-  static JniString create(String value)
-      native 'JniString_Create';
-
-  // Retrieve the value as a Dart string.
-  String get text native 'JniString_GetText';
-}
-
-/// Wrapper for a Java array.
-class JniArray extends JniObject {
-  int get length native 'JniArray_GetLength';
-}
-
-class JniObjectArray extends JniArray {
-  static JniObjectArray create(JniClass clazz, int length)
-      native 'JniObjectArray_Create';
-
-  JniObject operator [](int index)
-      native 'JniObjectArray_GetArrayElement';
-
-  void operator []=(int index, JniObject value)
-      native 'JniObjectArray_SetArrayElement';
-}
-
-class JniBooleanArray extends JniArray {
-  static JniBooleanArray create(int length)
-      native 'JniBooleanArray_Create';
-
-  bool operator [](int index)
-      native 'JniBooleanArray_GetArrayElement';
-
-  void operator []=(int index, bool value)
-      native 'JniBooleanArray_SetArrayElement';
-}
-
-class JniByteArray extends JniArray {
-  static JniByteArray create(int length)
-      native 'JniByteArray_Create';
-
-  int operator [](int index)
-      native 'JniByteArray_GetArrayElement';
-
-  void operator []=(int index, int value)
-      native 'JniByteArray_SetArrayElement';
-}
-
-class JniCharArray extends JniArray {
-  static JniCharArray create(int length)
-      native 'JniCharArray_Create';
-
-  int operator [](int index)
-      native 'JniCharArray_GetArrayElement';
-
-  void operator []=(int index, int value)
-      native 'JniCharArray_SetArrayElement';
-}
-
-class JniShortArray extends JniArray {
-  static JniShortArray create(int length)
-      native 'JniShortArray_Create';
-
-  int operator [](int index)
-      native 'JniShortArray_GetArrayElement';
-
-  void operator []=(int index, int value)
-      native 'JniShortArray_SetArrayElement';
-}
-
-class JniIntArray extends JniArray {
-  static JniIntArray create(int length)
-      native 'JniIntArray_Create';
-
-  int operator [](int index)
-      native 'JniIntArray_GetArrayElement';
-
-  void operator []=(int index, int value)
-      native 'JniIntArray_SetArrayElement';
-}
-
-class JniLongArray extends JniArray {
-  static JniLongArray create(int length)
-      native 'JniLongArray_Create';
-
-  int operator [](int index)
-      native 'JniLongArray_GetArrayElement';
-
-  void operator []=(int index, int value)
-      native 'JniLongArray_SetArrayElement';
-}
-
-class JniFloatArray extends JniArray {
-  static JniFloatArray create(int length)
-      native 'JniFloatArray_Create';
-
-  double operator [](int index)
-      native 'JniFloatArray_GetArrayElement';
-
-  void operator []=(int index, double value)
-      native 'JniFloatArray_SetArrayElement';
-}
-
-class JniDoubleArray extends JniArray {
-  static JniDoubleArray create(int length)
-      native 'JniDoubleArray_Create';
-
-  double operator [](int index)
-      native 'JniDoubleArray_GetArrayElement';
-
-  void operator []=(int index, double value)
-      native 'JniDoubleArray_SetArrayElement';
-}
-
-/// Used to pass arguments of type "float" to Java methods.
-class JniFloat {
-  final double value;
-  JniFloat(this.value);
-}
+part 'jni_raw.dart';
+part 'jni_helper.dart';

sky/engine/bindings/jni/jni_api.cc

+// Copyright 2016 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 "sky/engine/bindings/jni/jni_api.h"
+
+#include "sky/engine/bindings/jni/dart_jni.h"
+
+namespace blink {
+
+int64_t JniApi::FromReflectedField(const JniObject* field) {
+  Dart_Handle exception = nullptr;
+  {
+    ENTER_JNI();
+
+    jfieldID result = env->FromReflectedField(field->java_object());
+    if (CheckJniException(env, &exception)) goto fail;
+
+    return reinterpret_cast<int64_t>(result);
+  }
+fail:
+  Dart_ThrowException(exception);
+  ASSERT_NOT_REACHED();
+  return 0;
+}
+
+int64_t JniApi::FromReflectedMethod(const JniObject* method) {
+  Dart_Handle exception = nullptr;
+  {
+    ENTER_JNI();
+
+    jmethodID result = env->FromReflectedMethod(method->java_object());
+    if (CheckJniException(env, &exception)) goto fail;
+
+    return reinterpret_cast<int64_t>(result);
+  }
+fail:
+  Dart_ThrowException(exception);
+  ASSERT_NOT_REACHED();
+  return 0;
+}
+
+PassRefPtr<JniObject> JniApi::GetApplicationContext() {
+  ENTER_JNI();
+  return JniObject::Create(env, base::android::GetApplicationContext());
+}
+
+PassRefPtr<JniObject> JniApi::GetClassLoader() {
+  ENTER_JNI();
+  return JniObject::Create(env, DartJni::class_loader());
+}
+
+} // namespace blink

sky/engine/bindings/jni/jni_api.h

+// Copyright 2016 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.
+
+#ifndef SKY_ENGINE_BINDINGS_JNI_JNI_API_H_
+#define SKY_ENGINE_BINDINGS_JNI_JNI_API_H_
+
+#include "sky/engine/bindings/jni/jni_object.h"
+
+namespace blink {
+
+// Dart wrappers for basic JNI APIs.
+class JniApi {
+ public:
+  static int64_t FromReflectedField(const JniObject* field);
+  static int64_t FromReflectedMethod(const JniObject* method);
+  static PassRefPtr<JniObject> GetApplicationContext();
+  static PassRefPtr<JniObject> GetClassLoader();
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_BINDINGS_JNI_JNI_API_H_

sky/engine/bindings/jni/jni_class.cc

@@ -5,7 +5,6 @@
 #include "sky/engine/bindings/jni/jni_class.h"
 
 #include "sky/engine/bindings/jni/dart_jni.h"
-#include "sky/engine/bindings/jni/jni_object.h"
 
 namespace blink {
 
@@ -14,8 +13,7 @@ using base::android::ScopedJavaLocalRef;
 IMPLEMENT_WRAPPERTYPEINFO(jni, JniClass);
 
 JniClass::JniClass(JNIEnv* env, jclass clazz)
-    : clazz_(env, clazz) {
-}
+    : JniObject(env, clazz) {}
 
 JniClass::~JniClass() {
 }

sky/engine/bindings/jni/jni_class.h

@@ -8,6 +8,7 @@
 #include <jni.h>
 
 #include "base/android/jni_android.h"
+#include "sky/engine/bindings/jni/jni_object.h"
 #include "sky/engine/tonic/dart_wrappable.h"
 #include "sky/engine/wtf/PassRefPtr.h"
 #include "sky/engine/wtf/RefCounted.h"
@@ -17,8 +18,9 @@ namespace blink {
 class JniObject;
 
 // Wrapper that exposes a JNI jclass to Dart
-class JniClass : public RefCounted<JniClass>, public DartWrappable {
+class JniClass : public JniObject {
   DEFINE_WRAPPERTYPEINFO();
+  friend class JniObject;
 
  public:
   ~JniClass() override;
@@ -26,7 +28,7 @@ class JniClass : public RefCounted<JniClass>, public DartWrappable {
   static PassRefPtr<JniClass> FromName(const char* className);
   static PassRefPtr<JniClass> FromClassObject(const JniObject* clazz);
 
-  jclass java_class() const { return clazz_.obj(); }
+  jclass java_class() const { return static_cast<jclass>(object_.obj()); }
 
   intptr_t GetFieldId(const char* name, const char* sig);
   intptr_t GetStaticFieldId(const char* name, const char* sig);
@@ -79,8 +81,6 @@ class JniClass : public RefCounted<JniClass>, public DartWrappable {
 
  private:
   JniClass(JNIEnv* env, jclass clazz);
-
-  base::android::ScopedJavaGlobalRef<jclass> clazz_;
 };
 
 } // namespace blink

sky/engine/bindings/jni/jni_object.cc

@@ -30,6 +30,8 @@ PassRefPtr<JniObject> JniObject::Create(JNIEnv* env, jobject object) {
 
   if (class_name == "java.lang.String") {
     result = new JniString(env, static_cast<jstring>(object));
+  } else if (class_name == "java.lang.Class") {
+    result = new JniClass(env, static_cast<jclass>(object));
   } else if (base::StartsWith(class_name, "[L", base::CompareCase::SENSITIVE)) {
     result = new JniObjectArray(env, static_cast<jobjectArray>(object));
   } else if (class_name == "[Z") {

sky/engine/bindings/jni/jni_raw.dart

+// Copyright 2016 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.
+
+part of dart_jni;
+
+/// Invoke Java Native Interface APIs from Dart.
+class JniApi {
+  static int fromReflectedField(JniObject field)
+      native 'JniApi_FromReflectedField';
+  static int fromReflectedMethod(JniObject method)
+      native 'JniApi_FromReflectedMethod';
+
+  static JniObject getApplicationContext()
+      native 'JniApi_GetApplicationContext';
+  static JniObject getClassLoader()
+      native 'JniApi_GetClassLoader';
+}
+
+/// Wrapper for a Java object accessed via JNI.
+class JniObject extends NativeFieldWrapperClass2 {
+  JniObject getObjectField(int fieldId)
+      native 'JniObject_GetObjectField';
+  bool getBooleanField(int fieldId)
+      native 'JniObject_GetBooleanField';
+  int getByteField(int fieldId)
+      native 'JniObject_GetByteField';
+  int getCharField(int fieldId)
+      native 'JniObject_GetCharField';
+  int getShortField(int fieldId)
+      native 'JniObject_GetShortField';
+  int getIntField(int fieldId)
+      native 'JniObject_GetIntField';
+  int getLongField(int fieldId)
+      native 'JniObject_GetLongField';
+  double getFloatField(int fieldId)
+      native 'JniObject_GetFloatField';
+  double getDoubleField(int fieldId)
+      native 'JniObject_GetDoubleField';
+
+  void setObjectField(int fieldId, JniObject value)
+      native 'JniObject_SetObjectField';
+  void setBooleanField(int fieldId, bool value)
+      native 'JniObject_SetBooleanField';
+  void setByteField(int fieldId, int value)
+      native 'JniObject_SetByteField';
+  void setCharField(int fieldId, int value)
+      native 'JniObject_SetCharField';
+  void setShortField(int fieldId, int value)
+      native 'JniObject_SetShortField';
+  void setIntField(int fieldId, int value)
+      native 'JniObject_SetIntField';
+  void setLongField(int fieldId, int value)
+      native 'JniObject_SetLongField';
+  void setFloatField(int fieldId, double value)
+      native 'JniObject_SetFloatField';
+  void setDoubleField(int fieldId, double value)
+      native 'JniObject_SetDoubleField';
+
+  JniObject callObjectMethod(int methodId, List args)
+      native 'JniObject_CallObjectMethod';
+  bool callBooleanMethod(int methodId, List args)
+      native 'JniObject_CallBooleanMethod';
+  int callByteMethod(int methodId, List args)
+      native 'JniObject_CallByteMethod';
+  int callCharMethod(int methodId, List args)
+      native 'JniObject_CallCharMethod';
+  int callShortMethod(int methodId, List args)
+      native 'JniObject_CallShortMethod';
+  int callIntMethod(int methodId, List args)
+      native 'JniObject_CallIntMethod';
+  int callLongMethod(int methodId, List args)
+      native 'JniObject_CallLongMethod';
+  double callFloatMethod(int methodId, List args)
+      native 'JniObject_CallFloatMethod';
+  double callDoubleMethod(int methodId, List args)
+      native 'JniObject_CallDoubleMethod';
+  void callVoidMethod(int methodId, List args)
+      native 'JniObject_CallVoidMethod';
+}
+
+/// Wrapper for a Java class accessed via JNI.
+class JniClass extends JniObject {
+  static JniClass fromName(String name)
+      native 'JniClass_FromName';
+  static JniClass fromClassObject(JniObject classObject)
+      native 'JniClass_FromClassObject';
+
+  int getFieldId(String name, String sig)
+      native 'JniClass_GetFieldId';
+  int getStaticFieldId(String name, String sig)
+      native 'JniClass_GetStaticFieldId';
+  int getMethodId(String name, String sig)
+      native 'JniClass_GetMethodId';
+  int getStaticMethodId(String name, String sig)
+      native 'JniClass_GetStaticMethodId';
+
+  JniObject newObject(int methodId, List args)
+      native 'JniClass_NewObject';
+
+  JniObject getStaticObjectField(int fieldId)
+      native 'JniClass_GetStaticObjectField';
+  bool getStaticBooleanField(int fieldId)
+      native 'JniClass_GetStaticBooleanField';
+  int getStaticByteField(int fieldId)
+      native 'JniClass_GetStaticByteField';
+  int getStaticCharField(int fieldId)
+      native 'JniClass_GetStaticCharField';
+  int getStaticShortField(int fieldId)
+      native 'JniClass_GetStaticShortField';
+  int getStaticIntField(int fieldId)
+      native 'JniClass_GetStaticIntField';
+  int getStaticLongField(int fieldId)
+      native 'JniClass_GetStaticLongField';
+  double getStaticFloatField(int fieldId)
+      native 'JniClass_GetStaticFloatField';
+  double getStaticDoubleField(int fieldId)
+      native 'JniClass_GetStaticDoubleField';
+
+  void setStaticObjectField(int fieldId, JniObject value)
+      native 'JniClass_SetStaticObjectField';
+  void setStaticBooleanField(int fieldId, bool value)
+      native 'JniClass_SetStaticBooleanField';
+  void setStaticByteField(int fieldId, int value)
+      native 'JniClass_SetStaticByteField';
+  void setStaticCharField(int fieldId, int value)
+      native 'JniClass_SetStaticCharField';
+  void setStaticShortField(int fieldId, int value)
+      native 'JniClass_SetStaticShortField';
+  void setStaticIntField(int fieldId, int value)
+      native 'JniClass_SetStaticIntField';
+  void setStaticLongField(int fieldId, int value)
+      native 'JniClass_SetStaticLongField';
+  void setStaticFloatField(int fieldId, double value)
+      native 'JniClass_SetStaticFloatField';
+  void setStaticDoubleField(int fieldId, double value)
+      native 'JniClass_SetStaticDoubleField';
+
+  JniObject callStaticObjectMethod(int methodId, List args)
+      native 'JniClass_CallStaticObjectMethod';
+  bool callStaticBooleanMethod(int methodId, List args)
+      native 'JniClass_CallStaticBooleanMethod';
+  int callStaticByteMethod(int methodId, List args)
+      native 'JniClass_CallStaticByteMethod';
+  int callStaticCharMethod(int methodId, List args)
+      native 'JniClass_CallStaticCharMethod';
+  int callStaticShortMethod(int methodId, List args)
+      native 'JniClass_CallStaticShortMethod';
+  int callStaticIntMethod(int methodId, List args)
+      native 'JniClass_CallStaticIntMethod';
+  int callStaticLongMethod(int methodId, List args)
+      native 'JniClass_CallStaticLongMethod';
+  double callStaticFloatMethod(int methodId, List args)
+      native 'JniClass_CallStaticFloatMethod';
+  double callStaticDoubleMethod(int methodId, List args)
+      native 'JniClass_CallStaticDoubleMethod';
+  void callStaticVoidMethod(int methodId, List args)
+      native 'JniClass_CallStaticVoidMethod';
+}
+
+/// Wrapper for a Java string.
+class JniString extends JniObject {
+  static JniString create(String value)
+      native 'JniString_Create';
+
+  // Retrieve the value as a Dart string.
+  String get text native 'JniString_GetText';
+
+  static String unwrap(JniObject object) => (object as JniString).text;
+}
+
+/// Wrapper for a Java array.
+class JniArray extends JniObject {
+  int get length native 'JniArray_GetLength';
+
+  void set length(int value) { throw new UnsupportedError("Not supported."); }
+}
+
+class JniObjectArray extends JniArray with ListMixin<JniObject> {
+  static JniObjectArray create(JniClass clazz, int length)
+      native 'JniObjectArray_Create';
+
+  JniObject operator [](int index)
+      native 'JniObjectArray_GetArrayElement';
+
+  void operator []=(int index, JniObject value)
+      native 'JniObjectArray_SetArrayElement';
+}
+
+class JniBooleanArray extends JniArray with ListMixin<bool> {
+  static JniBooleanArray create(int length)
+      native 'JniBooleanArray_Create';
+
+  bool operator [](int index)
+      native 'JniBooleanArray_GetArrayElement';
+
+  void operator []=(int index, bool value)
+      native 'JniBooleanArray_SetArrayElement';
+}
+
+class JniByteArray extends JniArray with ListMixin<int> {
+  static JniByteArray create(int length)
+      native 'JniByteArray_Create';
+
+  int operator [](int index)
+      native 'JniByteArray_GetArrayElement';
+
+  void operator []=(int index, int value)
+      native 'JniByteArray_SetArrayElement';
+}
+
+class JniCharArray extends JniArray with ListMixin<int> {
+  static JniCharArray create(int length)
+      native 'JniCharArray_Create';
+
+  int operator [](int index)
+      native 'JniCharArray_GetArrayElement';
+
+  void operator []=(int index, int value)
+      native 'JniCharArray_SetArrayElement';
+}
+
+class JniShortArray extends JniArray with ListMixin<int> {
+  static JniShortArray create(int length)
+      native 'JniShortArray_Create';
+
+  int operator [](int index)
+      native 'JniShortArray_GetArrayElement';
+
+  void operator []=(int index, int value)
+      native 'JniShortArray_SetArrayElement';
+}
+
+class JniIntArray extends JniArray with ListMixin<int> {
+  static JniIntArray create(int length)
+      native 'JniIntArray_Create';
+
+  int operator [](int index)
+      native 'JniIntArray_GetArrayElement';
+
+  void operator []=(int index, int value)
+      native 'JniIntArray_SetArrayElement';
+}
+
+class JniLongArray extends JniArray with ListMixin<int> {
+  static JniLongArray create(int length)
+      native 'JniLongArray_Create';
+
+  int operator [](int index)
+      native 'JniLongArray_GetArrayElement';
+
+  void operator []=(int index, int value)
+      native 'JniLongArray_SetArrayElement';
+}
+
+class JniFloatArray extends JniArray with ListMixin<double> {
+  static JniFloatArray create(int length)
+      native 'JniFloatArray_Create';
+
+  double operator [](int index)
+      native 'JniFloatArray_GetArrayElement';
+
+  void operator []=(int index, double value)
+      native 'JniFloatArray_SetArrayElement';
+}
+
+class JniDoubleArray extends JniArray with ListMixin<double> {
+  static JniDoubleArray create(int length)
+      native 'JniDoubleArray_Create';
+
+  double operator [](int index)
+      native 'JniDoubleArray_GetArrayElement';
+
+  void operator []=(int index, double value)
+      native 'JniDoubleArray_SetArrayElement';
+}
+
+/// Used to pass arguments of type "float" to Java methods.
+class JniFloat {
+  final double value;
+  JniFloat(this.value);
+}