Android's paths and message loop implementation with JNI

base/android/jni_android.cc

+// Copyright (c) 2011 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 "base/android/jni_android.h"
+
+#include "base/android/auto_jobject.h"
+#include "base/logging.h"
+
+namespace {
+JavaVM* g_jvm = 0;
+jobject g_application_context = NULL;
+}
+
+namespace base {
+namespace android {
+
+JNIEnv* AttachCurrentThread() {
+  if (!g_jvm)

[M-A Ruel, 2011/11/11 13:09:07]

Having this function silently fail is a recipe for hard-to-find bugs.

+    return NULL;
+
+  JNIEnv* env = NULL;
+  jint ret = g_jvm->AttachCurrentThread(&env, NULL);
+  DCHECK_EQ(ret, JNI_OK);
+  return env;
+}
+
+void DetachFromVM() {
+  // Ignore the return value, if the thread is not attached, DetachCurrentThread
+  // will fail. But it is ok as the native thread may never be attached.
+  if (g_jvm)
+    g_jvm->DetachCurrentThread();
+}
+
+void InitVM(JavaVM* vm) {
+  DCHECK(!g_jvm);
+  g_jvm = vm;
+}
+
+void InitApplicationContext(jobject context) {
+  DCHECK(!g_application_context);
+  g_application_context = context;
+}
+
+jobject GetApplicationContext() {
+  DCHECK(g_application_context);
+  return g_application_context;
+}
+
+jmethodID GetMethodID(JNIEnv* env,
+                      jclass clazz,
+                      const char* const method,
+                      const char* const jni_signature) {
+  jmethodID id = env->GetMethodID(clazz, method, jni_signature);
+  DCHECK(id) << method;
+  CheckException(env);
+  return id;
+}
+
+bool CheckException(JNIEnv* env) {
+  if (env->ExceptionCheck() == JNI_FALSE)
+    return false;
+  env->ExceptionDescribe();
+  env->ExceptionClear();
+  return true;
+}
+
+}  // namespace android
+}  // namespace base