upload android base code part6

android/libnativehelper/include/nativehelper/ScopedStringChars.h

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+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SCOPED_STRING_CHARS_H_included
+#define SCOPED_STRING_CHARS_H_included
+
+#include "JNIHelp.h"
+
+// A smart pointer that provides access to a jchar* given a JNI jstring.
+// Unlike GetStringChars, we throw NullPointerException rather than abort if
+// passed a null jstring, and get will return NULL.
+// This makes the correct idiom very simple:
+//
+//   ScopedStringChars name(env, java_name);
+//   if (name.get() == NULL) {
+//     return NULL;
+//   }
+class ScopedStringChars {
+ public:
+  ScopedStringChars(JNIEnv* env, jstring s) : env_(env), string_(s), size_(0) {
+    if (s == NULL) {
+      chars_ = NULL;
+      jniThrowNullPointerException(env, NULL);
+    } else {
+      chars_ = env->GetStringChars(string_, NULL);
+      if (chars_ != NULL) {
+        size_ = env->GetStringLength(string_);
+      }
+    }
+  }
+
+  ~ScopedStringChars() {
+    if (chars_ != NULL) {
+      env_->ReleaseStringChars(string_, chars_);
+    }
+  }
+
+  const jchar* get() const {
+    return chars_;
+  }
+
+  size_t size() const {
+    return size_;
+  }
+
+  const jchar& operator[](size_t n) const {
+    return chars_[n];
+  }
+
+ private:
+  JNIEnv* const env_;
+  const jstring string_;
+  const jchar* chars_;
+  size_t size_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedStringChars);
+};
+
+#endif  // SCOPED_STRING_CHARS_H_included