JNI学习一(最简单的java调 用本地c代码 )

public class HelloJni extends Activity
{
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

TextView  tv = new TextView(this);
//调用c 代码
tv.setText( stringFromJNI() );
setContentView(tv);
}
//c本地方法
public native String  stringFromJNI();

//加载c库
static {
System.loadLibrary("hello-jni");
}
}

# Copyright (C) 2009 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.
#
LOCAL_PATH := $(call my-dir)
#清理所在变量，除classpath外，每个模块都是以include $(CLEAR_VARS)开始，以include $(BUILD_SHARED_LIBRARY)结束
include $(CLEAR_VARS)
#生成的库名hello-jni
LOCAL_MODULE    := hello-jni
#源文件
LOCAL_SRC_FILES := hello-jni.c
#生成动态共享库
include $(BUILD_SHARED_LIBRARY)

#include <string.h>
//导进jni头文件
#include <jni.h>
//返回java字符串
jstring
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
                                                  jobject thiz )
{
<span style="white-space:pre">	</span>//*env 上下文环境变量，具体怎么用，下一篇介绍
<span style="white-space:pre">	</span>//thiz 调用当前方法的对象
<span style="white-space:pre">	</span>/**
<span style="white-space:pre">	</span> * 创建java 字符串并返回，NewStringUTF，可以在jni.h文件JNINativeInterface 找到，表示，java c 本地方法接
<span style="white-space:pre">	</span> * 后面将会根据实际应用进行说解
<span style="white-space:pre">	</span> */
    return (*env)->NewStringUTF(env, "Hello from JNI qqq!");
}