Android平台调用jni来调C函数

一,调用的Activity,注意红色文字

/*
* 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.
*/
package com.example.hellojni;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;

public class HelloJni extends Activity {
    private static final String TAG = "HelloJni";

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

        TextView tv = new TextView(this);
        tv.setText(stringFromJNI());
        setContentView(tv);
    }

    public native String stringFromJNI();

    public native String unimplementedStringFromJNI();

    static {

        try {
            System.loadLibrary("hello-jni");
        } catch (Exception e) {
            // TODO Auto-generated catch block

            Log.d(TAG, "没找到jni");
            e.printStackTrace();
        }
    }
}

二,C函数的部分写法

Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
                                                  jobject thiz )
{
    return (*env)->NewStringUTF(env, "Hello from JNI !");
   // printf("hello world\n");
}

三,将编译好的文件放到eclipse 项目libs/armeabi/libhello-jni.so文件下面,最后运行结果

jni