首页 > 代码库 > Android NDK初步涉猎
Android NDK初步涉猎
大致分是这几步:
(1)新建Android工程:
HelloJni.java代码
package com.panpass.main; public class HelloJni { static{ System.loadLibrary("demo-jni"); } public void sayHello(){} public native String jniSay(); }
MainActivity.java代码
package com.panpass.main; import android.app.Activity; import android.os.Bundle; import android.widget.TextView; import com.example.demo.R; public class MainActivity extends Activity { private TextView mTextView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main_activity); mTextView = (TextView) findViewById(R.id.text_view); HelloJni demojin = new HelloJni(); mTextView.setText(demojin.jniSay()); } }(2)生成头文件。
在cmd中进入相应的目录下:
例如我的工程在这里:
最终是进入到这里:
也就是打开cmd后输入命令:
cd C:\android\workone\Demo\bin\classes
接着输入:javah -jni com.panpass.main.HelloJni
就会生成.h文件。
(3)新建jni文件。
demo-jni.c就是c层函数的具体实现。如下:
/* * 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. * */ #include <string.h> #include <jni.h> /* This is a trivial JNI example where we use a native method * to return a new VM String. See the corresponding Java source * file located at: * * apps/samples/hello-jni/project/src/com/example/hellojni/HelloJni.java */ jstring Java_com_panpass_main_HelloJni_jniSay( JNIEnv* env, jobject thiz) { return (*env)->NewStringUTF(env, "hello jni"); }
其中的
Java_com_panpass_main_HelloJni_jniSay( JNIEnv* env, jobject thiz)就是从生成的.h文件中来的。看生成的.h文件:
/* DO NOT EDIT THIS FILE - it is machine generated */ #include <jni.h> /* Header for class com_panpass_main_HelloJni */ #ifndef _Included_com_panpass_main_HelloJni #define _Included_com_panpass_main_HelloJni #ifdef __cplusplus extern "C" { #endif /* * Class: com_panpass_main_HelloJni * Method: haveReturnFromJni * Signature: (Ljava/lang/String;)Ljava/lang/String; */ JNIEXPORT jstring JNICALL Java_com_panpass_main_HelloJni_haveReturnFromJni (JNIEnv *, jobject, jstring); /* * Class: com_panpass_main_HelloJni * Method: jniSay * Signature: ()Ljava/lang/String; */ JNIEXPORT jstring JNICALL Java_com_panpass_main_HelloJni_jniSay (JNIEnv *, jobject); #ifdef __cplusplus } #endif #endif
Android.mk代码如下:
# 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) include $(CLEAR_VARS) LOCAL_MODULE := demo-jni LOCAL_SRC_FILES := demo-jni.c include $(BUILD_SHARED_LIBRARY)具体意思可以baidu。
(4)下载ndk使用ndk生成.so库。
ndk下载去百度。
配置ndk环境变量:
其中NDK:
在cmd中进入工程根目录:
接着执行:
ndk-build
刷新工程你就会发现:
多了libs和obj
最后运行,OK。
Android NDK初步涉猎
声明:以上内容来自用户投稿及互联网公开渠道收集整理发布,本网站不拥有所有权,未作人工编辑处理,也不承担相关法律责任,若内容有误或涉及侵权可进行投诉: 投诉/举报 工作人员会在5个工作日内联系你,一经查实,本站将立刻删除涉嫌侵权内容。