06_锅炉压力案例_progressbar实现

相关的native方法可以用javah来生成一个头文件。拿着这个的MainActivity,用它来生成一个头文件。

Signature是当前这个方法的方法签名。() V全空参数返回的是void.

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_itheima_pressurediagram_MainActivity */

#ifndef _Included_com_itheima_pressurediagram_MainActivity
#define _Included_com_itheima_pressurediagram_MainActivity
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_itheima_pressurediagram_MainActivity
 * Method:    startMonitor
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_itheima_pressurediagram_MainActivity_startMonitor
  (JNIEnv *, jobject);

/*
 * Class:     com_itheima_pressurediagram_MainActivity
 * Method:    stopMonitor
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_itheima_pressurediagram_MainActivity_stopMonitor
  (JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

用插件指定一下我的include目录在什么位置上。

[2017-07-16 14:31:20 - Unable to launch cygpath. Is Cygwin on the path?] java.io.IOException: Cannot run program "cygpath": CreateProcess error=2, ϵͳÕҲ»µ½ָ¶

接下来clean一下就好了

**** Clean-only build of configuration Default for project JNIDay03_02_锅炉压力 ****

H:NDKandroid-ndk-r9d-windows-x86_64android-ndk-r9d
dk-build.cmd clean 
Android NDK: WARNING: APP_PLATFORM android-18 is larger than android:minSdkVersion 8 in ./AndroidManifest.xml    
[armeabi] Clean          : pressure [armeabi]
[armeabi] Clean          : stdc++ [armeabi]

**** Build Finished ****

一些问题与解决方法：

问题一：Android NDK: WARNING: APP_PLATFORM android-14 is larger than android:minSdkVersion 8 in ./AndroidManifest.xml （这个是NDK工具的一个BUG，若build Target大于minSdkVersion，则会报这个错误，导致无法运行）
解决方法：
android-ndk-r8e/build/core/add-application.mk第128行把__ndk_warning改为__ndk_info；然后重新build一次项目即可消除错误。
原文：
this problem may be safely fixed by changing this line in add-application.mk from __ndk_warning to __ndk_info
链接：
https://code.google.com/p/android/issues/detail?id=39752

APP_PLATFORM := android-8

**** Build of configuration Default for project JNIDay03_02_锅炉压力 ****

H:NDKandroid-ndk-r9d-windows-x86_64android-ndk-r9d
dk-build.cmd all 
[armeabi] Install        : libpressure.so => libs/armeabi/libpressure.so

**** Build Finished ****

**** Clean-only build of configuration Default for project JNIDay03_02_锅炉压力 ****

H:NDKandroid-ndk-r9d-windows-x86_64android-ndk-r9d
dk-build.cmd clean 
[armeabi] Clean          : pressure [armeabi]
[armeabi] Clean          : stdc++ [armeabi]

**** Build Finished ****