Android NDK调试方式之一： adb logcat

查看程序执行过程中所打印的log信息，用于辅助调试排除代码错误。

一、采用NDK安装包下Samples/hello-jni工程做实验

1）修改jni/hello-jni.c文件

#include <android/log.h>

__android_log_print(ANDROID_LOG_INFO, "HelloJniTag", "The value is %d", 1000);

2）修改jni/Android.mk文件

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
LOCAL_LDLIBS    := -llog

include $(BUILD_SHARED_LIBRARY)

3）使用eclipse打开当前项目，运行测试，Debug As...

4）在eclipse的logcat监控窗口观察日志信息

二、NDK开发的一般步骤

1）启动eclipse创建android application工程；

2）创建activity应用类（可仿照HelloJni中HelloJni.java）；

3）在activity应用类中加入native函数声明及调用；

     public native String  stringFromJNI();

    /* This is another native method declaration that is *not*
     * implemented by ‘hello-jni‘. This is simply to show that
     * you can declare as many native methods in your Java code
     * as you want, their implementation is searched in the
     * currently loaded native libraries only the first time
     * you call them.
     *
     * Trying to call this function will result in a
     * java.lang.UnsatisfiedLinkError exception !
     */
    public native String  unimplementedStringFromJNI();

    /* this is used to load the ‘hello-jni‘ library on application
     * startup. The library has already been unpacked into
     * /data/data/com.example.hellojni/lib/libhello-jni.so at
     * installation time by the package manager.
     */
    static {
        System.loadLibrary("HelloJni1");
    }

4）在命令行模式下使用javah生成jni头文件，并创建c或c++实现文件；

javah -jni -d jni -cp bin/classes:Android-20.jar  com.example.hellojni.HelloJni

5）在jni目录下创建Android.mk、Application.mk编辑脚本

#Android.mk

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
LOCAL_LDLIBS    := -llog

include $(BUILD_SHARED_LIBRARY)

#Application.mk

APP_ABI := all

6）修改AndroidManifest.xml文件，仿照HelloJni添加工程启动的Activity配置项。

7）eclipse启动Debug As...进行调试。