JNI入门笔记-编译和使用so文件
1. 声明native方法
public class CruiseApi {
public static native void init();
public static native void start();
public static native void stop();
public static native void resume();
...
}2. 命令行进入xxx\YourProject\app\src\main\java目录
3. 执行javah -jni [class],class为完整路径
如果文件内有中文注释，会出现以下错误，去掉即可
4. 然后xxx\YourProject\app\src\main\java目录下会生成一个xxx.h文件
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_woosiyuan_cruiserobot_algorithm_CruiseApi */
#ifndef _Included_com_woosiyuan_cruiserobot_algorithm_CruiseApi
#define _Included_com_woosiyuan_cruiserobot_algorithm_CruiseApi
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: init
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_init
(JNIEnv *, jclass);
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: start
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_start
(JNIEnv *, jclass);
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: stop
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_stop
(JNIEnv *, jclass);
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: resume
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_resume
(JNIEnv *, jclass);
...省略其它方法
#ifdef __cplusplus
}
#endif
#endif5. 在xxx\YourProject\app\src\main目录下新建jni文件夹
5.1. 把上一步生成的xxx.h文件放进来
5.2. 创建*.c文件,文件名可根据你的业务逻辑进行命名即可。然后把生成的.h文件里面的方法在这里进行实现，这里只是打印一下日志
#include <jni.h>
#include "com_woosiyuan_cruiserobot_algorithm_CruiseApi.h"
#include <android/log.h>
#define LOG_TAG "CruiseRobot_algorithm"
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: init
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_init
(JNIEnv *env, jclass cls){
LOGD("hello world - init");
}
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: start
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_start
(JNIEnv *env, jclass cls){
LOGD("hello world - start");
}
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: stop
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_stop
(JNIEnv *env, jclass cls){
LOGD("hello world - stop");
}
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: resume
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_resume
(JNIEnv *env, jclass cls){
LOGD("hello world - resume");
}
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: getPosition
* Signature: ()Ljava/lang/String;
*/
JNIEXPORT jstring JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_getPosition
(JNIEnv *env, jclass cls){
LOGD("hello world - getPosition");
jstring rtstr = (*env)->NewStringUTF(env, "hello world - getPosition");
return rtstr;
}
/*
* Class: com_woosiyuan_cruiserobot_algorithm_CruiseApi
* Method: detectPosition
* Signature: ()C
*/
JNIEXPORT jchar JNICALL Java_com_woosiyuan_cruiserobot_algorithm_CruiseApi_detectPosition
(JNIEnv *env, jclass cls){
LOGD("hello world - detectPosition");
return 0;
}
...5.3. 创建Android.mk文件
LOCAL_PATH: 是描述所有要编译的C文件所在的根目录，这边的赋值为$(call my-dir)，代表根目录即为Android.mk所在的目录。 include $(CLEAR_VARS): 清除之前的一些系统变量。 LOCAL_MODULE: 编译的目标对象，生成后会加上前缀
lib和后缀.so。 LOCAL_SRC_FILES: 编译的源文件,就是上一步创建的.c文件 include $(BUILD_SHARED_LIBRARY): 指明要编译成动态库
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := cruise
LOCAL_SRC_FILES := CruiseAlgorithm.c
LOCAL_LDLIBS := -llog
include $(BUILD_SHARED_LIBRARY)6. 编译生成.so文件
命令行进入xxx\YourProject\app\src\main\jni目录,执行命令ndk-build
7. 添加.so文件到项目中，调用方法进行测试
7.1. 在第一步的native方法中加载.so文件
public class CruiseApi {
static {
System.loadLibrary("cruise");
}
public static native void init();
public static native void start();
public static native void stop();
public static native void resume();
...
}7.2. 调用native方法进行测试
private void testCruise(){
CruiseApi.init();
CruiseApi.start();
CruiseApi.stop();
CruiseApi.resume();
...
}控制台输入日志，表示调用成功
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原始发表：2016.07.01 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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