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android 调用JNI SO动态库的方法

程序员文章站 2022-06-24 10:10:20
总结一下:android 调用jni 分为静态调用与动态调用(不论动态还是静态前提都是ndk环境已经配置好的前提下)一、静态主要就是将c(.c)或者c++(cpp)的源文件直接加到项目中进行调用,然后...

总结一下:

android 调用jni 分为静态调用与动态调用(不论动态还是静态前提都是ndk环境已经配置好的前提下)

一、静态主要就是将c(.c)或者c++(cpp)的源文件直接加到项目中进行调用,

android 调用JNI SO动态库的方法

然后在cmakelists.txt中进行配置。

 二、动态调用

1、动态调用使用已经编译好的动态库.so文件

android 调用JNI SO动态库的方法

 2、android调用ndk类

android 调用JNI SO动态库的方法

生成后的so文件

public class serialport {

p
*/
public static native int getsover(string ar);

static {
system.loadlibrary("serialport");//初始化so库(注意这里添加是需要去掉lib与.so)

}
}

3、.c文件添加

/*
 * copyright 2009-2011 cedric priscal
 *
 * 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 <jni.h>
#include <termios.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include "m1900_drv.h"
#include "serialport.h"
#include "include/tinyalsa/audio_i2s.h"
#include "include/tinyalsa/asoundlib.h"
#include "android/log.h"
#include "newland_linux_so.h"
 
static const char *tag = "serial_port";
#define logi(fmt, args...) __android_log_print(android_log_info,  tag, fmt, ##args)
#define logd(fmt, args...) __android_log_print(android_log_debug, tag, fmt, ##args)
#define loge(fmt, args...) __android_log_print(android_log_error, tag, fmt, ##args)
 
//测试  java_(固定)_com_littt_util_serialport(android包名原来的.更改为_,string ar 传入的字符串参数,jnienv *env, jclass固定写法)
jniexport jint jnicall 
java_com_littt_util_serialport_getsover(jnienv *env, jclass clazz, jstring ar) {
	// todo: implement getsover()
	return 9;//返回一个9的值
}

4、.h头文件中声明

/* do not edit this file - it is machine generated */
#include <jni.h>
/* header for class android_serialport_api_serialport */
#ifndef _included_android_serialport_api_serialport
#define _included_android_serialport_api_serialport
#ifdef __cplusplus
extern "c" {
#endif
jniexport jint jnicall
java_com_littt_util_serialport_getsover(jnienv *env, jclass clazz,jstring v);
#ifdef __cplusplus
}
#endif
#endif

 5、头文件与c文件写好了,就需要在cmake 中添加.c与.h都需要添加

# for more information about using cmake with android studio, read the
# documentation: https://d.android.com/studio/projects/add-native-code.html
 
# sets the minimum version of cmake required to build the native library.
 
cmake_minimum_required(version 3.4.1)
 
# creates and names a library, sets it as either static
# or shared, and provides the relative paths to its source code.
# you can define multiple libraries, and cmake builds them for you.
# gradle automatically packages shared libraries with your apk.
 
add_library( # sets the name of the library.
        serialport
 
        # sets the library as a shared library.
        shared
 
        # provides a relative path to your source file(s).
        m1900_drv.c
        m1900_drv.h
        audio_i2s.c
       linux_so.cpp
        mixer.c
        
        include/tinyalsa/asoundlib.h
        include/tinyalsa/audio_i2s.h
        )
 
# searches for a specified prebuilt library and stores the path as a
# variable. because cmake includes system libraries in the search path by
# default, you only need to specify the name of the public ndk library
# you want to add. cmake verifies that the library exists before
# completing its build.
 
find_library( # sets the name of the path variable.
        log-lib
 
        # specifies the name of the ndk library that
        # you want cmake to locate.
        log)
 
# specifies libraries cmake should link to your target library. you
# can link multiple libraries, such as libraries you define in this
# build script, prebuilt third-party libraries, or system libraries.
 
target_link_libraries( # specifies the target library.
        serialport
 
        # links the target library to the log library
        # included in the ndk.
        ${log-lib})
 
set(cmake_c_flags_release "${cmake_c_flags_release} -s")
set(cmake_cxx_flags_release "${cmake_cxx_flags_release} -s")

6、在build.gradle同样需要配置

plugins {
    id 'com.android.application'
}
 
android {
    compilesdkversion 28
    buildtoolsversion "28.0.3"
 
    defaultconfig {
        applicationid "com.littt.interphone"
        minsdkversion 17
        targetsdkversion 28
        versioncode 1
        versionname "1.0"
 
        testinstrumentationrunner "androidx.test.runner.androidjunitrunner"
        // cmake
        externalnativebuild {
            cmake {
                cppflags ""
                abifilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
            }
        }
 
    }
    externalnativebuild {
        cmake {
            path "src/main/cpp/cmakelists.txt"
            version "3.10.2"
 
        }
    }
    buildtypes {
        release {
            minifyenabled false
            proguardfiles getdefaultproguardfile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    sourcesets {
        main {
            jnilibs.srcdirs = ['libs']
        }
    }
    compileoptions {
        sourcecompatibility javaversion.version_1_8
        targetcompatibility javaversion.version_1_8
    }
 
    ndkversion '22.1.7171670'
}
dependencies {
//    implementation 'androidx.appcompat:appcompat:1.2.0'
//    implementation 'com.google.android.material:material:1.2.1'
  
}

7、如果静态调用可以成功,那么就可以生成动态so库文件

android 调用JNI SO动态库的方法 

点击图中锤子会进行编译。完成后可以打开如下路径查看 

android 调用JNI SO动态库的方法

红框中生成后 so文件

7.1、生成的.so文件(工程文件夹模式)目录为app/build/intermediates/ndk/lib,将其复制到另一个工程的app/lib目录下。

7.2、要使用上述的.so文件 ,必须将工程的包名改为生成.so文件时的包名,要不然 编译能通过,但是app不能正常运行。logcat会提示找不到所调用函数的实现。

7.3、将so文件复制到需要的路径下。
7.4、在gradle.properties中最后加一行:android.usedeprecatedndk=true。

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