【移动应用开发技术】Android Studio下Java Jni技术

【移动应用开发技术】AndroidStudio下JavaJni技术

最近开发Android的过程中需要通过C来调用Android终端中的某些API，而我是用JAVA语言来开发的Android程序，所以就需要用到JNI调用。

流程是，用C来调用Android硬件接口，约定JAVA调用C的接口，然后把这些代码封装编译成.so文件。然后就是怎么引入与调用了。1、将.so文件加入到libs目录下，.so文件命名规范为lib*，lib后加上名字。2、加入jniLibs路径配置，在build.gradle中加入如下配置：android

{

……

sourceSets

{

main

{

jniLibs.srcDirs

=

['libs']

}

}

}3、JAVA调用public

class

UspJni

{

private

final

static

String

TAG

=

"USPJNI";

static

{

try{

System.loadLibrary("uspjni");//加载libuspjni.so

Log.d(TAG,

"libuspjni.so

load");

}catch(Exception

e){

System.err.println("Native

code

library

failed

to

load.\n"+e);

}

}

public

static

UspJni

getInstance()

{

if

(jni

==

null)

{

jni

=

new

UspJni();

}

return

jni;

}

public

int

uartOpen(String

path,

int

flags)

{

Log.d(TAG,

"(uartOpen)path="

+

path

+

",flags="

+

String.valueOf(flags));

uartFd

=

this.open(path,

flags);

if

(uartFd

<

0)

{

Log.d(TAG,

"(uartOpen)failed"

+

",uartFd="

+

String.valueOf(uartFd));

}

return

uartFd;

}

public

int

uartClose()

{

Log.d(TAG,

"(uartClose)");

int

status

=

this.close(uartFd);

uartFd

=

-1;

if

(status

!=

0)

{

Log.d(TAG,

"(uartClose)failed,status="

+

String.valueOf(status)

+

",uartFd="

+

uartFd);

}

return

status;

}

public

byte[]

uartRead(int

timeout)

{

Log.d(TAG,

"(uartRead)timeout="

+

timeout);

byte[]

buff

=

this.read(uartFd,timeout);

if

(buff==null)

{

return

new

byte[0];

}

Log.d(TAG,

"(uartRead)len="

+

buff.length);

return

buff;

}

public

int

uartFlush()

{

Log.d(TAG,

"(uartFlush)");

byte[]

data;

do

{

data

=

UspJni.getInstance().uartRead(50);//调用

}while(data.length>0);

return

0;

}

public

native

int

gpioSetStatus(int

ioId,

int

status);

public

native

int

gpioGetStatus(int

ioId);

private

native

int

open(String

path,

int

flags);

private

native

int

close(int

fd);

private

native

byte[]

read(int

fd,int

timeout);

private

native