Qt安卓JNI交互之(2) C++调用JAVA对象的动态方法(1)

数据类型签名对照表:

jobject
Ljava/lang/Object;

jclass
Ljava/lang/Class;

jstring
Ljava/lang/String;

jthrowable
Ljava/lang/Throwable;

jobjectArray
[Ljava/lang/Object;

jarray
[<type>

jbooleanArray
[Z

jbyteArray
[B

jcharArray
[C
jshortArray
[S

jintArray
[I

jlongArray
[J

jfloatArray
[F

jdoubleArray
[D

Primitive Types

jboolean
Z

jbyte
B

jchar
C

jshort
S

jint
I
jlong
J

jfloat
F

jdouble
D

void
V
Custom type
L<fully-qualified-name>;

JAVA中的String
String是一个类,在JAVA中非常常用,和C++交互也很常用.QT封装了他,只需要调用:
QAndroidJniObject::fromString("字符串");

返回一个String对象,使用的时候JNI识别jstring,需要强制转换:
对象.object<jstring>());  转换成jstring

QtAndroid::androidActivity()
QtAndroid::androidActivity() 返回当前安卓层的Activity对象。

调用动态对象的动态方法:
对象.callMethod<返回值类型>("方法名","参数类型签名",参数)

//JAVA层
public class QtActivity extends Activity
{
....
...
..
void  QMessage(String s)
{
Toast  toast =  Toast.makeText(this, s, 500);
toast.show();

}

}

//C++调用
void MyJni::QMessage(QString s)
{

QtAndroid::runOnAndroidThread([=](){

QAndroidJniEnvironment   EV;
QAndroidJniObject activity =QtAndroid::androidActivity();
QAndroidJniObject str =QAndroidJniObject::fromString(s);
activity.callMethod<void>("QMessage","(Ljava/lang/String;)V",str.object<jstring>());
qDebug()<<"WAIT*****END";

});

}

c++:
void MyJni::QMessage(QString s)
{
QtAndroid::runOnAndroidThread([=](){
QAndroidJniEnvironment   EV;
QAndroidJniObject str =QAndroidJniObject::fromString(s);
QAndroidJniObject selfobj = QAndroidJniObject::callStaticObjectMethod<jobject>("org/qtproject/qt5/android/bindings/QtActivity", "getobj");
selfobj.callMethod<void>("QMessage","(Ljava/lang/String;)V",str.object<jstring>());

});

}
JAVA:
public static QtActivity selfObj =null;
public QtActivity()
{
selfObj = this;
m_loader = new QtActivityLoader(this);
if (Build.VERSION.SDK_INT >= 21) {
QT_ANDROID_THEMES = new String[] {"Theme_Holo_Light"};
QT_ANDROID_DEFAULT_THEME = "Theme_Holo_Light";
} else {
QT_ANDROID_THEMES = new String[] {"Theme_DeviceDefault_Light"};
QT_ANDROID_DEFAULT_THEME = "Theme_DeviceDefault_Light";
}
}
public  static  Object getobj(){
return selfObj;
}