目前的情况是
    先从java掉用C++，然后C++调用JAVA 这个过程就是回调

    1. binding.buttonTestSyncDialog.setOnClickListener{
    2.      BetwinNative.callShowSyncDialog()
    3. }

    callShowSyncDialog()这个函数在BetwinNative.kt的文件中
    这个文件中会有如下一行代码

    1. external fun callShowSyncDialog()

    external关键字，相当于java的native
    那么点进去之后发现

    在 native-lib.cpp 找到

    static const JNINativeMethod methods[] = {

    1.     {"registerOperation",              "(Ljava/lang/String;)V",                  (void *) registerOperation},<br />        {"nativeCallMethod",               "(Ljava/lang/String;)Ljava/lang/String;", (void *) nativeCallMethod},<br />        {"runQCoreApplication",            "()V",                                    (void *) runQCoreApplication},<br />        {"callShowSyncDialog",             "()V",                                    (void *) callShowSyncDialog},<br />        {"callShowSyncInputDialog",        "()V",                                    (void *) callShowSyncInputDialog},<br />        {"callToastMessage",               "()V",                                    (void *) callToastMessage},<br />        {"callChangeKeyPasswordDialog",    "()V",                                    (void *) callChangeKeyPasswordDialog},<br />        {"callChangeClientPasswordDialog", "()V",                                    (void *) callChangeClientPasswordDialog},

    };

    void callShowSyncDialog(JNIEnv *env) {
    //测试C++调用java
    jint value = callJavaMethodShowSyncDialog(env, 10, “C++标题”, “C++内容”);
    logd(“ java return value ShowSyncDialog %d “, value);
    }

    在callback.h文件中找到如下内容

    jint callJavaMethodShowSyncDialog(JNIEnv *env, int errorCode, std::string title, std::string content) {
    jclass jclazz = env->FindClass(“com/cslc/minipos/jni/nativefunc/BetWinCallback”); //找到需要回调的类
    if (jclazz == 0) {
    logd(“class not find “);
    return false;
    }

    1. jmethodID methodid = env->GetStaticMethodID(jclazz, "showSyncDialog",                       //找到需要回调的方法<br />                                                "(ILjava/lang/String;Ljava/lang/String;)I");<br />    if (methodid == 0) {  <br />        logd("helloFromJava method not find ");<br />        return false;<br />    }<br />    jint param1 = errorCode;<br />    jstring param2 = env->NewStringUTF(title.c_str());<br />    jstring param3 = env->NewStringUTF(content.c_str());<br />    return env->CallStaticIntMethod(jclazz, methodid, param1, param2, param3);<br />}

    上面这个方法 在jni.h中声明了
    jint (CallStaticIntMethod)(JNIEnv, jclass, jmethodID, …);
    jint (CallStaticIntMethodV)(JNIEnv, jclass, jmethodID, va_list);
    jint (CallStaticIntMethodA)(JNIEnv, jclass, jmethodID, const jvalue*);

    具体的回调 都可以在callJavaMethodShowSyncDialog中进行实现

    如果要写一个.h文件 那么首先要在 CMakeLists.txt 文件中的
    add_library( # Sets the name of the library.
    betwin

    1.     # Sets the library as a shared library.<br />        SHARED
    3.     # Provides a relative path to your source file(s).<br />        native-lib.cpp
    5.     entity/CommonResponse.h<br />        entity/DataTerminalLoginOutput.h<br />        entity/DataTerminalLoginOutput.cpp<br />        utils/StringUtil.h<br />        utils/StringUtil.cpp<br />        utils/logutil.h<br />        jsoncpp/json_tool.h<br />        jsoncpp/json_reader.cpp<br />        jsoncpp/json_valueiterator.inl<br />        jsoncpp/json_value.cpp<br />        jsoncpp/json_writer.cpp<br />        jsoncpp/assertions.h<br />        jsoncpp/allocator.h<br />        jsoncpp/config.h<br />        jsoncpp/json_features.h<br />        jsoncpp/forwards.h<br />        jsoncpp/json.h<br />        jsoncpp/reader.h<br />        jsoncpp/value.h<br />        jsoncpp/version.h<br />        jsoncpp/writer.h<br />        nativeImpl/terminlLogin.h<br />        nativeImpl/sellerLogin.h<br />        nativeImpl/hardwareDetection.h<br />        nativeImpl/register.h<br />        nativeImpl/callback.h<br />        nativeImpl/test.h<br />        )<br />加上这个声明才能够在你自己的.h文件中调用相应的#include <jni.h> 才能够正确的有引进这个文件