处理JNI DETECTED ERROR IN APPLICATION: GetStringUTFChars received NULL jstring的崩溃 case 要注意实际的调用栈

如题，最近fix历史的坑— JNI DETECTED ERROR IN APPLICATION: GetStringUTFChars received NULL jstring 的case
然后很自信的根据如下信息去排查代码，结果做了几个小时的无用功。

A/k.myapplicatio: java_vm_ext.cc:545] JNI DETECTED ERROR IN APPLICATION: GetStringUTFChars received NULL jstring
    java_vm_ext.cc:545]     in call to GetStringUTFChars
    java_vm_ext.cc:545]     from void com.sdk.myapplication.MainActivity.triggerGetStringUTFCharsNPE(java.lang.String, java.lang.String)

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原因上面的出现信息中， from 某个Jni的方法是指JVM调到该方法后GetStringUTFChars入参jstring为空的情况，必不是特指该方法体中调GetStringUTFChars的地方出现了NULl指针，而是包括该方法中调用其它的C/C++方法出现NULL指针的情况。所以我们去定位这类问题，还是要细仔看个崩溃堆栈，才能快速定位到是那个地方产出的NULL指针，避免无效输出

如上示例是根据自己的业务代码，抽像出来的
示例代码如下
java

public class MainActivity extends AppCompatActivity {

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Example of a call to a native method
        TextView tv = findViewById(R.id.sample_text);
        tv.setText(stringFromJNI());
        triggerGetStringUTFCharsNPE("hello", null);//故意传一个null
    }

    /**
     * A native method that is implemented by the 'native-lib' native library,
     * which is packaged with this application.
     */
    public native String stringFromJNI();


    public native void triggerGetStringUTFCharsNPE(String p1, String p2);
}
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jni

#include <jni.h>
#include <string>
#include <android/log.h>

static const char* TAG = "Demo";


void nestFunction(JNIEnv *env, jstring p2) {
    //这里p1简单通过参数传进来，但实际业务逻辑中可能是通过其它方法/方式获取到的
    const char* pStr = env->GetStringUTFChars(p2, nullptr);
    __android_log_print(ANDROID_LOG_DEBUG, TAG, "pStr:%s", pStr);
    env->ReleaseStringUTFChars(p2, pStr);
}

extern "C" JNIEXPORT jstring JNICALL
Java_com_sdk_myapplication_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject /* this */) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}extern "C"
JNIEXPORT void JNICALL
Java_com_sdk_myapplication_MainActivity_triggerGetStringUTFCharsNPE(JNIEnv *env, jobject thiz,
                                                                    jstring p1, jstring p2) {
    const char* pStr1 = env->GetStringUTFChars(p1, nullptr);
    __android_log_print(ANDROID_LOG_DEBUG, TAG, "pStr1:%s", pStr1);
    env->ReleaseStringUTFChars(p1, pStr1);
    //故意让nestFunction产生 JNI DETECTED ERROR IN APPLICATION: GetStringUTFChars received NULL jstring
    nestFunction(env, p2);
}
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