jstring 和char 之间的转换方法

//jstring to char*

char* jstringTostring(JNIEnv* env, jstring jstr) 
{ 
char* rtn = NULL; 
jclass clsstring = env->FindClass("java/lang/String"); 
jstring strencode = env->NewStringUTF("utf-8"); 
jmethodID mid = env->GetMethodID(clsstring, "getBytes", "(Ljava/lang/String;)[B"); 
jbyteArray barr= (jbyteArray)env->CallObjectMethod(jstr, mid, strencode); 
jsize alen = env->GetArrayLength(barr); 
jbyte* ba = env->GetByteArrayElements(barr, JNI_FALSE); 
if (alen > 0) 
{ 
rtn = (char*)malloc(alen + 1); 
memcpy(rtn, ba, alen); 
rtn[alen] = 0; 
} 
env->ReleaseByteArrayElements(barr, ba, 0); 
return rtn; 
} 

//char* to jstring

jstring CStr2Jstring( JNIEnv* env, const char* pat )
{
     //定义java String类 strClass
     jclass strClass = (env)->FindClass("Ljava/lang/String;");
     //获取java String类方法String(byte[],String)的构造器,用于将本地byte[]数组转换为一个新String
    jmethodID ctorID = (env)->GetMethodID(strClass, "<init>", "([BLjava/lang/String;)V");
    //建立byte数组
    jbyteArray bytes = (env)->NewByteArray((jsize)strlen(pat));
    //将char* 转换为byte数组
    (env)->SetByteArrayRegion(bytes, 0, (jsize)strlen(pat), (jbyte*)pat);
    //设置String, 保存语言类型,用于byte数组转换至String时的参数
    jstring encoding = (env)->NewStringUTF("utf-8"); 
    //将byte数组转换为java String,并输出
    return (jstring)(env)->NewObject(strClass, ctorID, bytes, encoding);
}

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