jstring与const char* 相互转换

【原创文章，转载请保留或注明出处：/article/9060337.html】

//将const char*类型转换成jstring类型

jstring CStr2Jstring(JNIEnv* env, const char* pat)

{

//定义java String类 strClass

jclass strClass = (env)->FindClass("java/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("GB2312");

//将byte数组转换为java String,并输出

return (jstring)(env)->NewObject(strClass, ctorID, bytes, encoding);

}

//将jstring类型转换成char*类型

char* Jstring2CStr(JNIEnv* env, jstring jstr)

{

char* rtn = NULL;

jclass clsstring = env->FindClass("java/lang/String");

jstring strencode = env->NewStringUTF("GB2312");

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); //new char[alen+1];

memcpy(rtn,ba,alen);

rtn[alen]=0;

}

env->ReleaseByteArrayElements(barr,ba,0);

return rtn;

}

//将jstring类型转换成string类型

std::string jstring2str(JNIEnv* env, jstring jstr)

{

char* rtn = NULL;

jclass clsstring = env->FindClass("java/lang/String");

jstring strencode = env->NewStringUTF("GB2312");

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);

std::string stemp(rtn);

free(rtn);

return stemp;

}