JNI Android - 将 char* 转换为字节数组并将其返回给 java
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JNI Android - Converting char* to byte array and return it to java
提问by Vektor88
I initially used a function to return a char* to java as UTF-8 string, but since I kept getting errors, I wrote the following function to return a char*as a Java byte[], so that I could try to convert the array into a String in java side:
我最初使用一个函数将 char* 作为 UTF-8 字符串返回给 java，但由于我不断收到错误，我编写了以下函数以将 achar*作为 Java返回byte[]，以便我可以尝试将数组转换为 String java端：
jbyteArray Java_com_vektor_amapper_util_InputDeviceManager_getDevNameBytes(JNIEnv* env, jobject thiz, jint index) {
if(pDevs[index].device_name == NULL) return NULL;
int n=0;
while(pDevs[index].device_name){
n++;
} if (n==0) return NULL;
jbyteArray arr = (*env)->NewByteArray(env, n);
(*env)->SetByteArrayRegion(env,arr,0,n, (jbyte*)pDevs[index].device_name);
return arr;
}
But when I call it my application crashes. Am I missing something?
但是当我调用它时，我的应用程序崩溃了。我错过了什么吗？
Update:The condition was missing a ++ and this caused an infinite loop. But now with the following code:
更新：条件缺少 ++，这导致了无限循环。但是现在使用以下代码：
jbyteArray Java_com_vektor_amapper_util_InputDeviceManager_getDevNameBytes(JNIEnv* env, jobject thiz, jint index) {
int n=0;
if(pDevs[index].device_name == NULL) return NULL;
while(pDevs[index].device_name++){
n++;
} if(n==0) return NULL;
jbyteArray arr = (*env)->NewByteArray(env, n);
(*env)->SetByteArrayRegion(env,arr,0,n, (jbyte*)pDevs[index].device_name);
return arr;
}
I get this weird JNI warning:
我收到这个奇怪的 JNI 警告：
06-15 22:40:02.303: W/dalvikvm(7616): JNI WARNING: negative jsize (NewByteArray)
06-15 22:40:02.303：W/dalvikvm(7616)：JNI 警告：负 jsize (NewByteArray)
How can it be since I am only increasing the value of n?
怎么会因为我只是增加了 的价值n？
Update 2:the following code works:
更新 2：以下代码有效：
jbyteArray Java_com_vektor_amapper_util_InputDeviceManager_getDevNameBytes(
JNIEnv* env, jobject thiz, jint index) {
if(pDevs[index].device_name == NULL) return NULL;
int n=0;
char* p = pDevs[index].device_name;
while(*p++){
n++;
} if(n<=0) return NULL;
jbyteArray arr = (*env)->NewByteArray(env, n);
(*env)->SetByteArrayRegion(env,arr,0,n, (jbyte*)pDevs[index].device_name);
return arr;
}
采纳答案by xqterry
Shouldn't be this ?
不应该是这个吗？
char* p = pDevs[index].device_name;
while( *p++) {
...
}
