通过多个 jni 调用保持某种 c++ 对象处于活动状态
问题说明
我的 java 代码将调用现有的 c 代码来解析文件.它将生成一个保存许多数据的对象.我将调用jni的第二种方法来访问这些数据，当我调用第二种方法时，我必须再次解析文件.这显然是正确的行为.
My java code will call the exist c code to parse the file. it will generate an object which keep many data. I will call the jni's second method to access such data, When I call the second method, I have to parse the file again. it is obviously the right behavior.
有没有办法解决这个问题?顺便说一句:我是 C 新手.
Is there a way to handle this ? BTW: I am newly to c .
正确答案
我不确定我是否理解你的问题.但我猜你想要做的是让某种 c 对象在多个 jni 调用中保持活跃.
I am not sure if I understand your question correct. But I guess what you want to do is to keep some sort of c object alive over multiple jni calls.
你可以做很多事情.首先解析您的文件并将您的 c 对象存储在全局变量中.这是最简单的解决方案，但不是很好.
You can do multiple things. First parse your file and store your c object in a global variable. This is the simplest solution but not a nice one.
您还可以将 c 对象的生命周期移到 java 中.
You can also move the life cycle of your c object into java.
jlong java_some_class_jni_method(...)
{
.... parse your text file ....
MyParseclass* cls = new MyParseclass(...);
....
return (jlong) cls;
}
但请记住，您需要再次删除这个原生 c 类.所以你需要一个 jni 方法，并且一定要调用它.
But keep in mind that you need to delete this native c class again. So you need a jni method to this and be sure to call it.
void java_some_calls_jni_method(..., jlong clsPtr)
{
MyParseclass* cls = (MyParseclass*)clsPtr;
... do maybe do something with cls and access the data...
delete cls; // do not use the jlong again in any call
}
顺便说一句:如果您发布一些代码会更有帮助.但我希望这里的伪代码能有所帮助.
BTW: It would be much more helpful if you would post some code. But I hope this pseudo code here helps a little.
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