[英]Handling C++ exceptions in Java via SWIG
I'm attempting to use SWIG to wrap a C++ class into a Java class. 我正在尝试使用SWIG将C ++类包装到Java类中。 This C++ class has a method that throws an exception.
这个C ++类有一个抛出异常的方法。
I have three goals, none of which are currently happening although I have followed the manual as I understand it: 我有三个目标,虽然我按照我的理解遵循了手册,但目前都没有这个目标:
throws <exceptiontype>
on the method that throws in C++ throws <exceptiontype>
java.lang.Exception
java.lang.Exception
Exception.getMessage()
in the generated SWIG class. Exception.getMessage()
。 It seems that the root of the problem seems that my typemap
s are not being applied, as none of the above happens. 似乎问题的根源似乎没有应用我的
typemap
,因为上述情况都不会发生。 What have I done wrong? 我做错了什么?
Minimal example is below. 最小的例子如下。 The C++ does not have to compile, I'm only interested in the generated Java.
C ++不需要编译,我只对生成的Java感兴趣。 The class of the exception is irrelevant, and the code below uses IOException just because the documentation uses it.
异常的类是无关紧要的,下面的代码使用IOException只是因为文档使用它。 All code is adapted from examples here:
所有代码都是根据以下示例改编的:
C++ header file (test.h): C ++头文件(test.h):
#include <string>
class CustomException {
private:
std::string message;
public:
CustomException(const std::string& message) : message(msg) {}
~CustomException() {}
std::string what() {
return message;
}
};
class Test {
public:
Test() {}
~Test() {}
void something() throw(CustomException) {};
};
SWIG .i file: SWIG .i文件:
%module TestModule
%{
#include "test.h"
%}
%include "std_string.i" // for std::string typemaps
%include "test.h"
// Allow C++ exceptions to be handled in Java
%typemap(throws, throws="java.io.IOException") CustomException {
jclass excep = jenv->FindClass("java/io/IOException");
if (excep)
jenv->ThrowNew(excep, $1.what());
return $null;
}
// Force the CustomException Java class to extend java.lang.Exception
%typemap(javabase) CustomException "java.lang.Exception";
// Override getMessage()
%typemap(javacode) CustomException %{
public String getMessage() {
return what();
}
%}
When running this with swig -c++ -verbose -java test.i
with SWIG 2.0.4, the exception class does not extend java.lang.Exception
and none of the Java methods have a throws
declaration. 当使用
swig -c++ -verbose -java test.i
和SWIG 2.0.4运行它时,异常类不会扩展java.lang.Exception
并且没有任何Java方法具有throws
声明。
You're going to kick yourself when you see this. 当你看到这个时,你会踢自己。 A fixed version of your SWIG interface is:
SWIG界面的固定版本是:
%module TestModule
%{
#include "test.h"
%}
%include "std_string.i" // for std::string typemaps
// Allow C++ exceptions to be handled in Java
%typemap(throws, throws="java.io.IOException") CustomException {
jclass excep = jenv->FindClass("java/io/IOException");
if (excep)
jenv->ThrowNew(excep, $1.what());
return $null;
}
// Force the CustomException Java class to extend java.lang.Exception
%typemap(javabase) CustomException "java.lang.Exception";
// Override getMessage()
%typemap(javacode) CustomException %{
public String getMessage() {
return what();
}
%}
%include "test.h"
Ie %include "test.h"
comes after the typemaps you wish to apply to the classes in test.h, not before. 即
%include "test.h"
在您希望应用于test.h中的类的类型映射之后,而不是之前。 The typemaps need to have been seen by SWIG at the time the classes they apply to are first seen. SWIG在他们申请的课程首次出现时需要看到这些类型地图。
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