/// <summary>
/// Create the Java VM and wrap it.
/// </summary>
/// <param name="jvmDllPath">(Optional) Path to jvm.dll where we'll load the JNI library. If not provided we'll try to infer its location from the Java install path.</param>
/// <param name="attemptVmReuse">
/// This is an annoying workaround to a fundamental JNI problem: you can't host a JVM within the process again once you've hosted it once
/// (ever, even if you destroy the first one). So if this flag is <c>true</c>, we'll attempt to find an existing JVM in the process and use that
/// if available, and we won't destroy the JVM on dispose so subsequent constructions of this object will succeed.
/// The downside of reuse of course is that if we're reusing it then we won't be able to construct it with fresh arguments.
/// </param>
internal JniWrapper(string jvmDllPath, bool attemptVmReuse, IEnumerable <JavaOption> options)
{
_currentThreadEnv = new ThreadLocal <IntPtr>(() =>
{
IntPtr ret;
unsafe
{
if (_vm.GetDelegate <GetEnv>()(_vmP, (IntPtr)(&ret), _jniVersion) == -2)
{
_vm.GetDelegate <AttachCurrentThread>()(_vmP, (IntPtr)(&ret), IntPtr.Zero);
}
return(ret);
}
});
if (String.IsNullOrEmpty(jvmDllPath))
{
string javaHome = GetJavaInstallationPath();
_vmDll = Path.Combine(javaHome, "bin", "server", "jvm.dll");
}
else
{
_vmDll = jvmDllPath;
}
if (!File.Exists(_vmDll))
{
throw new InvalidOperationException("Couldn't find the runtime library for Java at: " + _vmDll);
}
IntPtr envP;
IntPtr vmP;
_vmDllModule = LoadLibrary(_vmDll);
if (_vmDllModule == IntPtr.Zero)
{
throw new Win32Exception();
}
if (attemptVmReuse)
{
_vmReuse = true;
int numVms;
unsafe
{
ThrowOnBadResult(GetDelegateFromJni <GetCreatedJavaVMs>("JNI_GetCreatedJavaVMs")(&vmP, 1, out numVms), "GetCreatedJavaVMs");
if (numVms >= 1)
{
_vmP = vmP;
_vm = (JavaVM)Marshal.PtrToStructure(vmP, typeof(JavaVM));
ThrowOnBadResult(_vm.GetDelegate <AttachCurrentThread>()(_vmP, (IntPtr)(&envP), IntPtr.Zero), "AttachCurrentThread");
_envP = envP;
_env = (JniEnv)Marshal.PtrToStructure(envP, typeof(JniEnv));
return;
}
}
}
JavaVMInitArgs vmArgs = new JavaVMInitArgs();
GetDelegateFromJni <GetDefaultJavaVMInitArgs>("JNI_GetDefaultJavaVMInitArgs")(ref vmArgs);
vmArgs.Version = _jniVersion;
vmArgs._nOptions = options.Count();
vmArgs._options = Marshal.AllocHGlobal(vmArgs._nOptions * Marshal.SizeOf(typeof(JavaVMOption)));
IntPtr vmArgsP = Marshal.AllocHGlobal(Marshal.SizeOf(vmArgs));
try
{
int optionsLocation = 0;
foreach (JavaOption currentOption in options)
{
Marshal.StructureToPtr(currentOption.ActualOption, vmArgs._options + optionsLocation * Marshal.SizeOf(typeof(JavaVMOption)), false);
optionsLocation++;
}
Marshal.StructureToPtr(vmArgs, vmArgsP, false);
unsafe
{
ThrowOnBadResult(GetDelegateFromJni <CreateJavaVM>("JNI_CreateJavaVM")(&vmP, &envP, vmArgsP), "CreateJavaVM");
_vm = (JavaVM)Marshal.PtrToStructure(vmP, typeof(JavaVM));
_env = (JniEnv)Marshal.PtrToStructure(envP, typeof(JniEnv));
_envP = envP;
_vmP = vmP;
}
}
finally
{
Marshal.DestroyStructure(vmArgsP, typeof(JavaVMInitArgs));
Marshal.FreeHGlobal(vmArgsP);
Marshal.FreeHGlobal(vmArgs._options);
}
}
