在C#中調(diào)用Java包,需要使用Java的互操作性(Java Interoperability)功能。常用的方法是通過(guò)Java Native Interface(JNI)或Java Native Access(JNA)來(lái)實(shí)現(xiàn)。下面是一個(gè)使用JNI的示例:
using System;
using System.Runtime.InteropServices;
public class Program
{
// 加載Java庫(kù)
[DllImport("jvm.dll")]
private static extern int JNI_CreateJavaVM(out IntPtr jvm, out IntPtr env, IntPtr vmArgs);
static void Main(string[] args)
{
// 創(chuàng)建Java虛擬機(jī)
IntPtr jvm;
IntPtr env;
int result = JNI_CreateJavaVM(out jvm, out env, IntPtr.Zero);
if (result < 0)
{
Console.WriteLine("無(wú)法創(chuàng)建Java虛擬機(jī)");
return;
}
try
{
// 調(diào)用Java代碼
JNIEnv jniEnv = new JNIEnv(env);
JClass stdioClass = jniEnv.FindClass("java/lang/StdIO");
if (stdioClass == null)
{
Console.WriteLine("無(wú)法找到j(luò)ava.lang.StdIO類");
return;
}
// 調(diào)用StdIO的方法
JMethodID printMethod = jniEnv.GetStaticMethodID(stdioClass, "print", "(Ljava/lang/String;)V");
if (printMethod == null)
{
Console.WriteLine("無(wú)法找到print方法");
return;
}
jstring message = jniEnv.NewStringUTF("Hello from C#!");
jniEnv.CallStaticVoidMethod(stdioClass, printMethod, message);
}
finally
{
// 銷毀Java虛擬機(jī)
jniEnv.DestroyJavaVM();
}
}
}
// 輔助類來(lái)處理JNI調(diào)用
public class JNIEnv
{
private IntPtr env;
public JNIEnv(IntPtr env)
{
this.env = env;
}
public JClass FindClass(string className)
{
IntPtr classRef = CallObjectMethod("FindClass", new JString(className).Handle);
return new JClass(classRef, this);
}
public JMethodID GetStaticMethodID(JClass classRef, string methodName, string signature)
{
return new JMethodID(CallObjectMethod("GetStaticMethodID", classRef.Handle, new JString(methodName).Handle, new JString(signature).Handle), this);
}
public void CallStaticVoidMethod(JClass classRef, JMethodID methodId, jvalue[] args)
{
CallVoidMethod("CallStaticVoidMethod", classRef.Handle, methodId.Handle, args);
}
public void DestroyJavaVM()
{
CallVoidMethod("DestroyJavaVM");
}
private IntPtr CallObjectMethod(string methodName, params IntPtr[] args)
{
IntPtr methodId = GetMethodID(methodName, args);
return CallObjectMethod(methodId, args);
}
private IntPtr CallObjectMethod(IntPtr methodId, params IntPtr[] args)
{
return JNI.CallObjectMethod(env, methodId, args);
}
private void CallVoidMethod(string methodName, params IntPtr[] args)
{
IntPtr methodId = GetMethodID(methodName, args);
CallVoidMethod(methodId, args);
}
private void CallVoidMethod(IntPtr methodId, params IntPtr[] args)
{
JNI.CallVoidMethod(env, methodId, args);
}
private IntPtr GetMethodID(string methodName, IntPtr[] args)
{
return CallObjectMethod("GetMethodID", args[0], new JString(methodName).Handle, args[1]);
}
}
// Java字符串類的封裝
public class JString
{
public IntPtr Handle { get; private set; }
public JString(string value)
{
Handle = JNI.NewStringUTF(value);
}
~JString()
{
JNI.DeleteLocalRef(Handle);
}
}
// Java類的封裝
public class JClass
{
public IntPtr Handle { get; private set; }
private JNIEnv env;
public JClass(IntPtr handle, JNIEnv env)
{
Handle = handle;
this.env = env;
}
public JMethodID GetStaticMethodID(string methodName, string signature)
{
return env.GetStaticMethodID(this, methodName, signature);
}
}
// Java方法的封裝
public class JMethodID
{
public IntPtr Handle { get; private set; }
private JNIEnv env;
public JMethodID(IntPtr handle, JNIEnv env)
{
Handle = handle;
this.env = env;
}
public void CallStaticVoidMethod(params jvalue[] args)
{
env.CallStaticVoidMethod(this, args);
}
}
//