add xa support

src/main/java/com/alibaba/druid/util/H2Utils.java

@@ -0,0 +1,52 @@
+package com.alibaba.druid.util;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
+import java.sql.Connection;
+import java.sql.SQLException;
+
+import javax.sql.XAConnection;
+
+import org.h2.jdbc.JdbcConnection;
+import org.h2.jdbcx.JdbcDataSourceFactory;
+import org.h2.jdbcx.JdbcXAConnection;
+import org.h2.message.TraceObject;
+
+public class H2Utils {
+
+    private static volatile Constructor<JdbcXAConnection> constructor;
+
+    private static volatile Method                        method;
+
+    public static final int                               XA_DATA_SOURCE = 13;
+
+    public static Object createJdbcDataSourceFactory() {
+        return new JdbcDataSourceFactory();
+    }
+
+    public static XAConnection createXAConnection(Object factory, Connection physicalConn) throws SQLException {
+
+        try {
+            if (constructor == null) {
+                constructor = JdbcXAConnection.class.getConstructor(JdbcDataSourceFactory.class, int.class,
+                                                                    JdbcConnection.class);
+                constructor.setAccessible(true);
+            }
+
+            int id = getNextId(XA_DATA_SOURCE);
+
+            return constructor.newInstance(factory, id, physicalConn);
+        } catch (Exception e) {
+            throw new SQLException("createXAConnection error", e);
+        }
+    }
+
+    public static int getNextId(int type) throws Exception {
+        if (method == null) {
+            method = TraceObject.class.getMethod("getNextId", int.class);
+            method.setAccessible(true);
+        }
+
+        return (Integer) method.invoke(null, type);
+    }
+}