add method OracleUtils.isBultinFunction

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

@@ -19,6 +19,8 @@ import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.util.HashSet;
+import java.util.Set;
 
 import javax.sql.XAConnection;
 import javax.transaction.xa.XAException;
@@ -161,4 +163,24 @@ public class OracleUtils {
         OracleResultSet oracleResultSet = rs.unwrap(OracleResultSet.class);
         return oracleResultSet.getROWID(columnIndex);
     }
+
+    private static Set<String> builtinFunctions;
+
+    public static boolean isBuiltinFunction(String function) {
+        if (function == null) {
+            return false;
+        }
+
+        String function_lower = function.toLowerCase();
+
+        Set<String> functions = builtinFunctions;
+
+        if (functions == null) {
+            functions = new HashSet<String>();
+            Utils.loadFromFile("META-INF/druid/parser/oracle/builtin_functions", functions);
+            builtinFunctions = functions;
+        }
+
+        return functions.contains(function_lower);
+    }
 }

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

@@ -15,21 +15,14 @@
  */
 package com.alibaba.druid.util;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.io.OutputStream;
-import java.io.PrintWriter;
-import java.io.Reader;
-import java.io.StringWriter;
-import java.io.UnsupportedEncodingException;
+import java.io.*;
 import java.lang.management.ManagementFactory;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.Properties;
+import java.util.Set;
 
 import javax.servlet.GenericServlet;
 
@@ -447,4 +440,31 @@ public class Utils {
 
         return hash;
     }
+
+    public static void loadFromFile(String path, Set<String> set) {
+        InputStream is = null;
+        BufferedReader reader = null;
+        try {
+            is = Thread.currentThread().getContextClassLoader().getResourceAsStream(path);
+            reader = new BufferedReader(new InputStreamReader(is));
+            for (; ; ) {
+                String line = reader.readLine();
+                if (line == null) {
+                    break;
+                }
+
+                line = line.trim().toLowerCase();
+
+                if (line.length() == 0) {
+                    continue;
+                }
+                set.add(line);
+            }
+        } catch (Exception ex) {
+            // skip
+        } finally {
+            JdbcUtils.close(is);
+            JdbcUtils.close(reader);
+        }
+    }
 }