improve wall filter

src/main/java/com/alibaba/druid/sql/dialect/mysql/parser/MySqlLexer.java

@@ -67,6 +67,11 @@ public class MySqlLexer extends Lexer {
             throw new ParserException("illegal stat");
         }
         
+        if (charAt(pos + 1) == '{') {
+            scanVariable();
+            return;
+        }
+        
         Token lastToken = this.token;
         
         scanChar();
@@ -420,7 +425,7 @@ public class MySqlLexer extends Lexer {
             }
 
             if (isHint) {
-                stringVal = subString(mark + startHintSp, (bufPos - startHintSp) - 1);
+                stringVal = subString(mark + startHintSp, (bufPos - startHintSp) - 2);
                 token = Token.HINT;
             } else {
                 stringVal = subString(mark, bufPos);

src/test/java/com/alibaba/druid/bvt/sql/cobar/HintsTest.java

@@ -43,4 +43,13 @@ public class HintsTest extends TestCase {
         String output = SQLUtils.toMySqlString(stmt);
         Assert.assertEquals("SELECT /*! STRAIGHT_JOIN */ col1\nFROM table1, table2", output);
     }
+    
+    public void test_hints_none() throws Exception {
+        String sql = "SELECT /* STRAIGHT_JOIN */ col1 FROM table1,table2";
+        MySqlStatementParser parser = new MySqlStatementParser(sql);
+        SQLStatement stmt = parser.parseStatementList().get(0);
+        parser.match(Token.EOF);
+        String output = SQLUtils.toMySqlString(stmt);
+        Assert.assertEquals("SELECT col1\nFROM table1, table2", output);
+    }
 }