Merge branch feature/remove_sql_comments into develop

        Title: 移除sql前后的注释，从而支持多set单query的执行 
        Link: https://code.alibaba-inc.com/odps/odps-jdbc/codereview/12205311

src/main/java/com/aliyun/odps/jdbc/utils/Utils.java

@@ -130,7 +130,8 @@ public static String parseSetting(String sql, Properties properties) {
       throw new IllegalArgumentException("Invalid query :" + sql);
     }
 
-    sql = sql.trim();
+    //移除comments
+    sql = removeComments(sql);
     if (!sql.endsWith(";")) {
       sql += ";";
     }
@@ -158,4 +159,31 @@ public static String parseSetting(String sql, Properties properties) {
       return sql.substring(index).trim();
     }
   }
+
+  private static String removeComments(String sql) {
+    String[] sqlArray = sql.trim().split(";");
+
+    StringBuilder sb = new StringBuilder();
+    for (String s : sqlArray) {
+      int index;
+      boolean isComments = false;
+      s = s.trim();
+
+      while (!StringUtils.isEmpty(s) && s.startsWith("--")) {
+        index = s.indexOf("\n");
+        if (index == -1) {
+          isComments = true;
+          break;
+        }
+        s = s.substring(index + 1).trim();
+      }
+
+      if (!isComments) {
+        sb.append(s).append(";");
+      }
+    }
+    return sb.toString();
+  }
+
+
 }

src/test/java/com/aliyun/odps/jdbc/utils/UtilsTest.java

@@ -154,4 +154,24 @@ public void testParseSetting() {
       Assert.assertTrue(properties.isEmpty());
     }
   }
+
+  @Test
+  public void testParseSettingWithComments() {
+    String comment1 = "-- I am Comment1;\n";
+    String comment2 = "-- I am Comment2\n";
+    String setting1 = "set 1= 1;\n";
+    String setting2 = "set 2=2;";
+    String query = "select 1;";
+
+    String sql = comment1 + comment2 + setting1 + comment1 + setting2 + comment2 + query;
+
+    Properties properties = new Properties();
+    String res = Utils.parseSetting(sql, properties);
+
+    Assert.assertEquals(query, res);
+    Assert.assertEquals(properties.size(), 2);
+    Assert.assertEquals(properties.getProperty("1"), "1");
+    Assert.assertEquals(properties.getProperty("2"), "2");
+  }
+
 }