HHH-6294 use enum instead of constant

hibernate-core/src/main/java/org/hibernate/sql/JoinType.java

@@ -0,0 +1,42 @@
+package org.hibernate.sql;
+
+import org.hibernate.HibernateException;
+
+/**
+ * @author Strong Liu
+ */
+
+public enum JoinType {
+	NONE( -666 ),
+	INNER_JOIN( 0 ),
+	LEFT_OUTER_JOIN( 1 ),
+	RIGHT_OUTER_JOIN( 2 ),
+	FULL_JOIN( 4 );
+	private int joinTypeValue;
+
+	JoinType(int joinTypeValue) {
+		this.joinTypeValue = joinTypeValue;
+	}
+
+	public int getJoinTypeValue() {
+		return joinTypeValue;
+	}
+
+	public static JoinType parse(int joinType){
+		if(joinType<0){
+			return NONE;
+		}
+		switch ( joinType ){
+			case 0:
+				return INNER_JOIN;
+			case 1:
+				return LEFT_OUTER_JOIN;
+			case 2:
+				return RIGHT_OUTER_JOIN;
+			case 4:
+				return FULL_JOIN;
+			default:
+				throw new HibernateException( "unknown join type: "+joinType );
+		}
+	}
+}