getInt getLong getFloat getDouble 互相之间自动转换类型，添加 getShort 方法

src/main/java/com/jfinal/plugin/activerecord/Record.java

@@ -215,14 +215,16 @@ public class Record implements Serializable {
 	 * Get column of mysql type: int, integer, tinyint(n) n > 1, smallint, mediumint
 	 */
 	public Integer getInt(String column) {
-		return (Integer)getColumns().get(column);
+		Number n = getNumber(column);
+		return n != null ? n.intValue() : null;
 	}
 	
 	/**
 	 * Get column of mysql type: bigint
 	 */
 	public Long getLong(String column) {
-		return (Long)getColumns().get(column);
+		Number n = getNumber(column);
+		return n != null ? n.longValue() : null;
 	}
 	
 	/**
@@ -257,14 +259,21 @@ public class Record implements Serializable {
 	 * Get column of mysql type: real, double
 	 */
 	public Double getDouble(String column) {
-		return (Double)getColumns().get(column);
+		Number n = getNumber(column);
+		return n != null ? n.doubleValue() : null;
 	}
 	
 	/**
 	 * Get column of mysql type: float
 	 */
 	public Float getFloat(String column) {
-		return (Float)getColumns().get(column);
+		Number n = getNumber(column);
+		return n != null ? n.floatValue() : null;
+	}
+	
+	public Short getShort(String column) {
+		Number n = getNumber(column);
+		return n != null ? n.shortValue() : null;
 	}
 	
 	/**