1 /*
2 * Copyright 2009-2024 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.apache.ibatis.annotations;
17
18 import java.lang.annotation.Documented;
19 import java.lang.annotation.ElementType;
20 import java.lang.annotation.Retention;
21 import java.lang.annotation.RetentionPolicy;
22 import java.lang.annotation.Target;
23
24 import org.apache.ibatis.type.JdbcType;
25 import org.apache.ibatis.type.TypeHandler;
26 import org.apache.ibatis.type.UnknownTypeHandler;
27
28 /**
29 * The annotation that be grouping conditional mapping definitions.
30 * <p>
31 * <b>How to use:</b>
32 *
33 * <pre>{@code
34 * public interface UserMapper {
35 * @Select("SELECT id, name, type FROM users ORDER BY id")
36 * @TypeDiscriminator(column = "type", javaType = String.class, cases = {
37 * @Case(value = "1", type = PremiumUser.class), @Case(value = "2", type = GeneralUser.class),
38 * @Case(value = "3", type = TemporaryUser.class) })
39 * List<User> selectAll();
40 * }
41 * }</pre>
42 *
43 * @author Clinton Begin
44 */
45 @Documented
46 @Retention(RetentionPolicy.RUNTIME)
47 @Target(ElementType.METHOD)
48 public @interface TypeDiscriminator {
49
50 /**
51 * Returns the column name(column label) that hold conditional value.
52 *
53 * @return the column name(column label)
54 */
55 String column();
56
57 /**
58 * Return the java type for conditional value.
59 *
60 * @return the java type
61 */
62 Class<?> javaType() default void.class;
63
64 /**
65 * Return the jdbc type for column that hold conditional value.
66 *
67 * @return the jdbc type
68 */
69 JdbcType jdbcType() default JdbcType.UNDEFINED;
70
71 /**
72 * Returns the {@link TypeHandler} type for retrieving a column value from result set.
73 *
74 * @return the {@link TypeHandler} type
75 */
76 Class<? extends TypeHandler> typeHandler() default UnknownTypeHandler.class;
77
78 /**
79 * Returns conditional mapping definitions.
80 *
81 * @return conditional mapping definitions
82 */
83 Case[] cases();
84 }