SelectProvider · mybatis源码解析

~~~ /** * Copyright 2009-2019 the original author or authors. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.ibatis.annotations; import java.lang.annotation.Documented; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * The annotation that specify a method that provide an SQL for retrieving record(s). * * * How to use: * <pre> * public interface UserMapper { * * @SelectProvider(type = SqlProvider.class, method = "selectById") * User selectById(int id); * * public static class SqlProvider { * public static String selectById() { * return "SELECT id, name FROM users WHERE id = #{id}"; * } * } * * } * </pre> * @author Clinton Begin */ @Documented @Retention(RetentionPolicy.RUNTIME) @Target(ElementType.METHOD) public @interface SelectProvider { /** * Specify a type that implements an SQL provider method. * * @return a type that implements an SQL provider method * @since 3.5.2 * @see #type() */ Class<?> value() default void.class; /** * Specify a type that implements an SQL provider method. * * This attribute is alias of {@link #value()}. * * * @return a type that implements an SQL provider method * @see #value() */ Class<?> type() default void.class; /** * Specify a method for providing an SQL. * * * Since 3.5.1, this attribute can omit. * If this attribute omit, the MyBatis will call a method that decide by following rules. * <ul> * <li> * If class that specified the {@link #type()} attribute implements the {@link org.apache.ibatis.builder.annotation.ProviderMethodResolver}, * the MyBatis use a method that returned by it * </li> * <li> * If cannot resolve a method by {@link org.apache.ibatis.builder.annotation.ProviderMethodResolver}(= not implement it or it was returned {@code null}), * the MyBatis will search and use a fallback method that named {@code provideSql} from specified type * </li> * </ul> * * @return a method name of method for providing an SQL */ String method() default ""; } ~~~