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场景
项目搭建专栏:
https://blog.csdn/BADAO_LIUMANG_QIZHI/column/info/37194
基础搭建:
https://blog.csdn/BADAO_LIUMANG_QIZHI/article/details/89407994
条件构造器介绍使用:
https://blog.csdn/BADAO_LIUMANG_QIZHI/article/details/89482201
实现
查看Condition的源码可知其继承自Wrapper方法,所以Wrapper的方法都可以使用。
它有一个获取实例的方法
/**
* 获取实例
*/
public static Condition create() {
return new Condition();
}
编写测试方法:
/***
*条件构造器 Condition
*/
@Test
public void testConditionOrderBy() {
List<Employee> employeeList=employeeMapper.selectList(Condition.create()
.eq("gender",1)
.like("name", "霸")
.orderBy("age")
.last("desc limit 1,2")
//.orderDesc(Arrays.asList(new String[] {"age"}))
//.orderAsc(Arrays.asList(new String[] {"age"}))
);
System.out.println("*******************"+employeeList);
for (Employee employee : employeeList) {
System.out.println(employee.getAge());
}
}
源码下载
https://download.csdn/download/badao_liumang_qizhi/11142337
Condition源码
/**
* Copyright (c) 2011-2020, hubin (jobob@qq).
* <p>
* 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
* <p>
* http://www.apache/licenses/LICENSE-2.0
* <p>
* 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 EntityWrapperS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.baomidou.mybatisplus.mapper;
import com.baomidou.mybatisplus.toolkit.StringUtils;
/**
* <p>
* 条件查询构造器
* </p>
*
* @author hubin Caratacus
* @date 2016-11-7
*/
@SuppressWarnings({"rawtypes", "serial"})
public class Condition extends Wrapper {
/**
* 构建一个Empty条件构造 避免传递参数使用null
*/
public static final Wrapper EMPTY = new Wrapper() {
@Override
public String getSqlSegment() {
return null;
}
};
/**
* 获取实例
*/
public static Condition create() {
return new Condition();
}
/**
* SQL 片段
*/
@Override
public String getSqlSegment() {
if (SqlHelper.isEmptyOfWrapper(this)) {
return null;
}
/*
* 无条件
*/
String sqlWhere = sql.toString();
if (StringUtils.isEmpty(sqlWhere)) {
return null;
}
/*
* 根据当前实体判断是否需要将WHERE替换成 AND 增加实体不为空但所有属性为空的情况
*/
return isWhere != null ? (isWhere ? sqlWhere : sqlWhere.replaceFirst("WHERE", AND_OR)) : sqlWhere.replaceFirst("WHERE", AND_OR);
}
/**
* 构造一个空的Wrapper<T></>
*
* @param <T>
* @return
*/
public static <T> Wrapper<T> empty() {
return (Wrapper<T>) EMPTY;
}
/**
* 构造一个Wrapper<T></>
*
* @param <T>
* @return
*/
public static <T> EntityWrapper<T> wrapper() {
return new EntityWrapper<>();
}
}
本文标签: 条件MyBatisPluscondition
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