【框架篇】Mybatis的内置方法，撸代码更快捷~~weixin42777004的博客-

掌握内置方法，在撸代码的过程中就可以让我们的代码更加简洁优雅，提高我们的开发效率，以下是我在日常开发中常用的方法，希望能帮助到大家，话不多说，直接上Demo~~~

一、insert —————- 新增

People people= new People(); people.setId("001"); people.setAge("18"); people.setName("xianYu"); peopleDAO.insert (people); 

相当于：insert into people(id, age, name) values (‘001’, ‘18’, ‘xianYu’);

二、updateByPrimaryKey —————- 根据主键ID更新

People people= new People(); people.setId("001"); people.setAge("20"); people.setName("chouXianYu"); peopleDAO.updateByPrimaryKey(people); 

相当于update people set age = ‘20’, name = ‘chouXianYu’ where id = ‘001’

三、selectByPrimaryKey —————- 根据主键ID查询

People people = new People(); people = peopleDAO.selectByPrimaryKey("001"); 

相当于select * form people where id = ‘001’；

四、selectByExample —————- 根据条件查询返回列表

Example exampl = new Example (People.class); Criteria = criteria = exampl .createCriteria(); criteria.andNameEqualTo("xianYu"); criteria.andAgeIsNull(); exampl.setOrderByClause("name asc, age desc"); List<People> people = peopleDAO.selectByExample(exampl); 

相当于：select * from people where name = ‘xianYu’ and age is null order by name asc,age desc;

当然在日常撸代码的时候我还是喜欢下面这种写法，各位看官也可以比较比较：

Example exampl = new Example (People.class); Criteria = criteria = exampl .createCriteria(); criteria.andEqualTo("name","xianYu").andEqualTo("age","18"); List<People> people = peopleDAO.selectByExample(exampl); 

相当于：select * from people where name = ‘xianYu’ and age = ‘18’;

Note：在iBator 生成的文件Example.java中包含一个static 的内部类 Criteria ，在Criteria中有很多方法，主要是定义SQL 语句where后的查询条件。

五、selectOne —————- 根据条件查询返回对象

 People people = new People();  people.setName("xianYu");  people.setAge("18");  people = peopleDAO.selectOne(people); 

相当于：select * from people where name = ‘xianYu’ and age = ‘18’;

Note： selectOne方法在使用的时候一定要对查询出的对象做盼空

六、countByExample —————->根据条件数量

Example exampl = new Example (People.class); Criteria = criteria = exampl .createCriteria(); criteria.andNameEqualTo("xianYu"); int count = peopleDAO.countByExample(exampl); 

相当于：select count(*) from people where name = ‘xianYu’;