搭建使用环境（SpringBoot)Mybatis-Plus（简称MP）是一个 Mybatis 的增强工具，在 Mybatis
的基础上只做增强不做改变，避免了我们重复CRUD语句。
1.创建一个简单点的maven工程
2.在pom.xml中引入依赖
org.springframework.boot spring-boot-starter-parent 2.3.0.RELEASE 4.0.0 MybatisPlusDemo UTF-8 UTF-8 1.8 3.3.2 true org.springframework.boot spring-boot-starter com.h2database h2 runtime com.baomidou mybatis-plus-boot-starter ${mybatisplus.version} org.assertj assertj-core test org.projectlombok lombok provided org.springframework.boot spring-boot-starter-test test com.github.pagehelper pagehelper 5.1.11 org.springframework.boot spring-boot-maven-plugin
3.在资源目录下创建application.yml配置文件和目录
在application.yml中写上数据库的配置和Mybatis扫描
# DataSource Config
spring:
datasource:
driver-class-name: org.h2.Driver
schema: classpath:db/schema-h2.sql
data: classpath:db/data-h2.sql
url: jdbc:h2:mem:test
username: root
password: test
# Logger Config
logging:
level:
com.da: debug
# 配置mybatis plus
mybatis-plus:
type-aliases-package: com.da.domain #别名搜索
mapper-locations: classpath:/mapper
ASSIGN_ID(3)
排除实体类中非表字段
使用 @TableField(exist = false) 注解
@Test
public void insert(){
User user=new User();
user.setId(26L);
user.setName("我是insert");
user.setAge(23);
user.setEmail("da@163.com");
int insert = userMapper.insert(user);
if(insert>0){
System.out.println("插入成功！！！");
List users = userMapper.selectList(null);
users.forEach(user1 -> {
System.out.println(user1);
});
}else{
System.out.println("插入失败！！");
}
}
结果：
@Test
public void select(){
//查询全部
List users = userMapper.selectList(null);
users.forEach(user ->{
System.out.println(user);
});
System.out.println("===========================根据条件查询=====================");
//根据条件查询
List users1 = userMapper.selectList(new QueryWrapper().like("name", "J"));
users1.forEach(user ->{
System.out.println(user);
});
//根据条件查询一个
System.out.println("===========================根据条件查询一个=====================");
User user = userMapper.selectOne(new QueryWrapper().eq("name", "Biie"));
System.out.println(user);
//根据主键查询
System.out.println("===========================根据主键查询一个=====================");
User user1 = userMapper.selectById(2);
System.out.println(user1);
}
结果
@Test
public void update(){
User user=new User();
user.setId(5L);
user.setName("我修改后的数据");
user.setAge(230);
user.setEmail("dada@163.com");
//根据id修改
System.out.println("根据id修改");
userMapper.updateById(user);
User user1 = userMapper.selectById(5);
System.out.println(user1);
System.out.println("=======================根据条件修改方式1===============================");
userMapper.update(null, Wrappers.update().set("email","@update.com").like("name","B"));
List users = userMapper.selectList(new QueryWrapper().like("name", "B"));
users.forEach(user11 -> {
System.out.println(user11);
});
user.setName("根据条件修改方式2");
System.out.println("=======================根据条件修改方式2===============================");
userMapper.update(user, Wrappers.update().eq("id","5"));
List users1 = userMapper.selectList(new QueryWrapper().eq("id", "5"));
users1.forEach(user11 -> {
System.out.println(user11);
});
}
结果
@Test
public void delete(){
//根据Id删除
int i = userMapper.deleteById(1);
if(i>0){
System.out.println("删除成功！！！");
userMapper.selectList(null).forEach(user -> {
System.out.println(user);
});
}
//根据条件删除方式1
int delete = userMapper.delete(new QueryWrapper().like("name", "J"));
if(delete>0){
System.out.println("根据条件删除方式1删除成功");
userMapper.selectList(null).forEach(user -> {
System.out.println(user);
});
}
//根据条件删除方式2
int delete1 = userMapper.delete(Wrappers.query().like("name", "T"));
if(delete1>0){
System.out.println("根据条件删除方式2删除成功");
userMapper.selectList(null).forEach(user -> {
System.out.println(user);
});
}
}
结果
在pom.xml中引入pageHelper分页依赖
com.github.pagehelper pagehelper 5.1.11
在config包中新键分页配置类
MybatisPlusConfig
@Configuration
public class MybatisPlusConfig {
@Bean
public PaginationInterceptor paginationInterceptor() {
// 开启 count 的 join 优化,只针对 left join !!!
return new PaginationInterceptor().setCountSqlParser(new JsqlParserCountOptimize(true));
}
@Bean
public PageInterceptor pageInterceptor() {
return new PageInterceptor();
}
}
Mybatis Plus 内置分页
@Test
public void page(){
System.out.println("----baseMapper自带分页");
//第一个参数是当前页，第二参数是每页数
Pagepage=new Page<>(1,5);
IPage userPage = userMapper.selectPage(page, new QueryWrapper());
System.out.println("当前页码："+userPage.getCurrent());
System.out.println("每页数："+userPage.getSize());
System.out.println("总条数"+userPage.getTotal());
//获取分页的结果
userPage.getRecords().forEach(user ->{System.out.println(user);});
}
结果
自定义xml分页
application.yml配置文件
# 配置mybatis plus
mybatis-plus:
type-aliases-package: com.da.domain #别名搜索
mapper-locations: classpath:/mapper
public IPage selectUserByPage(@Param("p") IPage page, @Param("c") User
conditioin);
public ListselectUserByPage2(User u);
}
UserMapper.xml映射文件
select * from user2
测试
@Test
public void testPage(){
//自定义XML分页查询
Pagepage=new Page<>(1,5);
User user=new User();
user.setEmail("te");
user.setAge(331);
IPage userPage = userMapper.selectUserByPage(page, user);
System.out.println("当前页码："+userPage.getCurrent());
System.out.println("每页数："+userPage.getSize());
System.out.println("总条数"+userPage.getTotal());
//获取分页的结果
userPage.getRecords().forEach(user1 ->{System.out.println(user1);});
}
结果
开启扫描
UserMapper.xml映射文件
测试
@Test
public void pageHelper(){
//自定义XML分页查询
User user=new User();
user.setEmail("te");
user.setAge(331);
PageInfopage= PageHelper.startPage(1,5).doSelectPageInfo(
()-> userMapper.selectUserByPage2(user));
System.out.println("总行数=" + page.getTotal());
System.out.println("当前页=" + page.getPageNum());
System.out.println("每页行数=" + page.getPageSize());
System.out.println("总页数=" + page.getPages());
System.out.println("起始行数=" + page.getStartRow());
System.out.println("是第一页=" + page.isIsFirstPage());
System.out.println("是最后页=" + page.isIsLastPage());
System.out.println("还有下一页=" + page.isHasNextPage());
System.out.println("还有上一页=" + page.isHasPreviousPage());
System.out.println("页码列表" + Arrays.toString(page.getNavigatepageNums()));
page.getList().forEach(System.out::println);
}
结果
