MybatisPlus,无XML分分钟实现CRUD操作-eolink官网

MybatisPlus,无XML分分钟实现CRUD操作

不讲太多理论知识，官网都有，直接上手。

1.测试表

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (

`id` bigint(20) UNSIGNED NOT NULL,

`name` varchar(128) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '用户名',

`password` varchar(18) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL COMMENT '密码',

`age` int(4) DEFAULT NULL COMMENT '年龄',

`create_time` datetime(0) DEFAULT NULL COMMENT '创建时间',

`update_time` datetime(0) DEFAULT NULL COMMENT '更新时间',

PRIMARY KEY (`id`) USING BTREE

) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

引入依赖

com.baomidou

mybatis-plus-boot-starter

3.0.5

mysql

mysql-connector-java

配置文件，这里我用的是boot项目

spring:

datasource:

username: cjx

password: cjx19950616

url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai

driver-class-name: com.mysql.cj.jdbc.Driver

mybatis-plus:

mapper-locations: classpath:/mapper/*.xml

#configuration:

#map-underscore-to-camel-case: true

其实简单的crud甚至不需要mybatis-plus的配置，我这里没删除，本文也并没有用到配置文件。

实体类

public class User{

private Long id;

private String name;

private String password;

private int age;

private Date createTime;

private Date updateTime;

...

getter && setter

...

toString()

}

分页插件

@Configuration

public class MyBtaisPlusConfig {

/**

* 分页插件

* @return

@Bean

public PaginationInterceptor paginationInterceptor() {

System.out.println("加载分页插件");

return new PaginationInterceptor();

}

编写一个我们的接口

@Component

public interface UserDao extends BaseMapper {

Integer deleteById(Long id);

}

接下来就可以愉快的测试了，在我们的测试类里先注入dao

@Autowired

private UserDao userMapper;

新增测试

/**

* 新增

@Test

void save(){

User u = new User();

u.setAge(100);

u.setName("测试数据3");

u.setPassword("cjx1111");

u.setAge(25);

int row = userMapper.insert(u);

System.out.println(row);

}

是不是很简单？只需要这样就可以完成新增了，既然有单个插入，那少不了也有批量插入

批量新增测试

/**

* 批量插入

@Test

void save(){

List us = new LinkedList();

for (int i = 0;i < 50;i++){

User u = new User();

u.setName("测试数据"+i);

u.setAge((int)(Math.random()*90+10));

u.setPassword("mima"+i);

us.add(u);

}

userService.saveBatch(us);

}

其中用到了userService，我这里贴一下代码，需要我们接口继承Iservice,实现类继承ServiceImple,这样就可以直接调用mybatis-plus为我们提供的现成方法了。

public interface IUserService extends IService {

}

实现类

@Service public class UserServiceImpl extends ServiceImplimplements IUserService {

}

修改

/**

* 修改

@Test

void updateById(){

User u = new User();

//修改name

u.setId(1L);

u.setName("修改下数据--");

u.setPassword("123");

u.setAge(99);

int row = userMapper.updateById(u);

System.out.println(row);

}

/**

* 通过id查询

@Test

void selectById(){

//1.通过id来查询

User u = userMapper.selectById(1l);

System.out.println(u);

}

mybatis-plus有个特别好用的就是它的条件构造器，可以帮助我们构造常用的sql，具体用法我会贴在文章最后面。

/**

* 通过条件构造器查询

@Test

void selectByWrapper(){

//3.通过条件构造器wrapper

QueryWrapper qw = new QueryWrapper();

qw.like("name","测试");

qw.lt("age",50);//小于

qw.gt("age",15);//大于

List us = userMapper.selectList(qw);

us.stream().forEach(System.out::println);

}

既然有查询，自然少不了我们最关心的分页

/**

* 通过条件构造器和page分页查询

@Test

void selectByWrapperAndPage(){

//4.通过条件构造器wrapper和Page分页查询

QueryWrapper qw = new QueryWrapper();

qw.like("name","测试");

qw.lt("age",50);//小于

qw.gt("age",15);//大于

qw.orderByDesc("age");

IPage result = userMapper.selectPage(new Page<>(2,10),qw);

/**

* 查询总记录数

@Test

void selectCount(){

//5.通过条件查询总条数

QueryWrapper qw = new QueryWrapper();

qw.like("name","测试");

qw.lt("age",50);//小于

qw.gt("age",15);//大于

qw.orderByDesc("age");

int count = userMapper.selectCount(qw);

System.out.println(count);

}

删除

/**

* 通过id删除

@Test

void delete(){

int row = userMapper.deleteById(27l);

System.out.println(row);

}

/**

* 通过id批量删除

@Test

void deleteBatch(){

int row = userMapper.deleteBatchIds(Arrays.asList(67l,44l,37l,220l));

System.out.println(row);

}

/**

* 通过条件删除

@Test

void deleteByWrapper(){

QueryWrapper qw = new QueryWrapper<>();

qw.gt("age",70);

//先来看看有多少数据

int row = userMapper.selectCount(qw);

System.out.println(row);

//删除

int deleteRow = userMapper.delete(qw);

System.out.println(deleteRow);

}

今天就到这，后续会给大家分享下mybatis-plus提供的sql性能执行分析插件、乐观锁插件以及字段的自动填充。

补充知识：Mybatis-plus 自动生成代码后xml文件和mapper映射不到的原因

报了如下错误

找了很久都没找到原因

2020-06-08 18:48:12 |ERROR |http-nio-8130-exec-3 |GlobalExceptionHandler.java:25 |service.base.handler.GlobalExceptionHandler |org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): service.used.mapper.ClassifyMapper.selectNestedListByParentId

at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:235)

at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.(MybatisMapperMethod.java:50)

at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.lambda$cachedMapperMethod$0(MybatisMapperProxy.java:101)

at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660)

at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.cachedMapperMethod(MybatisMapperProxy.java:100)

at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:95)

at com.sun.proxy.$Proxy98.selectNestedListByParentId(Unknown Source)

at xyz.oneadd.platform.service.used.service.impl.ClassifyServiceImpl.nestedList(ClassifyServiceImpl.java:25)

at xyz.oneadd.platform.service.used.service.impl.ClassifyServiceImpl$$FastClassBySpringCGLIB$$85da3417.invoke()

at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)

at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:685)

at xyz.oneadd.platform.service.used.service.impl.ClassifyServiceImpl$$EnhancerBySpringCGLIB$$3b7bb86f.nestedList()

at xyz.oneadd.platform.service.used.controller.api.ApiClassifyController.classifyList(ApiClassifyController.java:34)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:106)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:888)

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)

at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)