Intellij IDEA Spring Boot (10) 集成mybatis以及分页
今天又花了点时间研究了mybatis。 研究了mybatis如何使用 通用mapper，如何分页查询，如何与ehcache集成缓存。
直接进入主题啦。
pom依赖
org.mybatis.spring.boot mybatis-spring-boot-starter 1.1.1
tk.mybatis mapper 3.4.3
com.github.pagehelper pagehelper 4.2.1
我对于创建数据库的表，又懒了。所以我希望依赖hibernate的自动建表功能。可选操作啊。org.springframework.boot spring-boot-starter-cache net.sf.ehcache ehcache
其它的pom依赖我也补上吧org.springframework.boot spring-boot-starter-data-jpa
mysql mysql-connector-java runtime org.springframework.boot spring-boot-devtools true true com.alibaba druid 1.0.31
org.springframework.boot spring-boot-starter-web
org.springframework.boot spring-boot-starter-test test
alimaven http://maven.aliyun.com/nexus/content/groups/public/ true true alimaven http://maven.aliyun.com/nexus/content/groups/public/ true true
这里忘记说一个重要的事情，就是分页插件的版本，一定要用4.x.x的版本，不要使用5，也不要使用3。我目前使用的是4的最高版本。我实验过了，5的办法，分页似乎有问题，不对劲。只有4的正确。
接下来讲配置：
package com.dashuai.mybatisboot.config;
import com.alibaba.druid.support.http.StatViewServlet;
import com.alibaba.druid.support.http.WebStatFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class DruidConfig {
@Bean
public ServletRegistrationBean druidStatView() {
ServletRegistrationBean registration = new ServletRegistrationBean(new StatViewServlet());
registration.addUrlMappings("/druid/*");
return registration;
}
@Bean
public FilterRegistrationBean druidWebStatFilter() {
FilterRegistrationBean registration = new FilterRegistrationBean(new WebStatFilter());
registration.addInitParameter("exclusions","/css/*,/style/*,/js/*,*.js,*.css,/druid*,/attached/*,*.jsp");
registration.addInitParameter("principalSessionName","sessionUser");
registration.addInitParameter("profileEnable","true");
registration.addUrlPatterns("/*");
registration.setOrder(1);
return registration;
}
}package com.dashuai.mybatisboot.config;
import com.github.pagehelper.PageHelper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import tk.mybatis.spring.mapper.MapperScannerConfigurer;
import java.util.Properties;
@Configuration
public class MyBatisConfig {
@Bean
public MapperScannerConfigurer mapperScannerConfigurer() {
MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory");
mapperScannerConfigurer.setBasePackage("com.dashuai.mybatisboot.mapper");//扫描该路径下的dao
Properties properties = new Properties();
properties.setProperty("mappers", "com.dashuai.mybatisboot.mybatisbase.MyBaseMapper");//通用dao
properties.setProperty("notEmpty", "false");
properties.setProperty("IDENTITY", "MYSQL");
mapperScannerConfigurer.setProperties(properties);
return mapperScannerConfigurer;
}
@Bean
public PageHelper pageHelper() {
PageHelper pageHelper = new PageHelper();
Properties p = new Properties();
p.setProperty("offsetAsPageNum", "true");
p.setProperty("rowBoundsWithCount", "true");
p.setProperty("reasonable", "true");
pageHelper.setProperties(p);
return pageHelper;
}
}
package com.dashuai.mybatisboot.mybatisbase;
import tk.mybatis.mapper.common.Mapper;
import tk.mybatis.mapper.common.MySqlMapper;
/**
* 这个MyBaseMapper 不要放在mapper包下，该类不能被当做普通Mapper一样被扫描，否则会出错。
* 出的错是： sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
* @param
*/
public interface MyBaseMapper extends Mapper,MySqlMapper{
}
application.properties的配置
#log
logging.level.root=info
logging.level.com.dashuai.mybatisboot=debug
#logging.level.org.hibernate.cache=DEBUG
#logging.level.org.springframework=debug
logging.file=mylog.log
#mysql
spring.datasource.driver-class-name= com.mysql.jdbc.Driver
spring.datasource.url=jdbc\:mysql\://localhost\:3306/mybatis?useUnicode\=true&characterEncoding\=UTF-8
spring.datasource.username=root
spring.datasource.password=123456
#druid
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.filters=stat
spring.datasource.maxActive= 20
spring.datasource.initialSize= 1
spring.datasource.maxWait= 60000
spring.datasource.minIdle =1
spring.datasource.timeBetweenEvictionRunsMillis= 60000
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery= select 'x'
spring.datasource.testWhileIdle= true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn= false
spring.datasource.poolPreparedStatements=true
spring.datasource.maxOpenPreparedStatements= 20
# 自动创表
spring.jpa.database=mysql
spring.jpa.hibernate.ddl-auto=update
# ehcache的配置
spring.cache.type=ehcache
spring.cache.ehcache.config=classpath:ehcache.xml
import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cache.annotation.EnableCaching; import org.springframework.transaction.annotation.EnableTransactionManagement; @EnableTransactionManagement @SpringBootApplication @EnableCaching public class MybatisbootApplication { public static void main(String[] args) { SpringApplication.run(MybatisbootApplication.class, args); } }
package com.dashuai.mybatisboot.entity;
import com.fasterxml.jackson.annotation.JsonFormat;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;
import java.util.Date;
@Entity
@Table(name="tb_user")
public class User implements Serializable {
@Id
private String uuid; // 表主键
@Column
private String username; // 登录用户名
@Column
private String password; // 登录密码
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
@Column
private Date registerDate;
@Column
private Integer status; // 账号状态： 0：正常；1：禁用
public String getUuid() {
return uuid;
}
public void setUuid(String uuid) {
this.uuid = uuid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Date getRegisterDate() {
return registerDate;
}
public void setRegisterDate(Date registerDate) {
this.registerDate = registerDate;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "\nUser [uuid=" + uuid + ", username=" + username + ", password=" + password + ", registerDate="
+ registerDate + ", status=" + status + "]\n";
}
}
package com.dashuai.mybatisboot.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;
@Entity
@Table(name="tb_role")
public class Role implements Serializable {
@Id
private String uuid; // 表主键
@Column
private String roleName; // 角色名
@Column
private String roleDesc; // 角色描述
public String getUuid() {
return uuid;
}
public void setUuid(String uuid) {
this.uuid = uuid;
}
public String getRoleName() {
return roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
public String getRoleDesc() {
return roleDesc;
}
public void setRoleDesc(String roleDesc) {
this.roleDesc = roleDesc;
}
}
package com.dashuai.mybatisboot.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;
import java.io.Serializable;
@Entity
@Table(name="tb_user_role")
public class UserRole implements Serializable {
@Id
private String uuid; // 表主键
@Column
private String userId;
@Column
private String roleId;
public String getUuid() {
return uuid;
}
public void setUuid(String uuid) {
this.uuid = uuid;
}
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getRoleId() {
return roleId;
}
public void setRoleId(String roleId) {
this.roleId = roleId;
}
}
package com.dashuai.mybatisboot.mapper;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.mybatisbase.MyBaseMapper;
public interface UserMapper extends MyBaseMapper {
} package com.dashuai.mybatisboot.mapper;
import com.dashuai.mybatisboot.entity.Role;
import com.dashuai.mybatisboot.mybatisbase.MyBaseMapper;
public interface RoleMapper extends MyBaseMapper{
} package com.dashuai.mybatisboot.entity;
import java.util.Map;
public class MyPager {
int page;
int rows;
Map params;
public MyPager(int page, int rows, Map params) {
this.page = page;
this.rows = rows;
this.params = params;
}
public int getPage() {
if(page<1){
page=1;
}
return page;
}
public void setPage(int page) {
this.page = page;
}
public int getRows() {
if(rows<1){
rows=1;
}
return rows;
}
public void setRows(int rows) {
this.rows = rows;
}
public Map getParams() {
return params;
}
public void setParams(Map params) {
this.params = params;
}
}
package com.dashuai.mybatisboot.entity.dto;
/**
* 根据用户Id 查询出 role实体类
*/
public class DtoUserRole {
private String userId; // 为null就是没有拥有角色。
private String roleId;
private String roleName;
private String roleDesc;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getRoleId() {
return roleId;
}
public void setRoleId(String roleId) {
this.roleId = roleId;
}
public String getRoleName() {
return roleName;
}
public void setRoleName(String roleName) {
this.roleName = roleName;
}
public String getRoleDesc() {
return roleDesc;
}
public void setRoleDesc(String roleDesc) {
this.roleDesc = roleDesc;
}
@Override
public String toString() {
return "\nDtoUserRole{" +
"\nuserId='" + userId + '\'' +
"\n, roleId='" + roleId + '\'' +
"\n, roleName='" + roleName + '\'' +
"\n, roleDesc='" + roleDesc + '\'' +
'}';
}
}
package com.dashuai.mybatisboot.service;
import com.dashuai.mybatisboot.entity.MyPager;
import com.dashuai.mybatisboot.entity.User;
import com.github.pagehelper.PageInfo;
import java.util.List;
public interface UserService {
User saveUser(User user);
User getUserByUsername(String username);
void deleteUserByUUID(String uuid);
void updateUser(User user);
List getAllUsers();
PageInfo getPageUsers(MyPager pager);
}
package com.dashuai.mybatisboot.service;
import com.dashuai.mybatisboot.entity.Role;
public interface RoleService {
Role saveRole(Role role);
Role findRoleByName(String name);
}
package com.dashuai.mybatisboot.service;
import com.dashuai.mybatisboot.entity.MyPager;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.entity.UserRole;
import com.dashuai.mybatisboot.entity.dto.DtoUserRole;
import com.github.pagehelper.PageInfo;
import java.util.List;
public interface UserRoleService {
public void saveUserRole(UserRole userRole);
List getUserHasAndNotHasRoles(String userId);
List getUserHasRoles(String userId);
List getUserByRoleName(String rolename);
PageInfo getUserPageByRoleName(MyPager pager, String rolename);
}
package com.dashuai.mybatisboot.service.impl;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import com.dashuai.mybatisboot.entity.MyPager;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.mapper.UserMapper;
import com.dashuai.mybatisboot.service.UserService;
import tk.mybatis.mapper.entity.Example;
@Service("userService")
@Transactional
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper UserMapper;
@Override
public User saveUser(User user) {
user.setUuid(UUID.randomUUID().toString().replace("-", ""));
UserMapper.insert(user);
return user;
}
@Transactional(readOnly = true)
@Override
public User getUserByUsername(String username) {
Example example = new Example(User.class);
example.createCriteria().andEqualTo("username", username);
List list = UserMapper.selectByExample(example);
if (null != list && !list.isEmpty()) {
return list.get(0);
}
return null;
}
@Override
public void deleteUserByUUID(String uuid) {
UserMapper.deleteByPrimaryKey(uuid);
}
@Override
public void updateUser(User user) {
UserMapper.updateByPrimaryKey(user);
}
@Cacheable(cacheNames = "cache_user")
@Transactional(readOnly = true)
@Override
public List getAllUsers() {
return UserMapper.selectAll();
}
@Transactional(readOnly = true)
@Override
public PageInfo getPageUsers(MyPager pager) {
Example example = new Example(User.class);
Map params = pager.getParams();
if (null != params && !params.isEmpty()) {
Example.Criteria criteria = example.createCriteria();
if (params.containsKey("username")) {
criteria.andLike("username", "%" + params.get("username") + "%");
}
if (params.containsKey("status")) {
criteria.andEqualTo("status", params.get("status"));
}
if (params.containsKey("registerDate")) {
criteria.andGreaterThan("registerDate", params.get("registerDate"));
}
}
//PageHelper.startPage(pager.getPage(),pager.getRows());
PageHelper.startPage(pager.getPage(), pager.getRows(), "register_date desc");
List list = UserMapper.selectByExample(example);
PageInfo pageInfo = new PageInfo<>(list);
return pageInfo;
}
}
package com.dashuai.mybatisboot.service.impl;
import com.dashuai.mybatisboot.entity.Role;
import com.dashuai.mybatisboot.mapper.RoleMapper;
import com.dashuai.mybatisboot.service.RoleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import tk.mybatis.mapper.entity.Example;
import java.util.List;
import java.util.UUID;
@Transactional
@Service("roleService")
public class RoleServiceImpl implements RoleService {
@Autowired
RoleMapper RoleMapper;
@Override
public Role saveRole(Role role) {
role.setUuid(UUID.randomUUID().toString().replace("-",""));
RoleMapper.insert(role);
return role;
}
@Transactional(readOnly = true)
@Override
public Role findRoleByName(String name) {
Example example = new Example(Role.class);
example.createCriteria().andEqualTo("roleName",name);
List list= RoleMapper.selectByExample(example);
if(null!=list&&!list.isEmpty()){
return list.get(0);
}
return null;
}
}
package com.dashuai.mybatisboot.service.impl;
import com.dashuai.mybatisboot.entity.MyPager;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.entity.UserRole;
import com.dashuai.mybatisboot.entity.dto.DtoUserRole;
import com.dashuai.mybatisboot.mapper.UserRoleMapper;
import com.dashuai.mybatisboot.service.UserRoleService;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
import java.util.UUID;
@Transactional
@Service("userRoleService")
public class UserRoleServiceImpl implements UserRoleService {
@Autowired
UserRoleMapper UserRoleMapper;
@Override
public void saveUserRole(UserRole userRole) {
userRole.setUuid(UUID.randomUUID().toString().replace("-",""));
UserRoleMapper.insert(userRole);
}
@Transactional(readOnly = true)
@Override
public List getUserHasAndNotHasRoles(String userId) {
return UserRoleMapper.getUserHasAndNotHasRoles(userId);
}
@Transactional(readOnly = true)
@Override
public List getUserHasRoles(String userId) {
return UserRoleMapper.getUserHasRoles(userId);
}
@Cacheable(cacheNames = "cache_user")
@Transactional(readOnly = true)
@Override
public List getUserByRoleName(String rolename) {
return UserRoleMapper.getUserByRoleName(rolename);
}
@Transactional(readOnly = true)
@Override
public PageInfo getUserPageByRoleName(MyPager pager,String rolename) {
PageHelper.startPage(pager.getPage(),pager.getRows());
List list = UserRoleMapper.getUserByRoleName(rolename);
PageInfo pageInfo=new PageInfo<>(list);
return pageInfo;
}
}
测试类
package com.dashuai.mybatisboot;
import com.dashuai.mybatisboot.entity.MyPager;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.service.UserService;
import com.github.pagehelper.PageInfo;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.*;
@RunWith(SpringRunner.class)
@SpringBootTest
public class TestUser {
@Autowired
UserService userService;
Logger logger = LoggerFactory.getLogger(getClass());
// @Test
// public void test1(){
// for(int i=1;i<21;i++){
// User user = new User();
// user.setPassword("123456");
// user.setUsername("zhangsan"+i);
// user.setRegisterDate(new Date());
// user.setStatus(0);
// userService.saveUser(user);
// }
// }
@Test
public void test2(){
List list = userService.getAllUsers();
logger.info("list: {} ",list.size());
List list2 = userService.getAllUsers();
logger.info("list: {} ",list2.size());
}
@Test
public void test3(){
User user = userService.getUserByUsername("zhangsan15");
logger.info("user: {} ",user);
}
@Test
public void test4(){
User user = userService.getUserByUsername("zhangsan6");
if(null!=user){
userService.deleteUserByUUID(user.getUuid());
}
}
@Test
public void test5(){
User user = userService.getUserByUsername("zhangsan7");
if(null!=user){
user.setPassword("1234567");
userService.updateUser(user);
}
}
@Test
public void test6(){
MyPager myPager = new MyPager(3,10,null);
PageInfo pageInfo = userService.getPageUsers(myPager);
logger.info("pageInfo page:{},total:{},totalPage:{} "
,pageInfo.getPageNum()
,pageInfo.getTotal()
,pageInfo.getPages());
List list = pageInfo.getList();
for(User u:list){
logger.info("User {}",u);
}
logger.info("pageInfo {}",pageInfo);
}
@Test
public void test7(){
MyPager myPager = new MyPager(2,10,null);
PageInfo pageInfo = userService.getPageUsers(myPager);
logger.info("pageInfo: {} ",pageInfo);
}
@Test
public void test8(){
Map params = new HashMap<>();
params.put("username","zhangsan1");
MyPager myPager = new MyPager(1,10,params);
PageInfo pageInfo = userService.getPageUsers(myPager);
logger.info("pageInfo: {} ",pageInfo);
}
@Test
public void test9(){
Map params = new HashMap<>();
params.put("username","zhangsan1");
params.put("status",0);
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY,8);
params.put("registerDate", calendar.getTime());
MyPager myPager = new MyPager(2,10,params);
PageInfo pageInfo = userService.getPageUsers(myPager);
logger.info("pageInfo: {} ",pageInfo);
}
}
package com.dashuai.mybatisboot;
import com.dashuai.mybatisboot.entity.MyPager;
import com.dashuai.mybatisboot.entity.Role;
import com.dashuai.mybatisboot.entity.User;
import com.dashuai.mybatisboot.entity.UserRole;
import com.dashuai.mybatisboot.entity.dto.DtoUserRole;
import com.dashuai.mybatisboot.service.RoleService;
import com.dashuai.mybatisboot.service.UserRoleService;
import com.dashuai.mybatisboot.service.UserService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;
@RunWith(SpringRunner.class)
@SpringBootTest
public class TestRole {
Logger logger = LoggerFactory.getLogger(getClass());
@Autowired
UserService userService;
@Autowired
RoleService roleService;
@Autowired
UserRoleService userRoleService;
// @Test
// public void saveRole(){
// for(int i=1;i<15;i++){
// Role role = new Role();
// role.setRoleName("vip"+i);
// role.setRoleDesc("会员等级"+i+"级");
// roleService.saveRole(role);
// }
// }
// @Test
// public void saveUserRole(){
//
// List list = userService.getAllUsers();
// Role role = roleService.findRoleByName("vip1");
//
// for(User user:list){
// UserRole userRole = new UserRole();
// userRole.setRoleId(role.getUuid());
// userRole.setUserId(user.getUuid());
// userRoleService.saveUserRole(userRole);
// }
//
// }
@Test
public void find1() {
User user = userService.getUserByUsername("zhangsan1");
List list = userRoleService.getUserHasAndNotHasRoles(user.getUuid());
logger.info("list: {}", list);
}
@Test
public void find2() {
User user = userService.getUserByUsername("zhangsan1");
List list = userRoleService.getUserHasRoles(user.getUuid());
logger.info("list: {}", list);
}
// @Test
// public void saveUserRole() {
//
// List list = userService.getAllUsers();
// Role role = roleService.findRoleByName("vip2");
// for (int i = 0; i < list.size(); i++) {
// if (i % 3 == 0) {
// UserRole userRole = new UserRole();
// userRole.setRoleId(role.getUuid());
// userRole.setUserId(list.get(i).getUuid());
// userRoleService.saveUserRole(userRole);
// }
// }
// }
@Test
public void find3(){
for(int i=1;i<3;i++){
logger.info("list: {}", userRoleService.getUserByRoleName("vip1"));
System.err.println("==================================================");
logger.info("list: {}", userRoleService.getUserByRoleName("vip2"));
}
}
@Test
public void find4(){
for(int i=1;i<3;i++) {
MyPager pager = new MyPager(2, 10, null);
logger.info("list: {}", userRoleService.getUserPageByRoleName(pager, "vip1"));
System.err.println("==================================================");
logger.info("list: {}", userRoleService.getUserPageByRoleName(pager, "vip2"));
}
}
}
代码什么的，基本都粘贴上去了。总结一下。
1. 使用了Hibernate的自动建表功能
org.springframework.boot spring-boot-starter-data-jpa
# 自动创表 spring.jpa.database=mysql spring.jpa.hibernate.ddl-auto=update
2. 引入了通用的mapper
tk.mybatis mapper 3.4.3
@Bean public MapperScannerConfigurer mapperScannerConfigurer() { MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer(); mapperScannerConfigurer.setSqlSessionFactoryBeanName("sqlSessionFactory"); mapperScannerConfigurer.setBasePackage("com.dashuai.mybatisboot.mapper");//扫描该路径下的dao Properties properties = new Properties(); properties.setProperty("mappers", "com.dashuai.mybatisboot.mybatisbase.MyBaseMapper");//通用dao properties.setProperty("notEmpty", "false"); properties.setProperty("IDENTITY", "MYSQL"); mapperScannerConfigurer.setProperties(properties); return mapperScannerConfigurer; }使用的时候，弄一个baseMapper，然后让其他Mapper继承baseMapper就行了，基本没有需要添加的代码了。
配置的时候，请参见MyBatisConfig
唯一要注意的是，baseMapper和其他实体类对应的mapper不要放在相同包中，否则会报异常。sun.reflect.generics.reflectiveObjects.TypeVariableImpl cannot be cast to java.lang.Class
3. 分页插件的使用。
com.github.pagehelper pagehelper 4.2.1
@Bean public PageHelper pageHelper() { PageHelper pageHelper = new PageHelper(); Properties p = new Properties(); p.setProperty("offsetAsPageNum", "true"); p.setProperty("rowBoundsWithCount", "true"); p.setProperty("reasonable", "true"); pageHelper.setProperties(p); return pageHelper; }版本确定是4.x.x。我用了5的反而不能正确分页，应该是没有正确配置。用法类似如下。
PageHelper.startPage(pager.getPage(), pager.getRows(), "register_date desc"); List但注意，startPage紧跟的后面查询语句才会分页，所以不要写多个查询，还指望都能分页。list = UserMapper.selectByExample(example); PageInfo pageInfo = new PageInfo<>(list);
还有一个稀奇的事情，就是 log日志输出 PageInfo
然后for循环list。这个小问题，我发现这个插件的5.x.x版本修复了，但是这个5.x.x版本的，我怎么都无法让他显示正确的分页。所以我还是 选用4.x.x版本的。
4. Ehcache的使用
org.springframework.boot spring-boot-starter-cache net.sf.ehcache ehcache
# ehcache的配置 spring.cache.type=ehcache spring.cache.ehcache.config=classpath:ehcache.xml
@EnableAutoConfiguration @SpringBootApplication @EnableCaching public class MybatisbootApplication { public static void main(String[] args) { SpringApplication.run(MybatisbootApplication.class, args); } }
第四步，再需要使用缓存的方法上面加上@Cacheable注解，但是还必须加上cacheNames的属性值。
所以你会在ehcache.xml中看到 我配置的 cache_user的cache
@Cacheable(cacheNames = "cache_user") @Transactional(readOnly = true) @Override public ListgetAllUsers() { return UserMapper.selectAll(); }
如果哪个方法不用缓存，那就不加@Cacheable注解，加了就表示要使用缓存。
好了，终于对 mybatis的使用 有了一个 更加熟练的掌握了。mybatis也可以做的非常简单的嘛。用用通用Mapper，用用分页插件，其实也不是那么多复杂嘛。如果需要用连接查询，看到我写的嘛，用注解嘛
// 根据用户的uuid查询该用户拥有的角色和未拥有的角色 @Select("select r.role_name as roleName," + "r.role_desc as roleDesc," + "r.uuid as roleId," + "ur.user_id as userId from tb_role r " + "left join tb_user_role ur " + "on r.uuid = ur.role_id " + "and ur.user_id =#{userId} ") public List那么基本上，mybatis的基本用法 我算是掌握了一些吧。getUserHasAndNotHasRoles(String userId);