Idea搭建简单springboot项目的详细教程（三）创建目录结构与基础dao、mapper.xml...
一、通过插件自动生成mapper.xml1、安装better-mybatis-gener 插件2、连接数据库3、 自动生成基础代码
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一、通过插件自动生成mapper.xml
1、安装better-mybatis-gener 插件
2、连接数据库
3、 自动生成基础代码
具体的代码示例：
Controller控制层自己写：
package com.example.demo.controller;
import com.example.demo.model.User;
import com.example.demo.model.UserKey;
import com.example.demo.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
/**
* 测试方法
* @return
*/
@RequestMapping(value = "/test",method = RequestMethod.GET)
public String requestTest() {
return "哈哈哈";
}
/**
* 通过主键查询用户信息
* @param userId 用户id
* @param username 用户名称
* @return
*/
@RequestMapping(value = "/findUser",method = RequestMethod.GET)
public User findUserByPrimaryKey(Integer userId, String username) {
UserKey userKey = new UserKey();
userKey.setUserId(userId);
userKey.setUsername(username);
return userService.findUserByPrimaryKey(userKey);
}
}
Service层
1、接口
package com.example.demo.service;
import com.example.demo.model.User;
import com.example.demo.model.UserKey;
public interface UserService {
/**
* 通过用户主键查询用户信息
* @param userKey
* @return
*/
User findUserByPrimaryKey(UserKey userKey);
}
2、接口实现
package com.example.demo.service.impl;
import com.example.demo.mapper.UserMapper;
import com.example.demo.model.User;
import com.example.demo.model.UserKey;
import com.example.demo.service.UserService;
import org.springframework.stereotype.Service;
import javax.annotation.Resource;
@Service
public class UserServiceImpl implements UserService {
@Resource
private UserMapper userMapper;
/**
* 通过用户主键查询用户信息
* @param userKey
* @return
*/
@Override
public User findUserByPrimaryKey(UserKey userKey) {
return userMapper.selectByPrimaryKey(userKey);
}
}
Dao/Mapper层
package com.example.demo.mapper;
import com.example.demo.model.User;
import com.example.demo.model.UserExample;
import com.example.demo.model.UserKey;
import java.util.List;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
@Mapper
public interface UserMapper {
long countByExample(UserExample example);
int deleteByExample(UserExample example);
int deleteByPrimaryKey(UserKey key);
int insert(User record);
int insertSelective(User record);
List<User> selectByExample(UserExample example);
User selectByPrimaryKey(UserKey key);
int updateByExampleSelective(@Param("record") User record, @Param("example") UserExample example);
int updateByExample(@Param("record") User record, @Param("example") UserExample example);
int updateByPrimaryKeySelective(User record);
int updateByPrimaryKey(User record);
}Mapper.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.demo.mapper.UserMapper">
<resultMap id="BaseResultMap" type="com.example.demo.model.User">
<id column="user_id" jdbcType="INTEGER" property="userId" />
<id column="username" jdbcType="VARCHAR" property="username" />
<result column="name" jdbcType="VARCHAR" property="name" />
<result column="password" jdbcType="VARCHAR" property="password" />
<result column="createtime" jdbcType="TIMESTAMP" property="createtime" />
<result column="creator" jdbcType="INTEGER" property="creator" />
<result column="role" jdbcType="VARCHAR" property="role" />
</resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
</when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Update_By_Example_Where_Clause">
<where>
<foreach collection="example.oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
</when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Base_Column_List">
user_id, username, `name`, `password`, createtime, creator, `role`
</sql>
<select id="selectByExample" parameterType="com.example.demo.model.UserExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
</if>
<include refid="Base_Column_List" />
from user
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
<if test="orderByClause != null">
order by ${orderByClause}
</if>
<if test="limit != null">
<if test="offset != null">
limit ${offset}, ${limit}
</if>
<if test="offset == null">
limit ${limit}
</if>
</if>
</select>
<select id="selectByPrimaryKey" parameterType="com.example.demo.model.UserKey" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from user
where user_id = #{userId,jdbcType=INTEGER}
and username = #{username,jdbcType=VARCHAR}
</select>
<delete id="deleteByPrimaryKey" parameterType="com.example.demo.model.UserKey">
delete from user
where user_id = #{userId,jdbcType=INTEGER}
and username = #{username,jdbcType=VARCHAR}
</delete>
<delete id="deleteByExample" parameterType="com.example.demo.model.UserExample">
delete from user
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</delete>
<insert id="insert" keyColumn="user_id" keyProperty="userId" parameterType="com.example.demo.model.User" useGeneratedKeys="true">
insert into user (username, `name`, `password`,
createtime, creator, `role`
)
values (#{username,jdbcType=VARCHAR}, #{name,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR},
#{createtime,jdbcType=TIMESTAMP}, #{creator,jdbcType=INTEGER}, #{role,jdbcType=VARCHAR}
)
</insert>
<insert id="insertSelective" keyColumn="user_id" keyProperty="userId" parameterType="com.example.demo.model.User" useGeneratedKeys="true">
insert into user
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="username != null">
username,
</if>
<if test="name != null">
`name`,
</if>
<if test="password != null">
`password`,
</if>
<if test="createtime != null">
createtime,
</if>
<if test="creator != null">
creator,
</if>
<if test="role != null">
`role`,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="username != null">
#{username,jdbcType=VARCHAR},
</if>
<if test="name != null">
#{name,jdbcType=VARCHAR},
</if>
<if test="password != null">
#{password,jdbcType=VARCHAR},
</if>
<if test="createtime != null">
#{createtime,jdbcType=TIMESTAMP},
</if>
<if test="creator != null">
#{creator,jdbcType=INTEGER},
</if>
<if test="role != null">
#{role,jdbcType=VARCHAR},
</if>
</trim>
</insert>
<select id="countByExample" parameterType="com.example.demo.model.UserExample" resultType="java.lang.Long">
select count(*) from user
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</select>
<update id="updateByExampleSelective" parameterType="map">
update user
<set>
<if test="record.userId != null">
user_id = #{record.userId,jdbcType=INTEGER},
</if>
<if test="record.username != null">
username = #{record.username,jdbcType=VARCHAR},
</if>
<if test="record.name != null">
`name` = #{record.name,jdbcType=VARCHAR},
</if>
<if test="record.password != null">
`password` = #{record.password,jdbcType=VARCHAR},
</if>
<if test="record.createtime != null">
createtime = #{record.createtime,jdbcType=TIMESTAMP},
</if>
<if test="record.creator != null">
creator = #{record.creator,jdbcType=INTEGER},
</if>
<if test="record.role != null">
`role` = #{record.role,jdbcType=VARCHAR},
</if>
</set>
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByExample" parameterType="map">
update user
set user_id = #{record.userId,jdbcType=INTEGER},
username = #{record.username,jdbcType=VARCHAR},
`name` = #{record.name,jdbcType=VARCHAR},
`password` = #{record.password,jdbcType=VARCHAR},
createtime = #{record.createtime,jdbcType=TIMESTAMP},
creator = #{record.creator,jdbcType=INTEGER},
`role` = #{record.role,jdbcType=VARCHAR}
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByPrimaryKeySelective" parameterType="com.example.demo.model.User">
update user
<set>
<if test="name != null">
`name` = #{name,jdbcType=VARCHAR},
</if>
<if test="password != null">
`password` = #{password,jdbcType=VARCHAR},
</if>
<if test="createtime != null">
createtime = #{createtime,jdbcType=TIMESTAMP},
</if>
<if test="creator != null">
creator = #{creator,jdbcType=INTEGER},
</if>
<if test="role != null">
`role` = #{role,jdbcType=VARCHAR},
</if>
</set>
where user_id = #{userId,jdbcType=INTEGER}
and username = #{username,jdbcType=VARCHAR}
</update>
<update id="updateByPrimaryKey" parameterType="com.example.demo.model.User">
update user
set `name` = #{name,jdbcType=VARCHAR},
`password` = #{password,jdbcType=VARCHAR},
createtime = #{createtime,jdbcType=TIMESTAMP},
creator = #{creator,jdbcType=INTEGER},
`role` = #{role,jdbcType=VARCHAR}
where user_id = #{userId,jdbcType=INTEGER}
and username = #{username,jdbcType=VARCHAR}
</update>
</mapper>测试结果
如果报错：org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.demo.mapper.UserMapper.selectByPrimaryKey
2020-11-09 16:27:59.053 INFO 13776 --- [nio-8080-exec-3] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2020-11-09 16:27:59.053 INFO 13776 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2020-11-09 16:27:59.059 INFO 13776 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet : Completed initialization in 6 ms
2020-11-09 16:27:59.142 ERROR 13776 --- [nio-8080-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.demo.mapper.UserMapper.selectByPrimaryKey] with root cause
org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.demo.mapper.UserMapper.selectByPrimaryKey
at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:235) ~[mybatis-3.5.5.jar:3.5.5]
at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:53) ~[mybatis-3.5.5.jar:3.5.5]
at org.apache.ibatis.binding.MapperProxy.lambda$cachedInvoker$0(MapperProxy.java:115) ~[mybatis-3.5.5.jar:3.5.5]
at java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1660) ~[na:1.8.0_131]
at org.apache.ibatis.binding.MapperProxy.cachedInvoker(MapperProxy.java:102) ~[mybatis-3.5.5.jar:3.5.5]
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:85) ~[mybatis-3.5.5.jar:3.5.5]
at com.sun.proxy.$Proxy53.selectByPrimaryKey(Unknown Source) ~[na:na]
at com.example.demo.service.impl.UserServiceImpl.findUserByPrimaryKey(UserServiceImpl.java:26) ~[classes/:na]
at com.example.demo.controller.UserController.findUserByPrimaryKey(UserController.java:38) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.38.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.9.RELEASE.jar:5.2.9.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590) [tomcat-embed-core-9.0.38.jar:9.0.38]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.38.jar:9.0.38]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.38.jar:9.0.38]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131]
原因：mapper接口找不到对应的mapper.xml文件
解决：在配置文件中，增加配置mybatis.mapper-locations，作用：扫描Mapper接口对应的XML文件
spring.datasource.url=jdbc:mysql://xxxx:3306/xxxx?characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
spring.datasource.username=xxx
spring.datasource.password=xxxx
#扫描Mapper接口对应的XML文件
mybatis.mapper-locations=classpath:mybatis-mapper/*.xml
mybatis.type-aliases-package=com.example.demo.model;
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