Mybatis多表查询一对一查询一对一查询的模型MapperScannerConfigurer
用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户
一对一查询的需求：查询一个订单，与此同时查询出该订单所属的用户
一对一查询的语句
对应的sql语句：
select * from orders o,user u where o.uid=u.id;
查询的结果如下：
创建Order和User实体public class Order { private int id; private Date ordertime; private double total; //代表当前订单从属于哪一个客户 private User user;}public class User { private int id; private String username; private String password; private Date birthday;}创建OrderMapper接口public interface OrderMapper { List<Order> findAll();}配置OrderMapper.xml<mapper namespace=”com.zjq.mapper.OrderMapper”> <resultMap id=”orderMap” type=”com.zjq.domain.Order”> <result column=”uid” property=”user.id”></result> <result column=”username” property=”user.username”></result> <result column=”password” property=”user.password”></result> <result column=”birthday” property=”user.birthday”></result> </resultMap> <select id=”findAll” resultMap=”orderMap”> select * from orders o,user u where o.uid=u.id </select></mapper>
其中还可以配置如下：
<resultMap id=”orderMap” type=”com.zjq.domain.Order”> <result property=”id” column=”id”></result> <result property=”ordertime” column=”ordertime”></result> <result property=”total” column=”total”></result> <association property=”user” javaType=”com.zjq.domain.User”> <result column=”uid” property=”id”></result> <result column=”username” property=”username”></result> <result column=”password” property=”password”></result> <result column=”birthday” property=”birthday”></result> </association></resultMap>测试结果OrderMapper mapper = sqlSession.getMapper(OrderMapper.class);List<Order> all = mapper.findAll();for(Order order : all){ System.out.println(order);}
输出：
11:29:37,682 DEBUG JdbcTransaction:137 – Opening JDBC Connection11:29:38,178 DEBUG PooledDataSource:406 – Created connection 1858609436.11:29:38,179 DEBUG JdbcTransaction:101 – Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]11:29:38,182 DEBUG findAll:159 – ==> Preparing: SELECT *,o.id oid FROM orders o,USER u WHERE o.uid=u.id 11:29:38,305 DEBUG findAll:159 – ==> Parameters: 11:29:38,351 DEBUG findAll:159 – <== Total: 311:29:38,357 DEBUG JdbcTransaction:123 – Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]Order{id=1, ordertime=Sun Dec 12 00:00:00 GMT+08:00 2021, total=3000.0, user=User{id=1, username=’zjq’, password=’abc’, birthday=Wed Jul 28 00:00:00 GMT+08:00 2021, roleList=null}}Order{id=2, ordertime=Sun Dec 12 00:00:00 GMT+08:00 2021, total=4000.0, user=User{id=1, username=’zjq’, password=’abc’, birthday=Wed Jul 28 00:00:00 GMT+08:00 2021, roleList=null}}Order{id=3, ordertime=Sun Dec 12 00:00:00 GMT+08:00 2021, total=5000.0, user=User{id=2, username=’jack’, password=’123456′, birthday=Fri Aug 20 00:00:00 GMT+08:00 2021, roleList=null}}一对多查询一对多查询的模型
用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户
一对多查询的需求：查询一个用户，与此同时查询出该用户具有的订单
一对多查询的语句
对应的sql语句：
select *,o.id oid from user u left join orders o on u.id=o.uid;
查询的结果如下：
修改User实体public class Order { private int id; private Date ordertime; private double total; //代表当前订单从属于哪一个客户 private User user;}public class User { private int id; private String username; private String password; private Date birthday; //代表当前用户具备哪些订单 private List<Order> orderList;}创建UserMapper接口public interface UserMapper { List<User> findAll();}配置UserMapper.xml<mapper namespace=”com.zjq.mapper.UserMapper”> <resultMap id=”userMap” type=”com.zjq.domain.User”> <result column=”id” property=”id”></result> <result column=”username” property=”username”></result> <result column=”password” property=”password”></result> <result column=”birthday” property=”birthday”></result> <collection property=”orderList” ofType=”com.zjq.domain.Order”> <result column=”oid” property=”id”></result> <result column=”ordertime” property=”ordertime”></result> <result column=”total” property=”total”></result> </collection> </resultMap> <select id=”findAll” resultMap=”userMap”> select *,o.id oid from user u left join orders o on u.id=o.uid </select></mapper>测试结果UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> all = mapper.findAll();for(User user : all){ System.out.println(user.getUsername()); List<Order> orderList = user.getOrderList(); for(Order order : orderList){ System.out.println(order); } System.out.println(“———————————-“);}
输出：
11:38:28,060 DEBUG findAll:159 – ==> Preparing: SELECT *,o.id oid FROM USER u,orders o WHERE u.id=o.uid 11:38:28,179 DEBUG findAll:159 – ==> Parameters: 11:38:28,254 DEBUG findAll:159 – <== Total: 3User{id=1, username=’zjq’, password=’abc’, birthday=Wed Jul 28 00:00:00 GMT+08:00 2021, roleList=null}User{id=2, username=’jack’, password=’123456′, birthday=Fri Aug 20 00:00:00 GMT+08:00 2021, roleList=null}11:38:28,265 DEBUG JdbcTransaction:123 – Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]11:38:28,265 DEBUG JdbcTransaction:91 – Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]11:38:28,265 DEBUG PooledDataSource:363 – Returned connection 1858609436 to pool.多对多查询多对多查询的模型
用户表和角色表的关系为，一个用户有多个角色，一个角色被多个用户使用
多对多查询的需求：查询用户同时查询出该用户的所有角色
多对多查询的语句
对应的sql语句：
select u.*,r.*,r.id rid from user u left join sys_user_role ur on u.id=ur.useridinner join sys_role r on ur.roleid=r.id;
查询的结果如下：
创建Role实体，修改User实体public class User { private int id; private String username; private String password; private Date birthday; //代表当前用户具备哪些订单 private List<Order> orderList; //代表当前用户具备哪些角色 private List<Role> roleList;}public class Role { private int id; private String rolename;}?添加UserMapper接口方法List<User> findAllUserAndRole();配置UserMapper.xml<resultMap id=”userRoleMap” type=”com.zjq.domain.User”> <result column=”id” property=”id”></result> <result column=”username” property=”username”></result> <result column=”password” property=”password”></result> <result column=”birthday” property=”birthday”></result> <collection property=”roleList” ofType=”com.zjq.domain.Role”> <result column=”rid” property=”id”></result> <result column=”rolename” property=”rolename”></result> </collection></resultMap><select id=”findAllUserAndRole” resultMap=”userRoleMap”> select u.*,r.*,r.id rid from user u left join sys_user_role ur on u.id=ur.userid inner join sys_role r on ur.roleid=r.id;</select>测试结果UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> all = mapper.findAllUserAndRole();for(User user : all){ System.out.println(user.getUsername()); List<Role> roleList = user.getRoleList(); for(Role role : roleList){ System.out.println(role); } System.out.println(“———————————-“);}11:45:51,443 DEBUG findUserAndRoleAll:159 – ==> Preparing: SELECT * FROM USER u,sys_user_role ur,sys_role r WHERE u.id=ur.userId AND ur.roleId=r.id 11:45:51,572 DEBUG findUserAndRoleAll:159 – ==> Parameters: User{id=1, username=’zjq’, password=’abc’, birthday=Wed Jul 28 00:00:00 GMT+08:00 2021, roleList=[Role{id=1, roleName=’CTO’, roleDesc=’CTO’}, Role{id=2, roleName=’COO’, roleDesc=’COO’}]}User{id=2, username=’jack’, password=’123456′, birthday=Fri Aug 20 00:00:00 GMT+08:00 2021, roleList=[Role{id=1, roleName=’CTO’, roleDesc=’CTO’}, Role{id=2, roleName=’COO’, roleDesc=’COO’}]}11:45:51,610 DEBUG findUserAndRoleAll:159 – <== Total: 411:45:51,618 DEBUG JdbcTransaction:123 – Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]11:45:51,619 DEBUG JdbcTransaction:91 – Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@6ec8211c]11:45:51,619 DEBUG PooledDataSource:363 – Returned connection 1858609436 to pool.Mybatis的注解开发MyBatis的常用注解
这几年来注解开发越来越流行，Mybatis也可以使用注解开发方式，这样我们就可以减少编写Mapper
映射文件了。我们先围绕一些基本的CRUD来学习，再学习复杂映射多表操作。
@Insert：实现新增
@Update：实现更新
@Delete：实现删除
@Select：实现查询
@Result：实现结果集封装
@Results：可以与@Result 一起使用，封装多个结果集
@One：实现一对一结果集封装
@Many：实现一对多结果集封装
MyBatis的增删改查
我们完成简单的user表的增删改查的操作
private UserMapper userMapper;@Beforepublic void before() throws IOException { InputStream resourceAsStream = Resources.getResourceAsStream(“SqlMapConfig.xml”); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream); SqlSession sqlSession = sqlSessionFactory.openSession(true); userMapper = sqlSession.getMapper(UserMapper.class);}@Testpublic void testAdd() { User user = new User(); user.setUsername(“测试数据”); user.setPassword(“123”); user.setBirthday(new Date()); userMapper.add(user);}@Testpublic void testUpdate() throws IOException { User user = new User(); user.setId(16); user.setUsername(“测试数据修改”); user.setPassword(“abc”); user.setBirthday(new Date()); userMapper.update(user);}@Testpublic void testDelete() throws IOException { userMapper.delete(16);}@Testpublic void testFindById() throws IOException { User user = userMapper.findById(1); System.out.println(user);}@Testpublic void testFindAll() throws IOException { List<User> all = userMapper.findAll(); for(User user : all){ System.out.println(user); }}
修改MyBatis的核心配置文件，我们使用了注解替代的映射文件，所以我们只需要加载使用了注解的Mapper接口即可
<mappers> <!–扫描使用注解的类–> <mapper class=”com.zjq.mapper.UserMapper”></mapper></mappers>
或者指定扫描包含映射关系的接口所在的包也可以
<mappers> <!–扫描使用注解的类所在的包–> <package name=”com.zjq.mapper”></package></mappers>MyBatis的注解实现复杂映射开发
实现复杂关系映射之前我们可以在映射文件中通过配置来实现，使用注解开发后，我们可以使用@Results注解，@Result注解，@One注解，@Many注解组合完成复杂关系的配置
一对一查询一对一查询的模型
用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户
一对一查询的需求：查询一个订单，与此同时查询出该订单所属的用户
一对一查询的语句
对应的sql语句：
select * from orders;select * from user where id=查询出订单的uid;创建Order和User实体public class Order { private int id; private Date ordertime; private double total; //代表当前订单从属于哪一个客户 private User user;}public class User { private int id; private String username; private String password; private Date birthday;}创建OrderMapper接口public interface OrderMapper { List<Order> findAll();}使用注解配置Mapperpublic interface OrderMapper { @Select(“select * from orders”) @Results({ @Result(id=true,property = “id”,column = “id”), @Result(property = “ordertime”,column = “ordertime”), @Result(property = “total”,column = “total”), @Result(property = “user”,column = “uid”, javaType = User.class, one = @One(select = “com.zjq.mapper.UserMapper.findById”)) }) List<Order> findAll();}public interface UserMapper { @Select(“select * from user where id=#{id}”) User findById(int id);}测试结果@Testpublic void testSelectOrderAndUser() { List<Order> all = orderMapper.findAll(); for(Order order : all){ System.out.println(order); }}一对多查询一对多查询的模型
用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户
一对多查询的需求：查询一个用户，与此同时查询出该用户具有的订单
一对多查询的语句
对应的sql语句：
select * from user;select * from orders where uid=查询出用户的id;修改User实体public class Order { private int id; private Date ordertime; private double total; //代表当前订单从属于哪一个客户 private User user;}public class User { private int id; private String username; private String password; private Date birthday; //代表当前用户具备哪些订单 private List<Order> orderList;}创建UserMapper接口List<User> findAllUserAndOrder();使用注解配置Mapperpublic interface UserMapper { @Select(“select * from user”) @Results({ @Result(id = true,property = “id”,column = “id”), @Result(property = “username”,column = “username”), @Result(property = “password”,column = “password”), @Result(property = “birthday”,column = “birthday”), @Result(property = “orderList”,column = “id”, javaType = List.class, many = @Many(select = “com.zjq.mapper.OrderMapper.findByUid”)) }) List<User> findAllUserAndOrder();}public interface OrderMapper { @Select(“select * from orders where uid=#{uid}”) List<Order> findByUid(int uid);}测试结果List<User> all = userMapper.findAllUserAndOrder();for(User user : all){ System.out.println(user.getUsername()); List<Order> orderList = user.getOrderList(); for(Order order : orderList){ System.out.println(order); } System.out.println(“—————————–“);}多对多查询多对多查询的模型
用户表和角色表的关系为，一个用户有多个角色，一个角色被多个用户使用
多对多查询的需求：查询用户同时查询出该用户的所有角色
多对多查询的语句
对应的sql语句：
select * from user;select * from role r,user_role ur where r.id=ur.role_id and ur.user_id=用户的id创建Role实体，修改User实体public class User { private int id; private String username; private String password; private Date birthday; //代表当前用户具备哪些订单 private List<Order> orderList; //代表当前用户具备哪些角色 private List<Role> roleList;}public class Role { private int id; private String rolename;}添加UserMapper接口方法List<User> findAllUserAndRole();使用注解配置Mapperpublic interface UserMapper { @Select(“select * from user”) @Results({ @Result(id = true,property = “id”,column = “id”), @Result(property = “username”,column = “username”), @Result(property = “password”,column = “password”), @Result(property = “birthday”,column = “birthday”), @Result(property = “roleList”,column = “id”, javaType = List.class, many = @Many(select = “com.zjq.mapper.RoleMapper.findByUid”))})List<User> findAllUserAndRole();}public interface RoleMapper { @Select(“select * from role r,user_role ur where r.id=ur.role_id and ur.user_id=#{uid}”) List<Role> findByUid(int uid);}测试结果UserMapper mapper = sqlSession.getMapper(UserMapper.class);List<User> all = mapper.findAllUserAndRole();for(User user : all){ System.out.println(user.getUsername()); List<Role> roleList = user.getRoleList(); for(Role role : roleList){ System.out.println(role); } System.out.println(“———————————-“);}SSM框架整合1.1 原始方式整合1.准备工作
2.创建Maven工程
3.导入Maven坐标
参考：素材/配置文件/pom.xml文件
4.编写实体类public class Account { private int id; private String name; private double money; //省略getter和setter方法}5.编写Mapper接口public interface AccountMapper { //保存账户数据 void save(Account account); //查询账户数据 List<Account> findAll();}6.编写Service接口public interface AccountService { void save(Account account); //保存账户数据 List<Account> findAll(); //查询账户数据}7.编写Service接口实现@Service(“accountService”)public class AccountServiceImpl implements AccountService { public void save(Account account) { SqlSession sqlSession = MyBatisUtils.openSession(); AccountMapper accountMapper = sqlSession.getMapper(AccountMapper.class); accountMapper.save(account); sqlSession.commit(); sqlSession.close(); } public List<Account> findAll() { SqlSession sqlSession = MyBatisUtils.openSession(); AccountMapper accountMapper = sqlSession.getMapper(AccountMapper.class); return accountMapper.findAll(); }}8.编写Controller@Controllerpublic class AccountController { @Autowired private AccountService accountService; @RequestMapping(“/save”) @ResponseBody public String save(Account account){ accountService.save(account); return “save success”; } @RequestMapping(“/findAll”) public ModelAndView findAll(){ ModelAndView modelAndView = new ModelAndView(); modelAndView.setViewName(“accountList”); modelAndView.addObject(“accountList”,accountService.findAll()); return modelAndView; }}9.编写添加页面<%@ page contentType=”text/html;charset=UTF-8″ language=”java” %><html><head> <title>Title</title></head><body> 保存账户信息表单 <form action=”${pageContext.request.contextPath}/save.action” method=”post”> 用户名称<input type=”text” name=”name”><br/> 账户金额<input type=”text” name=”money”><br/> <input type=”submit” value=”保存”><br/> </form></body></html>10.编写列表页面<table border=”1″> <tr> <th>账户id</th> <th>账户名称</th> <th>账户金额</th> </tr> <c:forEach items=”${accountList}” var=”account”> <tr> <td>${account.id}</td> <td>${account.name}</td> <td>${account.money}</td> </tr> </c:forEach></table>11.编写相应配置文件(文件参考目录：素材/配置文件)
?Spring配置文件：applicationContext.xml
?SprngMVC配置文件：spring-mvc.xml
?MyBatis映射文件：AccountMapper.xml
?MyBatis核心文件：sqlMapConfig.xml
?数据库连接信息文件：jdbc.properties
?Web.xml文件：web.xml
?日志文件：[log4j.xml](
12.测试添加账户
13.测试账户列表
1.2 Spring整合MyBatis1.整合思路
2.将SqlSessionFactory配置到Spring容器中<!–加载jdbc.properties–><context:property-placeholder location=”classpath:jdbc.properties”/><!–配置数据源–><bean id=”dataSource” class=”com.mchange.v2.c3p0.ComboPooledDataSource”> <property name=”driverClass” value=”${jdbc.driver}”/> <property name=”jdbcUrl” value=”${jdbc.url}”/> <property name=”user” value=”${jdbc.username}”/> <property name=”password” value=”${jdbc.password}”/></bean><!–配置MyBatis的SqlSessionFactory–><bean id=”sqlSessionFactory” class=”org.mybatis.spring.SqlSessionFactoryBean”> <property name=”dataSource” ref=”dataSource”/> <property name=”configLocation” value=”classpath:sqlMapConfig.xml”/></bean>3.扫描Mapper，让Spring容器产生Mapper实现类<!–配置Mapper扫描–><bean class=”org.mybatis.spring.mapper.MapperScannerConfigurer”> <property name=”basePackage” value=”com.zjq.mapper”/></bean>4.配置声明式事务控制<!–配置声明式事务控制–><bean id=”transacionManager” class=”org.springframework.jdbc.datasource.DataSourceTransactionManager”> <property name=”dataSource” ref=”dataSource”/></bean><tx:advice id=”txAdvice” transaction-manager=”transacionManager”> <tx:attributes> <tx:method name=”*”/> </tx:attributes></tx:advice><aop:config> <aop:pointcut id=”txPointcut” expression=”execution(* com.zjq.service.impl.*.*(..))”/> <aop:advisor advice-ref=”txAdvice” pointcut-ref=”txPointcut”/></aop:config>5.修改Service实现类代码@Service(“accountService”)public class AccountServiceImpl implements AccountService { @Autowired private AccountMapper accountMapper; public void save(Account account) { accountMapper.save(account); } public List<Account> findAll() { return accountMapper.findAll(); }}
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