mybatis基础教程

冷不防 2022-08-18 15:14 192阅读 0赞

# 1.   MyBatis介绍 #

MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis。

MyBatis是支持普通SQL查询，存储过程和高级映射的优秀持久层框架。MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及对结果集的检索封装。MyBatis可以使用简单的XML或注解用于配置和原始映射，将接口和Java的POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录.

# 2.   快速入门 #

1)         新建java工程，添加jar包（mybatis jar包和mysql jar包）

2)         在mysql中建库和表

<table> 
 <tbody> 
 <tr> 
 <td> CREATE DATABASE mybatis; USE mybatis; CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(20), age INT); INSERT INTO users(NAME, age) VALUES('Tom', 12); INSERT INTO users(NAME, age) VALUES('Jack', 11); </td> 
 </tr> 
 </tbody> 
</table>

3)         在src目录下添加mybatis的配置文件config.xml

4)         定义表所对应的实体类

<table> 
 <tbody> 
 <tr> 
 <td> package&nbsp;com.morris.mybatis.entity; public&nbsp;class&nbsp;UserEntity { &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;private&nbsp;Integer&nbsp;id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;private&nbsp;String&nbsp;name; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;private&nbsp;Integer&nbsp;age; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;UserEntity(Integer id, String name, Integer age) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;super(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.id&nbsp;= id; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.name&nbsp;= name; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.age&nbsp;= age; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;UserEntity() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;super(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;//&nbsp;TODO&nbsp;Auto-generated constructor stub &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;Integer getId() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;return&nbsp;id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;void&nbsp;setId(Integer id) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.id&nbsp;= id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;String getName() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;return&nbsp;name; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;void&nbsp;setName(String name) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.name&nbsp;= name; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;Integer getAge() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;return&nbsp;age; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;void&nbsp;setAge(Integer age) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;this.age&nbsp;= age; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;String toString() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;return&nbsp;"UserEntity [id="&nbsp;+&nbsp;id&nbsp;+&nbsp;", name="&nbsp;+&nbsp;name&nbsp;+&nbsp;", age="&nbsp;+age&nbsp;+&nbsp;"]"; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } } </td> 
 </tr> 
 </tbody> 
</table>

5)         定义操作users表的sql映射文件userMapper.xml

6)         在conf.xml文件中注册userMapper.xml文件

<table> 
 <tbody> 
 <tr> 
 <td> &lt;mappers&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;mapperresource="com/morris/mybatis/entity/userMapper.xml"&nbsp;/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;/mappers&gt; </td> 
 </tr> 
 </tbody> 
</table>

7)         编写测试代码：执行定义的select语句

<table> 
 <tbody> 
 <tr> 
 <td> package&nbsp;com.morris.mybatis.entity; import&nbsp;java.io.InputStream; import&nbsp;org.apache.ibatis.session.SqlSession; import&nbsp;org.apache.ibatis.session.SqlSessionFactory; import&nbsp;org.apache.ibatis.session.SqlSessionFactoryBuilder; &nbsp; public&nbsp;class&nbsp;Test { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;static&nbsp;void&nbsp;main(String[] args) { &nbsp; &nbsp; &nbsp; &nbsp; //加载配置文件 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; InputStream is = Test.class.getClassLoader().getResourceAsStream( &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;"config.xml"); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSessionFactory sessionFactory =&nbsp;newSqlSessionFactoryBuilder() &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; .build(is); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = sessionFactory.openSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String statement ="com.morris.mybatis.entity.userMapper.getUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; UserEntity ue = session.selectOne(statement, 1); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(ue); &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } } </td> 
 </tr> 
 </tbody> 
</table>

# 3.   对表的crud操作 #

## 3.1.  基于xml的实现 ##

1)         自定义sql xml文件

<table> 
 <tbody> 
 <tr> 
 <td> &lt;?xml&nbsp;version="1.0"&nbsp;encoding="UTF-8"&nbsp;?&gt; &lt;!DOCTYPE&nbsp;mapper&nbsp;PUBLIC&nbsp;"-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"&gt; &lt;mapper&nbsp;namespace="com.morris.mybatis.test2.userMapper"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;!--&nbsp;查询所有的用户&nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;select&nbsp;id="getAllUser"resultType="com.morris.mybatis.test2.UserEntity"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select * from users &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;/select&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;!--&nbsp;添加一个用户&nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;insert&nbsp;id="addUser"parameterType="com.morris.mybatis.test2.UserEntity"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; insert into users(name,age) values(#{name},#{age}) &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;/insert&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;!--&nbsp;修改一个用户&nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;update&nbsp;id="updateUser"parameterType="com.morris.mybatis.test2.UserEntity"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; update users set name=#{name},age=#{age} where id=#{id} &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;/update&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;!--&nbsp;删除一个用户&nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;delete&nbsp;id="deleteUser"&nbsp;parameterType="int"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; delete from users where &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; id=#{id} &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;/delete&gt; &lt;/mapper&gt; </td> 
 </tr> 
 </tbody> 
</table>

2)         在config.xml文件中注册

<table> 
 <tbody> 
 <tr> 
 <td> &lt;mapper resource="com/morris/mybatis/test2/userMapper.xml" /&gt; </td> 
 </tr> 
 </tbody> 
</table>

3)         在dao中调用

<table> 
 <tbody> 
 <tr> 
 <td> package com.morris.mybatis.test2; import java.io.InputStream; import java.util.List; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import org.junit.Test; import com.morris.mybatis.util.MyBatisUtil; &nbsp; public class Test2 { &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void addUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String paramString = "com.morris.mybatis.test2.userMapper.addUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = session.insert(paramString, new UserEntity(-1, "morris", 22)); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void deleteUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String statement = "com.morris.mybatis.test2.userMapper.deleteUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = session.update(statement, 4); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void getAllUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String statement = "com.morris.mybatis.test2.userMapper.getAllUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; List&lt;UserEntity&gt; list = session.selectList(statement); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; for (UserEntity userEntity : list) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println(userEntity); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void updateUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String statement = "com.morris.mybatis.test2.userMapper.updateUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = session.update(statement, new UserEntity(2, "morris", 25)); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; } </td> 
 </tr> 
 </tbody> 
</table>

## 3.2.  基于注解的实现 ##

1)         自定义接口UserMapper

<table> 
 <tbody> 
 <tr> 
 <td> package&nbsp;com.morris.mybatis.test3; &nbsp; import&nbsp;java.util.List; &nbsp; import&nbsp;org.apache.ibatis.annotations.Delete; import&nbsp;org.apache.ibatis.annotations.Insert; import&nbsp;org.apache.ibatis.annotations.Select; import&nbsp;org.apache.ibatis.annotations.Update; &nbsp; public&nbsp;interface&nbsp;UserMapper { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;@Insert("insert into users(name,age) values(#{name},#{age})") &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;int&nbsp;addUser(UserEntity userEntity); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;@Delete("delete from users where id=#{id}") &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;int&nbsp;deleteUser(int&nbsp;id); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;@Update("update users set name=#{name},age=#{age} where id=#{id}") &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;int&nbsp;updateUser(UserEntity userEntity); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;@Select("select * from users") &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;public&nbsp;List&lt;UserEntity&gt; getAllUsers(); } </td> 
 </tr> 
 </tbody> 
</table>

2)         在config.xml文件中注册接口

<table> 
 <tbody> 
 <tr> 
 <td> &lt;mapper class="com.morris.mybatis.test3.UserMapper" /&gt; </td> 
 </tr> 
 </tbody> 
</table>

3)         在dao中使用

<table> 
 <tbody> 
 <tr> 
 <td> package com.morris.mybatis.test3; &nbsp; import java.io.InputStream; import java.util.List; &nbsp; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import org.junit.Test; &nbsp; import com.morris.mybatis.util.MyBatisUtil; &nbsp; public class Test3 { &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void addUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; UserMapper mapper = session.getMapper(UserMapper.class); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = mapper.addUser(new UserEntity(-1, "morris131", 50)); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void deleteUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; UserMapper mapper = session.getMapper(UserMapper.class); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = mapper.deleteUser(8); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void getAllUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; UserMapper mapper = session.getMapper(UserMapper.class); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; List&lt;UserEntity&gt; list = mapper.getAllUsers(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; for (UserEntity userEntity : list) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; System.out.println(userEntity); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; @Test &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void updateUser() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession session = MyBatisUtil.getSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; UserMapper mapper = session.getMapper(UserMapper.class); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; int i = mapper.updateUser(new UserEntity(7, "morris131", 27)); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; session.close(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(i); &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; } </td> 
 </tr> 
 </tbody> 
</table>

# 4.   MyBatis的优化 #

## 4.1.  连接数据库的配置单独放在一个properties文件中 ##

1)         新建一个数据库的配置文件db.properties

<table> 
 <tbody> 
 <tr> 
 <td> driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis username=root password=root </td> 
 </tr> 
 </tbody> 
</table>

2)         在config.xml文件中使用

<table> 
 <tbody> 
 <tr> 
 <td> &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;properties resource="db.properties"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/properties&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;environments default="development"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;environment id="development"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &lt;transactionManager type="JDBC" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &lt;dataSource type="POOLED"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;property name="driver" value="${driver}" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;property name="url" value="${url}" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;property name="username" value="${username}" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;property name="password" value="${password}" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &lt;/dataSource&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/environment&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/environments&gt; </td> 
 </tr> 
 </tbody> 
</table>

## 4.2.  为实体类定义别名,简化sql映射xml文件中的引用 ##

1)         在config.xml文件中配置别名

<table> 
 <tbody> 
 <tr> 
 <td> &lt;typeAliases&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;package name="com.morris.mybatis.test2"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/typeAliases&gt; </td> 
 </tr> 
 </tbody> 
</table>

2)         在userMapper.xml文件中使用，结果类型不需要带包名了

<table> 
 <tbody> 
 <tr> 
 <td> &lt;select id="getAllUser" resultType="UserEntity"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select * from users &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/select&gt; </td> 
 </tr> 
 </tbody> 
</table>

## 4.3.  可以在src下加入log4j的配置文件,打印日志信息 ##

### 4.3.1.   方法一 ###

1)         引入log4j的jar包

2)         在src下新建log4j.xml文件

<table> 
 <tbody> 
 <tr> 
 <td> log4j.rootLogger=DEBUG, Console log4j.appender.Console=org.apache.log4j.ConsoleAppender log4j.appender.Console.layout=org.apache.log4j.PatternLayout log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n log4j.logger.java.sql.ResultSet=INFO log4j.logger.org.apache=INFO log4j.logger.java.sql.Connection=DEBUG log4j.logger.java.sql.Statement=DEBUG log4j.logger.java.sql.PreparedStatement=DEBUG </td> 
 </tr> 
 </tbody> 
</table>

### 4.3.2.   方法二 ###

1)         引入log4j的jar包

2)         在src下新建log4j.xml文件

<table> 
 <tbody> 
 <tr> 
 <td> &lt;?xml version="1.0" encoding="UTF-8" ?&gt; &lt;!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"&gt; &lt;log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;appender name="STDOUT" class="org.apache.log4j.ConsoleAppender"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;layout class="org.apache.log4j.PatternLayout"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &lt;param name="ConversionPattern" &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; value="%-5p %d{MM-dd HH:mm:ss,SSS} %m&nbsp; (%F:%L) \n" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/layout&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/appender&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;logger name="java.sql"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;level value="debug" /&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/logger&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;logger name="org.apache.ibatis"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;level value="debug" /&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/logger&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;root&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;level value="debug" /&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;appender-ref ref="STDOUT" /&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/root&gt; </td> 
 </tr> 
 </tbody> 
</table>

# 5.   解决字段名与属性名不相同的冲突 #

## 5.1.  准备表和数据 ##

<table> 
 <tbody> 
 <tr> 
 <td> CREATE TABLE orders( &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; order_id INT PRIMARY KEY AUTO_INCREMENT, &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; order_no VARCHAR(20), &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; order_price FLOAT ); INSERT INTO orders(order_no, order_price) VALUES('aaaa', 23); INSERT INTO orders(order_no, order_price) VALUES('bbbb', 33); INSERT INTO orders(order_no, order_price) VALUES('cccc', 22); </td> 
 </tr> 
 </tbody> 
</table>

## 5.2.  定义实体类 ##

<table> 
 <tbody> 
 <tr> 
 <td> &nbsp; package com.morris.mybatis.entity; &nbsp; public class OrderEntity { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private int id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private String orderNo; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private float price; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public int getId() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; return id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void setId(int id) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.id = id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public String getOrderNo() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; return orderNo; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void setOrderNo(String orderNo) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.orderNo = orderNo; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public float getPrice() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; return price; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public void setPrice(float price) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.price = price; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public OrderEntity(int id, String orderNo, float price) { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; super(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.id = id; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.orderNo = orderNo; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; this.price = price; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public OrderEntity() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; super(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; // TODO Auto-generated constructor stub &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; @Override &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public String toString() { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; return "OrderEntity [id=" + id + ", orderNo=" + orderNo + ", price=" &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; + price + "]"; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } &nbsp; } </td> 
 </tr> 
 </tbody> 
</table>

## 5.3.  实现getOrderById(id)的查询： ##

<table> 
 <tbody> 
 <tr> 
 <td> 方式一:&nbsp;通过在sql语句中定义别名 &lt;select id="selectOrder" parameterType="int" resultType="_Order"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select order_id id, order_no orderNo,order_price price from orders where order_id=#{id} &lt;/select&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 方式二:&nbsp;通过&lt;resultMap&gt; &lt;select id="selectOrderResultMap" parameterType="int"resultMap="orderResultMap"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select * from orders where order_id=#{id} &lt;/select&gt; &nbsp; &lt;resultMap&nbsp;type="_Order" id="orderResultMap"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;id property="id" column="order_id"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;result property="orderNo" column="order_no"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;result property="price" column="order_price"/&gt; &lt;/resultMap&gt; </td> 
 </tr> 
 </tbody> 
</table>

# 6.   一对多的关联查询 #

1)         建立一张学生表和班级表

<table> 
 <tbody> 
 <tr> 
 <td> CREATE TABLE classes ( &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; class_id &nbsp;&nbsp; INT&nbsp; &nbsp; &nbsp; &nbsp;&nbsp; AUTO_INCREMENT PRIMARY KEY, &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; class_name &nbsp; &nbsp;&nbsp; VARCHAR(20) ) &nbsp; INSERT INTO classes(class_name) VALUES('java') INSERT INTO classes(class_name) VALUES('android') &nbsp; SELECT * FROM classes &nbsp; &nbsp; CREATE TABLE student ( &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; stu_id &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; INT &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; AUTO_INCREMENT &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; PRIMARY KEY, &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; stu_name &nbsp; &nbsp; &nbsp; &nbsp; VARCHAR(20), &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; class_id &nbsp;&nbsp; INT &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; REFERENCES classes(class_id) ) &nbsp; INSERT INTO student(stu_name,class_id) VALUES('张三',1) INSERT INTO student(stu_name,class_id) VALUES('李四',1) INSERT INTO student(stu_name,class_id) VALUES('王五',2) &nbsp; SELECT * FROM student </td> 
 </tr> 
 </tbody> 
</table>

2)         创建学生实体类和班级实体类

<table> 
 <tbody> 
 <tr> 
 <td> public class Student { &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private int id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private String name; } public class Classes { &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private int id; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private String name; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; private List&lt;Student&gt; students; } </td> 
 </tr> 
 </tbody> 
</table>

3)         定义sql映射文件ClassMapper.xml

<table> 
 <tbody> 
 <tr> 
 <td> &lt;!-- 方式一:&nbsp;嵌套结果:&nbsp;使用嵌套结果映射来处理重复的联合结果的子集 SELECT * FROM class c,student s WHERE c.C_id=s.class_id AND&nbsp; c.c_id=1 &nbsp;--&gt; &lt;select id="getClass3" parameterType="int" resultMap="ClassResultMap3"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select * from class c, student s where c.C_id=s.class_id and&nbsp; c.c_id=#{id} &lt;/select&gt; &lt;resultMap type="_Classes" id="ClassResultMap3"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;id property="id" column="c_id"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;result property="name" column="c_name"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;!-- ofType指定students集合中的对象类型&nbsp;--&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;collection&nbsp;property="students"&nbsp;ofType="_Student"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;id property="id" column="s_id"/&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;result property="name" column="s_name"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/collection&gt; &lt;/resultMap&gt; &nbsp; &lt;!-- &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;方式二：嵌套查询：通过执行另外一个SQL映射语句来返回预期的复杂类型 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SELECT * FROM class WHERE c_id=1; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SELECT * FROM student WHERE class_id=1&nbsp; //1是第一个查询得到的c_id字段的值 &nbsp;--&gt; &nbsp;&lt;select id="getClass4" parameterType="int" resultMap="ClassResultMap4"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; select * from class where c_id=#{id} &nbsp;&lt;/select&gt; &nbsp;&lt;resultMap type="_Classes" id="ClassResultMap4"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;id property="id" column="c_id"/&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;result property="name" column="c_name"/&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;collection&nbsp;property="students"&nbsp;ofType="_Student"column="c_id"&nbsp;select="getStudent"&gt;&lt;/collection&gt; &nbsp;&lt;/resultMap&gt; &nbsp; &nbsp;&lt;select id="getStudent" parameterType="int" resultType="_Student"&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SELECT s_id id, s_name name FROM student WHERE class_id=#{id} &nbsp;&lt;/select&gt; </td> 
 </tr> 
 </tbody> 
</table>

# 7.   动态sql与模糊查询 #

## 7.1.  提出需求: ##

实现多条件查询用户(姓名模糊匹配, 年龄在指定的最小值到最大值之间)

## 7.2.  准备数据表和数据: ##

<table> 
 <tbody> 
 <tr> 
 <td> create table d_user(&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; id int primary key auto_increment,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; name varchar(10), &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; age int(3) ); &nbsp; insert into d_user(name,age) values('Tom',12);&nbsp; insert into d_user(name,age) values('Bob',13);&nbsp; insert into d_user(name,age) values('Jack',18); </td> 
 </tr> 
 </tbody> 
</table>

## 7.3.  ConditionUser(查询条件实体类) ##

<table> 
 <tbody> 
 <tr> 
 <td> private String name; private int minAge; private int maxAge; </td> 
 </tr> 
 </tbody> 
</table>

## 7.4.  User(表实体类) ##

<table> 
 <tbody> 
 <tr> 
 <td> private int id; private String name; private int age; </td> 
 </tr> 
 </tbody> 
</table>

## 7.5.  userMapper.xml(映射文件) ##

<table> 
 <tbody> 
 <tr> 
 <td> &lt;?xml version="1.0" encoding="UTF-8" ?&gt; &lt;!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; "http://mybatis.org/dtd/mybatis-3-mapper.dtd"&gt; &lt;mapper namespace="com.atguigu.day03_mybatis.test6.userMapper"&gt; &lt;select id="getUser" parameterType="com.atguigu.day03_mybatis.test6.ConditionUser" resultType="com.atguigu.day03_mybatis.test6.User"&gt; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; select * from d_user where age&gt;=#{minAge} and age&amp;lt;=#{maxAge} &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&lt;if test='name!="%null%"'&gt;and name like #{name}&lt;/if&gt; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &lt;/select&gt; &lt;/mapper&gt; </td> 
 </tr> 
 </tbody> 
</table>

## 7.6.  UserTest(测试) ##

<table> 
 <tbody> 
 <tr> 
 <td> public class UserTest { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; public static void main(String[] args) throws IOException { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Reader reader = Resources.getResourceAsReader("conf.xml"); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; SqlSession sqlSession = sessionFactory.openSession(); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; String statement = "com.atguigu.day03_mybatis.test6.userMapper.getUser"; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; List&lt;User&gt; list = sqlSession.selectList(statement, new ConditionUser("%a%", 1, 12)); &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; System.out.println(list); &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; } } </td> 
 </tr> 
 </tbody> 
</table>

## 7.7.  MyBatis中可用的动态SQL标签 ##

![clip_image001fce19e77-07d6-4dcc-a3a8-6fd70c77a473.png][]

[clip_image001fce19e77-07d6-4dcc-a3a8-6fd70c77a473.png]: https://note.wiz.cn/api/document/files/unzip/e7e44252-f257-41d4-8bc1-3960ae3ef7c0/b20011ee-8f78-446e-a273-f69ca3d4c717.2251/index_files/clip_image001fce19e77-07d6-4dcc-a3a8-6fd70c77a473.png