入门步骤：
先给出项目结构：
0：新建Maven工程，导入Maven依赖：mysql-connector-java、mybatis、junit。
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.example</groupId> <artifactId>mybatis-test</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.16</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </dependency> </dependencies> </project>
1.1、准备好数据库，新建account表(id，name，money)，填充若干条记录。
database：test port：3306 table：account
1.2、编写account表对应的实体类Account。
package cn.liuxingchang.domain; import java.io.Serializable; public class Account implements Serializable { private Integer id; private String name; private Double money; @Override public String toString() { return "Account{" + "id=" + id + ", name='" + name + '\'' + ", money=" + money + '}'; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Double getMoney() { return money; } public void setMoney(Double money) { this.money = money; } }
1.3、编写QueryVo，封装Account作为查询参数parameterType。
package cn.liuxingchang.domain; public class QueryVo { private Account account; public Account getAccount() { return account; } public void setAccount(Account account) { this.account = account; } @Override public String toString() { return super.toString(); } }
2.1、编写AccountDao接口。
package cn.liuxingchang.dao; import cn.liuxingchang.domain.Account; import cn.liuxingchang.domain.QueryVo; import java.util.List; public interface AccountDao { List<Account> findByQueryVo(QueryVo queryVo); }
2.2、编写AccountMapper.xml。
<?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="cn.liuxingchang.dao.AccountDao"> <select id="findByQueryVo" resultType="cn.liuxingchang.domain.Account" parameterType="cn.liuxingchang.domain.QueryVo"> select * from account where name like #{account.name} </select> </mapper>说明：#{account.name}里的account.name这种写法叫做OGNL(Object Graph Navigation Language：对象图导航语言)。这种写法什么意思呢？很明显，这里的大括号是想通过parameterType为cn.liuxingchang.domain.QueryVo的一个实例(假如叫queryVo)，去获取它的成员account(Account类型)，再去获取account的成员name(String类型)，正常的Java格式是queryVo.getAccount().getName()，显然这种写法很长，OGNL把一个get方法的get和()去掉，剩下部分首字母小写。比如getAccount()，去掉get和()，剩下Account，再将首字母小写，变成了account。于是， queryVo.getAccount().getName()用OGNL就可以写成queryVo.account.name！明显变短了有没有！
3、编写MyBatis配置文件mybatis.xml。
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <environments default="mysql"> <environment id="mysql"> <transactionManager type="JDBC"></transactionManager> <dataSource type="POOLED"> <property name="driver" value="com.mysql.cj.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/Test?characterEncoding=UTF8&serverTimezone=Asia/Shanghai"/> <property name="username" value="root"/> <property name="password" value="root"/> </dataSource> </environment> </environments> <mappers> <mapper resource="mapper/AccountMapper.xml" /> </mappers> </configuration>
4、编写测试类Test。
import cn.liuxingchang.dao.AccountDao; import cn.liuxingchang.domain.Account; import cn.liuxingchang.domain.QueryVo; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.InputStream; import java.util.List; public class Test { @org.junit.Test public void test() throws Exception { InputStream in = Resources.getResourceAsStream("mybatis.xml"); SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder(); SqlSessionFactory factory = builder.build(in); SqlSession session = factory.openSession(); AccountDao accountDao = session.getMapper(AccountDao.class); Account a = new Account(); a.setName("%a%"); QueryVo queryVo = new QueryVo(); queryVo.setAccount(a); List<Account> accounts = accountDao.findByQueryVo(queryVo); for(Account account: accounts) { System.out.println(account); } session.close(); in.close(); } }
