mybatis-study

建立一个mybatis项目

进行父工程pom.xml编写，导入依赖,mysql驱动，mybatis官方文档和junit测试

<!--    导入依赖--><dependencies><!--        mysql驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>5.1.17</version><!--            如果与数据库不匹配将useeSSl=false--></dependency><!--官方文档配置--><!--        mybatis--><!-- https://mvnrepository.com/artifact/org.mybatis/mybatis --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.2</version></dependency><!--        junit--><!--        junit进行测试--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency></dependencies>

另外在父工程pom.xml中加入

    <properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties>

识别类型为utf-8

进行程序的编写

再进行程序中porm.xml的编写前面的配置基本相同，在build中配置resources，来防止资源导出失败的问题

<?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"><parent><artifactId>mybatis-study</artifactId><groupId>org.example</groupId><version>1.0-SNAPSHOT</version></parent><modelVersion>4.0.0</modelVersion><artifactId>mybatis-01</artifactId><!--    build中配置resources，来防止资源导出失败的问题--><build><resources><resource><directory>src/main/resources</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource><resource><directory>src/main/java</directory><includes><include>**/*.properties</include><include>**/*.xml</include></includes><filtering>true</filtering></resource></resources></build><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties></project>

编写工具类mybatisUtils

进行工具类的编写，通过sqlSessionFactoryBuilder获取SqlSessionFactory

package com.lyl.utils;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.IOException;
import java.io.InputStream;//sqlSessionFactory-->sqlSessionpublic class mybatisUtils {private static SqlSessionFactory sqlSessionFactory;static {try {//使用mybatis第一步：获取SqlSessionFactory对象String resource = "mybatis-config.xml";InputStream inputStream = Resources.getResourceAsStream(resource);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}//既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。//你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。public static SqlSession getSqlSession() {return sqlSessionFactory.openSession();}
}

mybatis配置文件

错误信息：The connection property ‘zeroDateTimeBehavior’ acceptable values are: ‘CONVERT_TO_NULL’,‘EXCEPTION’ or ‘ROUND’.The value ‘convertToNull’ is not acceptable.

解决方案
在jdbc 的配置文件中的URL加上 ?useSSL=false

原因
url地址中useSSL如果idea和mysql的版本不兼容
将useSSL=true改为useSSL=false

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--configuration核心配置文件-->
<configuration><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/>
<!--                useSSl=false说明idea和mysql版本不兼容-->
<!--                useSSl=false这是个主要的问题--><property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8"/><property name="username" value="root"/><property name="password" value="123456"/></dataSource></environment></environments>
<!--    每一个mapper都需要在mybatis核心配置文件中注册--><mappers><mapper resource="com/lyl/dao/UserMapper.xml"/></mappers>
</configuration>

进行实体类编写

有参，无参，get，set

package com.lyl.pojo;
//实体类
public  class User {private int id;private String name;private String pwd;public User() {}public User(int id, String name, String pwd) {this.id = id;this.name = name;this.pwd = pwd;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPassword() {return pwd;}public String getPwd() {return pwd;}
}

进行usermapper接口编写

package com.lyl.dao;import com.lyl.pojo.User;import java.util.List;public interface UserDao {List<User> getUserList();
}

进行userMapper.xml编写

查询所有的信息从user

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.lyl.dao.UserDao"><select id="getUserList" resultType="com.lyl.pojo.User">select * from mybatis.user</select>
</mapper>

进行测试编写test

建议测试类的位置与编写代码的位置保持一致

package com.lyl.dao;import com.lyl.pojo.User;
import com.lyl.utils.mybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;import java.util.List;public class UserDaoTest {@Testpublic void test(){//        第一步：获取SqlSession对象SqlSession sqlSession = mybatisUtils.getSqlSession();//       getMapper执行sqlUserDao userdao = sqlSession.getMapper(UserDao.class);List<User> userList = userdao.getUserList();for(User user: userList){System.out.println(user);}//        关闭sqlSessionsqlSession.close();}
}

出现的错误

错误信息：

com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException

解决方法：在pom.xml文件中配置

<properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties>

原因：
注解中的中文字符识别不了