Mybatis的配置文件

1.mybatis映射文件

1.1mybatis映射文件概述

1.2Mybatis增删改查的语句案例

2.mybatis核心配置文件

核心配置文件可以配置的标签

2.1environments标签 的环境配置

2.2mapper标签

2.3properties标签

2.4 typeAliases标签

3核心配置文件的深入

3.1typeHandlers

根据开发步骤我们依次完成
1.定义转换类继承类BaseTypeHandler
2.实现其方法

package com.itheima.handler;

import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Date;

public class DateTypeHandler extends BaseTypeHandler<Date> {
    //将java类型 转换成 数据库需要的类型
    public void setNonNullParameter(PreparedStatement preparedStatement, int i, Date date, JdbcType jdbcType) throws SQLException {
        long time = date.getTime();
        preparedStatement.setLong(i,time);
    }
//    public void setNonNullParameter(PreparedStatement preparedStatement,int i,Date date,JdbcType jdbcType) throws SQLException{
//        long time=date.getTime();
//        preparedStatement.setLong(i,time);
//    }
    //将数据库中类型 转换成java类型
    //String参数  要转换的字段名称
    //ResultSet 查询出的结果集
    public Date getNullableResult(ResultSet resultSet, String s) throws SQLException {
        //获得结果集中需要的数据(long) 转换成Date类型 返回
        long aLong = resultSet.getLong(s);
        Date date = new Date(aLong);
        return date;
    }
//    public Date getNullableResult(ResultSet resultSet,String s)throws SQLException{
//        long aLong=resultSet.getLong(s);
//        Date date=new Date(aLong)
//    }

    //将数据库中类型 转换成java类型
    public Date getNullableResult(ResultSet resultSet, int i) throws SQLException {
        long aLong = resultSet.getLong(i);
        Date date = new Date(aLong);
        return date;
    }

    //将数据库中类型 转换成java类型
    public Date getNullableResult(CallableStatement callableStatement, int i) throws SQLException {
        long aLong = callableStatement.getLong(i);
        Date date = new Date(aLong);
        return date;
    }
}

3.配置文件进行配置

   <!--注册类型处理器-->
    <typeHandlers>
        <typeHandler handler="com.itheima.handler.DateTypeHandler"></typeHandler>
    </typeHandlers>

4.test案例

    @Test
    public void test2() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user = mapper.findById(15);
        System.out.println("user中的birthday："+user.getBirthday());

        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void test1() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        //创建user
        User user = new User();
        user.setUsername("ceshi");
        user.setPassword("abc");
        user.setBirthday(new Date());
        //执行保存造作
        mapper.save(user);

        sqlSession.commit();
        sqlSession.close();
    }

3.2plugins标签

Mybatis使用第三方插件进行拓展，分页助手PageHelper是将分页的复杂操作进行的封装，使用简单的方式即可获得分页的相关数据。
开发步骤

1.pom.xml导入坐标

<?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>com.itheima</groupId>
  <artifactId>itheima_mybatis_config</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>


    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.32</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        
        
        
<!--        分页功能坐标配置-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>3.7.5</version>
        </dependency>
        <dependency>
            <groupId>com.github.jsqlparser</groupId>
            <artifactId>jsqlparser</artifactId>
            <version>0.9.1</version>
        </dependency>

    </dependencies>


</project>

2.再配置文件中配置PageHelper插件

    <!--配置分页助手插件-->
    <plugins>
        <plugin interceptor="com.github.pagehelper.PageHelper">
            <property name="dialect" value="mysql"></property>
        </plugin>
    </plugins>

3.测试

 @Test
    public void test3() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        //设置分页相关参数   当前页+每页显示的条数
        PageHelper.startPage(3,3);

        List<User> userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }

        //获得与分页相关参数
        PageInfo<User> pageInfo = new PageInfo<User>(userList);
        System.out.println("当前页："+pageInfo.getPageNum());
        System.out.println("每页显示条数："+pageInfo.getPageSize());
        System.out.println("总条数："+pageInfo.getTotal());
        System.out.println("总页数："+pageInfo.getPages());
        System.out.println("上一页："+pageInfo.getPrePage());
        System.out.println("下一页："+pageInfo.getNextPage());
        System.out.println("是否是第一个："+pageInfo.isIsFirstPage());
        System.out.println("是否是最后一个："+pageInfo.isIsLastPage());

        sqlSession.close();
    }

结果展示