MyBatis学习（七）

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MyBatis映射

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package com.xiaoguan.mapper;

import com.xiaoguan.pojo.Class;

public interface ClassMapper {
    Class selectByIdStep2(Integer cid);
    Class selectByCollection(Integer cid);
    Class selectByStep1(Integer cid);
}

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package com.xiaoguan.mapper;

import com.xiaoguan.pojo.Student;

import java.util.List;

public interface StudentMapper {
    Student selectByIdStep1(Integer id);
    Student selectByIdAssociation(Integer id);
    Student selectById(Integer id);
    List<Student> selectByCidStep2(Integer id);
}

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package com.xiaoguan.pojo;

import java.util.List;
import java.util.Objects;

public class Class {
    private Integer cid;
    private String cname;
    private List<Student> stus;

    @Override
    public String toString() {
        return "Class{" +
                "cid=" + cid +
                ", cname='" + cname + '\'' +
                ", stus=" + stus +
                '}';
    }

    public List<Student> getStus() {
        return stus;
    }

    public void setStus(List<Student> stus) {
        this.stus = stus;
    }

    public Class() {
    }

    public Class(Integer cid, String cname) {
        this.cid = cid;
        this.cname = cname;
    }

    public Integer getCid() {
        return cid;
    }

    public void setCid(Integer cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Class aClass = (Class) o;
        return Objects.equals(getCid(), aClass.getCid()) && Objects.equals(getCname(), aClass.getCname());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getCid(), getCname());
    }

}

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package com.xiaoguan.pojo;

import java.util.Objects;

public class Student {
    private Integer sid;
    private String sname;
    private Class clazz;

    @Override
    public String toString() {
        return "Student{" +
                "sid=" + sid +
                ", sname='" + sname + '\'' +
                ", clazz=" + clazz +
                '}';
    }

    public Class getClazz() {
        return clazz;
    }

    public void setClazz(Class clazz) {
        this.clazz = clazz;
    }

    public Student() {
    }

    public Student(Integer sid, String sname) {
        this.sid = sid;
        this.sname = sname;
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        return Objects.equals(getSid(), student.getSid()) && Objects.equals(getSname(), student.getSname());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getSid(), getSname());
    }

}

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package com.xiaoguan.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;

/**
 * MyBatis工具类
 */
public class SqlSessionUtils {
    private static SqlSessionFactory sqlSessionFactory;
    private SqlSessionUtils() {}
    static {
        try {
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private static ThreadLocal<SqlSession> local=new ThreadLocal<>();
    /**
     * 获取会话对象
     * @return 会话对象
     */
    public static SqlSession openSession(){
        SqlSession sqlSession = local.get();
        if (sqlSession==null) {
            sqlSession=sqlSessionFactory.openSession();
            local.set(sqlSession);
        }
        return sqlSession;

    }

    /**
     * 关闭sqlSession对象
     * @param sqlSession
     */
    public static void close(SqlSession sqlSession){
        if (sqlSession != null) {
            sqlSession.close();
            //移除sqlSession对象和当前线程绑定关系
            local.remove();
        }
    }
}

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<?xml version="1.0" encoding="UTF-8"?>

<configuration debug="false">
    <!-- 控制台输出 -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
    </appender>
    <!-- 按照每天生成日志文件 -->
    <!--mybatis log configure-->
    <logger name="com.apache.ibatis" level="TRACE"/>
    <logger name="java.sql.Connection" level="DEBUG"/>
    <logger name="java.sql.Statement" level="DEBUG"/>
    <logger name="java.sql.PreparedStatement" level="DEBUG"/>

    <!-- 日志输出级别,logback日志级别包括五个：TRACE < DEBUG < INFO < WARN < ERROR -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILE"/>
    </root>

</configuration>
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<?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>
    <properties resource="jdbc.properties"/>
    <settings>
        <!--开启驼峰映射-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <typeAliases>
        <package name="com.xiaoguan.pojo"/>
    </typeAliases>
    <environments default="mybatis">
        <environment id="mybatis">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <package name="com.xiaoguan.mapper"/>
    </mappers>
</configuration>
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package com.xiaoguan.test;

import com.xiaoguan.mapper.ClassMapper;
import com.xiaoguan.pojo.Class;
import com.xiaoguan.utils.SqlSessionUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

public class ClassMapperTest {
    @Test
    public void testSelectByCollection(){
        SqlSession sqlSession = SqlSessionUtils.openSession();
        ClassMapper mapper = sqlSession.getMapper(ClassMapper.class);
        Class clazz = mapper.selectByCollection(1000);
        System.out.println(clazz);
        sqlSession.close();
    }
    @Test
    public void testSelectByStep1() {
        SqlSession sqlSession = SqlSessionUtils.openSession();
        ClassMapper mapper = sqlSession.getMapper(ClassMapper.class);
        Class clazz = mapper.selectByStep1(1001);
        System.out.println(clazz);
        sqlSession.close();

    }
}

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package com.xiaoguan.test;

import com.xiaoguan.mapper.StudentMapper;
import com.xiaoguan.pojo.Student;
import com.xiaoguan.utils.SqlSessionUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.lang.annotation.Repeatable;

public class StudentMapperTest {
    @Test
    public void testSelectByIdStep1(){
        SqlSession sqlSession = SqlSessionUtils.openSession();
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectByIdStep1(1);
        System.out.println(student.getSname());
        sqlSession.close();
    }
    @Test
    public void testSelectByIdAssociation(){
        SqlSession sqlSession = SqlSessionUtils.openSession();
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectByIdAssociation(1);
        System.out.println(student);
        sqlSession.close();
    }
    @Test
    public void testSelectById(){
        SqlSession sqlSession = SqlSessionUtils.openSession();
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        Student student = mapper.selectById(1);
        System.out.println(student);
        sqlSession.close();
    }

}

MyBatis缓存

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package com.xiaoguan.mapper;


import com.xiaoguan.pojo.Car;

public interface CarMapper {
    //测试二级缓存
    Car selectById3(Long id);
    Car selectById(Long id);

}

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package com.xiaoguan.pojo;

import java.io.Serializable;
import java.util.Objects;

/**
 * 封装汽车相关信息的普通java类
 */
public class Car implements Serializable {
    //建议使用包装类
    private Long id;
    private String carNum;
    private  String brand;
    private Double guidePrice;
    private String produceTime;
    private String carType;

    public Car() {
    }

    public Car(Long id, String carNum, String brand, Double guidePrice, String produceTime, String carType) {
        this.id = id;
        this.carNum = carNum;
        this.brand = brand;
        this.guidePrice = guidePrice;
        this.produceTime = produceTime;
        this.carType = carType;
    }

    @Override
    public String toString() {
        return "Car{" +
                "id=" + id +
                ", carNum='" + carNum + '\'' +
                ", brand='" + brand + '\'' +
                ", guidePrice=" + guidePrice +
                ", produceTime='" + produceTime + '\'' +
                ", carType='" + carType + '\'' +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Car car = (Car) o;
        return Objects.equals(getId(), car.getId()) && Objects.equals(getCarNum(), car.getCarNum()) && Objects.equals(getBrand(), car.getBrand()) && Objects.equals(getGuidePrice(), car.getGuidePrice()) && Objects.equals(getProduceTime(), car.getProduceTime()) && Objects.equals(getCarType(), car.getCarType());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getId(), getCarNum(), getBrand(), getGuidePrice(), getProduceTime(), getCarType());
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getCarNum() {
        return carNum;
    }

    public void setCarNum(String carNum) {
        this.carNum = carNum;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public Double getGuidePrice() {
        return guidePrice;
    }

    public void setGuidePrice(Double guidePrice) {
        this.guidePrice = guidePrice;
    }

    public String getProduceTime() {
        return produceTime;
    }

    public void setProduceTime(String produceTime) {
        this.produceTime = produceTime;
    }

    public String getCarType() {
        return carType;
    }

    public void setCarType(String carType) {
        this.carType = carType;
    }
}

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package com.xiaoguan.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;

/**
 * MyBatis工具类
 */
public class SqlSessionUtils {
    private static SqlSessionFactory sqlSessionFactory;
    private SqlSessionUtils() {}
    static {
        try {
           sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private static ThreadLocal<SqlSession> local=new ThreadLocal<>();
    /**
     * 获取会话对象
     * @return 会话对象
     */
    public static SqlSession openSession(){
        SqlSession sqlSession = local.get();
        if (sqlSession==null) {
            sqlSession=sqlSessionFactory.openSession();
            local.set(sqlSession);
        }
        return sqlSession;

    }

    /**
     * 关闭sqlSession对象
     * @param sqlSession
     */
    public static void close(SqlSession sqlSession){
        if (sqlSession != null) {
            sqlSession.close();
            //移除sqlSession对象和当前线程绑定关系
            local.remove();
        }
    }
}

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<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
         updateCheck="false">
    <!--磁盘存储:将缓存中暂时不使用的对象,转移到硬盘,类似于Windows系统的虚拟内存-->
    <diskStore path="e:/ehcache"/>

    <!--defaultCache：默认的管理策略-->
    <!--eternal：设定缓存的elements是否永远不过期。如果为true，则缓存的数据始终有效，如果为false那么还要根据timeToIdleSeconds，timeToLiveSeconds判断-->
    <!--maxElementsInMemory：在内存中缓存的element的最大数目-->
    <!--overflowToDisk：如果内存中数据超过内存限制，是否要缓存到磁盘上-->
    <!--diskPersistent：是否在磁盘上持久化。指重启jvm后，数据是否有效。默认为false-->
    <!--timeToIdleSeconds：对象空闲时间(单位：秒)，指对象在多长时间没有被访问就会失效。只对eternal为false的有效。默认值0，表示一直可以访问-->
    <!--timeToLiveSeconds：对象存活时间(单位：秒)，指对象从创建到失效所需要的时间。只对eternal为false的有效。默认值0，表示一直可以访问-->
    <!--memoryStoreEvictionPolicy：缓存的3 种清空策略-->
    <!--FIFO：first in first out (先进先出)-->
    <!--LFU：Less Frequently Used (最少使用).意思是一直以来最少被使用的。缓存的元素有一个hit 属性，hit 值最小的将会被清出缓存-->
    <!--LRU：Least Recently Used(最近最少使用). (ehcache 默认值).缓存的元素有一个时间戳，当缓存容量满了，而又需要腾出地方来缓存新的元素的时候，那么现有缓存元素中时间戳离当前时间最远的元素将被清出缓存-->
    <defaultCache eternal="false" maxElementsInMemory="1000" overflowToDisk="false" diskPersistent="false"
                  timeToIdleSeconds="0" timeToLiveSeconds="600" memoryStoreEvictionPolicy="LRU"/>

</ehcache>
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<?xml version="1.0" encoding="UTF-8"?>

<configuration debug="false">
    <!-- 控制台输出 -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
            <!--格式化输出：%d表示日期，%thread表示线程名，%-5level：级别从左显示5个字符宽度%msg：日志消息，%n是换行符-->
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{50} - %msg%n</pattern>
        </encoder>
    </appender>
    <!-- 按照每天生成日志文件 -->
    <!--mybatis log configure-->
    <logger name="com.apache.ibatis" level="TRACE"/>
    <logger name="java.sql.Connection" level="DEBUG"/>
    <logger name="java.sql.Statement" level="DEBUG"/>
    <logger name="java.sql.PreparedStatement" level="DEBUG"/>

    <!-- 日志输出级别,logback日志级别包括五个：TRACE < DEBUG < INFO < WARN < ERROR -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
        <appender-ref ref="FILE"/>
    </root>

</configuration>
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<?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>
    <properties resource="jdbc.properties"/>
    <settings>
        <!--开启驼峰映射-->
        <setting name="mapUnderscoreToCamelCase" value="true"/>
    </settings>
    <typeAliases>
        <package name="com.xiaoguan.pojo"/>
    </typeAliases>
    <environments default="mybatis">
        <environment id="mybatis">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <package name="com.xiaoguan.mapper"/>
    </mappers>
</configuration>
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package com.xiaoguan.test;

import com.xiaoguan.mapper.CarMapper;
import com.xiaoguan.pojo.Car;
import com.xiaoguan.utils.SqlSessionUtils;
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 org.junit.Test;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
//文档rs4n
public class CarTest {
    //要用二级缓存pojo类必须实现序列化接口
    @Test
    public void testSelectById2() throws IOException {
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        Car car = mapper.selectById(34L);
        System.out.println(car);
        SqlSession sqlSession1 = sqlSessionFactory.openSession();
        CarMapper mapper1 = sqlSession1.getMapper(CarMapper.class);
        Car car1 = mapper1.selectById(34L);
        System.out.println(car1);
        sqlSession.close();
        sqlSession1.close();
    }
    @Test
    public void testSelectById(){
        SqlSession sqlSession = SqlSessionUtils.openSession();
        CarMapper mapper = sqlSession.getMapper(CarMapper.class);
        Car car = mapper.selectById(34L);
        System.out.println(car);
        //执行sqlSession的clearCache方法可以让sqlSession的一级缓存清空或者执行了其他修改表的语句会自动清空
        sqlSession.clearCache();
        Car car1 = mapper.selectById(34L);
        System.out.println(car1);
        sqlSession.close();
    }
    @Test
    public void testcomSelectById3() throws IOException {
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession1 = sqlSessionFactory.openSession();
        SqlSession sqlSession2 = sqlSessionFactory.openSession();
        CarMapper mapper1 = sqlSession1.getMapper(CarMapper.class);
        CarMapper mapper2 = sqlSession2.getMapper(CarMapper.class);
        Car car1=mapper1.selectById3(34L);
        System.out.println(car1);
        sqlSession1.close();
        Car car2=mapper2.selectById3(34L);
        System.out.println(car2);
        sqlSession2.close();
    }

}