5.mybatis的CURD操作

Posted 2020-10-01 想~(●—●)肥~

5.mybatis的CURD操作

1.导包（使用maven创建工程，导包只需要配置pom.xml即可，此处导入jackson是为测试查询打印结果）

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

<!-- $Id: pom.xml 642118 2008-03-28 08:04:16Z reinhard $ -->
<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <packaging>jar</packaging>
    <name>Mybatis01</name>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <groupId>Mybatis01</groupId>
    <artifactId>Mybatis01</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!--junit依赖-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
            <scope>test</scope>
        </dependency>
        <!--mybatis依赖-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.4</version>
        </dependency>
        <!--jackson2.1.0依赖-->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.2.1</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.2.1</version>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <version>RELEASE</version>
        </dependency>
        <!--mysql驱动依赖-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.43</version>
        </dependency>
    </dependencies>

</project>

 

2.配置mybatis核心文件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>
    <!-- 加载配置文件,只能放在这个位置-->
    <properties resource="db.properties"></properties>

    <settings>
        <setting name="useGeneratedKeys" value="false"/>
        <setting name="useColumnLabel" value="true"/>
    </settings>

    <!-- 配置对应的javabean的路径,应用别名-->
    <typeAliases>
      <typeAlias alias="Person" type="entity.Person"/>
    </typeAliases>

    <!-- 配置数据库的连接信息 -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC">
                <property name="" value=""/>
            </transactionManager>
            <!--使用连接池方式获取连接-->
            <dataSource type="POOLED">
                <!--配置数据库连接的信息-->
                <property name="driver" value="${mysql.driver}"/>
                <property name="url" value="${mysql.url}"/>
                <property name="username" value="${mysql.username}"/>
                <property name="password" value="${mysql.password}"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 配置映射类xml文件的路径 -->
    <mappers>
        <mapper resource="mappers/PersonMapper.xml"/>
    </mappers>

</configuration>

 

3.创建sqlSession的工具类

package util;

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.Reader;

/**
 * 工具类
 * Created by Administrator on 2017/8/6.
 */
public class MybatisUtil {
    private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    private static SqlSessionFactory sqlSessionFactory;

    /**
     * 加载位于src/mybatis.xml配置文件
     */
    static {
        try {
            Reader reader = Resources.getResourceAsReader("mybatis.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }

    /**
     * 禁止外界通过new方法直接创建,否则会不断运行影响性能
     * 使用方法：将这个类的构造方法设置为私有
     */
    private MybatisUtil() {
    }

    /**
     * 获取SqlSession
     *
     * @return sqlSession
     */
    public static SqlSession getSqlSession() {
        //从当前线程中获取sqlsession对象
        SqlSession sqlSession = threadLocal.get();
        //如果sqlSession对象为空则从sqlSessionFacety中从新获取
        if (sqlSession == null) {
            sqlSession = sqlSessionFactory.openSession();
            //将sqlSession与当前线程进行绑定
            threadLocal.set(sqlSession);
        }
        return sqlSession;
    }

    /**
     * 关闭SqlSession与当前线程分开
     */
    public static void closeSqlSession() {
        //从当前线程中获取sqlSession
        SqlSession sqlSession = threadLocal.get();
        //如果sqlSession不为空则关闭它，并且分离线程：如不分离线程，则会数据库操作会越来越慢
        if (sqlSession != null) {
            sqlSession.close();
            threadLocal.remove();//让GC尽快回收，释放内存
        }
    }
}

 3.1测试工具类

import util.MybatisUtil;

import java.sql.Connection;

/**
 * Created by Administrator on 2017/8/6.
 * 测试获取qlSession
 */
public class test1 {
    public static void main(String[] args) {
        Connection conn = MybatisUtil.getSqlSession().getConnection();
        System.out.println(conn != null?"连接成功!":"连接失败!");
    }
}

 

4.创建javabean，注意：一定要写无参的构造函数，

防止后面要使用带参的构造函数会覆盖，会出现mybatis无法创建JavaBean导致查询失败

5.配置Mapper.xml文件，并将配置文件的路径配置加到mybatis.xml中

package entity;

/**
 * Created by Administrator on 2017/8/5.
 * Person的实体类
 */
public class Person {
    private Integer id;
    private String name;
    private Integer age;
    private String remark;

    /*mybatis对应的javabean中必须得有一个默认无参的构造函数，
    * 如果我们自定义了有参的构造函数时，会将其覆盖，执行查询时，
    *mybatis无法将参数存入，所以要将其显性的写出来
    */
    public Person () {

    }

    //全参数的构造函数
    public Person (Integer id, String name, Integer age,String  remark) {
        super();
        this.id = id;
        this.name = name;
        this.age = age;
        this.remark = remark;
    }

    //不含id的构造函数
    public Person (String name, Integer age,String  remark) {
        super();
        this.name = name;
        this.age = age;
        this.remark = remark;
    }

    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 Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }
}

 

6.书写JavaBean的Dao类

package dao;

import entity.Person;
import org.apache.ibatis.jdbc.SQL;
import org.apache.ibatis.session.SqlSession;
import util.MybatisUtil;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by Administrator on 2017/8/6.
 */
public class PersonDao {
    //*****************************************急速入门********************************************
    //增加一条信息
    public Integer addPerson (Person person){
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Integer i = sqlSession.insert("Person.addPerson",person);
            sqlSession.commit();
            return i;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    //根据id删除人员信息
    public Integer deletePersonById (int id) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Integer i = sqlSession.delete("Person.deletePersonById",id);
            sqlSession.commit();
            return i;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    //根据id修改一个人的信息
   public Integer updatePersonById (Person person) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Integer i = sqlSession.update("Person.updatePersonById",person);
            sqlSession.commit();
            return i;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    //通过id获取person
    public Person getPersonById (int id) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Person person = sqlSession.selectOne("Person.getPersonById",id);
            return person;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    //根据分页查询
    public List<Person> getPersonList (Integer start, Integer limit) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("start", start);
            map.put("limit", limit);
            List<Person> li = sqlSession.selectList("Person.getPersonList",map);
            return li;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    //*****************************************动态CRUD,mybatis相较于hibernate的优势********************************************
    /**
     * 根据三个条件中的任意一个或多个进行动态查询
     * @param name
     * @param age
     * @param remark
     * @return
     */
    public List<Person> getPersonLList2 (String name, Integer age, String remark) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Map<String, Object> map = new HashMap<String, Object>();
            map.put("name",name);
            map.put("age",age);
            map.put("remark",remark);
            List<Person> li = sqlSession.selectList("Person.getPersonList2",map);
            return li;
        } catch (Exception e) {
            e.printStackTrace();
            return new ArrayList<Person>();
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    public Integer updatePerson1 (Person person) {
        try{
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Integer i = sqlSession.update("Person.updatePerson1",person);
            sqlSession.commit();
            return i;
        }catch (Exception e) {
            e.printStackTrace();
            return -1;
        }finally {
           MybatisUtil.closeSqlSession();
        }
    }
    public Integer deletePerson1 (int... id) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
            Integer i = sqlSession.delete("Person.deldetPerson1",id);
            sqlSession.commit();
            return i;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        } finally {
            MybatisUtil.closeSqlSession();
        }
    }
    public Integer addPerson1 (Person person) {
        try {
            SqlSession sqlSession = MybatisUtil.getSqlSession();
             Integer i = sqlSession.insert("Person.addPerson1",person);
             sqlSession.commit();
             return i;
        } catch (Exception e) {
            e.printStackTrace();
            return -1;
        }finally {
            MybatisUtil.closeSqlSession();
        }
    }
}

 

7.测试（其他测试类以此类推）

import util.MybatisUtil;

import java.sql.Connection;

/**
 * Created by Administrator on 2017/8/6.
 * 测试获取qlSession
 */
public class test1 {
    public static void main(String[] args) {
        Connection conn = MybatisUtil.getSqlSession().getConnection();
        System.out.println(conn != null?"连接成功!":"连接失败!");
    }
}

8.项目文件结构

package util;

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.Reader;

/**
 * 工具类
 * Created by Administrator on 2017/8/6.
 */
public class MybatisUtil {
    private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
    private static SqlSessionFactory sqlSessionFactory;

/**
     * 加载位于src/mybatis.xml配置文件
     */
static {
        try {
            Reader reader = Resources.getResourceAsReader("mybatis.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(e);
}
    }

    /**
     * 禁止外界通过new方法直接创建,否则会不断运行影响性能
     * 使用方法：将这个类的构造方法设置为私有
     */
private MybatisUtil() {
    }

    /**
     * 获取SqlSession
     *
     * @return sqlSession
     */
public static SqlSession getSqlSession() {
        //从当前线程中获取sqlsession对象
SqlSession sqlSession = threadLocal.get();
//如果sqlSession对象为空则从sqlSessionFacety中从新获取
if (sqlSession == null) {
            sqlSession = sqlSessionFactory.openSession();
//将sqlSession与当前线程进行绑定
threadLocal.set(sqlSession);
}
        return sqlSession;
}

    /**
     * 关闭SqlSession与当前线程分开
     */
public static void closeSqlSession() {
        //从当前线程中获取sqlSession
SqlSession sqlSession = threadLocal.get();
//如果sqlSession不为空则关闭它，并且分离线程：如不分离线程，则会数据库操作会越来越慢
if (sqlSession != null) {
            sqlSession.close();
threadLocal.remove();//让GC尽快回收，释放内存
}
    }
}