MyBatis的使用增删改查(两种分页查询)

文件目录

写一下每个文件的代码

 UserDao.java

package cn.zys.dao;

import java.io.IOException;
import java.util.List;

import org.apache.ibatis.session.SqlSession;

import cn.zys.entity.User;
import cn.zys.until.MyBatisUtils;

public class UserDao {
    //根据id查用户
    public User getById(int id) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        User user = sqlsession.selectOne("cn.zys.entity.UserMapper.selectUser", id);
        /*System.out.println(user.toString());*/
        sqlsession.close();
        return user;
    }
    
    //查询所有用户
    public List<User> selectAll() throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        List<User> list = sqlsession.selectList("cn.zys.entity.UserMapper.selectAll");
        sqlsession.close();
        return list;
    }
    
    //添加用户
    public int addUser(User user) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        int res = sqlsession.insert("cn.zys.entity.UserMapper.insertUser",user);
        sqlsession.commit();
        sqlsession.close();
        return res;
    }
    
    //更新用户
    public int updateUser(User user) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        int res = sqlsession.update("cn.zys.entity.UserMapper.updateUser",user);
        sqlsession.commit();
        sqlsession.close();
        return res;
    }
    
    //删除用户
    public int deleteUser(int id) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        int res = sqlsession.delete("cn.zys.entity.UserMapper.deleteUser",id);
        sqlsession.commit();
        sqlsession.close();
        return res;
    }    

//分页查询
    public List<User> selectLimt(int startindex,int pagenum) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        Map<String,Integer> maps = new HashMap<String, Integer>();
        maps.put("startindex", (startindex-1)*pagenum);
        maps.put("pagenum", pagenum);
        List<User> list = sqlsession.selectList("cn.zys.entity.UserMapper.selectLimit",maps);
        sqlsession.commit();
        sqlsession.close();
        return list;
    }
    
    //rowbangs分页查询
    public List<User> selectLimts(int startindex,int pagenum) throws IOException{
        SqlSession sqlsession = MyBatisUtils.getSqlSession();
        RowBounds rowbounds = new RowBounds((startindex-1)*pagenum,pagenum);
        List<User> list = sqlsession.selectList("cn.zys.entity.UserMapper.selectLimits",null,rowbounds);
        sqlsession.commit();
        sqlsession.close();
        return list;
    }

}

User.java

package cn.zys.entity;

public class User {
    private int id;
    private String name;
    private String 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 getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", name=" + name + ", pwd=" + pwd + "]";
    } 
}

user-mappers.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">
<!-- 命名空间规则   本包下的类名+Mapper   -->
<mapper namespace="cn.zys.entity.UserMapper">
    <select id="selectUser" resultType="User">
        select * from user where id = #{id}
    </select>
    
    <!-- 查询所有 -->
    <select id="selectAll" resultType="User" 返回值类型 >
        select * from user
    </select>

    <!-- 分页 -->
    <select id="selectLimit" parameterType="Map" resultType="User">
        select * from user limit #{startindex},#{pagenum}
    </select>
    
    <!-- 使用rowbangs分页 -->
        <select id="selectLimits" parameterType="Map" resultType="User">
        select * from user
    </select>

    <insert id="insertUser" parameterType="User" 此处的属性为参数类型 useGeneratedKeys="true" 此处属性为是否使用自增字段 >   增删改默认返回int类型
        insert into user(name,pwd) values(#{name},#{pwd})
    </insert>
    
    <update id="updateUser" parameterType="User" >
        update user set name=#{name},pwd=#{pwd} where id=#{id}
    </update>
    
    <delete id="deleteUser" >
        delete from user where id=#{id}
    </delete>
</mapper>

MyBatisUtils.java

package cn.zys.until;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class MyBatisUtils {
    public static SqlSessionFactory getSqlSessionFactory() throws IOException{
        String resource = "mybatis.config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        return sqlSessionFactory;
    }
    
    public static SqlSession getSqlSession() throws IOException{
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
        return sqlSessionFactory.openSession();
    }
}

db.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis1
username=root
password=root

mybatis.config.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>
    <!-- 外部引入数据库配置 -->
    <properties resource="db.properties"></properties>
    
    <!-- 为某个类型指定别名   方便在某个引用时使用    比如传值 在此处使用在 user-mappers.xml的resultType -->
    <typeAliases>
        <!-- <typeAlias type="cn.zys.entity.User" alias="User" /> -->
        <!-- 为某个包下的所有类指定别名  默认别名是对应类名   -->
        <package name="cn.zys.entity"  />
    </typeAliases>
    
    <environments default="development">
        <environment id="development">
    <transactionManager type="JDBC"/>
        <dataSource type="POOLED">
            <property name="driver" value="${driver}"/>
            <property name="url" value="${url}"/>
            <property name="username" value="${username}"/>
            <property name="password" value="${password}"/>
        </dataSource>
        </environment>
    </environments>
<mappers>
    <mapper resource="cn/zys/entity/user-mappers.xml"/>
</mappers>
</configuration>

test.java

package cn.zys.test;

import java.io.IOException;
import java.util.List;


import cn.zys.dao.UserDao;
import cn.zys.entity.User;

public class test {
    public static void main(String[] args) throws IOException {
        UserDao userdao = new UserDao();
　　　　　

　　　　　　//新用户
　　　　　　/* User user = new User();
　　　　　　user.setName("002");
　　　　　　user.setPwd("002");
　　　　　　userdao.addUser(user);*/

　　　　　　//分页测试
　　　　　　List<User> list = userdao.selectLimts(0, 2);
　　　　　　System.out.println(list);

    }
}

最后的测试中只测试了最后一个查询多条数据