mybatis连接数据库（注解和配置文件俩种方法调用方法）

之前的很多代码中链接数据库都采用的是jdbc的版本，在项目开发过程中目前都采用mybatis完成链接数据库的操作

下面，我们来介绍如何使用mybatis链接数据库

1.先展示注解的写法（俩种方法配置的核心文件都是一样的）

首先配置mybatis核心文件

conf.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><settings>   <setting name="cacheEnabled" value="true"/></settings>    <environments default="development">        <environment id="development">            <transactionManager type="JDBC" />            <!-- 配置数据库连接信息 -->            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://localhost:3306/luntan" />                <property name="username" value="root" />                <property name="password" value="mysql" />            </dataSource>        </environment>    </environments>    <mappers>       <mapper class="it.com.db.IUsersMapper"/><!--路径,也可以用resource写的是斜杠类型的路径-->         </mappers>    </configuration>

SF.java类似于jbdc里的connection

package it.com.db;import java.io.IOException;import java.io.Reader;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 SF { public static SqlSession getSession(){ SqlSession session=null; String resource="conf.xml";//路径，一般不建议直接写在外面，这里只是示范Reader is=null;try {is = Resources.getResourceAsReader(resource);SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);session = sessionFactory.openSession();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();} return session; }  public static void closeSession(SqlSession session){ if(session!=null){ session.close(); } }/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubSF.getSession();}}

IUserMapper是一个接口文件，在接口中编写了mysql数据库中执行的操作，相当于是将sql于java端分离了

下面测试了增删改查的简单操作

package it.com.db;import java.util.List;import java.util.Map;import org.apache.ibatis.annotations.Delete;import org.apache.ibatis.annotations.Insert;import org.apache.ibatis.annotations.Param;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.Update;public interface IUsersMapper {@Select("select * from users")public List<Map> findAll();@Select("select count(1) from users where userName=#{userName}")public int findById(@Param("userName") String userName);@Select("select count(1) from users where userName=#{userName} and userPwd=#{userPwd}")public int findByIdPwd(@Param("userName") String userName,@Param("userPwd") String userPwd);@Insert("insert into users(userName,userPwd) values (#{userName},#{userPwd})")public void insertUser(@Param("userName") String userName,@Param("userPwd") String userPwd);@Update("update users set userPwd=#{userPwd} where userName=#{userName}")public void updateUser(@Param("userName") String userName,@Param("userPwd")String userPwd);@Delete("delete from users where userName=#{userName}")public void deleteUser(@Param("userName") String userName);//表关联@Select("select content.*,users.Email from content,users where content.userName=users.userName")public List<Map> findTwo();//存储过程@Select("call pp11()")public List<Map> findAll_a();}

最后建立实体类。userDao在实体类中完成功能的调用测试

package it.com.dao;import it.com.db.IUsersMapper;import it.com.db.SF;import java.util.List;import java.util.Map;import org.apache.ibatis.session.SqlSession;public class UsersDao {/** * @param args */public List<Map> findAll() {List<Map> list =null;//创建listSqlSession session =SF.getSession();//获取session对象//加载mapper文件，获取mapper文件数据库持久化的方法IUsersMapper um=session.getMapper(IUsersMapper.class);list=um.findAll();return list;}public int findById(String userName){SqlSession session = SF.getSession();IUsersMapper um = session.getMapper(IUsersMapper.class);int n = um.findById(userName);return n;}public int findByIdPwd(String userName,String userPwd){SqlSession session = SF.getSession();IUsersMapper um = session.getMapper(IUsersMapper.class);int n = um.findByIdPwd(userName, userPwd);return n;}public void insertUser(String userName,String userPwd){SqlSession session = SF.getSession();IUsersMapper um = session.getMapper(IUsersMapper.class);um.insertUser(userName, userPwd);session.commit();//事务提交，数据库改变时使用（增删改）}public void updateUser(String userName,String userPwd){SqlSession session =SF.getSession();IUsersMapper um=session.getMapper(IUsersMapper.class);um.updateUser(userName, userPwd);session.commit();//事务提交，数据库改变时使用（增删改）}public void deleteUser(String userName){SqlSession session = SF.getSession();IUsersMapper um=session.getMapper(IUsersMapper.class);um.deleteUser(userName);session.commit();}public List<Map> findTwo(){List<Map> list = null;SqlSession session = SF.getSession();IUsersMapper um=session.getMapper(IUsersMapper.class);list=um.findTwo();return list;}public List<Map> findAll_a(){List<Map> list= null;SqlSession session = SF.getSession();IUsersMapper um = session.getMapper(IUsersMapper.class);list=um.findAll_a();return list;}public static void main(String[] args) {// TODO Auto-generated method stubUsersDao user = new UsersDao();//List<Map> list = user.findAll();//for(Map map:list){//System.out.println(map);//}//System.out.println(user.findByIdPwd("admire", "111111"));//user.insertUser("alibaba", "hhhxxx");//user.updateUser("alibaba", "111111");//user.deleteUser("alibaba");//List<Map> list=user.findTwo();//for(Map map:list){//System.out.println(map);//}//List<Map> list=user.findAll_a();//for(Map map:list){//System.out.println(map);//}}}

2.下面来展示配置文件的写法

是用一个xml文件代替了上面的IUsermapper的注解接口文件，代码如下：

<?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"><mapper namespace="it.com.dao">   <select id="findall" resultType="Map">      select * from users   </select>   <select id="findById" resultType="Map" parameterType="String">      select * from users where userName = #{userName}   </select>   <select id="findByIdPwd" resultType="Map" parameterType="Map">      select * from users where userName = #{userName} and userPwd=#{userPwd}   </select>   <insert id="insertByIdPwd" parameterType="Map">      insert into users(userName,userPwd) values (#{userName},#{userPwd})   </insert></mapper>

同样它的实现类：

package it.com.dao;import it.com.db.SF;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.ibatis.session.SqlSession;public class UserDao {public List<Map> findAll(){List<Map> list=null;SqlSession session = SF.getSession();list=session.selectList("findall");     //不带参return list;}public List<Map> findById(String userName){List<Map> list=null;SqlSession session = SF.getSession();list=session.selectList("findById",userName); //带一个参数return list;}public Object findByIdPwd(String userName,String userPwd){Object obj = null;SqlSession session = SF.getSession();Map map = new HashMap();map.put("userName", userName);map.put("userPwd", userPwd);                 //selectone 也可以                  obj=session.selectList("findByIdPwd",map);  //带俩个以上参数，这里的map最能体现java三大特性的封装return obj;}public void insertByIdPwd(String userName,String userPwd){SqlSession session = SF.getSession();Map map = new HashMap();map.put("userName", userName);map.put("userPwd", userPwd);session.insert("insertByIdPwd", map);}public static void main(String[] args){UserDao user = new UserDao();//List<Map> list=user.findAll();//for(Map map:list){//System.out.println(map);//}//System.out.println(user.findAll());//System.out.println(user.findById("admire"));//System.out.println(user.findByIdPwd("admire", "111111"));user.insertByIdPwd("kkkkkkk", "oaoaoaoa");}}