3、intellij idea中搭建Mybatis简单例子，并对数据库做增删改查
1、新建项目，如下图
2、导入mybatis所需要jar包，并加入依赖 add as library
mybatis需要jar包：mybatis-3.4.6.jar
mysql驱动jar包：mysql-connector-java-5.1.42.-bin.jar
日志记录jar包：log4j-1.2.14.jar
junit测试包：junit-4.12.jar和hamcrest-core-1.3.jar
所需jar包下载地址,包含整个项目代码
https://download.csdn.net/download/nba_linshuhao/10671396
3、创建数据库，数据名字Student、表名字user
注意：字段id设置成自动递增
4、IDEA配置Mysql数据源
idea右侧栏，选中DATABASE,然后点击+号—-DataSource-Mysql
5、创建包，代码结构如下
6、src下创建文件jdbc.properties
加上的useSSL=false原因是：
https://blog.csdn.net/u010429286/article/details/77750177
jdbc.properties代码如下：
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=UTF-8&useSSL=false
jdbc.username=root
jdbc.password=root7、src下添加mybatis配置文件mybatis.cfg.xml，
创建mybatis.cfg.xml文件具体步骤看连接：
https://blog.csdn.net/nba_linshuhao/article/details/82735770
mybatis.cfg.xml代码如下：（不是最终的，因为下面还需要添加内容）
<configuration>
<properties resource="jdbc.properties">properties>
<environments default="cybatis">
<environment id="cybatis">
<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>
configuration>8、log4j.properties代码如下：
### 设置Logger输出级别和输出目的地 ###
log4j.rootLogger=debug,stdout,logfile
### 把日志信息输出到控制台 ###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
#log4j.appender.stdout.Target=System.err
log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout
### 把日志信息输出到文件：jbit.log ###
log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=jbit.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %F %p %m%n
###显示SQL语句部分
log4j.logger.com.ibatis=DEBUG
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=DEBUG
log4j.logger.com.ibatis.common.jdbc.ScriptRunner=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
9、创建对应的实体对象文件： User.java
容易出错的点，忘记写无参构造方法，在接收查询结果时会用无参方法创建对象
详细解释见Userservice的方法selectUserById（）中
package com.cy.mybatis.beans;
import java.io.Serializable;
public class User implements Serializable {
public User(){};
public User(String username,String password,Double account){
this.username=username;
this.password=password;
this.account=account;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public Double getAccount() {
return account;
}
public void setAccount(Double account) {
this.account = account;
}
private Integer id;
private String username;
private String password;
private Double account;
public String toString() {
return "User [id=" + id + ", username=" + username + ", password="
+ password + ", account=" + account + "]";
}
}
10.创建方法接口UserMapper.java和定义操作user表的sql映射文件UserMapper.xml
01 接口UserMapper.java代码如下：
package com.cy.mybatis.mapper;
import com.cy.mybatis.beans.User;
import java.util.List;
public interface UserMapper {
/**
* 新增用戶
* @param user
* @return
* @throws Exception
*/
public int insertUser(User user) throws Exception;
/**
* 修改用戶
* @param user
* @param id
* @return
* @throws Exception
*/
public int updateUser (User user,int id) throws Exception;
/**
* 刪除用戶
* @param id
* @return
* @throws Exception
*/
public int deleteUser(int id) throws Exception;
/**
* 根据id查询用户信息
* @param id
* @return
* @throws Exception
*/
public User selectUserById(int id) throws Exception;
/**
* 查询所有的用户信息
* @return
* @throws Exception
*/
public List selectAllUser() throws Exception;
}
02、UserMapper.xml
代码如下：
<mapper namespace="com.cy.mybatis.mapper.UserMapper">
<resultMap id="userMap" type="User">
<id property="id" column="id" javaType="java.lang.Integer">id>
<result property="username" column="username" javaType="java.lang.String">result>
<result property="password" column="password" javaType="java.lang.String">result>
<result property="account" column="account" javaType="java.lang.Double">result>
resultMap>
<insert id="insertUser" useGeneratedKeys="true" keyProperty="id">
insert into user (username,password,account) values (#{username},#{password},#{account})
insert>
<update id="updateUser" >
update user set username=#{username},password=#{password},account=#{account} where id=#{id}
update>
<delete id="deleteUser" parameterType="int">
delete from user where id=#{id}
delete>
<select id="selectUserById" parameterType="int" resultMap="userMap">
select * from user where id=#{id}
select>
<select id="selectAllUser" resultMap="userMap">
select * from user
select>
mapper>
11、这时需要在mybatis.cfg.xml里注册UserMapper.xml文件
mybatis.cfg.xml的完整代码如下
<configuration>
<properties resource="jdbc.properties">properties>
<typeAliases >
<package name="com.cy.mybatis.beans"/>
typeAliases>
<environments default="cybatis">
<environment id="cybatis">
<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>
<mapper resource="com/cy/mybatis/mapper/UserMapper.xml"/>
mappers>
configuration>12、创建工具类文件DBTools.java
代码如下：
package com.cy.mybatis.tools;
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.Reader;
public class DBTools {
public static SqlSessionFactory sessionFactory;
static{
try {
//使用MyBatis提供的Resources类加载mybatis的配置文件
Reader reader = Resources.getResourceAsReader("mybatis.cfg.xml");
//构建sqlSession的工厂
sessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (Exception e) {
e.printStackTrace();
}
}
//创建能执行映射文件中sql的sqlSession
public static SqlSession getSession(){
return sessionFactory.openSession();
}
}
13、编写测试文件UserServiceTest.java
代码如下：
package com.cy.mybatis.service;
import com.cy.mybatis.beans.User;
import com.cy.mybatis.mapper.UserMapper;
import com.cy.mybatis.tools.DBTools;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class UserServiceTest {
@Test
//添加操作
public void insertUser() throws Exception {
SqlSession session = DBTools.getSession();
UserMapper mapper = session.getMapper(UserMapper.class);
User user = new User("香蕉", "8888", 8888.8);
try {
mapper.insertUser(user);
System.out.println(user.toString());
session.commit();
} catch (Exception e) {
e.printStackTrace();
session.rollback();
}
}
@Test
//删除操作
public void deleteUser() throws Exception {
SqlSession session=DBTools.getSession();
UserMapper mapper=session.getMapper(UserMapper.class);
try {
mapper.deleteUser(1);
session.commit();
} catch (Exception e) {
e.printStackTrace();
session.rollback();
}
}
@Test
//选择操作
public void selectUserById() throws Exception {
SqlSession session=DBTools.getSession();
UserMapper mapper=session.getMapper(UserMapper.class);
try {
//这里用到User类的无参构造方法创建对象，User user=new User（）；
User user =mapper.selectUserById(2);
System.out.println(user.toString());
session.commit();
} catch (Exception e) {
e.printStackTrace();
session.rollback();
}
}
@Test
public void selectAllUser() throws Exception {
SqlSession session= DBTools.getSession();
UserMapper mapper=session.getMapper(UserMapper.class);
try {
List user=mapper.selectAllUser();
System.out.println(user.toString());
session.commit();
} catch (Exception e) {
e.printStackTrace();
session.rollback();
}
}
} 14、运行，在每个增删改查对应的方法上面运行即可，
整体项目打包下载地址：
https://download.csdn.net/download/nba_linshuhao/10671396
遇到的问题
1、数据库表id字段未设置自动递增，这样添加数据会报错，因为本例中无构造方法中没有id，并且UserMapper.xml添加数据中没有添加id字段
2、不会创建mybatis.cfg.xml 和UserMapper.xml
下载之后直接用InteliJ IDEA打开即可运行，注意下看lib下的包有没有加入依赖，没有的话注意加入依赖add as library
这是我亲自运行后总结的，如果还有不明白的可以直接评论，看到后我会为你解答。