开发Web应用,数据的存储和处理往往离不开数据库和SQL语句。在使用Java开发的Web应用中,自然也少不了连接数据库的步骤。在底层连接数据库的时候,一般优胜JDBC技术,也就是Java的一种提供数据库连接和操作SQL的底层API。但是互联网技术正在飞速发展,使用原始JDBC已经满足不了项目的开发需求了,这就使得Hibernate,MyBatis(iBatis),JPA,JDO等一些优秀的ORM框架诞生,它们不公结合了原生JDBC的功能,还使开发简捷化,规范化。
前一章我讲了使用maven在idea下搭建SpringMVC,下面接着讲使用maven在idea下搭建MyBatis。
首先在mysql中创建一个名为test的数据库,然后在数据库中创建表“userinfo”:
1,打开之前项目,pom.xm中加入MyBatis的引用:
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.12</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.20</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.41</version>
</dependency>
<dependency>
<groupId>com.microsoft.sqlserver</groupId>
<artifactId>sqljdbc4</artifactId>
<version>4.0</version>
</dependency>
2,在Java文件夹下创建包"cn.com.mybatis.pojo",在包下创建java类"UserInfo":
package cn.com.mybatis.pojo;
import java.io.Serializable;
public class UserInfo implements Serializable {
private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
private String userName;
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
private String password;
private int age;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
2,在"resource"文件夹下新建一个"mybatis"文件夹,
编写SQL映射文件:
在mybatis文件夹加新建一个mapper文件夹,并在mapper下创建名为userinfo的xml文件,编辑如下:
<?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="test">
<select id="findById" parameterType="int" resultType="cn.com.mybatis.pojo.UserInfo">
SELECT * FROM userinfo WHERE id=#{id}
</select>
</mapper>
在"mybatis"文件夹下新建名为"SqlMapConfig"的xml文件,并编辑:
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTDConfig 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="drever" value="org.gjt.mm.mysql.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/test?characterEncoding=utf-8"></property>
<property name="username" value="root"></property>
<property name="password" value="123456"></property>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mybatis/mapper/userinfo.xml"></mapper>
</mappers>
</configuration>
3,在Java文件夹下创建包"cn.com.mybatis.datasource",在包下创建并编写数据库交互类(DataConnection):
package cn.com.mybatis.datasource;
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.InputStream;
public class DataConnection {
private String resource="mybatis/SqlMapConfig.xml";
private SqlSessionFactory sqlSessionFactory;
private SqlSession sqlSession;
public SqlSession getSqlSession() throws IOException{
InputStream inputStream= Resources.getResourceAsStream(resource);
sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
sqlSession=sqlSessionFactory.openSession();
return sqlSession;
}
}
在Java文件夹下创建包"cn.com.mybatis.dao",在包下创建并编写数据库访问类(UserInfoDAO):
package cn.com.mybatis.dao;
import cn.com.mybatis.datasource.DataConnection;
import cn.com.mybatis.pojo.UserInfo;
import org.apache.ibatis.session.SqlSession;
import java.io.IOException;
public class UserInfoDAO {
public DataConnection dataConn = new DataConnection();
public UserInfo GetUserById() throws IOException{
SqlSession sqlSession=dataConn.getSqlSession();
UserInfo user = sqlSession.selectOne("test.findById",1);
sqlSession.close();
return user;
}
}
最后,在表现层显示数据:
修改src/main/webapp/Java/cn.com.controller/Home
package cn.com.controller;
import cn.com.mybatis.dao.UserInfoDAO;
import cn.com.mybatis.pojo.UserInfo;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import java.io.IOException;
@Controller
@RequestMapping("/Home")
public class Home {
@RequestMapping("/Index")
public ModelAndView Index() throws IOException {
ModelAndView view = new ModelAndView();
UserInfoDAO userInfoDTO=new UserInfoDAO();
UserInfo user = userInfoDTO.GetUserById();
view.addObject("userInfo",user);
view.setViewName("Index");
return view;
}
}
修改Index.JSP文件
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2018-12-07
Time: 16:52
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h2>Index</h2>
<ul>
<li>${userInfo.id}</li>
<li>${userInfo.userName}</li>
<li>${userInfo.age}</li>
</ul>
</body>
</html>
大功告成!
运行Tomcat
目录结构: