SpringMVC Mybatis基础

mybatis是一个持久层框架，支持SQL查询，存储过程等，配置灵活，使用方便。通过使用XML配置很好的和JDBC结合，很方便的操作数据库

配置POM.XML

首先通过maven引入mybatis的第三方组件

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.39</version>
</dependency>


<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.0</version>
</dependency>


<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.3.0</version>
</dependency>

创建数据表

CREATE TABLE 'Student' (
  'Id' int(11) NOT NULL AUTO_INCREMENT,
  'Name' varchar(50) DEFAULT NULL,
  'Code' varchar(50) DEFAULT NULL,
  PRIMARY KEY ('Id')
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf-8

创建表实体

package dto;

public class Student{
    private int Id ;
    public int getId() {
        return Id;
    }
    public void setId(int id) {
        Id = id;
    }

    private String Code;
    public String getCode() {
        return Code;
    }
    public void setCode(String Code) {
        Code = Code;
    }
    
    private String Name ; 
    public String getName() {
        return Name;
    }
    public void setName(String Name) {
        Name = Name;
    }
}

Studentmapper.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">
<mapper namespace="mapping.Studentmapper">
   <!-- 指定查询SQL, parameterType是传入参数类型，resultType是返回结果-->
    <select id="getStudent" parameterType="int" resultType="dto.Student">
        SELECT * FROM Student WHERE id=#{id}
    </select>
</mapper>

'#'号

• '#'号可以进行预编译，即进行类型匹配
• '#'号传入的数据会依据数据类型转换成相应的sql语句片段

  int i=1;String s="s123";

  id=#i# and name=#{s} ----> id=1 and name='s123' //使用#会在字符串类型外面自动加上单引号''

  id=$i$ and name=${s} ----> id=1 and name=s123 //使用$时，直接替换内容，不作其他处理

• '#'号主要用于参数的传入

配置数据库连接信息

<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <!-- 配置数据库连接信息  url中的erp为数据名称-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost:3306/erp" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    
     <mappers>
        <!-- 指定映射文件 -->
        <mapper resource="mapping/skusMapper.xml"/>
    </mappers>

</configuration>

查询

@Controller
@RequestMapping("/Home")
public class HomeController {

    @Resource(name="applePhone")
    private IMobilePhone phone;
    
    @RequestMapping(value="index")
    public String Index()
    {
        String msg=phone.PhoneBrand();
        
        System.out.print(msg);
        
          String resource = "/conf.xml";
            //加载mybatis的配置文件
            InputStream inputstream =this.getClass().getResourceAsStream(resource);
           
            SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(inputstream);
          
            SqlSession session = sessionFactory.openSession();
           
            String statesql= "mapping.Studentmapper.getStudent";        //在StudentMapper.xml中有命名空间+方法名
            
            Student student = session.selectOne(statesql, 1);
            System.out.println(student.getName());
            
        return "index";
    }