SSM框架学习笔记之MyBatis入门程序

1.Mybatis工作流程

2.入门程序

log4j配置文件：log4j.properties

# Global logging configuration
log4j.rootLogger = ERROR,stdout
# MyBatis logging configuration...
log4j.logger.top.mootong = DEBUG
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] -%m%n

持久类：Customer.java

package top.mootong.po;

public class Customer {
    private Integer id;
    private String userName;
    private String jobs;
    private String phone;

    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 getJobs() {
        return jobs;
    }

    public void setJobs(String jobs) {
        this.jobs = jobs;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    @Override
    public String toString() {
        return "Customer{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", jobs='" + jobs + '\'' +
                ", phone='" + phone + '\'' +
                '}';
    }
}

映射文件：CusteomerMapper.xml

    
        select * from t_customer where id = #{id}
    
    
        select * from t_customer where username like '%${value}%'
    
    
        insert into t_customer(username,jobs,phone) values (#{username},#{jobs},#{phone})
    
    
        update t_customer set username=#{username},jobs=#{jobs},phone=#{phone} where id =#{id}
    
    
        delete from t_customer where id=#{id}
    

*元素是配置文件的根元素，它包含一个namespace属性，该属性为这个元素指定了唯一的命名空间，通常会设置成”包名+SQL映射文件名“的形式
*在定义的SQL查询语句中，“#{}”用于表示一个占位符，相当于？，而“#{id}”表示该占位符待接收参数的名称为id。
MyBatis配置文件：mybatis-config.xml

*配置文件一方面配置了环境（数据源），另一方面配置了映射文件的位置
测试类：MyBatisTest

package top.mootong.top.mootong.test;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;


import top.mootong.po.Customer;
import top.mootong.util.SqlSessionUtil;

public class MybatisTest {
   private String resource = "mybatis-config.xml";
    @Test
    public void findCustomerByIdTest() throws Exception {

        SqlSession sqlSession = SqlSessionUtil.getSqlSession(resource);
        Customer customer = sqlSession.selectOne("top.mootong.mapper.CustomerMapper.findCustomerById",1);
        System.out.println(customer);
        sqlSession.close();
    }

}

3.其他操作示例：

3.1 根据用户名模糊查询客户信息

    select * from t_customer where username like '%${value}%'

*SQL语句中的"$"用来拼接SQL的字符串，即不加解释的原样输出"${value}"表示要拼接的简单类型参数；
*使用${}无法避免参数注入的问题，所以既要实现模糊查询，又要防止SQL注入，可以使用concat()函数进行拼接：

select * from t_customer where username like concat('%',#{value},'%')

3.2 添加客户

    insert into t_customer(username,jobs,phone) values (#{username},#{jobs},#{phone})

*#{username}会查找参数对象的username属性；

3.3 更新客户

    update t_customer set username=#{username},jobs=#{jobs},phone=#{phone} where id =#{id}

3.4 删除客户

    delete from t_customer where id=#{id}