mybatis框架的一些步骤

1.10 编写一个简单的mybatis进行插入数据的实例

1.10.1 数据库建表:dob—>Date Of Birth

CREATE TABLE STUDENTS (
stud_id number PRIMARY KEY,
name varchar2(50) ,
email varchar2(50) ,
dob date
);

1.10.2 新建一个项目,创建好相应的package及class

package com.briup.pojo;
import java.util.Date;
public class Student {
private Integer studId;
private String name;
private String email;
private Date dob;
get/set
}

1.10.3 项目中引入mybatis的核心包以及可选的依赖包

必须的包 mybatis-3.3.0.jar ojdbc14.jar

可选的包 junit-4.7.jar log4j-1.2.17.jar

1.10.4 mybatis中的配置文件和映射文件分别引入到项目中

src下面的mybatis-config.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>
<typeAliases>
<typeAlias type="com.briup.pojo.Student" alias="Student" />
</typeAliases>

<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="oracle.jdbc.driver.OracleDriver" />
<property name="url" value="jdbc:oracle:thin:@127.0.0.1:1521:XE" />
<property name="username" value="test" />
<property name="password" value="test" />
</dataSource>
</environment>
</environments>

<mappers>
<mapper resource="com/briup/mappers/StudentMapper.xml"/>
</mappers>

</configuration>

com.briup.mappers包下面的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">
<!-- com.briup.mappers.StudentMapper是我们定义接口的全限定名字 这样就可以使用接口调用映射的SQL语句了 这个名字一定要和接口对应上-->
<mapper namespace="com.briup.mappers.StudentMapper">

<resultMap type="Student" id="StudentResult">
<id property="studId" column="stud_id" />
<result property="name" column="name" />
<result property="email" column="email" />
<result property="dob" column="dob" />
</resultMap>

<select id="findAllStudents" resultMap="StudentResult">
SELECT * FROM STUDENTS
</select>

<!-- 列名和属性名字不一致可以给查询的列起一个别名 -->
<select id="findStudentById" parameterType="int" resultType="Student">
SELECT STUD_ID AS STUDID,NAME,EMAIL,DOB
FROM STUDENTS
WHERE
STUD_ID=#{id}
</select>
<insert id="insertStudent" parameterType="Student">
INSERT INTO
STUDENTS(STUD_ID,NAME,EMAIL,DOB)
VALUES(#{studId},#{name},#{email},#{dob})
</insert>
</mapper>

1.10.5 配置log4j.properties文件中的日志输出:

位置src下面

内容:

log4j.rootLogger=DEBUG, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d [%-5p] %c - %m%n
#show sql
log4j.logger.java.sql.ResultSet=INFO
log4j.logger.org.apache=INFO
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG

1.10.6 com.briup.mappers包下面新建一个接口StudentMapper.java,用来对应xml文件中的sql语句(映射),从而方便我们调用

package com.briup.mappers;

import java.util.List;

import com.briup.pojo.Student;

//创建映射器Mapper接口StudentMapper

//方法名和StudentMapper.xml中定义的SQL映射定义名相同

//这个其实就是dao层接口(数据访问层,负责和数据库进行交互)

public interface StudentMapper {
List<Student> findAllStudents();
Student findStudentById(Integer id);
void insertStudent(Student student);
}

1.10.7 创建一个测试类StudentMapperTest.java

package test;
import java.io.InputStream;
import java.util.Date;

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 org.junit.Test;

import com.briup.mappers.StudentMapper;
import com.briup.pojo.Student;

public class StudentMapperTest {

@Test
public void testCreateStudent(){

try {
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();

StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
Student s = new Student(1,"tom","123@briup.com",new Date());
studentMapper.insertStudent(s);
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
}

}
}

1.10.8 运行成功后会在控制台中看到log4j日志输出的这个程序运行的相关信息

1.10.9 对mybatis的一些基本封装

每次读取配置文件,产生一个工厂对象SqlSessionFactory,然后再生成出SqlSession对象,这个过程虽然并不复杂,但是也都是一些重复的代码流程,所以我们可以对其进行一个简单的封装:

package com.briup.utils;

import java.io.IOException;
import java.io.InputStream;

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 MyBatisSqlSessionFactory {
private static SqlSessionFactory sqlSessionFactory;

public static SqlSessionFactory getSqlSessionFactory(){
if(sqlSessionFactory == null){
InputStream inputStream = null;
try {
inputStream = Resources.getResourceAsStream("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e.getCause());
}
}
return sqlSessionFactory;
}

public static SqlSession openSession() {
return openSession(false);
}
public static SqlSession openSession(boolean autoCommit) {
return getSqlSessionFactory().openSession(autoCommit);
}

}

之后每次使用的时候只需要调用该类中的静态方法openSession即可

上面的代码可简写为: //注意事务是自动提交还是手动提交

MyBatisSqlSessionFactory.openSession().getMapper(StudentMapper.class).insertStudent(s);

为了让MyBatis明白怎样处理这个自定义的Java对象类型，如PhoneNumber，我们可以创建一个自定义的类型处理器,MyBatis提供了抽象类BaseTypeHandler ，我们可以继承此类创建自定义类型处理器。

代码如下所示:

package com.briup.typehandlers;

import java.sql.CallableStatement;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import org.apache.ibatis.type.BaseTypeHandler;

import org.apache.ibatis.type.JdbcType;

import com.briup.pojo.PhoneNumber;

public class PhoneTypeHandler extends BaseTypeHandler{

//遇到PhoneNumber参数的时候应该如何在ps中设置值

@Override

public void setNonNullParameter(PreparedStatement ps, int i, PhoneNumber parameter, JdbcType jdbcType)

throws SQLException {

ps.setString(i, parameter.getAsString());

}

//查询中遇到PhoneNumber类型的应该如何封装(使用列名封装)

@Override

public PhoneNumber getNullableResult(ResultSet rs, String columnName) throws SQLException {

return new PhoneNumber(rs.getString(columnName));

}

//查询中遇到PhoneNumber类型的应该如何封装(使用列的下标)

@Override

public PhoneNumber getNullableResult(ResultSet rs, int columnIndex) throws SQLException {

return new PhoneNumber(rs.getString(columnIndex));

}

//CallableStatement使用中遇到了PhoneNumber类型的应该如何封装

@Override

public PhoneNumber getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {

return new PhoneNumber(cs.getString(columnIndex));

}

}

注意:使用ps.setString()和rs.getString()方法是 :因为在数据库的表中phone列是VARCHAR类型。

最后一旦我们实现了自定义的类型处理器，我们需要在mybatis-config.xml中注册它：

<?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>

<properties resource="application.properties" />

<typeHandlers>

<typeHandler handler="com.briup.typehandlers.PhoneTypeHandler" />

</typeHandlers>

</configuration

>

注册PhoneTypeHandler后, MyBatis就能够将Phone类型的对象值存储到VARCHAR类型的列上。