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,DOBFROM STUDENTSWHERESTUD_ID=#{id}</select><insert id="insertStudent" parameterType="Student"> INSERT INTOSTUDENTS(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 sqllog4j.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 {@Testpublic 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","[e-mail]",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。