MyBatis入门

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本文介绍了MyBatis持久层框架的基本概念与配置方法，并通过一个CRUD操作案例详细展示了如何利用MyBatis进行数据库交互，包括SqlSessionFactory的创建、Mapper接口的使用以及常见生命周期管理。

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引用：http://xdwangiflytek.iteye.com/blog/1745560

在前面简单学习了iBatis ，因为项目中使用了MyBatis，所以给了一个机会能够实战中总结总结MyBatis。

首先我门简单了解一下什么是MyBatis。 MyBatis是支持普通SQL查询，存储过程和高级映射的优秀持久层框架，MyBatis消除了几乎所有的JDBC代码和参数的手工设置以及结果集的检索。MyBatis使用简单的XML或注解用于配置和原始映射，将接口和Java的POJOs映射成数据库中的记录。

从事Java开发在接触常用的J2EE框架时，都应该知道这些框架都需要提供一个全局配置文件，用于指定程序正常运行所需要的设置和参数信息。而针对常用的持久层框架而言（Hibernate、JPA、MyBatis|iBatis等），则通常需要配置两类文件：一类用于指定数据源、事务属性以及其他一些参数配置信息（通常是一个独立的文件，全局配置文件）；另一类则用于指定数据库表与程序实体之间的映射信息（可能不止一个哦，映射文件）。

首先我们以一个CURD的操作来进行说明

每一个MyBatis的应用程序都是以一个SqlSessionFactory对象的实例为核心，SqlSessionFactory 对象的实例可以通过 SqlSessionFactoryBuilder 对象来获得。 SqlSessionFactoryBuilder 对象可以从 XML 配置文件,或从 Configuration 类的习惯准备的实例中构建 SqlSessionFactory 对象（通过Java类的方式大家可以查阅一下官方的文档）。这里我们建议使用XML的形式。

这里我们可以写一个工具类，专门是为了获取SqlSessionFactory对象，MyBatisUtil.java

Java代码

package com.iflytek.util;
import java.io.IOException;
import java.io.Reader;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午6:30:53
*
* @description MyBatis帮助类，获取SqlSessionFactory
*
*/
public class MyBatisUtil {
private static SqlSessionFactory factory;
private MyBatisUtil() {
}
static {
Reader reader = null;
try {
reader = Resources.getResourceAsReader("com/iflytek/resources/mybatis-config.xml");
// InputStream inputStream =
// Resources.getResourceAsStream("com/iflytek/resources/mybatis-config.xml");
// factory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
throw new RuntimeException(e.getMessage());
}
factory = new SqlSessionFactoryBuilder().build(reader);
}
/**
* @descrption 获取SqlSessionFactory对象
* @author xdwang
* @create 2012-12-10下午6:32:24
* @return 返回SqlSessionFactory对象
*/
public static SqlSessionFactory getSqlSessionFactory() {
return factory;
}
}

上面指定的资源
mybatis-config.xml

Xml代码

<?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="database.properties" />
<settings>
<setting name="useGeneratedKeys" value="true" />
<setting name="defaultExecutorType" value="REUSE" />
</settings>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${database.driver}" />
<property name="url" value="${database.url}" />
<property name="username" value="${database.username}" />
<property name="password" value="${database.password}" />
</dataSource>
</environment>
</environments>
<mappers>
<mapper class="com.iflytek.dao.mapper.BlogMapper" />
<mapper resource="com/iflytek/dao/xml/StudentMapper.xml" />
</mappers>
</configuration>

这里先简单列举重要的节点，后面再详细描述
database.properties

Java代码

database.driver=com.mysql.jdbc.Driver
database.url=jdbc:mysql://localhost:3306/ibatis
database.username=root
database.password=123

下面我们有了SqlSessionFactory对象，可以通过SqlSessionFactory构造SqlSession，再通过SqlSession获取不同实体对应的Mapper接口，最后通过Mapper接口中定义的方法进行相关的数据操作。
对于Mapper接口的定义，有两种方式，一是通过XML的方式，二是通过注解的方式。
一、XML方式（这里的Model、Mapper、XML是通过generator自动生成的）
Student.java

Java代码

package com.iflytek.dao.model;
import java.text.MessageFormat;
import java.util.Date;
public class Student {
private Integer id;
private String name;
private Date birth;
private Float score;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name == null ? null : name.trim();
}
public Date getBirth() {
return birth;
}
public void setBirth(Date birth) {
this.birth = birth;
}
public Float getScore() {
return score;
}
public void setScore(Float score) {
this.score = score;
}
@Override
public String toString() {
return MessageFormat.format("id：{0},姓名：{1},出生日期:{2},分数：{3}", id, name, birth, score);
}
}

StudentExample.java

Java代码

package com.iflytek.dao.model;
import java.util.ArrayList;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
public class StudentExample {
protected String orderByClause;
protected boolean distinct;
protected List<Criteria> oredCriteria;
public StudentExample() {
oredCriteria = new ArrayList<Criteria>();
}
public void setOrderByClause(String orderByClause) {
this.orderByClause = orderByClause;
}
public String getOrderByClause() {
return orderByClause;
}
public void setDistinct(boolean distinct) {
this.distinct = distinct;
}
public boolean isDistinct() {
return distinct;
}
public List<Criteria> getOredCriteria() {
return oredCriteria;
}
public void or(Criteria criteria) {
oredCriteria.add(criteria);
}
public Criteria or() {
Criteria criteria = createCriteriaInternal();
oredCriteria.add(criteria);
return criteria;
}
public Criteria createCriteria() {
Criteria criteria = createCriteriaInternal();
if (oredCriteria.size() == 0) {
oredCriteria.add(criteria);
}
return criteria;
}
protected Criteria createCriteriaInternal() {
Criteria criteria = new Criteria();
return criteria;
}
public void clear() {
oredCriteria.clear();
orderByClause = null;
distinct = false;
}
protected abstract static class GeneratedCriteria {
protected List<Criterion> criteria;
protected GeneratedCriteria() {
super();
criteria = new ArrayList<Criterion>();
}
public boolean isValid() {
return criteria.size() > 0;
}
public List<Criterion> getAllCriteria() {
return criteria;
}
public List<Criterion> getCriteria() {
return criteria;
}
protected void addCriterion(String condition) {
if (condition == null) {
throw new RuntimeException("Value for condition cannot be null");
}
criteria.add(new Criterion(condition));
}
protected void addCriterion(String condition, Object value, String property) {
if (value == null) {
throw new RuntimeException("Value for " + property + " cannot be null");
}
criteria.add(new Criterion(condition, value));
}
protected void addCriterion(String condition, Object value1, Object value2, String property) {
if (value1 == null || value2 == null) {
throw new RuntimeException("Between values for " + property + " cannot be null");
}
criteria.add(new Criterion(condition, value1, value2));
}
protected void addCriterionForJDBCDate(String condition, Date value, String property) {
if (value == null) {
throw new RuntimeException("Value for " + property + " cannot be null");
}
addCriterion(condition, new java.sql.Date(value.getTime()), property);
}
protected void addCriterionForJDBCDate(String condition, List<Date> values, String property) {
if (values == null || values.size() == 0) {
throw new RuntimeException("Value list for " + property + " cannot be null or empty");
}
List<java.sql.Date> dateList = new ArrayList<java.sql.Date>();
Iterator<Date> iter = values.iterator();
while (iter.hasNext()) {
dateList.add(new java.sql.Date(iter.next().getTime()));
}
addCriterion(condition, dateList, property);
}
protected void addCriterionForJDBCDate(String condition, Date value1, Date value2, String property) {
if (value1 == null || value2 == null) {
throw new RuntimeException("Between values for " + property + " cannot be null");
}
addCriterion(condition, new java.sql.Date(value1.getTime()), new java.sql.Date(value2.getTime()), property);
}
public Criteria andIdIsNull() {
addCriterion("id is null");
return (Criteria) this;
}
public Criteria andIdIsNotNull() {
addCriterion("id is not null");
return (Criteria) this;
}
public Criteria andIdEqualTo(Integer value) {
addCriterion("id =", value, "id");
return (Criteria) this;
}
public Criteria andIdNotEqualTo(Integer value) {
addCriterion("id <>", value, "id");
return (Criteria) this;
}
public Criteria andIdGreaterThan(Integer value) {
addCriterion("id >", value, "id");
return (Criteria) this;
}
public Criteria andIdGreaterThanOrEqualTo(Integer value) {
addCriterion("id >=", value, "id");
return (Criteria) this;
}
public Criteria andIdLessThan(Integer value) {
addCriterion("id <", value, "id");
return (Criteria) this;
}
public Criteria andIdLessThanOrEqualTo(Integer value) {
addCriterion("id <=", value, "id");
return (Criteria) this;
}
public Criteria andIdIn(List<Integer> values) {
addCriterion("id in", values, "id");
return (Criteria) this;
}
public Criteria andIdNotIn(List<Integer> values) {
addCriterion("id not in", values, "id");
return (Criteria) this;
}
public Criteria andIdBetween(Integer value1, Integer value2) {
addCriterion("id between", value1, value2, "id");
return (Criteria) this;
}
public Criteria andIdNotBetween(Integer value1, Integer value2) {
addCriterion("id not between", value1, value2, "id");
return (Criteria) this;
}
public Criteria andNameIsNull() {
addCriterion("name is null");
return (Criteria) this;
}
public Criteria andNameIsNotNull() {
addCriterion("name is not null");
return (Criteria) this;
}
public Criteria andNameEqualTo(String value) {
addCriterion("name =", value, "name");
return (Criteria) this;
}
public Criteria andNameNotEqualTo(String value) {
addCriterion("name <>", value, "name");
return (Criteria) this;
}
public Criteria andNameGreaterThan(String value) {
addCriterion("name >", value, "name");
return (Criteria) this;
}
public Criteria andNameGreaterThanOrEqualTo(String value) {
addCriterion("name >=", value, "name");
return (Criteria) this;
}
public Criteria andNameLessThan(String value) {
addCriterion("name <", value, "name");
return (Criteria) this;
}
public Criteria andNameLessThanOrEqualTo(String value) {
addCriterion("name <=", value, "name");
return (Criteria) this;
}
public Criteria andNameLike(String value) {
addCriterion("name like", value, "name");
return (Criteria) this;
}
public Criteria andNameNotLike(String value) {
addCriterion("name not like", value, "name");
return (Criteria) this;
}
public Criteria andNameIn(List<String> values) {
addCriterion("name in", values, "name");
return (Criteria) this;
}
public Criteria andNameNotIn(List<String> values) {
addCriterion("name not in", values, "name");
return (Criteria) this;
}
public Criteria andNameBetween(String value1, String value2) {
addCriterion("name between", value1, value2, "name");
return (Criteria) this;
}
public Criteria andNameNotBetween(String value1, String value2) {
addCriterion("name not between", value1, value2, "name");
return (Criteria) this;
}
public Criteria andBirthIsNull() {
addCriterion("birth is null");
return (Criteria) this;
}
public Criteria andBirthIsNotNull() {
addCriterion("birth is not null");
return (Criteria) this;
}
public Criteria andBirthEqualTo(Date value) {
addCriterionForJDBCDate("birth =", value, "birth");
return (Criteria) this;
}
public Criteria andBirthNotEqualTo(Date value) {
addCriterionForJDBCDate("birth <>", value, "birth");
return (Criteria) this;
}
public Criteria andBirthGreaterThan(Date value) {
addCriterionForJDBCDate("birth >", value, "birth");
return (Criteria) this;
}
public Criteria andBirthGreaterThanOrEqualTo(Date value) {
addCriterionForJDBCDate("birth >=", value, "birth");
return (Criteria) this;
}
public Criteria andBirthLessThan(Date value) {
addCriterionForJDBCDate("birth <", value, "birth");
return (Criteria) this;
}
public Criteria andBirthLessThanOrEqualTo(Date value) {
addCriterionForJDBCDate("birth <=", value, "birth");
return (Criteria) this;
}
public Criteria andBirthIn(List<Date> values) {
addCriterionForJDBCDate("birth in", values, "birth");
return (Criteria) this;
}
public Criteria andBirthNotIn(List<Date> values) {
addCriterionForJDBCDate("birth not in", values, "birth");
return (Criteria) this;
}
public Criteria andBirthBetween(Date value1, Date value2) {
addCriterionForJDBCDate("birth between", value1, value2, "birth");
return (Criteria) this;
}
public Criteria andBirthNotBetween(Date value1, Date value2) {
addCriterionForJDBCDate("birth not between", value1, value2, "birth");
return (Criteria) this;
}
public Criteria andScoreIsNull() {
addCriterion("score is null");
return (Criteria) this;
}
public Criteria andScoreIsNotNull() {
addCriterion("score is not null");
return (Criteria) this;
}
public Criteria andScoreEqualTo(Float value) {
addCriterion("score =", value, "score");
return (Criteria) this;
}
public Criteria andScoreNotEqualTo(Float value) {
addCriterion("score <>", value, "score");
return (Criteria) this;
}
public Criteria andScoreGreaterThan(Float value) {
addCriterion("score >", value, "score");
return (Criteria) this;
}
public Criteria andScoreGreaterThanOrEqualTo(Float value) {
addCriterion("score >=", value, "score");
return (Criteria) this;
}
public Criteria andScoreLessThan(Float value) {
addCriterion("score <", value, "score");
return (Criteria) this;
}
public Criteria andScoreLessThanOrEqualTo(Float value) {
addCriterion("score <=", value, "score");
return (Criteria) this;
}
public Criteria andScoreIn(List<Float> values) {
addCriterion("score in", values, "score");
return (Criteria) this;
}
public Criteria andScoreNotIn(List<Float> values) {
addCriterion("score not in", values, "score");
return (Criteria) this;
}
public Criteria andScoreBetween(Float value1, Float value2) {
addCriterion("score between", value1, value2, "score");
return (Criteria) this;
}
public Criteria andScoreNotBetween(Float value1, Float value2) {
addCriterion("score not between", value1, value2, "score");
return (Criteria) this;
}
}
public static class Criteria extends GeneratedCriteria {
protected Criteria() {
super();
}
}
public static class Criterion {
private String condition;
private Object value;
private Object secondValue;
private boolean noValue;
private boolean singleValue;
private boolean betweenValue;
private boolean listValue;
private String typeHandler;
public String getCondition() {
return condition;
}
public Object getValue() {
return value;
}
public Object getSecondValue() {
return secondValue;
}
public boolean isNoValue() {
return noValue;
}
public boolean isSingleValue() {
return singleValue;
}
public boolean isBetweenValue() {
return betweenValue;
}
public boolean isListValue() {
return listValue;
}
public String getTypeHandler() {
return typeHandler;
}
protected Criterion(String condition) {
super();
this.condition = condition;
this.typeHandler = null;
this.noValue = true;
}
protected Criterion(String condition, Object value, String typeHandler) {
super();
this.condition = condition;
this.value = value;
this.typeHandler = typeHandler;
if (value instanceof List<?>) {
this.listValue = true;
} else {
this.singleValue = true;
}
}
protected Criterion(String condition, Object value) {
this(condition, value, null);
}
protected Criterion(String condition, Object value, Object secondValue, String typeHandler) {
super();
this.condition = condition;
this.value = value;
this.secondValue = secondValue;
this.typeHandler = typeHandler;
this.betweenValue = true;
}
protected Criterion(String condition, Object value, Object secondValue) {
this(condition, value, secondValue, null);
}
}
}

StudentMapper.xml

Xml代码

<?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="com.iflytek.dao.mapper.StudentMapper" >
<resultMap id="BaseResultMap" type="com.iflytek.dao.model.Student" >
<id column="id" property="id" jdbcType="INTEGER" />
<result column="name" property="name" jdbcType="VARCHAR" />
<result column="birth" property="birth" jdbcType="DATE" />
<result column="score" property="score" jdbcType="REAL" />
</resultMap>
<sql id="Example_Where_Clause" >
<where >
<foreach collection="oredCriteria" item="criteria" separator="or" >
<if test="criteria.valid" >
<trim prefix="(" suffix=")" prefixOverrides="and" >
<foreach collection="criteria.criteria" item="criterion" >
<choose >
<when test="criterion.noValue" >
and ${criterion.condition}
</when>
<when test="criterion.singleValue" >
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue" >
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue" >
and ${criterion.condition}
<foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Update_By_Example_Where_Clause" >
<where >
<foreach collection="example.oredCriteria" item="criteria" separator="or" >
<if test="criteria.valid" >
<trim prefix="(" suffix=")" prefixOverrides="and" >
<foreach collection="criteria.criteria" item="criterion" >
<choose >
<when test="criterion.noValue" >
and ${criterion.condition}
</when>
<when test="criterion.singleValue" >
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue" >
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue" >
and ${criterion.condition}
<foreach collection="criterion.value" item="listItem" open="(" close=")" separator="," >
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Base_Column_List" >
id, name, birth, score
</sql>
<select id="selectByExample" resultMap="BaseResultMap" parameterType="com.iflytek.dao.model.StudentExample" >
select
<if test="distinct" >
distinct
</if>
<include refid="Base_Column_List" />
from tbl_student
<if test="_parameter != null" >
<include refid="Example_Where_Clause" />
</if>
<if test="orderByClause != null" >
order by ${orderByClause}
</if>
</select>
<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
select
<include refid="Base_Column_List" />
from tbl_student
where id = #{id,jdbcType=INTEGER}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
delete from tbl_student
where id = #{id,jdbcType=INTEGER}
</delete>
<delete id="deleteByExample" parameterType="com.iflytek.dao.model.StudentExample" >
delete from tbl_student
<if test="_parameter != null" >
<include refid="Example_Where_Clause" />
</if>
</delete>
<insert id="insert" parameterType="com.iflytek.dao.model.Student" >
<selectKey resultType="java.lang.Integer" keyProperty="id" order="AFTER" >
SELECT LAST_INSERT_ID()
</selectKey>
insert into tbl_student (name, birth, score)
values (#{name,jdbcType=VARCHAR}, #{birth,jdbcType=DATE}, #{score,jdbcType=REAL})
</insert>
<insert id="insertSelective" parameterType="com.iflytek.dao.model.Student" >
<selectKey resultType="java.lang.Integer" keyProperty="id" order="AFTER" >
SELECT LAST_INSERT_ID()
</selectKey>
insert into tbl_student
<trim prefix="(" suffix=")" suffixOverrides="," >
<if test="name != null" >
name,
</if>
<if test="birth != null" >
birth,
</if>
<if test="score != null" >
score,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides="," >
<if test="name != null" >
#{name,jdbcType=VARCHAR},
</if>
<if test="birth != null" >
#{birth,jdbcType=DATE},
</if>
<if test="score != null" >
#{score,jdbcType=REAL},
</if>
</trim>
</insert>
<select id="countByExample" parameterType="com.iflytek.dao.model.StudentExample" resultType="java.lang.Integer" >
select count(*) from tbl_student
<if test="_parameter != null" >
<include refid="Example_Where_Clause" />
</if>
</select>
<update id="updateByExampleSelective" parameterType="map" >
update tbl_student
<set >
<if test="record.id != null" >
id = #{record.id,jdbcType=INTEGER},
</if>
<if test="record.name != null" >
name = #{record.name,jdbcType=VARCHAR},
</if>
<if test="record.birth != null" >
birth = #{record.birth,jdbcType=DATE},
</if>
<if test="record.score != null" >
score = #{record.score,jdbcType=REAL},
</if>
</set>
<if test="_parameter != null" >
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByExample" parameterType="map" >
update tbl_student
set id = #{record.id,jdbcType=INTEGER},
name = #{record.name,jdbcType=VARCHAR},
birth = #{record.birth,jdbcType=DATE},
score = #{record.score,jdbcType=REAL}
<if test="_parameter != null" >
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByPrimaryKeySelective" parameterType="com.iflytek.dao.model.Student" >
update tbl_student
<set >
<if test="name != null" >
name = #{name,jdbcType=VARCHAR},
</if>
<if test="birth != null" >
birth = #{birth,jdbcType=DATE},
</if>
<if test="score != null" >
score = #{score,jdbcType=REAL},
</if>
</set>
where id = #{id,jdbcType=INTEGER}
</update>
<update id="updateByPrimaryKey" parameterType="com.iflytek.dao.model.Student" >
update tbl_student
set name = #{name,jdbcType=VARCHAR},
birth = #{birth,jdbcType=DATE},
score = #{score,jdbcType=REAL}
where id = #{id,jdbcType=INTEGER}
</update>
</mapper>

StudentMapper.java

Java代码

package com.iflytek.dao.mapper;
import com.iflytek.dao.model.Student;
import com.iflytek.dao.model.StudentExample;
import java.util.List;
import org.apache.ibatis.annotations.Param;
public interface StudentMapper {
int countByExample(StudentExample example);
int deleteByExample(StudentExample example);
int deleteByPrimaryKey(Integer id);
int insert(Student record);
int insertSelective(Student record);
List<Student> selectByExample(StudentExample example);
Student selectByPrimaryKey(Integer id);
int updateByExampleSelective(@Param("record") Student record, @Param("example") StudentExample example);
int updateByExample(@Param("record") Student record, @Param("example") StudentExample example);
int updateByPrimaryKeySelective(Student record);
int updateByPrimaryKey(Student record);
}

StudentService.java

Java代码

package com.iflytek.service;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import com.iflytek.dao.mapper.StudentMapper;
import com.iflytek.dao.model.Student;
import com.iflytek.dao.model.StudentExample;
import com.iflytek.util.MyBatisUtil;
/**
*
* @author xdwang
*
* @ceate 2012-12-10 下午6:33:26
*
* @description 业务逻辑层，Mapper和XML是通过generator自动生成的
*
*/
public class StudentService {
/**
* @descrption 添加
* @author xdwang
* @create 2012-12-10下午6:42:48
* @param student
* 学生实体
* @return 是否成功
*/
public boolean insertStudent(Student student) {
boolean flag = false;
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
int result = studentMapper.insert(student);
if (result > 0) {
flag = true;
}
sqlSession.commit();
} finally {
sqlSession.close();
}
return flag;
}
/**
* @descrption 根据学生id获取学生实体信息
* @author xdwang
* @create 2012-12-10下午6:46:09
* @param studentId
* 学生id
* @return 学生实体信息
*/
public Student getStudentById(int studentId) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
StudentMapper StudentMapper = sqlSession.getMapper(StudentMapper.class);
return StudentMapper.selectByPrimaryKey(studentId);
} finally {
sqlSession.close();
}
}
/**
* @descrption 获取所有学生信息集合
* @author xdwang
* @create 2012-12-10下午6:46:55
* @return 学生集合
*/
public List<Student> getAllStudents() {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
StudentMapper StudentMapper = sqlSession.getMapper(StudentMapper.class);
return StudentMapper.selectByExample(new StudentExample());
} finally {
sqlSession.close();
}
}
/**
* @descrption 更新学生信息
* @author xdwang
* @create 2012-12-10下午6:47:13
* @param Student
* 学生实体信息
* @return 更新成功与否
*/
public boolean updateStudent(Student Student) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
boolean flag = false;
try {
StudentMapper StudentMapper = sqlSession.getMapper(StudentMapper.class);
int result = StudentMapper.updateByPrimaryKey(Student);
if (result > 0) {
flag = true;
}
sqlSession.commit();
} finally {
sqlSession.close();
}
return flag;
}
/**
* @descrption 根据学生id删除学生信息
* @author xdwang
* @create 2012-12-10下午6:49:05
* @param studentId
* 学生id
* @return 删除成功与否
*/
public boolean deleteStudent(int studentId) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
boolean flag = false;
try {
StudentMapper StudentMapper = sqlSession.getMapper(StudentMapper.class);
int result = StudentMapper.deleteByPrimaryKey(studentId);
if (result > 0) {
flag = true;
}
sqlSession.commit();
} finally {
sqlSession.close();
}
return flag;
}
}

StudentServiceTest.java

Java代码

package com.iflytek.test;
import java.util.Date;
import java.util.List;
import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import com.iflytek.dao.model.Student;
import com.iflytek.service.StudentService;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午7:02:08
*
* @description 测试业务逻辑
*
*/
public class StudentServiceTest {
private static StudentService studentService;
@BeforeClass
public static void setup() {
studentService = new StudentService();
}
@AfterClass
public static void teardown() {
studentService = null;
}
@Test
public void testInsertStudent() {
Student student = new Student();
student.setName("xwang");
student.setBirth(new Date());
student.setScore((float) 99.5);
System.out.println(studentService.insertStudent(student));
}
@Test
public void testGetStudentById() {
Student student = studentService.getStudentById(1);
Assert.assertNotNull(student);
System.out.println(student);
}
@Test
public void testGetAllStudents() {
List<Student> students = studentService.getAllStudents();
Assert.assertNotNull(students);
for (Student student : students) {
System.out.println(student);
}
}
@Test
public void testUpdateStudent() {
Student student = studentService.getStudentById(1);
student.setName("xdwang03");
System.out.println(studentService.deleteStudent(1));
}
@Test
public void testDeleteStudent() {
System.out.println(studentService.deleteStudent(1));
}
}

二、注解
Blog.java

Java代码

package com.iflytek.dao.model;
import java.text.MessageFormat;
import java.util.Date;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午7:29:08
*
* @description 博客实体类，手动创建
*
*/
public class Blog {
private Integer blogId;
private String blogName;
private Date createdOn;
public Integer getBlogId() {
return blogId;
}
public void setBlogId(Integer blogId) {
this.blogId = blogId;
}
public String getBlogName() {
return blogName;
}
public void setBlogName(String blogName) {
this.blogName = blogName;
}
public Date getCreatedOn() {
return createdOn;
}
public void setCreatedOn(Date createdOn) {
this.createdOn = createdOn;
}
@Override
public String toString() {
return MessageFormat.format("Blog [blogId={0}, blogName={1}, createdOn={2}]", blogId, blogName, createdOn);
}
}

BlogMapper.java

Java代码

package com.iflytek.dao.mapper;
import java.util.List;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import com.iflytek.dao.model.Blog;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午7:30:44
*
* @description 数据访问层接口，手动添加，基于注解的模式
*/
public interface BlogMapper {
@Insert("INSERT INTO BLOG(BLOG_NAME, CREATED_ON) VALUES(#{blogName}, #{createdOn})")
@Options(useGeneratedKeys = true, keyProperty = "blogId")
public void insertBlog(Blog blog);
@Select("SELECT BLOG_ID AS blogId, BLOG_NAME as blogName, CREATED_ON as createdOn FROM BLOG WHERE BLOG_ID=#{blogId}")
public Blog getBlogById(Integer blogId);
@Select("SELECT * FROM BLOG ")
@Results({ @Result(id = true, property = "blogId", column = "BLOG_ID"), @Result(property = "blogName", column = "BLOG_NAME"),
@Result(property = "createdOn", column = "CREATED_ON") })
public List<Blog> getAllBlogs();
@Update("UPDATE BLOG SET BLOG_NAME=#{blogName}, CREATED_ON=#{createdOn} WHERE BLOG_ID=#{blogId}")
public void updateBlog(Blog blog);
@Delete("DELETE FROM BLOG WHERE BLOG_ID=#{blogId}")
public void deleteBlog(Integer blogId);
}

BlogService.java

Java代码

package com.iflytek.service;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import com.iflytek.dao.mapper.BlogMapper;
import com.iflytek.dao.model.Blog;
import com.iflytek.util.MyBatisUtil;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午7:39:34
*
* @description 博客业务逻辑层，调用注解的接口实现
*
*/
public class BlogService {
public void insertBlog(Blog blog) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
//使用注解的时候一定要将XXXMapper注册一下，跟XML配置namespace一样
//MyBatisUtil.getSqlSessionFactory().getConfiguration().addMapper(BlogMapper.class);
try {
BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
blogMapper.insertBlog(blog);
sqlSession.commit();
} finally {
sqlSession.close();
}
}
public Blog getBlogById(Integer blogId) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
return blogMapper.getBlogById(blogId);
} finally {
sqlSession.close();
}
}
public List<Blog> getAllBlogs() {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
return blogMapper.getAllBlogs();
} finally {
sqlSession.close();
}
}
public void updateBlog(Blog blog) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
blogMapper.updateBlog(blog);
sqlSession.commit();
} finally {
sqlSession.close();
}
}
public void deleteBlog(Integer blogId) {
SqlSession sqlSession = MyBatisUtil.getSqlSessionFactory().openSession();
try {
BlogMapper blogMapper = sqlSession.getMapper(BlogMapper.class);
blogMapper.deleteBlog(blogId);
sqlSession.commit();
} finally {
sqlSession.close();
}
}
}

BlogServiceTest.java

Java代码

package com.iflytek.test;
import java.util.Date;
import java.util.List;
import org.junit.AfterClass;
import org.junit.Assert;
import org.junit.BeforeClass;
import org.junit.Test;
import com.iflytek.dao.model.Blog;
import com.iflytek.service.BlogService;
/**
* @author xdwang
*
* @ceate 2012-12-10 下午7:42:41
*
* @description 基于注解的CRUD 测试
*
*/
public class BlogServiceTest {
private static BlogService blogService;
@BeforeClass
public static void setUp() throws Exception {
blogService = new BlogService();
}
@AfterClass
public static void tearDown() throws Exception {
blogService = null;
}
@Test
public void testInsertBlog() {
Blog blog = new Blog();
blog.setBlogName("test_blog_" + System.currentTimeMillis());
blog.setCreatedOn(new Date());
blogService.insertBlog(blog);
Assert.assertTrue(blog.getBlogId() != 0);
Blog createdBlog = blogService.getBlogById(blog.getBlogId());
Assert.assertNotNull(createdBlog);
Assert.assertEquals(blog.getBlogName(), createdBlog.getBlogName());
}
@Test
public void testGetBlogById() {
Blog blog = blogService.getBlogById(1);
Assert.assertNotNull(blog);
System.out.println(blog);
}
@Test
public void testGetAllBlogs() {
List<Blog> blogs = blogService.getAllBlogs();
Assert.assertNotNull(blogs);
for (Blog blog : blogs) {
System.out.println(blog);
}
}
@Test
public void testUpdateBlog() {
long timestamp = System.currentTimeMillis();
Blog blog = blogService.getBlogById(2);
blog.setBlogName("TestBlogName" + timestamp);
blogService.updateBlog(blog);
Blog updatedBlog = blogService.getBlogById(2);
Assert.assertEquals(blog.getBlogName(), updatedBlog.getBlogName());
}
@Test
public void testDeleteBlog() {
Blog blog = blogService.getBlogById(4);
blogService.deleteBlog(blog.getBlogId());
Blog deletedBlog = blogService.getBlogById(4);
Assert.assertNull(deletedBlog);
}
}

对于简单语句来说，使用注解代码会更加清晰，然后Java 注解对于复杂语句来说就会混乱, 应该限制使用。因此, 如果你不得不做复杂的事情, 那么最好使用 XML 来映射语句。

几个重要的范围和生命周期

1、SqlSessionFactoryBuilder

这个类可以被实例化使用和丢弃。一旦你创建了SqlSessionFactory 后,这个类就不需要存在了。因此 SqlSessionFactoryBuilder 实例的最佳范围是方法范围 (也就是本地方法变量)。你可以重用 SqlSessionFactoryBuilder来创建多个SqlSessionFactory实例,但是最好的方式是不需要保持它一直存在来保证所有 XML 解析资源,因为还有更重要的事情要做。

2、SqlSessionFactory

一旦被创建,SqlSessionFactory 应该在你的应用执行期间都存在。没有理由来处理或重新创建它。使用 SqlSessionFactory的最佳实践是在应用运行期间不要重复创建多次。这样的操作将被视为是非常糟糕的。因此 SqlSessionFactory 的最佳范围是应用范围。有很多方法可以做到,最简单的就是使用单例模式或者静态单例模式。

3、SqlSession

每个线程都应该有它自己的SqlSession 实例。SqlSession的实例不能被共享,也是线程不安全的。因此最佳的范围是请求或方法范围。绝对不能将 SqlSession 实例的引用放在一个类的静态字段甚至是实例字段中。也绝不能将SqlSession实例的引用放在任何类型的管理范围中, 比如Serlvet架构中的 HttpSession。如果你现在正用任意的Web框架,要考虑 SqlSession放在一个和 HTTP 请求对象相似的范围内。换句话说,基于收到的HTTP请求,你可以打开了一个SqlSession,然后返回响应,就可以关闭它了。关闭Session很重要,你应该确保使用 finally 块来关闭它。下面的示例就是一个确保 SqlSession 关闭的基本模式:

Java代码

SqlSession session = sqlSessionFactory.openSession();
try {
// do work
} finally {
session.close();
}

在你的代码中一贯地使用这种模式, 将会保证所有数据库资源都正确地关闭 (假设你没有通过你自己的连接关闭,这会给 MyBatis 造成一种迹象表明你要自己管理连接资源) 。

4、Mapper 实例

映射器是你创建绑定映射语句的接口。映射器接口的实例可以从 SqlSession 中获得。那么从技术上来说,当被请求时,任意映射器实例的最宽范围和 SqlSession 是相同的。然而, 映射器实例的最佳范围是方法范围。也就是说,它们应该在使用它们的方法中被请求,然后就抛弃掉。它们不需要明确地关闭,那么在请求对象中保留它们也就不是什么问题了,这和 SqlSession 相似。你也许会发现,在这个水平上管理太多的资源的话会失控。保持简单,将映射器放在方法范围内。