MyBatis入门

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iBatis/myBatis

MyBatis MyBatis注解 SqlSessionFactoryBuilder SqlSessionFactory SqlSession

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

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 version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!-- version: $Id$ -->
<configuration>
	<!-- 引用JDBC属性的配置文件 -->
	<properties resource="database.properties" />

	<settings>
		<!-- 允许使用自定义的主键值(比如由程序生成的UUID 32位编码作为键值)，数据表的PK生成策略将被覆盖 -->
		<setting name="useGeneratedKeys" value="true" />
		<setting name="defaultExecutorType" value="REUSE" />
	</settings>

	<environments default="development">
		<environment id="development">
			<!-- 使用JDBC的事务管理 -->
			<transactionManager type="JDBC" />
			<!-- POOLED ：JDBC连接对象的数据源连接池的实现，不直接支持第三方数据库连接池 -->
			<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>

	<!-- ORM映射文件 -->
	<mappers>
		<!-- 注解的方式 -->
		<mapper class="com.iflytek.dao.mapper.BlogMapper" />
		<!-- XML的方式 -->
		<mapper resource="com/iflytek/dao/xml/StudentMapper.xml" />
		<!-- 这里对于注解，还可以通过<package name="com.iflytek.dao.mapper"/> -->
	</mappers>
</configuration>

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

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

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

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 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

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

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

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

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

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

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

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:

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。

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2012-12-11 09:04
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