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Mybatis SQL映射文�g�Q��{载）

alexprefect — Thu, 29 Mar 2012 03:08:00 GMT

前面学习的都是一些配�|�，mybatis的精华也��集中在SQL的映��文件上�Q�相比实现相同功能的jdbc代码�Q�节�U�了95%的代码量�?/p>

一、select可以可以说是使用最多的元素�Q��用也很简�?/p>

<select id="getUserById" parameterType="int" resultType="User">
select * from tbl_user where id = #{id}
select>

    <select id="getUserById" parameterType="int" resultType="User">
        select * from tbl_user where id = #{id}
    </select>

< select>元素中的一些属�?�U�色为用的较多的属�?

id	在命名空间中唯一的标识符�Q�可以被用来引用�q�条语句
parameterType	��会传入�q�条语句的参数类的完全限定名或别名�?/td>
resultType	从这条语句中�q�回的期望类型的�cȝ��完全限定名或别名�?br />意集合情形，那应该是集合可以包含的类型，而不能是集合本��n。��?resultType�?resultMap�Q?br />但不能同时��?/span>。（可以是基本类型int�{�，复合�c�d��User�Q�集合类型map,list�{�）
resultMap	命名引用外部的resultMap。返回map是MyBat is 最具力量的�Ҏ��，对其有一个很好的理解的话�Q?br />多复杂映��的情�Ş��p��被解决了�?br />使用 resultMap 或resultType�Q�但不能同时使用�?/td>
flushCache	��其讄��?true�Q�不��句什么时候被带哦用，都会��D��~�存被清�I�。默认��\|��false
useCache	��其讄��?true�Q�将会导致本条语句的�l�果被缓存�?br />默认��\|��true
timeout	�q�个讄��驱动�E�序�{�待数据库返回请求结果，�q�抛�?br />异常旉��的最大等待倹{��默认不讄��Q�驱动自行处理）
fetchSize	�q�是暗示驱动�E�序每次扚w��q�回的结果行数�?br />默认不设�\|�（驱动自行处理�Q?/td>
statementType	STATEMENT,PREPARED �?CALLABLE 的一�U��?br />�q�会�?MyBat is使用选择使用 Statement�Q�PreparedStatement�?CallableStatement�?br />默认��\|��PREPARED�?/td>
resultSetType	FORWARD_ONLY�Q?br />SCROLL_SENSITIVE�Q?br />SCROLL_INSENSITIVE中的一�U��?br />默认是不讄��Q�驱动自行处理）

二、insert插入数据库，�q�行插入操作时主要是要拿到插入数据自增的主键

id	在命名空间中唯一的标识符�Q�可以被用来引用�q�条语句�?/td>
parameterType	��会传入�q�条语句的参数类的完全限定名或别�?/td>
flushCache	��其讄��?true�Q�不��句什么时候被带哦用，都会��D��~�存被清�I�。默认��\|��false�?/td>
timeout	�q�个讄��驱动�E�序�{�待数据库返回请求结果，�q�抛出异常时间的最大等待倹{�?br />默认不设�\|�（驱动自行处理�Q��?
statementType	STATEMENT,PREPARED �?CALLABLE 的一�U�。这会让 MyBat is使用选择使用 Statement�Q�PreparedStatement �?CallableStatement。默认��\|��PREPARED�?
useGeneratedKeys	�Q?span style="color: rgb(255, 0, 0);">仅对 insert �?�?/span> �Q?�q?�?�?�?MyBat is 使用 JDBC 的getGeneratedKeys �Ҏ��来取出由数据�Q�比如：�?MySQL �?SQL Server �q�样的数据库��理�pȝ��的自动递增字段�Q�内部生成的主键。默认��\|��false�?/td>
keyProperty	�Q?span style="color: rgb(255, 0, 0);">仅对insert有用�Q?标记一个属性， MyBat is会通过getGeneratedKeys或者通过 insert 语句的selectKey 子元素设�\|�它的倹{��默认：不设�\|��?/td>

在进行insert�Q�update,delete之后session要进行commit操作�Q�不然数据库不会更新到数据库

insert的Demo

另一�U�获取主键的�Ҏ��

[html] view plain copy print ?

<insert id="addUserLastId" parameterType="User">
<selectKey resultType="int" order="AFTER" keyProperty="id">
SELECT LAST_INSERT_ID() AS id
selectKey>
insert into tbl_user(name,age) values(#{name},#{age})
insert>

    <insert id="addUserLastId" parameterType="User">
    	<selectKey resultType="int" order="AFTER" keyProperty="id">
    		SELECT LAST_INSERT_ID() AS id
    	</selectKey>
    	insert into tbl_user(name,age) values(#{name},#{age})
    </insert>

[html] view plain copy print ?

<insert id="addUser" parameterType="User" keyProperty="id" useGeneratedKeys="true" >
insert into tbl_user(name,age) values(#{name},#{age})
insert>

    <insert id="addUser" parameterType="User" keyProperty="id" useGeneratedKeys="true" >
    	insert into tbl_user(name,age) values(#{name},#{age})
    </insert>

[java] view plain copy print ?

@Test
public void testInsert() throws IOException {
UserMapper mapper = session.getMapper(UserMapper.class) ;
User user = new User() ;
user.setName("zhangss") ;
user.setAge(22) ;
int i = mapper.addUser(user) ;
session.commit() ;
session.close() ;
System.out.println("id:"+i+"--"+user.getId());
}

	@Test
	public void testInsert() throws IOException {
		UserMapper mapper = session.getMapper(UserMapper.class) ; 
		User user = new User() ;
		user.setName("zhangss") ;
		user.setAge(22) ;
		int i = mapper.addUser(user) ;
		session.commit() ;
		session.close() ;
		System.out.println("id:"+i+"--"+user.getId());
	}

update的Demo

[html] view plain copy print ?

<update id="updateUser" parameterType="User">
update tbl_user set name = #{name} ,age = #{age} where id = #{id}
update>

    <update id="updateUser" parameterType="User">
    	update tbl_user set name = #{name} ,age = #{age} where id = #{id}
    </update>

[java] view plain copy print ?

@Test
public void testUpdate(){
UserMapper mapper = session.getMapper(UserMapper.class) ;
User user = new User() ;
user.setId(27) ;
user.setName("zhang27") ;
user.setAge(227) ;
int i = mapper.updateUser(user) ;
session.commit() ;
session.close() ;
System.out.println("id:"+i+"--"+user.getId());
}

	@Test
	public void testUpdate(){
		UserMapper mapper = session.getMapper(UserMapper.class) ; 
		User user = new User() ;
		user.setId(27) ;
		user.setName("zhang27") ;
		user.setAge(227) ;
		int i = mapper.updateUser(user) ;
		session.commit() ;
		session.close() ;
		System.out.println("id:"+i+"--"+user.getId());
	}

三、sql定义可重用的sql语句

[html] view plain copy print ?

<sql id="selectItem">id,name,agesql>

<sql id="selectItem">id,name,age</sql>

[html] view plain copy print ?

<select id="getUserById" parameterType="int" resultType="User">
select <include refid="selectItem"/> from tbl_user where id = #{id}
select>

    <select id="getUserById" parameterType="int" resultType="User">
    	
    	<!-- 
        select * from tbl_user where id = #{id}
         -->
         select <include refid="selectItem"/> from tbl_user where id = #{id}
    </select>

四、Parameter

#{department, mode=OUT, jdbcType=CURSOR, javaType=ResultSet,resultMap=departmentResultMap}

五、resultMap所做的工作��是��从数据库中获取的ResultSet�l�果集放入指定的对象中，避免大量的setter getter代码�Q�实现自动装配的功能�Q�实现结果的映射

1、简单映��?/p>

[html] view plain copy print ?

<select id=”selectUsers” parameterType=”int” resultType=”hashmap”>
select id, username, hashedPassword from some_table where id = #{id}
select>

<select id=”selectUsers” parameterType=”int” resultType=”hashmap”> 
	select id, username, hashedPassword from some_table where id = #{id} 
</select>

所有列被自动映��到 HashMap 的键上，key为列名，value为数据库中的数据

[html] view plain copy print ?

<select id=”selectUsers” parameterType=”int” resultType=”com.someapp.model.User”>
select id, username, hashedPassword from some_table where id = #{id}
select>

<select id=”selectUsers” parameterType=”int” resultType=”com.someapp.model.User”> 
	select id, username, hashedPassword from some_table where id = #{id} 
</select>

��所有从数据库中取得数据自动装配到JavaBean中，如果列名与属性名相同�Q�则无需作�Q务的�q�预卛_��完成装配�?p>

如果数据库中的列名与javabean的属性名�U�C��同可以在查询的时候取别名�Q�如

[html] view plain copy print ?

<select id=”selectUsers” parameterType=”int” resultType=”User”>
select user_id as “id”, user_name as “userName”, hashed_password as “hashedPassword” from some_table where id = #{id}
select>

<select id=”selectUsers” parameterType=”int” resultType=”User”> 
	select user_id as “id”, user_name as “userName”, hashed_password as “hashedPassword”  from some_table where id = #{id} 
</select>

也可以��用resultMap�q�行映射的指�?p>

[html] view plain copy print ?

<resultMap id="userResultMap" type="User">
<id property="id" column="user_id" />
<result property="username" column="username"/>
<result property="password" column="password"/>
resultMap>
<select id=”selectUsers” parameterType=”int” resultMap=”userResultMap”>
select user_id, user_name, hashed_password from some_table where id = #{id}
select>

<resultMap id="userResultMap" type="User"> 
	<id property="id" column="user_id" /> 
	<result property="username" column="username"/> 
	<result property="password" column="password"/> 
</resultMap> 

<select id=”selectUsers” parameterType=”int”  resultMap=”userResultMap”> 
	select user_id, user_name, hashed_password from some_table where id = #{id} 
</select>

2、resultMap高��映射

alexprefect 2012-03-29 11:08 发表评论

Mybatis 配置文�g�Q��{载）

alexprefect — Thu, 29 Mar 2012 03:07:00 GMT

�q�篇文章学习的是mybatis的主配置文�gConfiguration.xml�Q�这个配�|�文件主要配�|�一些全局的属性，如数据库的连接，�cȝ��别名�Q�不同的

场景�q�行不同的配�|�等�{��?/p>

一、Configuration.xml中可以配�|�的所有内�?/p>

configuration 配置
	properties 属�?/td>
	settings 讄��
	typeAliases �c�d��命名
	typeHandlers �c�d��处理�?
	objectFactory 对象工厂
	plugins 插�g
	environments 环境
		environment 环境变量
			transactionManager 事务��理�?
			dataSource 数据�?
	映射�?/span>

二、Properties标签

可以用来引用外部的属性文件进行配�|�，比如所有的配置都在一个eas.properties中配�|�，只需要在properties中配�|�一�ơ，��可以做��C��ơ配�|�到处引用�?/p>

如现在配�|�一个eas.properties

[plain] view plain copy print ?

#db config
db.driver:com.sybase.jdbc3.jdbc.SybDriver
db.url:jdbc:sybase:Tds:192.168.2.143:2678/SMM_win2k8_portal
db.username:dba
db.password:smmsql
#server config
server.url:http://192.168.2.101:8080/EAS

#db config
db.driver:com.sybase.jdbc3.jdbc.SybDriver
db.url:jdbc:sybase:Tds:192.168.2.143:2678/SMM_win2k8_portal
db.username:dba
db.password:smmsql

#server config
server.url:http://192.168.2.101:8080/EAS

在configuration.xml中对属性文件中的��D��行引�?p>

[html] view plain copy print ?

xml version="1.0" encoding="UTF-8"?>
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties resource="eas.properties" />
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${db.driver}"/>
<property name="url" value="${db.url}"/>
<property name="username" value="${db.username}"/>
<property name="password" value="${db.password}"/>
dataSource>
environment>
environments>
configuration>

<?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="eas.properties" />
	
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${db.driver}"/>
                <property name="url" value="${db.url}"/>
                <property name="username" value="${db.username}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

三、Setteing标签�Q�对mybatis的一些行��行设�|?/p>

配置

< /settings>

四、typeAliases ��Z��c�设�|�别名，方便书写

[html] view plain copy print ?

<typeAliases>
<typeAlias alias="App" type="com.justsy.eas.domain.App"/>
<typeAlias alias="Content" type="com.justsy.eas.domain.Content"/>
<typeAlias alias="AppDevice" type="com.justsy.eas.domain.AppDevice"/>
<typeAlias alias="ListApp" type="com.justsy.eas.http.domain.ListApp"/>
<typeAlias alias="ClientApp" type="com.justsy.eas.http.domain.ClientApp"/>
typeAliases>

	<typeAliases>
		<!-- simple alias for full class name -->
		<typeAlias alias="App" type="com.justsy.eas.domain.App"/>
		<typeAlias alias="Content" type="com.justsy.eas.domain.Content"/>
		<typeAlias alias="AppDevice" type="com.justsy.eas.domain.AppDevice"/>
		<typeAlias alias="ListApp" type="com.justsy.eas.http.domain.ListApp"/>
		<typeAlias alias="ClientApp" type="com.justsy.eas.http.domain.ClientApp"/>
	</typeAliases>

java 中一些简单类型的别名

别名映射的类�?
_byte byte
_long long
_short short
_int   int
_integer   int
_double double
_float   float
_boolean boolean
string String
byte Byte
long Long
short Short
int   Integer
integer   Integer
double Double
float   Float
boolean Boolean
date Date
decimal BigDecimal
bigdecimal BigDecimal
object Object
map Map
hashmap HashMap
list List
arraylist ArrayList
collection Collection
iterator Iterator

五、typeHandlers 的作用是��Java�c�d��与数据库中类型进行匹配，在statement讑ր�和ResultSet��索值时可以正确的�{换，可以实现TypeHandler接口实现自己的类型处理器。mybatis中内建的�c�d��处理�?Type Handler )

六、ObjectFactory 每次创徏新的�l�果对象是调用这个ObjectFactory的对象来�q�行创徏�Q�它会比直接调用构造函数创建对象做更多的工�?/p>

七、plugins主要用来实现拦截器的功能�Q��用到了动态代理，可以指定在某些操作时执行一些拦截操作，比如在一条记录插入数据库之前写入一条日志，或查询一�?/p>

权限�{�等

�?nbsp; Executor
(update, query, flushStatements, commit, rollback, getTransaction, close, isClosed)
�?nbsp; ParameterHandler
(getParameterObject, setParameters)
�?nbsp; ResultSetHandler
(handleResultSets, handleOutputParameters)
�?nbsp; StatementHandler
(prepare, parameterize, batch, update, query)

[java] view plain copy print ?

// ExamplePlugin.java
@Intercepts({ @Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class }) })
public class ExamplePlugin implements Interceptor {
public Object intercept(Invocation invocation) throws Throwable {
return invocation.proceed();
}
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
public void setProperties(Properties properties) {
}
}

	// ExamplePlugin.java
	@Intercepts({ @Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class }) })
	public class ExamplePlugin implements Interceptor {
		public Object intercept(Invocation invocation) throws Throwable {
			return invocation.proceed();
		}

		public Object plugin(Object target) {
			return Plugin.wrap(target, this);
		}

		public void setProperties(Properties properties) {
		}
	}

[html] view plain copy print ?

<plugins>
<plugin interceptor="org.mybatis.example.ExamplePlugin">
<property name="someProperty" value="100"/>
plugin>
plugins>

	<plugins> 
	  <plugin interceptor="org.mybatis.example.ExamplePlugin"> 
	    <property name="someProperty" value="100"/> 
	  </plugin> 
	</plugins>

��׃��在所有执行update动作之前�q�行拦截�Q�执行ExamplePlugin中自定义的一些逻辑

对select�q�行拦截的plugin

[java] view plain copy print ?

import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
@Intercepts({ @Signature(args = { MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class }, method = "query", type = Executor.class) })
public class LogInterceptor implements Interceptor {
int index;
@Override
public Object intercept(Invocation invocation) throws Throwable {
System.out.println("some log!!!");
return invocation.proceed();
}
@Override
public Object plugin(Object target) {
System.out.println("1223--------------" + (index++));
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
}
}

import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

@Intercepts({ @Signature(args = { MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class }, method = "query", type = Executor.class) })
public class LogInterceptor implements Interceptor {

	int index;

	@Override
	public Object intercept(Invocation invocation) throws Throwable {
		System.out.println("some log!!!");
		return invocation.proceed();
	}

	@Override
	public Object plugin(Object target) {
		System.out.println("1223--------------" + (index++));
		return Plugin.wrap(target, this);
	}

	@Override
	public void setProperties(Properties properties) {

	}
}

[html] view plain copy print ?

<plugins>
<plugin interceptor="com.akwolf.interceptor.LogInterceptor">
plugin>
plugins>

	<plugins>
    	<plugin interceptor="com.akwolf.interceptor.LogInterceptor">
    	</plugin>
    </plugins>

八、environments 对于一个应用可能连接多个数据库�Q�那��需要配�|�不同的环境来连接不同的数据库，每一个SqlSessionFactory对应一个environments

也可以设�|�不同的环境应用于开发或��试的环�?/p>

如果环境被忽略，那么默认环境��会被加载，也就是default="development"的作用了

九、transactionManager讄��事物的管理类型是 type=”[JDBC|MANAGED]”

JDBC使用datasource的连接来��理事物范围�?/p>

MANAGED自己不进行事物的提交和回滚，依靠容器来管理事物，讄��closeConnection为false�Q�取消自动关闭连�?/p>

[html] view plain copy print ?

<transactionManager type="MANAGED">
<property name="closeConnection" value="false"/>
transactionManager>

<transactionManager type="MANAGED"> 
	<property name="closeConnection" value="false"/> 
</transactionManager>

十、dataSource讄��数据源[UNPOOLED|POOLED|JNDI]

POOLED:每次被请求时��单打开和关闭连�?br />

POOLED:JDBC �q�接对象的数据源�q�接池的实现�Q�用来避免创建新的连接实例时必要的初始连接和认证旉��?br />

poolMaximumActiveConnections – 在�Q意时间存在的�z�d��Q�也��是正在使用�Q�连接的数量。默认��|��10

poolMaximumIdleConnections – ��L��旉��存在的空闲连接数�?/span>

oolMaximumCheckoutTime – 在被强制�q�回之前�Q�池中连接被��查的旉��。默认��|��20000 毫秒�Q�也��是 20 �U�）

poolTimeToWait – �q�是�l�连接池一个打印日志状态机会的低层�ơ设�|�，�q�有重新��试获得�q�接�Q�这些情况下往往需要很长时��_��Z��避免�q�接池没有配�|�时静默��p�|�Q��?默认��|��20000 毫秒�Q�也��是 20 �U�）

poolPingQuery – 发送到数据的侦��查询，用来验证�q�接是否正常工作�Q��ƈ且准备接受请求。默认是“NO PING QUERY SET”�Q�这会引赯��多数据库驱动�q�接�׃��个错误信息而导致失败�?

poolPingEnabled – �q�是开启或��用侦测查询。如果开启，你必��ȝ��一个合法的SQL语句�Q�最好是很快速的�Q�设�|?poolPingQuery 属性。默认��|��false�?/span>

poolPingConnectionsNotUsedFor – �q�是用来配置 poolPingQuery 多次旉��被用一�ơ。这可以被设�|�匹配标准的数据库连接超时时��_��来避免不必要的侦��。默认��|��0 �Q�也��是所有连接每一时刻都被侦测-但仅仅当 poolPingEnabled �?true 旉��用�Q��?nbsp;

JNDI – �q�个数据源的实现是�ؓ了��用如 Spring 或应用服务器�q�类的容器，容器可以集中或在外部配置数据源，然后攄��一�?JNDI 上下文的引用�?br />

initial_context – �q�个属性用来从初始上下文中��L��环境�Q�也��是initialContext.lookup�Q�init ial——context�Q�）。这是个可选属性，如果被忽略，那么data_source 属性将会直接以 init ialContext ��景再�ơ寻找�?

data_source – �q�是引用数据源实例位�|�的上下文的路径。它会以�?init ial_context查询�q�回的环境�ؓ背景来查找，如果 init ial_context 没有�q�回�l�果�Ӟ��直接以初始上�?文�ؓ环境来查找�?

十一、mappers用来注册映射文�g�?/p>

alexprefect 2012-03-29 11:07 发表评论

mybatis环境搭徏�Q��{载）

alexprefect — Thu, 29 Mar 2012 03:06:00 GMT

最�q�一�D�|��间过的有些迷茫了�Q�好了不能在�q�样了，��g��军_��振作��h��开始好好学习一些东西吧。研�I�mybatis吧！

万里之行起于��步�Q�从搭徏环境开始�?/p>

一、下载好jar包，既然是基本环境搭建就不用弄的太复杂就加入三个最基本的jar�?/p>

1、mybatis-3.1.0-SNAPSHOT.jar

2、mysql-connector-java-5.0.8-bin.jar

3、log4j-1.2.16.jar

二、mybatis是基于log4j日志框架的，恩，把log4j的日志数据配�|�文件也配置一下，��先把��别设定在debug的��别上

[plain] view plain copy print ?

# Rules reminder:
# DEBUG < INFO < WARN < ERROR < FATAL
# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# My logging configuration...
log4j.logger.org.mybatis.jpetstore=DEBUG
## Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p %d %C: %m%n

# Rules reminder:
# DEBUG < INFO < WARN < ERROR < FATAL

# Global logging configuration
log4j.rootLogger=DEBUG, stdout

# My logging configuration...
log4j.logger.org.mybatis.jpetstore=DEBUG

## Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p %d %C: %m%n

三、现在就开始对mybatis�q�行配置�Q�配�|�文件�ؓ一个xml文�g�Q�文件名自己军_��Q�暂且就叫Configuration.xml�?p>

[html] view plain copy print ?

xml version="1.0" encoding="UTF-8"?>
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeAliases>
<typeAlias alias="User" type="com.akwolf.domain.User"/>
typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://192.168.2.110:3306/mybatis"/>
<property name="username" value="zhangh"/>
<property name="password" value="123456"/>
dataSource>
environment>
environments>
<mappers>
<mapper resource="com/akwolf/persistence/UserMapper.xml"/>
mappers>
configuration>

<?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>
		<!-- simple alias for full class name -->
		<typeAlias alias="User" type="com.akwolf.domain.User"/>
	</typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://192.168.2.110:3306/mybatis"/>
                <property name="username" value="zhangh"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/akwolf/persistence/UserMapper.xml"/>
    </mappers>
</configuration>

上面�q�个配置文�g相当于一个全局的配�|�，所以在�q�里面配�|�也会媄响到其他的配�|�文�?/p>

�q�里先对上面几个标签陌生标签解释一�?/p>

��是��Zؓ一个完整的�c�d��M��个别名，我猜你不会愿意在每次用到一个类旉��把类的完整�\劲给带上�Q�所以上面的User��可以代表com.akwolf.domain.User

�q�样做的��是一件很省力气的�?/p>

也就是在不同的环境中选择不同的配�|�，如果现在是开发环境连接的数据库可能就与测试连接数据库的配�|�不同，default代表的就是一个默认��用的环境�?/p>也就是注册你写了哪些Mapper映射文�g�?br />�q�个��先��单介�l�一下，下一��文章就把每一个标�{��使用和用处罗嗦一遍�?br />

四、徏立领域模型User

[java] view plain copy print ?

import java.io.Serializable;
public class User implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private String name;
private int age;
//setter && getter
}

import java.io.Serializable;


public class User implements Serializable {
	private static final long serialVersionUID = 1L;

	private int id;

	private String name;
	private int age;
	
	//setter && getter
}

五、徏立对数据库操作的dao接口

[java] view plain copy print ?

package com.akwolf.persistence;
import com.akwolf.domain.User;
public interface UserMapper {
/**
* 通过id查询用户
*
* @param id
* 用户id
* @return 用户实体
*/
public User getUserById(int id);
}

package com.akwolf.persistence;

import com.akwolf.domain.User;

public interface UserMapper {

	/**
	 * 通过id查询用户
	 * 
	 * @param id
	 *            用户id
	 * @return 用户实体
	 */
	public User getUserById(int id);
}

六、编写对dao接口�q�行实现的Mapper【UserMapper.xml】，��是一些sql语句

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xml version="1.0" encoding="UTF-8"?>
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.akwolf.persistence.UserMapper">
<select id="getUserById" parameterType="int" resultType="User">
select * from tbl_user where id = #{id}
select>
mapper>

<?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.akwolf.persistence.UserMapper">
    <select id="getUserById" parameterType="int" resultType="User">
        select * from tbl_user where id = #{id}
    </select>
</mapper>

#{id}表示传入的参敎ͼ�是一个变�?p>

到此一个基本的mybatis�q�行环境已经搭徏��h��Q�用��试�c�L��试一�?/p>

[java] view plain copy print ?

package com.akwolf.test;
import java.io.IOException;
import java.io.Reader;
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.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;
import com.akwolf.domain.User;
import com.akwolf.persistence.UserMapper;
public class UserTest {
private static SqlSession session ;
@BeforeClass
public static void init(){
// 配置文�g的�\�?/span>
String res = "com/akwolf/conf/Configuration.xml" ;
try {
// 1、加载配�|�文�?/span>
Reader reader = Resources.getResourceAsReader(res);
// 2、创建SqlSessionFactory�Q�用于取得SqlSession
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader) ;
// 3、取得一个SqlSession(对Jdbc中connection的封�?
session = factory.openSession() ;
} catch (IOException e) {
e.printStackTrace();
}
}
@Test
public void testGet() {
// 4、取得mybatis实现�q�实例化好的UserMapper接口实例
UserMapper mapper = session.getMapper(UserMapper.class) ;
// 5、进行dao层的操作
User u = mapper.getUserById(1) ;
System.out.println(u);
}
@AfterClass
public static void destory(){
// 6、关闭SqlSession
session.close() ;
}
}

package com.akwolf.test;

import java.io.IOException;
import java.io.Reader;

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.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.akwolf.domain.User;
import com.akwolf.persistence.UserMapper;

public class UserTest {
	
	private static SqlSession session ;
	
	@BeforeClass
	public static void init(){
		// 配置文�g的�\�?
		String res = "com/akwolf/conf/Configuration.xml" ;
		try {
			// 1、加载配�|�文�?
			Reader reader = Resources.getResourceAsReader(res);
			// 2、创建SqlSessionFactory�Q�用于取得SqlSession
			SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(reader) ;
			// 3、取得一个SqlSession(对Jdbc中connection的封�?
			session = factory.openSession() ;
		} catch (IOException e) {
			e.printStackTrace();
		} 
	}

	@Test
	public void testGet() {
		// 4、取得mybatis实现�q�实例化好的UserMapper接口实例
		UserMapper mapper = session.getMapper(UserMapper.class) ; 
		// 5、进行dao层的操作
		User u = mapper.getUserById(1) ;
		System.out.println(u);
	}
	
	@AfterClass
	public static void destory(){
		// 6、关闭SqlSession
		session.close() ;
	}
}

上面��试�cȝ��主要建立数据库连接�ƈ�Ҏ��据库�q�行的操作，��Z��方便以后查看和大家的理解�Q�注释写的很详细�?/p>

好，到这里第一个mybatis�E�序�q�行成功�Q�下一�ơ就研究一下Mybatis配置文�g的详�l�配�|��?/p>

alexprefect 2012-03-29 11:06 发表评论