mybatis項目配置文件

##mybatis項目配置 首先這事一個簡單的mybatis項目配置文件：

<?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>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

###environment mybatis支持多個環境，能夠任意配置

好比：

<environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
    
    <environment id="test">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>

就會有兩個環境，environments中的defalut標籤選擇哪個，默認就是哪個 ###transactionManager mybatis支持兩種類型的事務管理器，jdbc和managed（託管）

jdbc：應用程序管理數據庫鏈接的生命週期

managed：由應用服務器負責管理數據庫鏈接的生命週期（通常商業服務器纔有此功能，如JBOSS WebLogic） ###dataSource type：用來配置數據源，類型有：UNPOOLED、POOLED、JNDI

UNPOOLED：沒有鏈接池，每次數據庫操做，mybatis都會建立一個新的鏈接，用完後，關閉：適合小併發項目

POOLED：有鏈接池

JNDI：使用應用服務器配置JNDI數據源獲取數據庫鏈接 ###properties 配置屬性

好比：

<properties resource="org/mybatis/example/config.properties">
  <property name="username" value="dev_user"/>
  <property name="password" value="F2Fa3!33TYyg"/>
</properties>

<dataSource type="POOLED">
  <property name="driver" value="${driver}"/>
  <property name="url" value="${url}"/>
  <property name="username" value="${username}"/>
  <property name="password" value="${password}"/>
</dataSource>

###typeAliases 給類的完整限定名取別名，方便使用

好比：

<typeAliases>
  <typeAlias alias="Author" type="domain.blog.Author"/>
  <typeAlias alias="Blog" type="domain.blog.Blog"/>
  <typeAlias alias="Comment" type="domain.blog.Comment"/>
  <typeAlias alias="Post" type="domain.blog.Post"/>
  <typeAlias alias="Section" type="domain.blog.Section"/>
  <typeAlias alias="Tag" type="domain.blog.Tag"/>
</typeAliases>
<!-- 最經常使用-->
<typeAliases>
  <package name="domain.blog"/>
</typeAliases>

###mappers 引入映射文件

<!-- Using classpath relative resources -->
<mappers>
  <mapper resource="org/mybatis/builder/AuthorMapper.xml"/>
  <mapper resource="org/mybatis/builder/BlogMapper.xml"/>
  <mapper resource="org/mybatis/builder/PostMapper.xml"/>
</mappers>
<!-- Using url fully qualified paths -->
<mappers>
  <mapper url="file:///var/mappers/AuthorMapper.xml"/>
  <mapper url="file:///var/mappers/BlogMapper.xml"/>
  <mapper url="file:///var/mappers/PostMapper.xml"/>
</mappers>
<!-- Using mapper interface classes -->
<mappers>
  <mapper class="org.mybatis.builder.AuthorMapper"/>
  <mapper class="org.mybatis.builder.BlogMapper"/>
  <mapper class="org.mybatis.builder.PostMapper"/>
</mappers>
<!-- Register all interfaces in a package as mappers -->
<mappers>
  <package name="org.mybatis.builder"/>
</mappers>

###settings An example of the settings element fully configured is as follows:

<settings>
  <setting name="cacheEnabled" value="true"/>
  <setting name="lazyLoadingEnabled" value="true"/>
  <setting name="multipleResultSetsEnabled" value="true"/>
  <setting name="useColumnLabel" value="true"/>
  <setting name="useGeneratedKeys" value="false"/>
  <setting name="autoMappingBehavior" value="PARTIAL"/>
  <setting name="autoMappingUnknownColumnBehavior" value="WARNING"/>
  <setting name="defaultExecutorType" value="SIMPLE"/>
  <setting name="defaultStatementTimeout" value="25"/>
  <setting name="defaultFetchSize" value="100"/>
  <setting name="safeRowBoundsEnabled" value="false"/>
  <setting name="mapUnderscoreToCamelCase" value="false"/>
  <setting name="localCacheScope" value="SESSION"/>
  <setting name="jdbcTypeForNull" value="OTHER"/>
  <setting name="lazyLoadTriggerMethods" value="equals,clone,hashCode,toString"/>
</settings>

###plugins 插件 好比：

分頁插件

<plugins>
	<plugin interceptor="com.github.pagehelper.PageHelper">
		<property name="dialect" value="mysql"/>
		<property name="offsetAsPageNum" value="true"/>
		<property name="rowBoundsWithCount" value="true"/>
		<property name="pageSizeZero" value="true"/>
	</plugin>
</plugins>