ibatis3.0配置

配置文件

 

配置文件的层次结构如下：

• configuration

    o properties

    o settings

    o typeAliases

    o typeHandlers

    o objectFactory

    o plugins

    o environments

     environment

          • transactionManager

          • dataSource

    o mappers

 

1 properties：

用来定义外部properties配置文件信息。比如

<properties resource="org/apache/ibatis/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>

 

 

那么username和password被替换成dev_user和F2Fa3!33TYyg，而drive和url属性将读取config.properties中的内容从而取得具体值

 

properties还可以通过SqlSessionFactoryBuilder的build方法作为参数传入:

 

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader, props);

// ... or ...

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader, environment, props);

 

property加载顺序：

1、properties元素内部

2、外部properties文件

3、SqlSessionFactoryBuilder的build方法参数

也就是说，build方法参数中的properties优先级高于前两个，因为它是最后被加载，所以会覆盖前两种加载方法加载的properties值。

 

2 settings

 

Setting 描述 合法值 默认值

cacheEnabled 是否使用全局缓存 true|false true

lazyLoadingEnabled 是否使用全局懒加载 true|false true

multipleResultSetsEnabled 是否允许返回多个结果集合（需要兼容的驱动） true|false true

useColumnLabel 使用列标签取代列名（不同驱动表现不同） true|false true

useGeneratedKeys 允许jdbc自动生成主键 true|false false

enhancementEnabled（该属性在测试的时候报错，提示不存在，查阅资料好像文档里写错了，这个属性已经取消） 全局性地启用或禁用运行时字节码增强，以优化enhancementEnabled访问Java Bean属性的性能，同时优化延迟加载的性能。 true|false false

defaultExecutorType 配置默认执行方式

SIMPLE： nothing special

REUSE： reuses prepared statemets

BATCH：reuses statements and batches updates SIMPLE

REUSE

BATCH  SIMPLE

defaultStatementTimeout 数据库超时时间 Any positive

integer  Not Set

(null) 

 

例子：

 

    cacheEnabled" value="true"/>

    lazyLoadingEnabled" value="true"/>

    multipleResultSetsEnabled" value="true"/>

    useColumnLabel" value="true"/>

    useGeneratedKeys" value="false"/>

    enhancementEnabled" value="false"/>

    defaultExecutorType" value="SIMPLE"/>

    defaultStatementTimeout" value="25000"/>

 

3 typeAliases

 

java类别名

 

<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>

4 typeHandlers

 

Type Handler Java Types JDBC Types

BooleanTypeHandler Boolean,boolean Any compatible BOOLEAN

ByteTypeHandler Byte,byte Any compatible NUMERIC or BYTE

ShortTypeHandler Short,short Any compatible NUMERIC or SHORT INTEGER

IntegerTypeHandler Integer,int Any compatible NUMERIC or INTEGER

LongTypeHandler Long,long Any compatible NUMERIC or LONG INTEGER

FloatTypeHandler Float,float Any compatible NUMERIC or FLOAT

DoubleTypeHandler Double,double Any compatible NUMERIC or DOUBLE

BigDecimalTypeHandler BigDecimal Any compatible NUMERIC or DECIMAL

StringTypeHandler String CHAR,VARCHAR

ClobTypeHandler String CLOB,LONGVARCHAR

NStringTypeHandler String NVARCHAR,NCHAR

NClobTypeHandler String NCLOB

ByteArrayTypeHandler byte[] Any compatible byte stream type

BlobTypeHandler byte[] BLOB,LONGVARBINARY

DateTypeHandler Date(java.util) TIMESTAMP

DateOnlyTypeHandler Date(java.util) DATE

TimeOnlyTypeHandler Date(java.util) TIME

SqlTimestampTypeHandler Timestamp(java.sql) TIMESTAMP

SqlDateTypeHadler Date(java.sql) DATE

SqlTimeTypeHandler Time(java.sql) TIME

ObjectTypeHandler Any OTHER,or unspecified

EnumTypeHandler Enumeration Type VARCHAR – any string compatible type,as the code is stored(not the index)

 

也可以通过实现TypeHandler接口来实现自定义的类型转换器

 

// ExampleTypeHandler.java

public class ExampleTypeHandler implements TypeHandler {

    public void setParameter(

        PreparedStatement ps, int i, Object parameter,JdbcType jdbcType)

    throws SQLException {

        ps.setString(i, (String) parameter);

    }

    public Object getResult(

        ResultSet rs, String columnName)

    throws SQLException {

        return rs.getString(columnName);

    }

    public Object getResult(

        CallableStatement cs, int columnIndex)

    throws SQLException {

        return cs.getString(columnIndex);

    }

}// MapperConfig.xml

 

    String" jdbcType="VARCHAR"

    handler="org.apache.ibatis.example.ExampleTypeHandler"/>

这样会覆盖原来ibatis默认的string varchar转换器5 objectFactory

 

ibatis使用objectFactory去创建result object的实例对象,这里可以自己继承DefaultObjectFactory类实现自己的ObjectFactory

 

// ExampleObjectFactory.java

public class ExampleObjectFactory extends DefaultObjectFactory {

    public Object create(Class type) {

        return super.create(type);

    }

    public Object create(

        Class type,

        List constructorArgTypes,

        List<> constructorArgs) {

        return super.create(type, constructorArgTypes, constructorArgs);

    }

    public void setProperties(Properties properties) {

        super.setProperties(properties);

    }

}// MapperConfig.xml

org.apache.ibatis.example.ExampleObjectFactory">

    someProperty" value="100"/>

6 plugins

 

ibatis允许插件截断以下方法调用

Executor(update,query,flushStatements,commit,rollback,getTransaction,close,isClosed)

ParameterHandler(getParameterObject,setParameters)

ResultSetHandler(handleResultSets,handleOutputParameters)

StatementHandler(prepare,parameterize,batch,update,query)

必须在理解这些方法的基础上很小心的使用插件，不然很容易破坏ibatis的核心

 

// 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) {

        }

}

 

// MapperConfig.xml

 

org.apache.ibatis.example.ExamplePlugin">

    someProperty" value="100"/>

 

7 environments

 

这个是ibatis 3非常好的一个配置，允许配置多个不懂运行环境参数，不过每个SqlSessionFactory只可以在一种环境下被创建。

利用SqlSessionFactory的build函数

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader,environment);

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader,environment,properties);

如果不知名environment参数，则应用默认的环境参数

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader);

SqlSessionFactory factory = sqlSessionFactoryBuilder.build(reader,properties);

 

xml中如下配置：

 

default="development">

    development">

        JDBC">

            " value=""/>

       

    POOLED">

        driver" value="${driver}"/>

        url" value="${url}"/>

        username" value="${username}"/>

        password" value="${password}"/>

   

   

 

几个注意点：

默认environment id： default="development">

environment id：development">

事务控制类型：JDBC">

   JDBC：根据jdbc控制事务的提交和回滚

    MANAGED：将事务控制转交给容器

数据源类型：POOLED">

   UNPOOLED：不使用池技术，在请求到来时直接打开或者关闭数据库连接

        必须配置的参数：driver、url、username、password

        可选参数：使用driver.xxx来配置，如：driver.encoding=UTF8

    POOLED：使用数据库连接池

        poolMaximumActiveConnections：同一时间内最大连接数 默认10

            

        poolMaximumIdleConnections：连接最大空闲数目

            

        poolMaximumCheckoutTime：连接被每个任务占用的最大时间 默认20000ms

            

        poolTimeToWait：连接池中无可用连接时，线程的等待时间 默认20000ms

            

        poolPingQuery：数据库连接状态检测语句，类似于ping的功能 默认NO PING QUERY SET

            

        poolPingEnabled：是否允许ping检测 默认false

           

        poolPingConnectionsNotUsedFor：对超过指定空闲时间的数据库连接进行状态监测 默认0 （必须在poolPingEnabled设置true情况下）

            

   JNDI：

        initial_context：可选，没看明白，原文：This property is used for the Context lookup from the InitialContext

        data_source：JNDI数据库名称

        使用env.xxx配置可选参数，如：env.encoding=UTF8

 

 

8 mappers

 

配置实体映射文件的路径// Using classpath relative resources

<mappers>

<mapper resource="org/apache/ibatis/builder/AuthorMapper.xml"/>

<mapper resource="org/apache/ibatis/builder/BlogMapper.xml"/>

<mapper resource="org/apache/ibatis/builder/PostMapper.xml"/>

mappers>

// Using url fully qualified paths

<mappers>

<mapper url="file:///var/sqlmaps/AuthorMapper.xml"/>

<mapper url="file:///var/sqlmaps/BlogMapper.xml"/>

<mapper url="file:///var/sqlmaps/PostMapper.xml"/>

mappers>