iBatis學(xué)習(xí)筆記：（versions 2.2.0 and higher）

配置文件SqlMapConfig.xml：

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE sqlMapConfig

PUBLIC "-//ibatis.apache.org//DTD SQL Map Config 2.0//EN"

"http://ibatis.apache.org/dtd/sql-map-config-2.dtd">

<!-- Always ensure to use the correct XML header as above! -->

<sqlMapConfig>

<!-- The properties (name=value) in the file specified here can be used placeholders in this config

file (e.g. “${driver}”. The file is relative to the classpath and is completely optional. -->

<properties resource=" examples/sqlmap/maps/SqlMapConfigExample.properties " />

<!-- These settings control SqlMapClient configuration details, primarily to do with transaction

management. They are all optional (more detail later in this document). -->

<settings

cacheModelsEnabled="true"

enhancementEnabled="true"

lazyLoadingEnabled="true"

maxRequests="128"

maxSessions="10"

maxTransactions="5"

useStatementNamespaces="false"

defaultStatementTimeout="5"

statementCachingEnabled="true"

classInfoCacheEnabled="true"

/>

<!-- This element declares a factory class that iBATIS will use for creating result objects.

This element is optional (more detail later in this document). -->

<resultObjectFactory type="com.mydomain.MyResultObjectFactory" >

<property name="someProperty" value="someValue"/>

</resultObjectFactory>

<!-- Type aliases allow you to use a shorter name for long fully qualified class names. -->

<typeAlias alias="order" type="testdomain.Order"/>

<!-- Configure a datasource to use with this SQL Map using SimpleDataSource.

Notice the use of the properties from the above resource -->

<transactionManager type="JDBC" >

<dataSource type="SIMPLE">

<property name="JDBC.Driver" value="${driver}"/>

<property name="JDBC.ConnectionURL" value="${url}"/>

<property name="JDBC.Username" value="${username}"/>

<property name="JDBC.Password" value="${password}"/>

<property name="JDBC.DefaultAutoCommit" value="true" />

<property name="Pool.MaximumActiveConnections" value="10"/>

<property name="Pool.MaximumIdleConnections" value="5"/>

<property name="Pool.MaximumCheckoutTime" value="120000"/>

<property name="Pool.TimeToWait" value="500"/>

<property name="Pool.PingQuery" value="select 1 from ACCOUNT"/>

<property name="Pool.PingEnabled" value="false"/>

<property name="Pool.PingConnectionsOlderThan" value="1"/>

<property name="Pool.PingConnectionsNotUsedFor" value="1"/>

</dataSource>

</transactionManager>

<!-- Identify all SQL Map XML files to be loaded by this SQL map. Notice the paths

are relative to the classpath. For now, we only have one… -->

<sqlMap resource="examples/sqlmap/maps/Person.xml" />

</sqlMapConfig>

其中：

<properties>元素指定了一個(gè)標(biāo)準(zhǔn)java properties文件的位置，用classpath相對(duì)位置或URL形式指定，之后整個(gè)配置文件以及所有被包含進(jìn)來(lái)的映射文件都可以用${key}形式的占位符來(lái)獲取properties文件中的value值。

<settings>元素：

設(shè)置一些全局屬性，如延遲加載、緩存模式等。

所有可設(shè)置屬性及其說(shuō)明如下：

maxRequests This is the maximum number of threads that can execute an SQL

statement at a time. Threads beyond the set value will be blocked until

another thread completes execution. Different DBMS have different

limits, but no database is without these limits. This should usually be at

least 10 times maxTransactions (see below) and should always be greater

than both maxSessions and maxTransactions. Often reducing the

maximum number of concurrent requests can increase performance.

Example: maxRequests= ”256”

Default: 512

maxSessions This is the number of sessions (or clients) that can be active at a given

time. A session is either an explicit session, requested

programmatically, or it is automatic whenever a thread makes use of an

SqlMapClient instance (e.g. executes a statement etc.). This should

always be greater than or equal to maxTransactions and less than

maxRequests. Reducing the maximum number of concurrent sessions

can reduce the overall memory footprint.

Example: maxSessions= ”64”

Default: 128

maxTransactions This is the maximum number of threads that can enter

SqlMapClient.startTransaction() at a time. Threads beyond the set value

will be blocked until another thread exits. Different DBMS have

different limits, but no database is without these limits. This value

should always be less than or equal to maxSessions and always much

less than maxRequests. Often reducing the maximum number of

concurrent transactions can increase performance.

Example: maxTransactions= ”16”

Default: 32

cacheModelsEnabled This setting globally enables or disables all cache models for an

SqlMapClient. This can come in handy for debugging.

Example: cacheModelsEnabled= ”true”

Default: true (enabled)

lazyLoadingEnabled This setting globally enables or disables all lazy loading for an

SqlMapClient. This can come in handy for debugging.

Example: lazyLoadingEnabled= ”true”

Default: true (enabled)

enhancementEnabled This setting enables runtime bytecode enhancement to facilitate

optimized JavaBean property access as well as enhanced lazy loading.

Example: enhancementEnabled = ”true”

Default: false (disabled)

useStatementNamespaces With this setting enabled, you must always refer to mapped statements

by their fully qualified name, which is the combination of the sqlMap

name and the statement name. For example:

queryForObject(“sqlMapName.statementName”);

Example: useStatementNamespaces= ”false”

Default: false (disabled)

defaultStatementTimeout (iBATIS versions 2.2.0 and later)

This setting is an integer value that will be applied as the JDBC query

timeout for all statements. This value can be overridden with the

“statement” attribute of any mapped statement. If not specified, no

query timeout will be set unless specified on the “statement” attribute of

a mapped statement. The specified value is the number of seconds the

driver will wait for a statement to finish. Note that not all drivers

support this setting.

classInfoCacheEnabled With this setting enabled, iBATIS will maintain a cache of introspected

classes. This will lead to a significant reduction in startup time if many

classes are reused.

Example: classInfoCacheEnabled= “true”

Default: true (enabled)

statementCachingEnabled (iBATIS versions 2.3.0 and later)

With this setting enabled, iBATIS will maintain a local cache of

prepared statements. This can lead to significant performance

improvements.

Example: statementCachingEnabled= “true”

Default: true (enabled)

<resultObjectFactory>元素：

指定對(duì)象生成工廠類，用于將查詢結(jié)果封裝成對(duì)象返回。這是可選設(shè)置，若不指定，ibatis將使用Class.newInstance()的方式生成查詢結(jié)果類。對(duì)象工廠類必須實(shí)現(xiàn)com.ibatis.sqlmap.engine.mapping.result.ResultObjectFactory接口。

<typeAlias>元素：

用來(lái)為一些亢長(zhǎng)的類名起“別名”，例如：

<typeAlias alias="shortname" type="com.long.class.path.Class"/>

以后就能用“shortname”來(lái)取代“com.long.class.path.Class”了。

除了自己定義別名外，iBatis框架預(yù)先定義了一些別名，以方便使用，他們是：

Transaction Manager Aliases：

JDBC??? com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransactionConfig

JTA???? com.ibatis.sqlmap.engine.transaction.jta.JtaTransactionConfig

EXTERNAL com.ibatis.sqlmap.engine.transaction.external.ExternalTransactionConfig

Data Source Factory Aliases：

SIMPLE?? com.ibatis.sqlmap.engine.datasource.SimpleDataSourceFactory

DBCP???? com.ibatis.sqlmap.engine.datasource.DbcpDataSourceFactory

JNDI????? com.ibatis.sqlmap.engine.datasource.JndiDataSourceFactory

<transactionManager>元素：

設(shè)置事務(wù)類型和<dataSource>元素，如上文所說(shuō)，預(yù)定義的事務(wù)類型有JDBC, JTA, EXTERNAL；數(shù)據(jù)源類型有SIMPLE, DBCP, JNDI；若指定EXTERNAL或JTA，那就還有額外的屬性需要設(shè)置：

?

<dataSource>元素：

在transactionManager元素中，定義數(shù)據(jù)源。預(yù)定義三種數(shù)據(jù)源工廠：SIMPLE, DBCP, JNDI，不過(guò)也可以自己寫一個(gè)。

SIMPLE:在沒(méi)有容器數(shù)據(jù)源支持的情況下使用的最簡(jiǎn)單的數(shù)據(jù)源實(shí)現(xiàn)，具體設(shè)置見剛才的例子。

DBCP:使用apache的DBCP數(shù)據(jù)源，ibatis框架對(duì)其直接提供支持，設(shè)置方法如下：

<transactionManager type="JDBC">

<dataSource type="DBCP">

<property name="driverClassName" value="${driver}"/>

<property name="url" value="${url}"/>

<property name="username" value="${username}"/>

<property name="password" value="${password}"/>

<!-- OPTIONAL PROPERTIES BELOW -->

<property name="maxActive" value="10"/>

<property name="maxIdle" value="5"/>

<property name="maxWait" value="60000"/>

<!-- Use of the validation query can be problematic.

If you have difficulty, try without it. -->

<property name="validationQuery" value="select * from ACCOUNT"/>

<property name="logAbandoned" value="false"/>

<property name="removeAbandoned" value="false"/>

<property name="removeAbandonedTimeout" value="50000"/>

<property name="Driver.DriverSpecificProperty" value="SomeValue"/>

</datasource>

</transactionManager>

所有的設(shè)置屬性請(qǐng)參考： http://jakarta.apache.org/commons/dbcp/configuration.html

注：以‘Driver.’開頭的屬性會(huì)被加入到JDBC的屬性中（有些JDBC需要）。

JNDI:指定配置的JNDI數(shù)據(jù)源。設(shè)置格式：

<transactionManager type="JDBC" >

<dataSource type="JNDI">

<property name="DataSource" value="java:comp/env/jdbc/jpetstore"/>

</dataSource>

</transactionManager>

上面只是使用普通的JDBC事務(wù)，但通常設(shè)置JNDI數(shù)據(jù)源更愿意用JTA全局事務(wù)：

<transactionManager type="JTA" >

<property name="UserTransaction" value="java:/comp/UserTransaction"/>

<dataSource type="JNDI">

<property name="DataSource" value="java:comp/env/jdbc/jpetstore"/>

</dataSource>

</transactionManager>

<sqlMap>元素：

用來(lái)包含SQL映射文件或另一個(gè)配置文件，以classpath或URL的形式：

<!-- CLASSPATH RESOURCES -->

<sqlMap resource="com/ibatis/examples/sql/Customer.xml" />

<sqlMap resource="com/ibatis/examples/sql/Account.xml" />

<sqlMap resource="com/ibatis/examples/sql/Product.xml" />

<!-- URL RESOURCES -->

<sqlMap url="file:///c:/config/Customer.xml " />

<sqlMap url="file:///c:/config/Account.xml " />

<sqlMap url="file:///c:/config/Product.xml" />

iBatis學(xué)習(xí)筆記（配置文件小結(jié)）