IBatis2中提供了3种DataSource的配置：JNDI, Apache DBCP, IBatis自带的SimpleDataSource。但在IBatis3中只提供了两种DataSource: UNPOOLED, POOLED。
如果要实现自定义的DataSource，就需要通过扩展DataSourceFactory。本文就演示一下这个过程。
准备工作：Connection Pool的选择，通过搜索发现目前比较流行的免费数据库连接池主要有3种：Apache DBCP, C3P0, Proxool。
看了一下，Proxool的最新版本是0.9.1(2008-08-23), C3P0的最新版本是0.9.1.2(2007-05-21), DBCP最新版本是1.2.2(2007-04-04)
好像这3个项目都已经挺长时间没有更新了。但是总体评价上C3P0无论从稳定上还是效率上都要好一点。
（具体这3个项目谁更优秀，并不是本文的重点，本文主要是介绍一下如何在IBatis3中自定义数据源）
大致步骤：
1、实现org.apache.ibatis.datasource.DataSourceFactory接口，主要是2个方法
a、public DataSource getDataSource() 如何具体地得到一个数据源
b、public void setProperties(Properties properties) 如何设置数据源的参数属性
2、实现javax.sql.DataSource，这个就是提供给DataSourceFactory的实例
3、在IBatis3中引用新加入的数据源
1. 从代码中可以看出，IBatis3与IBatis2不同，不再通过一个Configuration类来进行数据源属性的设置，而是使用反射机制直接调用数据源的方法来设置参数。
这就要求配置文件中的参数名称必须与数据源类中的方法名匹配.
ProxoolDataSourceFactory.java
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package com.xuanwu.ibatis;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.ibatis.datasource.DataSourceException;
import org.apache.ibatis.datasource.DataSourceFactory;
import org.apache.ibatis.reflection.MetaObject;
/**
* fisher 2010-7-14 下午06:18:16
*
* Proxool数据源连接池工厂
*
* @see http://www.blogjava.net/usherlight/archive/2010/02/01/311493.html
*
*/
public class ProxoolDataSourceFactory implements DataSourceFactory {
private DataSource dataSource;
public ProxoolDataSourceFactory() {
dataSource = new ProxoolDataSourceWrap();
}
public DataSource getDataSource() {
return dataSource;
}
/**
* IBatis3与IBatis2不同，不再通过一个Configuration类来进行数据源属性的设置，
* 而是使用反射机制直接调用数据源的方法来设置参数。
*/
public void setProperties(Properties properties) {
Properties driverProperties = new Properties();
MetaObject metaDataSource = MetaObject.forObject(dataSource);
for (Object key : properties.keySet()) {
String propertyName = (String) key;
if (propertyName.startsWith(DRIVER_PROPERTY_PREFIX)) {
String value = properties.getProperty(propertyName);
driverProperties.setProperty(propertyName
.substring(DRIVER_PROPERTY_PREFIX_LENGTH), value);
} else if (metaDataSource.hasSetter(propertyName)) {
String value = (String) properties.get(propertyName);
Object convertedValue = convertValue(metaDataSource,
propertyName, value);
metaDataSource.setValue(propertyName, convertedValue);
} else {
throw new DataSourceException("Unkown DataSource property: "
+ propertyName);
}
}
if (driverProperties.size() > 0) {
metaDataSource.setValue("driverProperties", driverProperties);
}
}
@SuppressWarnings("unchecked")
private Object convertValue(MetaObject metaDataSource, String propertyName,
String value) {
Object convertedValue = value;
Class targetType = metaDataSource.getSetterType(propertyName);
if (targetType == Integer.class || targetType == int.class) {
convertedValue = Integer.valueOf(value);
} else if (targetType == Long.class || targetType == long.class) {
convertedValue = Long.valueOf(value);
} else if (targetType == Boolean.class || targetType == boolean.class) {
convertedValue = Boolean.valueOf(value);
}
return convertedValue;
}
private static final String DRIVER_PROPERTY_PREFIX = "driver.";
private static final int DRIVER_PROPERTY_PREFIX_LENGTH = DRIVER_PROPERTY_PREFIX
.length();
}
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2. 数据源类，其中的一堆setter就是用于设置属性的。
ProxoolDataSourceWrap.java
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package com.xuanwu.ibatis;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import org.logicalcobwebs.proxool.ProxoolDataSource;
/**
* fisher 2010-7-14 下午06:18:16
*
* 数据源配置。配置文件xml上dataSource设置的属性与连接池对应桥梁。
*
* @see http://www.blogjava.net/usherlight/archive/2010/02/01/311493.html
*/
public class ProxoolDataSourceWrap implements DataSource {
private ProxoolDataSource dataSource;
public ProxoolDataSourceWrap() {
this.dataSource = new ProxoolDataSource();
}
public Connection getConnection() throws SQLException {
return dataSource.getConnection();
}
public Connection getConnection(String username, String password)
throws SQLException {
return dataSource.getConnection(username, password);
}
public PrintWriter getLogWriter() throws SQLException {
return dataSource.getLogWriter();
}
public int getLoginTimeout() throws SQLException {
return dataSource.getLoginTimeout();
}
public void setLogWriter(PrintWriter out) throws SQLException {
dataSource.setLogWriter(out);
}
public void setLoginTimeout(int seconds) throws SQLException {
dataSource.setLoginTimeout(seconds);
}
/** 以下setter，对应ibatis-config.xml dataSource下的property **/
//
//
//
//
//
// ...............
//
/** ProxoolDataSource setter源码 **/
// cpd.setAlias(getAlias());
// cpd.setDriver(getDriver());
// cpd.setFatalSqlExceptionsAsString(getFatalSqlExceptionsAsString());
// cpd.setFatalSqlExceptionWrapper(getFatalSqlExceptionWrapperClass());
// cpd.setHouseKeepingSleepTime(getHouseKeepingSleepTime());
// cpd.setHouseKeepingTestSql(getHouseKeepingTestSql());
// cpd.setMaximumActiveTime(getMaximumActiveTime());
// cpd.setMaximumConnectionCount(getMaximumConnectionCount());
// cpd.setMaximumConnectionLifetime(getMaximumConnectionLifetime());
// cpd.setMinimumConnectionCount(getMinimumConnectionCount());
// cpd.setOverloadWithoutRefusalLifetime(getOverloadWithoutRefusalLifetime());
// cpd.setPrototypeCount(getPrototypeCount());
// cpd.setRecentlyStartedThreshold(getRecentlyStartedThreshold());
// cpd.setSimultaneousBuildThrottle(getSimultaneousBuildThrottle());
// cpd.setStatistics(getStatistics());
// cpd.setStatisticsLogLevel(getStatisticsLogLevel());
// cpd.setTrace(isTrace());
// cpd.setUrl(getDriverUrl());
// cpd.setVerbose(isVerbose());
// cpd.setJmx(isJmx());
// cpd.setJmxAgentId(getJmxAgentId());
// cpd.setTestAfterUse(isTestAfterUse());
// cpd.setTestBeforeUse(isTestBeforeUse());
// cpd.setDelegateProperties(this.delegateProperties);
// cpd.setUser(getUser());
// cpd.setPassword(getPassword());
public void setAlias(String alias) {
dataSource.setAlias(alias);
}
public synchronized void setDriver(String driver) {
try {
dataSource.setDriver(driver);
} catch (Exception e) {
}
}
public void setFatalSqlExceptionsAsString(String fatalSqlExceptionsAsString) {
dataSource.setFatalSqlExceptionsAsString(fatalSqlExceptionsAsString);
}
public void setHouseKeepingSleepTime(int houseKeepingSleepTime) {
dataSource.setHouseKeepingSleepTime(houseKeepingSleepTime);
}
public void setHouseKeepingTestSql(String houseKeepingTestSql) {
dataSource.setHouseKeepingTestSql(houseKeepingTestSql);
}
public void setMaximumActiveTime(int maximumActiveTime) {
dataSource.setMaximumActiveTime(maximumActiveTime);
}
public void setMaximumConnectionCount(int maximumConnectionCount) {
dataSource.setMaximumConnectionCount(maximumConnectionCount);
}
public void setMaximumConnectionLifetime(int maximumConnectionLifetime) {
dataSource.setMaximumConnectionLifetime(maximumConnectionLifetime);
}
public void setMinimumConnectionCount(int minimumConnectionCount) {
dataSource.setMinimumConnectionCount(minimumConnectionCount);
}
public void setOverloadWithoutRefusalLifetime(int overloadWithoutRefusalLifetime) {
dataSource.setOverloadWithoutRefusalLifetime(overloadWithoutRefusalLifetime);
}
public void setPrototypeCount(int prototypeCount) {
dataSource.setPrototypeCount(prototypeCount);
}
public void setRecentlyStartedThreshold(int recentlyStartedThreshold) {
dataSource.setRecentlyStartedThreshold(recentlyStartedThreshold);
}
public void setSimultaneousBuildThrottle(int simultaneousBuildThrottle) {
dataSource.setSimultaneousBuildThrottle(simultaneousBuildThrottle);
}
public void setStatistics(String statistics) {
dataSource.setStatistics(statistics);
}
public void setStatisticsLogLevel(String statisticsLogLevel) {
dataSource.setStatisticsLogLevel(statisticsLogLevel);
}
public void setTrace(boolean trace) {
dataSource.setTrace(trace);
}
public void setUrl(String url) {
dataSource.setDriverUrl(url);
}
public void setVerbose(boolean verbose) {
dataSource.setVerbose(verbose);
}
public void setJmx(boolean jmx) {
dataSource.setJmx(jmx);
}
public void setJmxAgentId(String jmxAgentId) {
dataSource.setJmxAgentId(jmxAgentId);
}
public void setTestAfterUse(boolean testAfterUse) {
dataSource.setTestAfterUse(testAfterUse);
}
public void setTestBeforeUse(boolean testBeforeUse) {
dataSource.setTestBeforeUse(testBeforeUse);
}
public void setDelegateProperties(String delegateProperties) {
dataSource.setDelegateProperties(delegateProperties);
}
public void setUser(String user) {
dataSource.setUser(user);
}
public void setPassword(String password) {
dataSource.setPassword(password);
}
public void setUsername(String username) {
dataSource.setUser(username);
}
}
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3. 在配置文件Configuration.xml中，可以先定义数据源的别称，然后就象POOLED和UNPOOLED一样使用别称来引用数据源。
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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//ibatis.apache.org//DTD Config 3.0//EN"
"">
<configuration>
<properties resource="conf/jdbc-development.properties" />
<settings>
<setting name="cacheEnabled" value="false"/>
</settings>
<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="conf/ibatis/ibatis-base-mapper.xml"/>
<mapper resource="conf/ibatis/ibatis-difmnetmt-mapper.xml"/>
<mapper resource="conf/ibatis/ibatis-test-mapper.xml"/>
</mappers>
</configuration>
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相关资料：
1. iBatis官网用户手册：
2. IBatis3中使用自定义数据源C3P0：http://www.blogjava.net/usherlight/archive/2010/02/01/311493.html
3. 在ibatis2中使用proxool数据源：http://wt8414.javaeye.com/blog/514824
4. spring配置ibatis的jdbc方式和proxool、c3p0连接池方式：http://www.blogjava.net/landor2004/archive/2009/07/01/284978.html
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