MyBatis配置文件修改侦测及重载的实现

MyBatis配置文件修改侦测及重载的实现：

 

/**
 * 
 */
package cn.hshb.web.common.mybatis;

import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.ibatis.builder.xml.XMLConfigBuilder;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;


/**
 * 支持自动刷新配置文件的SqlSessionFactoryBean，以解决在开发过程中，每次修改XML Mapper时都要重启服务器的问题<br/>
 * 用法示例：
 * <pre>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

	<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
		<property name="driverClassName" value="com.mysql.jdbc.Driver" />
		<property name="url" value="jdbc:mysql://localhost:3306/test" />
		<property name="username" value="user" />
		<property name="password" value="password" />
	</bean>

	<context:annotation-config />
	<tx:annotation-driven />
	<!-- define the SqlSessionFactory -->
	<!--下面改成自定义的RefreshableSqlSessionFactoryBean-->
	<!-- <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> -->
	<bean id="sqlSessionFactory" class="cn.hshb.web.common.mybatis.RefreshableSqlSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<property name="typeAliasesPackage" value="com.example" />
		<property name="configLocation" value="classpath:mybatis/mybatis-config.xml" />
		<property name="interval" value="5000" /> <!-- 设置XML文件扫描间隔 -->
		<property name="mapperLocations" value="classpath:com/example/dao/*Mapper.xml" />
	</bean>

	<bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
		<constructor-arg ref="sqlSessionFactory" />
	</bean>

	<!-- scan for mappers and let them be autowired -->
	<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
		<property name="basePackage" value="com.example" />
	</bean>
	<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" p:dataSource-ref="dataSource" />
</beans>
 * </pre>
 * 
 * @author ShengYoufu
 * @version 1.0
 * @since 2015-07-31
 *
 */
public class RefreshableSqlSessionFactoryBean extends SqlSessionFactoryBean implements DisposableBean {
	private static final Log log = LogFactory.getLog(RefreshableSqlSessionFactoryBean.class);

	private SqlSessionFactory proxy;

	private int interval = 500;

	private Timer timer;

	private TimerTask task;

	private Resource configLocation;

	private Resource[] mapperLocations;

	private Properties configurationProperties;

	/**
	 * Set optional properties to be passed into the SqlSession configuration,
	 * as alternative to a {@code &lt;properties&gt;} tag in the configuration
	 * xml file. This will be used to resolve placeholders in the config file.
	 */
	public void setConfigurationProperties(Properties sqlSessionFactoryProperties) {
		super.setConfigurationProperties(sqlSessionFactoryProperties);
		this.configurationProperties = sqlSessionFactoryProperties;
	}

	private boolean running = false;	//设置监视器是否运行

	private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();

	private final Lock r = rwl.readLock();

	private final Lock w = rwl.writeLock();

	public void setConfigLocation(Resource configLocation) {
		super.setConfigLocation(configLocation);
		this.configLocation = configLocation;
	}

	public void setMapperLocations(Resource[] mapperLocations) {
		super.setMapperLocations(mapperLocations);
		this.mapperLocations = mapperLocations;
	}

	public void setInterval(int interval) {
		this.interval = interval;
	}

	public void refresh() throws Exception {
		if (log.isInfoEnabled()) {
			log.info("refreshing SqlSessionFactory.");
		}
		w.lock();
		try {
			super.afterPropertiesSet();
		} finally {
			w.unlock();
		}
	}

	public void afterPropertiesSet() throws Exception {
		super.afterPropertiesSet();
		setRefreshable();
	}

	private void setRefreshable() {
		proxy = (SqlSessionFactory) Proxy.newProxyInstance(

		SqlSessionFactory.class.getClassLoader(),

		new Class[] { SqlSessionFactory.class },

		new InvocationHandler() {
			public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
				// log.debug("method.getName() : " + method.getName());
				return method.invoke(getParentObject(), args);
			}
		});

		task = new TimerTask() {
			private Map<Resource, Long> map = new HashMap<Resource, Long>();
			public void run() {
				if (isModified()) {
					try {
						refresh();
					} catch (Exception e) {
						log.error("caught exception", e);
					}
				}
			}

			private boolean isModified() {
				boolean retVal = false;
				if (mapperLocations != null) {
					for (int i = 0; i < mapperLocations.length; i++) {
						Resource mappingLocation = mapperLocations[i];
						retVal |= findModifiedResource(mappingLocation);
						if (retVal)
							break;
					}
				} else if (configLocation != null) {
					Configuration configuration = null;

					XMLConfigBuilder xmlConfigBuilder = null;
					try {
						xmlConfigBuilder = new XMLConfigBuilder(configLocation.getInputStream(), null, configurationProperties);
						configuration = xmlConfigBuilder.getConfiguration();
					} catch (IOException e) {
						log.error(e);
					}

					if (xmlConfigBuilder != null) {
						try {
							xmlConfigBuilder.parse();

							Field loadedResourcesField = Configuration.class.getDeclaredField("loadedResources");
							loadedResourcesField.setAccessible(true);

							@SuppressWarnings("unchecked")
							Set<String> loadedResources = (Set<String>) loadedResourcesField.get(configuration);

							for (Iterator<String> iterator = loadedResources.iterator(); iterator.hasNext();) {
								String resourceStr = (String) iterator.next();
								if (resourceStr.endsWith(".xml")) {
									Resource mappingLocation = new ClassPathResource(resourceStr);
									retVal |= findModifiedResource(mappingLocation);
									if (retVal) {
										break;
									}
								}
							}

						} catch (Exception ex) {
							throw new RuntimeException("Failed to parse config resource: " + configLocation, ex);
						} finally {
							ErrorContext.instance().reset();
						}
					}
				}

				return retVal;
			}

			private boolean findModifiedResource(Resource resource) {
				boolean retVal = false;
				List<String> modifiedResources = new ArrayList<String>();
				try {
					long modified = resource.lastModified();

					if (map.containsKey(resource)) {
						long lastModified = ((Long) map.get(resource)).longValue();

						if (lastModified != modified) {
							map.put(resource, new Long(modified));
							modifiedResources.add(resource.getDescription());
							retVal = true;
						}
					} else {
						map.put(resource, new Long(modified));
					}
				} catch (IOException e) {
					log.error("caught exception", e);
				}

				if (retVal) {
					if (log.isInfoEnabled()) {
						log.info("modified files : " + modifiedResources);
					}
				}
				return retVal;
			}
		};

		timer = new Timer(true);
		resetInterval();
	}

	private Object getParentObject() throws Exception {
		r.lock();
		try {
			return super.getObject();
		} finally {
			r.unlock();
		}
	}

	public SqlSessionFactory getObject() {
		return this.proxy;
	}

	public Class<? extends SqlSessionFactory> getObjectType() {
		return (this.proxy != null ? this.proxy.getClass() : SqlSessionFactory.class);
	}

	public boolean isSingleton() {
		return true;
	}

	public void setCheckInterval(int ms) {
		interval = ms;

		if (timer != null) {
			resetInterval();
		}
	}

	private void resetInterval() {
		if (running) {
			timer.cancel();
			running = false;
		}

		if (interval > 0) {
			timer.schedule(task, 0, interval);
			running = true;
		}
	}

	public void destroy() throws Exception {
		timer.cancel();
	}
}