package com.myapp.util;import java.io.IOException;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.NestedIOException;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.stereotype.Service;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;/*** mapper.xml热加载，修改mapper.xml不需要重启tomcat,正式环境需要去掉*/
@Service
public class XMLMapperLoader implements DisposableBean, InitializingBean, ApplicationContextAware {private ConfigurableApplicationContext context = null;private transient String basePackage = null;private HashMap<String, String> fileMapping = new HashMap<String, String>();private Scanner scanner = null;private ScheduledExecutorService service = null;public void setApplicationContext(ApplicationContext applicationContext) {this.context = (ConfigurableApplicationContext) applicationContext;}public void afterPropertiesSet() throws Exception {try {service = Executors.newScheduledThreadPool(1);// 获取xml所在包MapperScannerConfigurer config = context.getBean(MapperScannerConfigurer.class);Field field = config.getClass().getDeclaredField("basePackage");field.setAccessible(true);basePackage = (String) field.get(config);// 触发文件监听事件scanner = new Scanner();scanner.scan();service.scheduleAtFixedRate(new Task(), 5, 5, TimeUnit.SECONDS);} catch (Exception e1) {e1.printStackTrace();}}class Task implements Runnable {public void run() {try {if (scanner.isChanged()) {System.out.println("*Mapper.xml文件改变,重新加载.");scanner.reloadXML();System.out.println("加载完毕.");}} catch (Exception e) {e.printStackTrace();}}}@SuppressWarnings({ "rawtypes" })class Scanner {private String[] basePackages;private static final String XML_RESOURCE_PATTERN = "**/*.xml";private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();public Scanner() {basePackages = StringUtils.tokenizeToStringArray(XMLMapperLoader.this.basePackage,ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);}public Resource[] getResource(String basePackage, String pattern) throws IOException {String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX+ ClassUtils.convertClassNameToResourcePath(context.getEnvironment().resolveRequiredPlaceholders(basePackage)) + "/" + pattern;Resource[] resources = resourcePatternResolver.getResources(packageSearchPath);return resources;}public void reloadXML() throws Exception {SqlSessionFactory factory = context.getBean(SqlSessionFactory.class);Configuration configuration = factory.getConfiguration();// 移除加载项removeConfig(configuration);// 重新扫描加载for (String basePackage : basePackages) {Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);if (resources != null) {for (int i = 0; i < resources.length; i++) {if (resources[i] == null) {continue;}try {XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(resources[i].getInputStream(),configuration, resources[i].toString(), configuration.getSqlFragments());xmlMapperBuilder.parse();} catch (Exception e) {throw new NestedIOException("Failed to parse mapping resource: '" + resources[i] + "'", e);} finally {ErrorContext.instance().reset();}}}}}private void removeConfig(Configuration configuration) throws Exception {Class<?> classConfig = configuration.getClass();clearMap(classConfig, configuration, "mappedStatements");clearMap(classConfig, configuration, "caches");clearMap(classConfig, configuration, "resultMaps");clearMap(classConfig, configuration, "parameterMaps");clearMap(classConfig, configuration, "keyGenerators");clearMap(classConfig, configuration, "sqlFragments");clearSet(classConfig, configuration, "loadedResources");}private void clearMap(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {Field field = classConfig.getDeclaredField(fieldName);field.setAccessible(true);Map mapConfig = (Map) field.get(configuration);mapConfig.clear();}private void clearSet(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {Field field = classConfig.getDeclaredField(fieldName);field.setAccessible(true);Set setConfig = (Set) field.get(configuration);setConfig.clear();}public void scan() throws IOException {if (!fileMapping.isEmpty()) {return;}for (String basePackage : basePackages) {Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);if (resources != null) {for (int i = 0; i < resources.length; i++) {String multi_key = getValue(resources[i]);fileMapping.put(resources[i].getFilename(), multi_key);}}}}private String getValue(Resource resource) throws IOException {String contentLength = String.valueOf((resource.contentLength()));String lastModified = String.valueOf((resource.lastModified()));return new StringBuilder(contentLength).append(lastModified).toString();}public boolean isChanged() throws IOException {boolean isChanged = false;for (String basePackage : basePackages) {Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);if (resources != null) {for (int i = 0; i < resources.length; i++) {String name = resources[i].getFilename();String value = fileMapping.get(name);String multi_key = getValue(resources[i]);if (!multi_key.equals(value)) {isChanged = true;fileMapping.put(name, multi_key);}}}}return isChanged;}}public void destroy() throws Exception {if (service != null) {service.shutdownNow();}}}