package com.jeeplus.common.persistence;
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import java.io.IOException;
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import java.lang.reflect.Field;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ScheduledExecutorService;
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import java.util.concurrent.TimeUnit;
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import org.apache.ibatis.builder.xml.XMLMapperBuilder;
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import org.apache.ibatis.executor.ErrorContext;
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import org.apache.ibatis.session.Configuration;
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import org.apache.ibatis.session.SqlSessionFactory;
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import org.mybatis.spring.mapper.MapperScannerConfigurer;
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import org.springframework.beans.BeansException;
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import org.springframework.beans.factory.DisposableBean;
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import org.springframework.beans.factory.InitializingBean;
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import org.springframework.context.ApplicationContext;
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import org.springframework.context.ApplicationContextAware;
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import org.springframework.context.ConfigurableApplicationContext;
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import org.springframework.core.NestedIOException;
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import org.springframework.core.io.Resource;
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import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
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import org.springframework.core.io.support.ResourcePatternResolver;
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import org.springframework.util.ClassUtils;
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import org.springframework.util.StringUtils;
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/**
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* Mybatis的mapper文件中的sql语句被修改后, 只能重启服务器才能被加载, 非常耗时,所以就写了一个自动加载的类,
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* 配置后检查xml文件更改,如果发生变化,重新加载xml里面的内容.
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*/
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//@Service
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//@Lazy(false)
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public class MapperLoader implements DisposableBean, InitializingBean, ApplicationContextAware {
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private ConfigurableApplicationContext context = null;
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private transient String basePackage = null;
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private HashMap<String, String> fileMapping = new HashMap<String, String>();
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private Scanner scanner = null;
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private ScheduledExecutorService service = null;
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@Override
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public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
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this.context = (ConfigurableApplicationContext) applicationContext;
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}
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@Override
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public void afterPropertiesSet() throws Exception {
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try {
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service = Executors.newScheduledThreadPool(1);
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// 获取xml所在包
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MapperScannerConfigurer config = context.getBean(MapperScannerConfigurer.class);
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Field field = config.getClass().getDeclaredField("basePackage");
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field.setAccessible(true);
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basePackage = (String) field.get(config);
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// 触发文件监听事件
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scanner = new Scanner();
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scanner.scan();
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service.scheduleAtFixedRate(new Task(), 5, 5, TimeUnit.SECONDS);
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} catch (Exception e1) {
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e1.printStackTrace();
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}
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}
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class Task implements Runnable {
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@Override
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public void run() {
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try {
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if (scanner.isChanged()) {
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System.out.println("*Mapper.xml文件改变,重新加载.");
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scanner.reloadXML();
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System.out.println("加载完毕.");
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}
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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@SuppressWarnings({ "rawtypes" })
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class Scanner {
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private String[] basePackages;
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private static final String XML_RESOURCE_PATTERN = "**/*.xml";
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private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
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public Scanner() {
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basePackages = StringUtils.tokenizeToStringArray(MapperLoader.this.basePackage,
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ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
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}
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public Resource[] getResource(String basePackage, String pattern) throws IOException {
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String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
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+ ClassUtils.convertClassNameToResourcePath(context.getEnvironment().resolveRequiredPlaceholders(
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basePackage)) + "/" + pattern;
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Resource[] resources = resourcePatternResolver.getResources(packageSearchPath);
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return resources;
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}
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public void reloadXML() throws Exception {
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SqlSessionFactory factory = context.getBean(SqlSessionFactory.class);
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Configuration configuration = factory.getConfiguration();
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// 移除加载项
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removeConfig(configuration);
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// 重新扫描加载
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for (String basePackage : basePackages) {
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Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);
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if (resources != null) {
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for (int i = 0; i < resources.length; i++) {
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if (resources[i] == null) {
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continue;
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}
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try {
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XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(resources[i].getInputStream(),
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configuration, resources[i].toString(), configuration.getSqlFragments());
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xmlMapperBuilder.parse();
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} catch (Exception e) {
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throw new NestedIOException("Failed to parse mapping resource: '" + resources[i] + "'", e);
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} finally {
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ErrorContext.instance().reset();
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}
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}
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}
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}
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}
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private void removeConfig(Configuration configuration) throws Exception {
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Class<?> classConfig = configuration.getClass();
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clearMap(classConfig, configuration, "mappedStatements");
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clearMap(classConfig, configuration, "caches");
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clearMap(classConfig, configuration, "resultMaps");
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clearMap(classConfig, configuration, "parameterMaps");
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clearMap(classConfig, configuration, "keyGenerators");
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clearMap(classConfig, configuration, "sqlFragments");
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clearSet(classConfig, configuration, "loadedResources");
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}
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private void clearMap(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {
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Field field = classConfig.getDeclaredField(fieldName);
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field.setAccessible(true);
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Map mapConfig = (Map) field.get(configuration);
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mapConfig.clear();
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}
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private void clearSet(Class<?> classConfig, Configuration configuration, String fieldName) throws Exception {
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Field field = classConfig.getDeclaredField(fieldName);
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field.setAccessible(true);
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Set setConfig = (Set) field.get(configuration);
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setConfig.clear();
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}
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public void scan() throws IOException {
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if (!fileMapping.isEmpty()) {
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return;
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}
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for (String basePackage : basePackages) {
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Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);
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if (resources != null) {
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for (int i = 0; i < resources.length; i++) {
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String multi_key = getValue(resources[i]);
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fileMapping.put(resources[i].getFilename(), multi_key);
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}
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}
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}
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}
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private String getValue(Resource resource) throws IOException {
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String contentLength = String.valueOf((resource.contentLength()));
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String lastModified = String.valueOf((resource.lastModified()));
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return new StringBuilder(contentLength).append(lastModified).toString();
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}
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public boolean isChanged() throws IOException {
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boolean isChanged = false;
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for (String basePackage : basePackages) {
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Resource[] resources = getResource(basePackage, XML_RESOURCE_PATTERN);
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if (resources != null) {
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for (int i = 0; i < resources.length; i++) {
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String name = resources[i].getFilename();
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String value = fileMapping.get(name);
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String multi_key = getValue(resources[i]);
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if (!multi_key.equals(value)) {
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isChanged = true;
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fileMapping.put(name, multi_key);
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}
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}
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}
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}
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return isChanged;
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}
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}
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@Override
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public void destroy() throws Exception {
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if (service != null) {
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service.shutdownNow();
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}
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}
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}
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