mybatis实现mapper文件热部署

 每次修改mybatis的sql脚本后，都要重启，因为mybatis的mapper文件默认只在启动时加载到缓存，改动后不会自动加载，于是研究了下mybatis配置文件的加载，分享如下：实现思路：使用定时器定时扫描mapper文件的改动，如果有改动则调用mapper文件的加载方法XMLMapperBuilder.parse()。一.写一个重新加载mapper文件的java类 首先需要构建一个sqlSessionFactory对象，并指定mybatis的Configuration.xml配置文件路径,之后定时扫描并判断mapper文件是否有改动，如果有改动则重新加载，代码如下：package zttc.itat.user.utils;import java.io.IOException;import java.io.InputStream;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.io.Resources;import org.apache.ibatis.session.Configuration;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.apache.log4j.Logger;import org.springframework.core.io.Resource;import org.springframework.core.io.support.PathMatchingResourcePatternResolver;/** * mybatis的mapper文件有改动时，进行重新加载 * @author ycblus * */public class SqlSessionCache {         private Logger log  = Logger.getLogger(SqlSessionCache.class);              private Resource[] mapperLocations;         private String packageSearchPath = "classpath*:zttc/itat/user/mapper/*.xml";         SqlSessionFactory sqlSessionFactory;    Configuration configuration;    private HashMap<String, Long> fileMapping = new HashMap<String, Long>();// 记录文件是否变化         {        String resource = "Configuration.xml";        InputStream inputStream;        try {            inputStream = Resources.getResourceAsStream(resource);            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream) ;            configuration = this.sqlSessionFactory.getConfiguration(); //扫描文件             } catch (IOException e) {            e.printStackTrace();        }            }        public void refreshMapper() throws Exception{                 try {                             try {                                 this.scanMapperXml();                             } catch (IOException e) {                                     log.error("packageSearchPath扫描包路径配置错误");                                     return;                             }                Runnable runnable = new Runnable() {                    public void run() {                        // task to run goes here                        try {                      // 判断是否有文件发生了变化                                     if (isChanged()) {                                             // 清理                                             this.removeConfig(configuration);                                              // 重新加载                                             for (Resource configLocation : mapperLocations) {                                                     try {                                                             XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(configLocation.getInputStream(),                                            configuration, configLocation.toString(), configuration.getSqlFragments());                                                             xmlMapperBuilder.parse();                                                             log.info("mapper文件[" + configLocation.getFilename() + "]加载成功");                                                         } catch (IOException e) {                                                                 log.error("mapper文件[" + configLocation.getFilename() + "]不存在或内容格式不对");                                                                 continue;                                                         }                                                 }                                         }                         } catch (Exception e) {                            // TODO Auto-generated catch block                            e.printStackTrace();                        }                 }                                     /**      * 清空Configuration中几个重要的缓存      * @param configuration      * @throws Exception      */                       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");                        }                                          /**      * 判断文件是否发生了变化      * @param resource      * @return      * @throws IOException      */                       boolean isChanged() throws IOException {                               boolean flag = false;                               for (Resource resource : mapperLocations) {                                       String resourceName = resource.getFilename();                                                    boolean addFlag = !fileMapping.isEmpty() && !fileMapping.containsKey(resourceName);// 此为新增标识                                                    // 修改文件:判断文件内容是否有变化                                       Long compareFrame = fileMapping.get(resourceName);                                       long lastFrame = resource.contentLength() + resource.lastModified();                                       boolean modifyFlag = null != compareFrame && compareFrame.longValue() != lastFrame;// 此为修改标识                                                     fileMapping.put(resourceName, Long.valueOf(lastFrame));// 文件内容帧值                          // 新增或是修改时,存储文件                                       if(addFlag || modifyFlag) {                              flag = true;                                       }                               }                               return flag;                       }               };               ScheduledExecutorService service = Executors                        .newSingleThreadScheduledExecutor();                // 第二个参数为首次执行的延时时间，第三个参数为定时执行的间隔时间                service.scheduleAtFixedRate(runnable, 1, 10, TimeUnit.SECONDS);                                               } catch (Exception e) {                         e.printStackTrace();                 }         }              public void setPackageSearchPath(String packageSearchPath) {                 this.packageSearchPath = packageSearchPath;         }             public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {                 this.sqlSessionFactory = sqlSessionFactory;         }          /**      * 扫描xml文件所在的路径      * @throws IOException       */         private void scanMapperXml() throws IOException {                 this.mapperLocations = new PathMatchingResourcePatternResolver().getResources(packageSearchPath);         }              /**      * 清空Configuration中几个重要的缓存      * @param configuration      * @throws Exception      */         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");          }              @SuppressWarnings("rawtypes")         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();         }          @SuppressWarnings("rawtypes")         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 static void main(String[] args) {        HashMap<String, Long> fileMapping = new HashMap<String, Long>();        boolean f = !fileMapping.isEmpty() && !fileMapping.containsKey("Hello.xml");        System.out.println(f);    }} 二.Configuration.xml配置文件这个配置文件在这里只作为扫描配置使用，可以看到其他配置都没有，因为我是在spring里面统一配置了<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration>     <mappers>         <mapper resource="zttc/itat/user/mapper/TUserMapper.xml"/>         <mapper resource="zttc/itat/user/mapper/TStoreMapper.xml"/>     </mappers> </configuration>三.写一个Servlet，在服务器启动时调用前面写好的定时加载类。代码如下： package zttc.itat.user.servlet;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import org.apache.log4j.Logger;import zttc.itat.user.utils.SqlSessionCache;/** * Servlet implementation class MapperReloadServlet *  * when mybatis files changed,reload them   */public class MapperReloadServlet extends HttpServlet {    private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public MapperReloadServlet() {        super();        // TODO Auto-generated constructor stub    }    public void init()throws ServletException    {      Logger logger = Logger.getLogger(this.getClass());      logger.info("The mapper reload timer starting... ");            try {        new SqlSessionCache().refreshMapper();    } catch (Exception e) {        // TODO Auto-generated catch block        e.printStackTrace();    }            }}此外，需在web.xml中加入这个servlet类，添加代码如下： <servlet>    <servlet-name>MapperReloadServlet</servlet-name>    <servlet-class>zttc.itat.user.servlet.MapperReloadServlet</servlet-class>    <load-on-startup>7</load-on-startup>  </servlet> 这样每次当mapper文件有改动时，就会重新加载。不过会把所有的mapper文件重新加载一遍，如果需要对指定文件进行加载也是可以的，需要修改下重新加载的类。