大家好，我是烤鸭:
今天介绍一下springboot mybatis 热加载mapper.xml文件。
本来不打算写的，看到网上比较流行的方式都比较麻烦，想着简化一下。
网上流行的版本。
https://www.cnblogs.com/oskyhg/p/8587701.html
总结一下需要：mybatis-config，mybatis-refresh.properties，MapperRefresh.java，SqlSessionFactoryBean.java
按照这个博客写的，确实挺好用的。但是，springboot简便就是简便在没有配置文件。
于是看看能不能优化一下。优化后只需要mybatis-refresh.properties，MapperRefresh.java+一行代码
环境：
springboot 2.0.0.RELEASE
mybatis 3.4.4
mybatis-spring-boot-starter 1.3.0
1. MapperRefresh.java(同上，复制)
定时读取指定目录下的mapper.xml文件，是否被修改
package com.xxx.web.common.config.mybatis;import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;import org.apache.commons.lang.StringUtils;
import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.session.Configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.NestedIOException;
import org.springframework.core.io.Resource;
import com.google.common.collect.Sets;
/** * 刷新MyBatis Mapper XML 线程 * @author ThinkGem * @version 2016-5-29 */
public class MapperRefresh implements java.lang.Runnable { public static Logger log = LoggerFactory.getLogger(MapperRefresh.class); private static String filename = "mybatis-refresh.properties"; private static Properties prop = new Properties(); private static boolean enabled; // 是否启用Mapper刷新线程功能 private static boolean refresh; // 刷新启用后，是否启动了刷新线程 private Set<String> location; // Mapper实际资源路径 private Resource[] mapperLocations; // Mapper资源路径 private Configuration configuration; // MyBatis配置对象 private Long beforeTime = 0L; // 上一次刷新时间 private static int delaySeconds; // 延迟刷新秒数 private static int sleepSeconds; // 休眠时间 private static String mappingPath; // xml文件夹匹配字符串，需要根据需要修改 static { // try {
// prop.load(MapperRefresh.class.getResourceAsStream(filename));
// } catch (Exception e) {
// e.printStackTrace();
// System.out.println("Load mybatis-refresh “"+filename+"” file error.");
// } URL url = MapperRefresh.class.getClassLoader().getResource(filename);InputStream is;try {is = url.openStream();if (is == null) {log.warn("applicationConfig.properties not found.");} else {prop.load(is);} } catch (IOException e) {e.printStackTrace();}String value = getPropString("enabled");System.out.println(value);enabled = "true".equalsIgnoreCase(value); delaySeconds = getPropInt("delaySeconds"); sleepSeconds = getPropInt("sleepSeconds"); mappingPath = getPropString("mappingPath"); delaySeconds = delaySeconds == 0 ? 50 : delaySeconds; sleepSeconds = sleepSeconds == 0 ? 3 : sleepSeconds; mappingPath = StringUtils.isBlank(mappingPath) ? "mappings" : mappingPath; log.debug("[enabled] " + enabled); log.debug("[delaySeconds] " + delaySeconds); log.debug("[sleepSeconds] " + sleepSeconds); log.debug("[mappingPath] " + mappingPath); } public static boolean isRefresh() { return refresh; } public MapperRefresh(Resource[] mapperLocations, Configuration configuration) { this.mapperLocations = mapperLocations; this.configuration = configuration; } @Override public void run() { beforeTime = System.currentTimeMillis(); log.debug("[location] " + location); log.debug("[configuration] " + configuration); if (enabled) { // 启动刷新线程 final MapperRefresh runnable = this; new Thread(new java.lang.Runnable() { @Override public void run() { if (location == null){ location = Sets.newHashSet(); log.debug("MapperLocation's length:" + mapperLocations.length); for (Resource mapperLocation : mapperLocations) { String s = mapperLocation.toString().replaceAll("\\\\", "/"); s = s.substring("file [".length(), s.lastIndexOf(mappingPath) + mappingPath.length()); if (!location.contains(s)) { location.add(s); log.debug("Location:" + s); } } log.debug("Locarion's size:" + location.size()); } try { Thread.sleep(delaySeconds * 1000); } catch (InterruptedException e2) { e2.printStackTrace(); } refresh = true; System.out.println("========= Enabled refresh mybatis mapper ========="); while (true) { try { for (String s : location) { runnable.refresh(s, beforeTime); } } catch (Exception e1) { e1.printStackTrace(); } try { Thread.sleep(sleepSeconds * 1000); } catch (InterruptedException e) { e.printStackTrace(); } } } }, "MyBatis-Mapper-Refresh").start(); } } /** * 执行刷新 * @param filePath 刷新目录 * @param beforeTime 上次刷新时间 * @throws NestedIOException 解析异常 * @throws FileNotFoundException 文件未找到 * @author ThinkGem */ @SuppressWarnings({ "rawtypes", "unchecked" }) private void refresh(String filePath, Long beforeTime) throws Exception { // 本次刷新时间 Long refrehTime = System.currentTimeMillis(); // 获取需要刷新的Mapper文件列表 List<File> fileList = this.getRefreshFile(new File(filePath), beforeTime); if (fileList.size() > 0) { log.debug("Refresh file: " + fileList.size()); } for (int i = 0; i < fileList.size(); i++) { InputStream inputStream = new FileInputStream(fileList.get(i)); String resource = fileList.get(i).getAbsolutePath(); try { // 清理原有资源，更新为自己的StrictMap方便，增量重新加载 String[] mapFieldNames = new String[]{ "mappedStatements", "caches", "resultMaps", "parameterMaps", "keyGenerators", "sqlFragments" }; for (String fieldName : mapFieldNames){ Field field = configuration.getClass().getDeclaredField(fieldName); field.setAccessible(true); Map map = ((Map)field.get(configuration)); if (!(map instanceof StrictMap)){ Map newMap = new StrictMap(StringUtils.capitalize(fieldName) + "collection"); for (Object key : map.keySet()){ try { newMap.put(key, map.get(key)); }catch(IllegalArgumentException ex){ newMap.put(key, ex.getMessage()); } } field.set(configuration, newMap); } } // 清理已加载的资源标识，方便让它重新加载。 Field loadedResourcesField = configuration.getClass().getDeclaredField("loadedResources"); loadedResourcesField.setAccessible(true); Set loadedResourcesSet = ((Set)loadedResourcesField.get(configuration)); loadedResourcesSet.remove(resource); //重新编译加载资源文件。 XMLMapperBuilder xmlMapperBuilder = new XMLMapperBuilder(inputStream, configuration, resource, configuration.getSqlFragments()); xmlMapperBuilder.parse(); } catch (Exception e) { throw new NestedIOException("Failed to parse mapping resource: '" + resource + "'", e); } finally { ErrorContext.instance().reset(); }
// System.out.println("Refresh file: " + mappingPath + StringUtils.substringAfterLast(fileList.get(i).getAbsolutePath(), mappingPath)); if (log.isDebugEnabled()) { log.debug("Refresh file: " + fileList.get(i).getAbsolutePath()); log.debug("Refresh filename: " + fileList.get(i).getName()); } } // 如果刷新了文件，则修改刷新时间，否则不修改 if (fileList.size() > 0) { this.beforeTime = refrehTime; } } /** * 获取需要刷新的文件列表 * @param dir 目录 * @param beforeTime 上次刷新时间 * @return 刷新文件列表 */ private List<File> getRefreshFile(File dir, Long beforeTime) { List<File> fileList = new ArrayList<File>(); File[] files = dir.listFiles(); if (files != null) { for (int i = 0; i < files.length; i++) { File file = files[i]; if (file.isDirectory()) { fileList.addAll(this.getRefreshFile(file, beforeTime)); } else if (file.isFile()) { if (this.checkFile(file, beforeTime)) { fileList.add(file); } } else { System.out.println("Error file." + file.getName()); } } } return fileList; } /** * 判断文件是否需要刷新 * @param file 文件 * @param beforeTime 上次刷新时间 * @return 需要刷新返回true，否则返回false */ private boolean checkFile(File file, Long beforeTime) { if (file.lastModified() > beforeTime) { return true; } return false; } /** * 获取整数属性 * @param key * @return */ private static int getPropInt(String key) { int i = 0; try { i = Integer.parseInt(getPropString(key)); } catch (Exception e) { } return i; } /** * 获取字符串属性 * @param key * @return */ private static String getPropString(String key) { return prop == null ? null : prop.getProperty(key).trim(); } /** * 重写 org.apache.ibatis.session.Configuration.StrictMap 类 * 来自 MyBatis3.4.0版本，修改 put 方法，允许反复 put更新。 */ public static class StrictMap<V> extends HashMap<String, V> { private static final long serialVersionUID = -4950446264854982944L; private String name; public StrictMap(String name, int initialCapacity, float loadFactor) { super(initialCapacity, loadFactor); this.name = name; } public StrictMap(String name, int initialCapacity) { super(initialCapacity); this.name = name; } public StrictMap(String name) { super(); this.name = name; } public StrictMap(String name, Map<String, ? extends V> m) { super(m); this.name = name; } @SuppressWarnings("unchecked") public V put(String key, V value) { // ThinkGem 如果现在状态为刷新，则刷新(先删除后添加) if (MapperRefresh.isRefresh()) { remove(key);
// MapperRefresh.log.debug("refresh key:" + key.substring(key.lastIndexOf(".") + 1)); } // ThinkGem end if (containsKey(key)) { throw new IllegalArgumentException(name + " already contains value for " + key); } if (key.contains(".")) { final String shortKey = getShortName(key); if (super.get(shortKey) == null) { super.put(shortKey, value); } else { super.put(shortKey, (V) new Ambiguity(shortKey)); } } return super.put(key, value); } public V get(Object key) { V value = super.get(key); if (value == null) { throw new IllegalArgumentException(name + " does not contain value for " + key); } if (value instanceof Ambiguity) { throw new IllegalArgumentException(((Ambiguity) value).getSubject() + " is ambiguous in " + name + " (try using the full name including the namespace, or rename one of the entries)"); } return value; } private String getShortName(String key) { final String[] keyparts = key.split("\\."); return keyparts[keyparts.length - 1]; } protected static class Ambiguity { private String subject; public Ambiguity(String subject) { this.subject = subject; } public String getSubject() { return subject; } } }
}
2. mybatis-refresh.properties(同上，复制)
设置读取配置文件的参数，定时和频率，是否多线程
enabled=true
delaySeconds=30
sleepSeconds=10
mappingPath=mybatis3. 关于sqlSessionFactory
网上大多的实现方式都是重新创建SqlSessionFactory，然后再注入。
类似这样：
我的疑问：
1. MapperRefresh需要当前sqlSessionBean的configuration。既然springboot都已经sqlSessionFactory把创建好了，直接获取sqlSessionBean的configuration不就好了么。
2. yml配置mybatis的时候，没有sqlMapConfig(myabtis-config).xml这个配置文件，还得先创建一个，很不方便。试着把配置文件那行注释掉，会报错，Location 不能为空。
4. 改进
只需要在mybatis的sqlSessionFactory创建完成，注入SqlSession，调用MapperRefresh启动。
RootConfiguration.java
package com.xxx.web.common.config;import java.io.IOException;
import java.util.concurrent.Executors;import javax.annotation.PostConstruct;import org.apache.ibatis.session.SqlSession;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.stereotype.Controller;import com.xxx.web.common.config.mybatis.MapperRefresh;@Configuration
@ComponentScan(value = "com.xxx", excludeFilters = { @Filter(Controller.class),@Filter(type = FilterType.ASSIGNABLE_TYPE, value = { RootConfiguration.class }) })
@MapperScan({"com.xxx.web.**.dao"})
public class RootConfiguration extends SpringBootServletInitializer {@Autowiredprivate SqlSession sqlSession;@Overrideprotected SpringApplicationBuilder configure(SpringApplicationBuilder application) {application.registerShutdownHook(false);return application.sources(RootConfiguration.class);}@PostConstructpublic void postConstruct() throws IOException {//Constant.threadPool = Executors.newFixedThreadPool(20);Resource[] resources = new PathMatchingResourcePatternResolver().getResources("classpath*:mybatis/**/*Mapper.xml");new MapperRefresh(resources, sqlSession.getConfiguration()).run();}
}启动类：
MainApplication.java
package com.xxx.web;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;import com.xxx.web.common.config.RootConfiguration;@SpringBootApplication
public class MainApplication {public static void main(String[] args) {SpringApplication.run(RootConfiguration.class, args);}
}
application.yml
spring: thymeleaf:prefix: classpath:/templates/datasource: type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.jdbc.Driverurl: jdbc:mysql://localhost:3306/xxx?allowMultiQueries=true&useUnicode=true&characterEncoding=utf-8username: adminpassword: admin@2017initialSize: 1minIdle: 3maxActive: 20# 配置获取连接等待超时的时间maxWait: 60000# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒timeBetweenEvictionRunsMillis: 60000# 配置一个连接在池中最小生存的时间，单位是毫秒minEvictableIdleTimeMillis: 50000validationQuery: select 'x'testWhileIdle: truetestOnBorrow: falsetestOnReturn: false# 打开PSCache，并且指定每个连接上PSCache的大小poolPreparedStatements: truemaxPoolPreparedStatementPerConnectionSize: 20# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙 #,wallfilters: stat,slf4j# 通过connectProperties属性来打开mergeSql功能；慢SQL记录connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000# 合并多个DruidDataSource的监控数据useGlobalDataSourceStat: true
mybatis: configuration:map-underscore-to-camel-case: true#打印日志log-impl: org.apache.ibatis.logging.stdout.StdOutImplmapper-locations: mybatis/**/*Mapper.xmltypeAliasesPackage: com.xxx.entity.*
#配置缓存和session存储方式，默认ehcache,可选redis
cacheType: ehcache5. 多说一句
关于mybatis-refresh.properties中mappingPath
指的是src/main/resources的最父级的mybatis文件夹，按下图的话：
mappingPath=mybatis
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