3.最后看看com.pingpeng.misp.common.SqlSessionCache这个缓存类refreshMapper方法是如何实现刷新的:
- package com.pingpeng.misp.common;
-
- import java.io.IOException;
- import java.lang.reflect.Field;
- import java.util.HashMap;
- import java.util.Map;
- import java.util.Set;
-
- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
- import org.apache.ibatis.builder.xml.XMLMapperBuilder;
- import org.apache.ibatis.session.Configuration;
- import org.apache.ibatis.session.SqlSessionFactory;
- import org.springframework.core.io.Resource;
- import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
-
- public class SqlSessionCache {
- private Log log = LogFactory.getLog(SqlSessionCache.class);
-
- private SqlSessionFactory sqlSessionFactory;
- private Resource[] mapperLocations;
- private String packageSearchPath;
- private HashMap<String, Long> fileMapping = new HashMap<String, Long>();// 记录文件是否变化
-
- public void refreshMapper() {
- try {
- Configuration configuration = this.sqlSessionFactory.getConfiguration();
-
- // step.1 扫描文件
- try {
- this.scanMapperXml();
- } catch (IOException e) {
- log.error("packageSearchPath扫描包路径配置错误");
- return;
- }
-
- System.out.println("==============刷新前mapper中的内容===============");
- for (String name : configuration.getMappedStatementNames()) {
- System.out.println(name);
- }
-
- // step.2 判断是否有文件发生了变化
- if (this.isChanged()) {
- // step.2.1 清理
- this.removeConfig(configuration);
-
- // step.2.2 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() + "]缓存加载成功");
- } catch (IOException e) {
- log.error("mapper文件[" + configLocation.getFilename() + "]不存在或内容格式不对");
- continue;
- }
- }
- }
-
- System.out.println("==============刷新后mapper中的内容===============");
- for (String name : configuration.getMappedStatementNames()) {
- System.out.println(name);
- }
- } 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();
- }
-
- /**
- * 判断文件是否发生了变化
- * @param resource
- * @return
- * @throws IOException
- */
- private boolean isChanged() throws IOException {
- boolean flag = false;
- for (Resource resource : mapperLocations) {
- String resourceName = resource.getFilename();
-
- boolean addFlag = !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
-
- // 新增或是修改时,存储文件
- if(addFlag || modifyFlag) {
- fileMapping.put(resourceName, Long.valueOf(lastFrame));// 文件内容帧值
- flag = true;
- }
- }
- return flag;
- }
- }
总结:
1.可以写个定时器每隔一段时间执行SqlSessionCache中refreshMapper()方法,这样就实现热部署功能
2.注意<property name="packageSearchPath" value="classpath*:com/pingpeng/misp/models/mybatis/mapper/**/*.xml"></property>配置的路径一定要是所有的mapper映射文件,而不是总管理文件
3.当前实现如果只改动了一个文件,那么也只重新加载所有文件,如何实现只加载更新的文件呢,这个有点复杂,请自行研究