mybatis动态更新xml文件后热部署,不重启应用的方法
mybatis应用程序，由于是半自动化的sql, 有大量的sql是在xml文件中配置的，而在开发程序的过程中，通常需要边写sql变调试应用。但在默认情况下，xml文件里配置的sql语句是被放入到缓存中去了，每次更改有sql语句的xml文件，需要重新启动应用，这样工作效率很低，于是很希望有一个动态加载xml文件的功能，自动加载新的sql语句，并重新写入到缓存中，在网上参考了很多资料，最终弄了一个简单的东西出来，直接写成了spring mvc的controller。代码如下: 
package com.yihaomen.controller;
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.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
@Scope("prototype")
@Controller
@RequestMapping("/sql")
public class SQLSessionCacheController {
private Log log = LogFactory.getLog(SQLSessionCacheController.class);
@Autowired
private SqlSessionFactory sqlSessionFactory;
private Resource[] mapperLocations;
private String packageSearchPath = "classpath*:**/mappers/*.xml";
private HashMap fileMapping = new HashMap();// 记录文件是否变化
@RequestMapping("/refresh")
@ResponseBody
public String 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 "packageSearchPath扫描包路径配置错误";
}
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);
}
return "刷新mybatis xml配置语句成功";
} catch (Exception e) {
e.printStackTrace();
return "刷新mybatis xml配置语句失败";
}
}
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;
}
}
注意事项：
在我的应用中，mybatis配置文件放在这里的：classpath*:**/mappers/*.xml， 因此我定义死了，需要修改成自己的路径.
测试方法：
可以通过controller提供的地址，直接在浏览器上输入url访问, 比如: http://localhost:8080/sql/refresh , 当然，你还可以通过js用ajax方式调用，都是可以的。