背景
有些需求可能更新sql的频率较高，但又不想频繁发布java应用程序，所以mybatis-mapper.xml热加载的需求顺势而出。
目的
只需调起加载mapper.xml的程序，无需重启整个java应用，低耦合。
实现方式
mapper.xml可以指定路径。如springboot工程resources目录下；亦可独立维护在某个git仓库，然后由程序加载到运行机器上去。
具体加载git仓库到运行机器代码如下：
package com.jason.git;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.jgit.api.CloneCommand;
import org.eclipse.jgit.api.Git;
import org.eclipse.jgit.api.PullResult;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.transport.UsernamePasswordCredentialsProvider;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Repository;
import java.io.File;
import java.io.IOException;
@Repository
public class GitConfigRepository {
private static final long MIN_CHECKOUT_INTERVAL = 1000L * 10;
private static final long MAX_LOCAL_LIFE_CYCLE = 2 * 86400 * 1000L;
private Log log = LogFactory.getLog(GitConfigRepository.class);
@Value("${git.repository:}")
private String gitRepositoryURL;
@Value("${git.branch:master}")
private String gitBranch;
@Value("${git.username:}")
private String gitUsername;
@Value("${git.password:}")
private String gitPassword;
@Value("${bi.meta.git.localRepository:}")
private String localRepository;
private long lastCheckoutTimestamp;
private long localRepositoryTimestamp;
private File gitDir;
private Git git;
public File getRepositoryDir() throws IOException, GitAPIException {
long now = System.currentTimeMillis();
if (now - lastCheckoutTimestamp > MIN_CHECKOUT_INTERVAL) {
this.lastCheckoutTimestamp = now;
if (StringUtils.isNotEmpty(localRepository)) {
gitDir = new File(localRepository);
} else {
boolean isNewDir = false;
if (gitDir != null && !gitDir.exists()) {
gitDir = null;
}
if (gitDir != null) {
if (now - localRepositoryTimestamp > MAX_LOCAL_LIFE_CYCLE) {
localRepositoryTimestamp = 0;
try {
gitDir.delete();
} catch (Exception e) {
// do nothing
}
gitDir = null;
}
File keyFile = new File(gitDir, "global/config/config.yml");
if (!(keyFile.exists() && keyFile.length() > 0)) {
try {
gitDir.delete();
} catch (Exception e) {
// do nothing
}
gitDir = null;
}
}
if (gitDir == null) {
gitDir = File.createTempFile("egret-meta", ".git");
if (!gitDir.delete()) {
throw new IOException("无法删除临时文件: " + gitDir.getAbsolutePath());
}
if (!gitDir.mkdir()) {
throw new IOException("创建历史Git本地目录失败: " + gitDir.getAbsolutePath());
}
gitDir.deleteOnExit();
isNewDir = true;
localRepositoryTimestamp = now;
}
if (StringUtils.isNotEmpty(gitRepositoryURL)) {
//设置远程服务器上的用户名和密码
UsernamePasswordCredentialsProvider usernamePasswordCredentialsProvider = new
UsernamePasswordCredentialsProvider(gitUsername, gitPassword);
if (isNewDir) {
//克隆代码库命令
CloneCommand cloneCommand = Git.cloneRepository();
git = cloneCommand.setURI(gitRepositoryURL)
.setBranch(gitBranch)
.setDirectory(gitDir)
.setCredentialsProvider(usernamePasswordCredentialsProvider)
.call();
}
log.info("Checkout meta configs from. [" + gitRepositoryURL + "|" + gitBranch + "]");
PullResult call = git.pull().setRemoteBranchName(gitBranch).setCredentialsProvider(usernamePasswordCredentialsProvider).call();
log.info("Checkout meta configs OK.");
}
}
}
return gitDir;
}
}
1、手动触发
public void reloadSqlXml() {
try {
File mapperXmlDir = gitConfigRepository.getRepositoryDir();
mapperHotDeployPlugin.reloadSqlXml(mapperXmlDir);
} catch (Exception e) {
log.error(e.getMessage(), e);
}
}
package com.jason.dao;
import cn.hutool.core.bean.BeanUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.builder.xml.XMLMapperEntityResolver;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.parsing.XPathParser;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import java.io.File;
import java.io.FileInputStream;
import java.util.*;
import java.util.stream.Collectors;
@Slf4j
@Component
public class MapperHotDeployPlugin implements InitializingBean {
@Autowired
private SqlSessionFactory sqlSessionFactory;
private volatile Configuration configuration;
@Override
public void afterPropertiesSet() {
configuration = sqlSessionFactory.getConfiguration();
}
public void reloadSqlXml(File file) {
if (file == null) {
return;
}
List<File> fileList = new ArrayList<>();
setFiles(file, fileList, ".xml");
reloadXml(fileList);
}
private void setFiles(File file, List<File> fileList, String suffix) {
File[] files = file.listFiles();
if (files == null || files.length == 0) {
return;
}
for (File f : files) {
if (f.isDirectory()) {
//递归调用
setFiles(f, fileList, suffix);
} else {
//保存文件路径到集合中
if (f.getAbsolutePath().contains(suffix)) {
fileList.add(f);
}
}
}
}
private void reloadXml(List<File> fileList) {
log.info("需要重新加载的文件列表: {}", fileList);
fileList.forEach(r -> {
try {
clearMap(getNamespace(r));
clearSet(r.getAbsolutePath());
XMLMapperBuilder xmlMapperBuilder =
new XMLMapperBuilder(new FileInputStream(r), getTarConfiguration(), r.toString(),
getTarConfiguration().getSqlFragments());
xmlMapperBuilder.parse();
} catch (Exception e) {
log.info("ERROR: 重新加载[{}]失败", r.toString(), e);
throw new RuntimeException("ERROR: 重新加载[" + r.toString() + "]失败", e);
} finally {
ErrorContext.instance().reset();
}
});
log.info("成功热部署文件列表: {}", fileList);
}
private Configuration getTarConfiguration() {
return configuration;
}
private void clearMap(String nameSpace) {
log.info(
"清理Mybatis的namespace={}在mappedStatements、caches、resultMaps、parameterMaps、keyGenerators、sqlFragments中的缓存");
Arrays.asList("mappedStatements", "caches", "resultMaps", "parameterMaps", "keyGenerators", "sqlFragments")
.forEach(fieldName -> {
Object value = BeanUtil.getFieldValue(getTarConfiguration(), fieldName);
if (value instanceof Map) {
Map<?, ?> map = (Map) value;
List<Object> list = map.keySet().stream().filter(o -> o.toString().startsWith(nameSpace + "."))
.collect(Collectors.toList());
log.info("需要清理的元素: {}", list);
list.forEach(k -> map.remove((Object) k));
}
});
}
private void clearSet(String resource) {
log.info("清理mybatis的资源{}在容器中的缓存", resource);
Object value = BeanUtil.getFieldValue(getTarConfiguration(), "loadedResources");
if (value instanceof Set) {
Set<?> set = (Set) value;
set.remove(resource);
set.remove("namespace:" + resource);
}
}
private String getNamespace(File file) {
try {
XPathParser parser = new XPathParser(new FileInputStream(file), true, null, new XMLMapperEntityResolver());
return parser.evalNode("/mapper").getStringAttribute("namespace");
} catch (Exception e) {
log.info("ERROR: 解析xml中namespace失败", e);
throw new RuntimeException("ERROR: 解析xml中namespace失败", e);
}
}
}
2、自动监控
package com.jason.replacer.config;
import lombok.SneakyThrows;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.builder.xml.XMLMapperEntityResolver;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.parsing.XPathParser;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.stereotype.Component;
import java.lang.reflect.Field;
import java.nio.file.*;
import java.util.*;
import java.util.stream.Collectors;
@Slf4j
@Component
public class MapperHotDeployPlugin implements InitializingBean {
@Autowired
private SqlSessionFactory sqlSessionFactory;
private volatile Configuration configuration;
@Value("${mybatis.mapper-locations}")
private String mybatisPath;
@Override
public void afterPropertiesSet() {
configuration = sqlSessionFactory.getConfiguration();
new WatchThread().start();
}
class WatchThread extends Thread {
@Override
public void run() {
startWatch();
}
private void startWatch() {
try {
WatchService watcher = FileSystems.getDefault().newWatchService();
getWatchPaths().forEach(p -> {
try {
Paths.get(p).register(watcher, StandardWatchEventKinds.ENTRY_CREATE,
StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
} catch (Exception e) {
log.error("ERROR: 注册xml监听事件", e);
throw new RuntimeException("ERROR: 注册xml监听事件", e);
}
});
while (true) {
WatchKey watchKey = watcher.take();
Set<String> set = new HashSet<>();
for (WatchEvent<?> event : watchKey.pollEvents()) {
set.add(event.context().toString());
}
// 重新加载xml
reloadXml(set);
boolean valid = watchKey.reset();
if (!valid) {
break;
}
}
} catch (Exception e) {
System.out.println("Mybatis的xml监控失败!");
log.info("Mybatis的xml监控失败!", e);
}
}
private Set<String> getWatchPaths() {
Set<String> set = new HashSet<>();
Arrays.stream(getResource()).forEach(r -> {
try {
log.info("资源路径:{}", r.toString());
set.add(r.getFile().getParentFile().getAbsolutePath());
} catch (Exception e) {
log.info("获取资源路径失败", e);
throw new RuntimeException("获取资源路径失败");
}
});
log.info("需要监听的xml资源: {}", set);
return set;
}
@SneakyThrows
private Resource[] getResource() {
return new PathMatchingResourcePatternResolver().getResources(mybatisPath);
}
private void clearMap(String nameSpace) {
log.info(
"清理Mybatis的namespace={}在mappedStatements、caches、resultMaps、parameterMaps、keyGenerators、sqlFragments中的缓存");
Arrays.asList("mappedStatements", "caches", "resultMaps", "parameterMaps", "keyGenerators", "sqlFragments")
.forEach(fieldName -> {
Object value = getFieldValue(configuration, fieldName);
if (value instanceof Map) {
Map<?, ?> map = (Map) value;
List<Object> list =
map.keySet().stream().filter(o -> o.toString().startsWith(nameSpace + "."))
.collect(Collectors.toList());
log.info("需要清理的元素: {}", list);
list.forEach(k -> map.remove((Object) k));
}
});
}
private void clearSet(String resource) {
log.info("清理mybatis的资源{}在容器中的缓存", resource);
Object value = getFieldValue(configuration, "loadedResources");
if (value instanceof Set) {
Set<?> set = (Set) value;
set.remove(resource);
set.remove("namespace:" + resource);
}
}
private Object getFieldValue(Object obj, String fieldName) {
log.info("从{}中加载{}属性", obj, fieldName);
try {
Field field = obj.getClass().getDeclaredField(fieldName);
boolean accessible = field.isAccessible();
field.setAccessible(true);
Object value = field.get(obj);
field.setAccessible(accessible);
return value;
} catch (Exception e) {
log.info("ERROR: 加载对象中[{}]", fieldName, e);
throw new RuntimeException("ERROR: 加载对象中[" + fieldName + "]", e);
}
}
private void reloadXml(Set<String> set) {
log.info("需要重新加载的文件列表: {}", set);
List<Resource> list = Arrays.stream(getResource()).filter(p -> set.contains(p.getFilename()))
.collect(Collectors.toList());
log.info("需要处理的资源路径:{}", list);
list.forEach(r -> {
try {
clearMap(getNamespace(r));
clearSet(r.toString());
XMLMapperBuilder xmlMapperBuilder =
new XMLMapperBuilder(r.getInputStream(), configuration, r.toString(),
configuration.getSqlFragments());
xmlMapperBuilder.parse();
} catch (Exception e) {
log.info("ERROR: 重新加载[{}]失败", r.toString(), e);
throw new RuntimeException("ERROR: 重新加载[" + r.toString() + "]失败", e);
} finally {
ErrorContext.instance().reset();
}
});
log.info("成功热部署文件列表: {}", set);
}
private String getNamespace(Resource resource) {
log.info("从{}获取namespace", resource.toString());
try {
XPathParser parser =
new XPathParser(resource.getInputStream(), true, null, new XMLMapperEntityResolver());
return parser.evalNode("/mapper").getStringAttribute("namespace");
} catch (Exception e) {
log.info("ERROR: 解析xml中namespace失败", e);
throw new RuntimeException("ERROR: 解析xml中namespace失败", e);
}
}
}
}
注
上面提供了加载mapper.xml文件的两种方式
读取文件绝对路径
public static List<File> getFiles(String dirPath) {
List<File> fileList = new ArrayList<>();
File file = new File(dirPath);
return getFiles(file, fileList, ".xml");
}
public static List<File> getFiles(File file, List<File> fileList, String suffix) {
File[] files = file.listFiles();
if (files == null || files.length == 0) {
return Collections.emptyList();
}
for (File f : files) {
if (f.isDirectory()) {
//递归调用
getFiles(f, fileList, suffix);
} else {
//保存文件路径到集合中
if (f.getAbsolutePath().contains(suffix)) {
fileList.add(f);
}
}
}
return fileList;
}
读取classpath下的资源路径
@SneakyThrows
private Resource[] getResource() {
return new PathMatchingResourcePatternResolver().getResources("classpath:mappers*.xml");
}
总结
到此这篇关于Mybatis中mapper.xml实现热加载介绍的文章就介绍到这了,更多相关Mybatis mapper.xml热加载内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
