24、SpringCloud Alibaba - nacos 从配置中心加载配置
启动流程
在启动main()过程中，会调用
SpringApplication.run(CloudApplication.class, args);
-> prepareContext() -> applyInitializers() -> initializer.initialize(context);
会调用ApplicationContextInitializer 的 initialize( ) 方法
PropertySourceBootstrapConfiguration 实现了 ApplicationContextInitializer 接口，定义在 spring.factories 中。
下面看一下它的 initialize( ) 方法
1、 initialize()；
@Override
public void initialize(ConfigurableApplicationContext applicationContext) {
List<PropertySource<?>> composite = new ArrayList<>();
AnnotationAwareOrderComparator.sort(this.propertySourceLocators);
boolean empty = true;
ConfigurableEnvironment environment = applicationContext.getEnvironment();
for (PropertySourceLocator locator : this.propertySourceLocators) {
//加载配置
Collection<PropertySource<?>> source = locator.locateCollection(environment);
if (source == null || source.size() == 0) {
continue;
}
List<PropertySource<?>> sourceList = new ArrayList<>();
for (PropertySource<?> p : source) {
if (p instanceof EnumerablePropertySource) {
EnumerablePropertySource<?> enumerable = (EnumerablePropertySource<?>) p;
sourceList.add(new BootstrapPropertySource<>(enumerable));
}
else {
sourceList.add(new SimpleBootstrapPropertySource(p));
}
}
logger.info("Located property source: " + sourceList);
composite.addAll(sourceList);
empty = false;
}
if (!empty) {
MutablePropertySources propertySources = environment.getPropertySources();
String logConfig = environment.resolvePlaceholders("${logging.config:}");
LogFile logFile = LogFile.get(environment);
for (PropertySource<?> p : environment.getPropertySources()) {
if (p.getName().startsWith(BOOTSTRAP_PROPERTY_SOURCE_NAME)) {
propertySources.remove(p.getName());
}
}
insertPropertySources(propertySources, composite);
reinitializeLoggingSystem(environment, logConfig, logFile);
setLogLevels(applicationContext, environment);
handleIncludedProfiles(environment);
}
}
2、 locateCollection()；
PropertySourceLocator 的实现类是 NacosPropertySourceLocator
default Collection<PropertySource<?>> locateCollection(Environment environment) {
return locateCollection(this, environment);
}
static Collection<PropertySource<?>> locateCollection(PropertySourceLocator locator, Environment environment) {
//加载配置
PropertySource<?> propertySource = locator.locate(environment);
if (propertySource == null) {
return Collections.emptyList();
}
if (CompositePropertySource.class.isInstance(propertySource)) {
Collection<PropertySource<?>> sources = ((CompositePropertySource) propertySource).getPropertySources();
List<PropertySource<?>> filteredSources = new ArrayList<>();
for (PropertySource<?> p : sources) {
if (p != null) {
filteredSources.add(p);
}
}
return filteredSources;
}
else {
return Arrays.asList(propertySource);
}
}
3、 locator.locate(environment)；
@Override
public PropertySource<?> locate(Environment env) {
nacosConfigProperties.setEnvironment(env);
//NacosConfigService
ConfigService configService = nacosConfigManager.getConfigService();
if (null == configService) {
log.warn("no instance of config service found, can't load config from nacos");
return null;
}
long timeout = nacosConfigProperties.getTimeout();
nacosPropertySourceBuilder = new NacosPropertySourceBuilder(configService,
timeout);
// dataIdPrefix 首先从spring.cloud.nacos.config.prefix获取，
//不存在时从spring.cloud.nacos.config.name获取，
//还不存在时从spring.application.name获取
//spring.cloud.nacos.config.name
String name = nacosConfigProperties.getName();
//spring.cloud.nacos.config.prefix
String dataIdPrefix = nacosConfigProperties.getPrefix();
if (StringUtils.isEmpty(dataIdPrefix)) {
dataIdPrefix = name;
}
if (StringUtils.isEmpty(dataIdPrefix)) {
//spring.application.name
dataIdPrefix = env.getProperty("spring.application.name");
}
CompositePropertySource composite = new CompositePropertySource(
NACOS_PROPERTY_SOURCE_NAME);
//加载共享的配置
// spring.cloud.nacos.config.sharedConfigs[0].dataId
loadSharedConfiguration(composite);
//加载额外的配置
// spring.cloud.nacos.config.extensionConfigs[0].dataId
loadExtConfiguration(composite);
//加载应用的配置
loadApplicationConfiguration(composite, dataIdPrefix, nacosConfigProperties, env);
return composite;
}
4、 loadApplicationConfiguration()；
private void loadApplicationConfiguration(
CompositePropertySource compositePropertySource, String dataIdPrefix,
NacosConfigProperties properties, Environment environment) {
//配置文件后缀，默认是 properties
String fileExtension = properties.getFileExtension();
//配置所属组，默认是 DEFAULT_GROUP
String nacosGroup = properties.getGroup();
// load directly once by default
loadNacosDataIfPresent(compositePropertySource, dataIdPrefix, nacosGroup,
fileExtension, true);
// load with suffix, which have a higher priority than the default
//加载配置文件，如 client.properties
loadNacosDataIfPresent(compositePropertySource,
dataIdPrefix + DOT + fileExtension, nacosGroup, fileExtension, true);
// Loaded with profile, which have a higher priority than the suffix
for (String profile : environment.getActiveProfiles()) {
//加载profile配置文件，如 client-dev.properties
String dataId = dataIdPrefix + SEP1 + profile + DOT + fileExtension;
loadNacosDataIfPresent(compositePropertySource, dataId, nacosGroup,
fileExtension, true);
}
}
5、 loadNacosDataIfPresent()；
private void loadNacosDataIfPresent(final CompositePropertySource composite,
final String dataId, final String group, String fileExtension,
boolean isRefreshable) {
if (null == dataId || dataId.trim().length() < 1) {
return;
}
if (null == group || group.trim().length() < 1) {
return;
}
//加载配置
NacosPropertySource propertySource = this.loadNacosPropertySource(dataId, group,
fileExtension, isRefreshable);
//放在CompositePropertySource 中的首位
this.addFirstPropertySource(composite, propertySource, false);
}
6、 loadNacosPropertySource()；
private NacosPropertySource loadNacosPropertySource(final String dataId,
final String group, String fileExtension, boolean isRefreshable) {
if (NacosContextRefresher.getRefreshCount() != 0) {
if (!isRefreshable) {
//从缓存中获取
return NacosPropertySourceRepository.getNacosPropertySource(dataId,
group);
}
}
//从远程获取
return nacosPropertySourceBuilder.build(dataId, group, fileExtension,
isRefreshable);
}
7、 nacosPropertySourceBuilder.build()；
NacosPropertySource build(String dataId, String group, String fileExtension,
boolean isRefreshable) {
//加载nacos服务端配置数据
List<PropertySource<?>> propertySources = loadNacosData(dataId, group,
fileExtension);
NacosPropertySource nacosPropertySource = new NacosPropertySource(propertySources,
group, dataId, new Date(), isRefreshable);
//放入缓存
NacosPropertySourceRepository.collectNacosPropertySource(nacosPropertySource);
return nacosPropertySource;
}
8、 loadNacosData()；
private List<PropertySource<?>> loadNacosData(String dataId, String group,
String fileExtension) {
String data = null;
try {
//加载配置
data = configService.getConfig(dataId, group, timeout);
if (StringUtils.isEmpty(data)) {
log.warn(
"Ignore the empty nacos configuration and get it based on dataId[{}] & group[{}]",
dataId, group);
return Collections.emptyList();
}
if (log.isDebugEnabled()) {
log.debug(String.format(
"Loading nacos data, dataId: '%s', group: '%s', data: %s", dataId,
group, data));
}
//解析配置
return NacosDataParserHandler.getInstance().parseNacosData(dataId, data,
fileExtension);
}
catch (NacosException e) {
log.error("get data from Nacos error,dataId:{} ", dataId, e);
}
catch (Exception e) {
log.error("parse data from Nacos error,dataId:{},data:{}", dataId, data, e);
}
return Collections.emptyList();
}
9、 configService.getConfig()；
@Override
public String getConfig(String dataId, String group, long timeoutMs) throws NacosException {
return getConfigInner(namespace, dataId, group, timeoutMs);
}
private String getConfigInner(String tenant, String dataId, String group, long timeoutMs) throws NacosException {
group = null2defaultGroup(group);
ParamUtils.checkKeyParam(dataId, group);
ConfigResponse cr = new ConfigResponse();
cr.setDataId(dataId);
cr.setTenant(tenant);
cr.setGroup(group);
// 优先使用本地配置
//故障转移，从本地获取
String content = LocalConfigInfoProcessor.getFailover(agent.getName(), dataId, group, tenant);
if (content != null) {
LOGGER.warn("[{}] [get-config] get failover ok, dataId={}, group={}, tenant={}, config={}", agent.getName(),
dataId, group, tenant, ContentUtils.truncateContent(content));
cr.setContent(content);
configFilterChainManager.doFilter(null, cr);
content = cr.getContent();
return content;
}
try {
//从远程获取
String[] ct = worker.getServerConfig(dataId, group, tenant, timeoutMs);
cr.setContent(ct[0]);
configFilterChainManager.doFilter(null, cr);
content = cr.getContent();
return content;
} catch (NacosException ioe) {
if (NacosException.NO_RIGHT == ioe.getErrCode()) {
throw ioe;
}
LOGGER.warn("[{}] [get-config] get from server error, dataId={}, group={}, tenant={}, msg={}",
agent.getName(), dataId, group, tenant, ioe.toString());
}
LOGGER.warn("[{}] [get-config] get snapshot ok, dataId={}, group={}, tenant={}, config={}", agent.getName(),
dataId, group, tenant, ContentUtils.truncateContent(content));
//从快照获取
content = LocalConfigInfoProcessor.getSnapshot(agent.getName(), dataId, group, tenant);
cr.setContent(content);
configFilterChainManager.doFilter(null, cr);
content = cr.getContent();
return content;
}
10、 getServerConfig()；
public String[] getServerConfig(String dataId, String group, String tenant, long readTimeout)
throws NacosException {
String[] ct = new String[2];
if (StringUtils.isBlank(group)) {
group = Constants.DEFAULT_GROUP;
}
HttpRestResult<String> result = null;
try {
Map<String, String> params = new HashMap<String, String>(3);
if (StringUtils.isBlank(tenant)) {
params.put("dataId", dataId);
params.put("group", group);
} else {
params.put("dataId", dataId);
params.put("group", group);
params.put("tenant", tenant);
}
//调用http get 获取
result = agent.httpGet(Constants.CONFIG_CONTROLLER_PATH, null, params, agent.getEncode(), readTimeout);
} catch (Exception ex) {
String message = String
.format("[%s] [sub-server] get server config exception, dataId=%s, group=%s, tenant=%s",
agent.getName(), dataId, group, tenant);
LOGGER.error(message, ex);
throw new NacosException(NacosException.SERVER_ERROR, ex);
}
switch (result.getCode()) {
case HttpURLConnection.HTTP_OK:
//200 响应成功，保存快照
LocalConfigInfoProcessor.saveSnapshot(agent.getName(), dataId, group, tenant, result.getData());
ct[0] = result.getData();
if (result.getHeader().getValue(CONFIG_TYPE) != null) {
ct[1] = result.getHeader().getValue(CONFIG_TYPE);
} else {
ct[1] = ConfigType.TEXT.getType();
}
return ct;
case HttpURLConnection.HTTP_NOT_FOUND:
//404资源不存在，清理本地快照
LocalConfigInfoProcessor.saveSnapshot(agent.getName(), dataId, group, tenant, null);
return ct;
case HttpURLConnection.HTTP_CONFLICT: {
LOGGER.error(
"[{}] [sub-server-error] get server config being modified concurrently, dataId={}, group={}, "
+ "tenant={}", agent.getName(), dataId, group, tenant);
throw new NacosException(NacosException.CONFLICT,
"data being modified, dataId=" + dataId + ",group=" + group + ",tenant=" + tenant);
}
case HttpURLConnection.HTTP_FORBIDDEN: {
LOGGER.error("[{}] [sub-server-error] no right, dataId={}, group={}, tenant={}", agent.getName(),
dataId, group, tenant);
throw new NacosException(result.getCode(), result.getMessage());
}
default: {
LOGGER.error("[{}] [sub-server-error] dataId={}, group={}, tenant={}, code={}", agent.getName(),
dataId, group, tenant, result.getCode());
throw new NacosException(result.getCode(),
"http error, code=" + result.getCode() + ",dataId=" + dataId + ",group=" + group + ",tenant="
+ tenant);
}
}
}
11、 httpGet()；
@Override
public HttpRestResult<String> httpGet(String path, Map<String, String> headers, Map<String, String> paramValues,
String encode, long readTimeoutMs) throws Exception {
Histogram.Timer timer = MetricsMonitor.getConfigRequestMonitor("GET", path, "NA");
HttpRestResult<String> result;
try {
//执行远程调用
result = httpAgent.httpGet(path, headers, paramValues, encode, readTimeoutMs);
} catch (IOException e) {
throw e;
} finally {
timer.observeDuration();
timer.close();
}
return result;
}
12、 httpAgent.httpGet()；
@Override
public HttpRestResult<String> httpGet(String path, Map<String, String> headers, Map<String, String> paramValues,
String encode, long readTimeoutMs) throws Exception {
final long endTime = System.currentTimeMillis() + readTimeoutMs;
injectSecurityInfo(paramValues);
//nacos 服务端地址
String currentServerAddr = serverListMgr.getCurrentServerAddr();
int maxRetry = this.maxRetry;
HttpClientConfig httpConfig = HttpClientConfig.builder()
.setReadTimeOutMillis(Long.valueOf(readTimeoutMs).intValue())
.setConTimeOutMillis(ConfigHttpClientManager.getInstance().getConnectTimeoutOrDefault(100)).build();
do {
try {
Header newHeaders = getSpasHeaders(paramValues, encode);
if (headers != null) {
newHeaders.addAll(headers);
}
Query query = Query.newInstance().initParams(paramValues);
//最终使用 java.net.HttpURLConnection 类进行远程调用
HttpRestResult<String> result = NACOS_RESTTEMPLATE
.get(getUrl(currentServerAddr, path), httpConfig, newHeaders, query, String.class);
if (isFail(result)) {
LOGGER.error("[NACOS ConnectException] currentServerAddr: {}, httpCode: {}",
serverListMgr.getCurrentServerAddr(), result.getCode());
} else {
// Update the currently available server addr
//更新当前可用的 nacos 服务地址
serverListMgr.updateCurrentServerAddr(currentServerAddr);
return result;
}
} catch (ConnectException connectException) {
LOGGER.error("[NACOS ConnectException httpGet] currentServerAddr:{}, err : {}",
serverListMgr.getCurrentServerAddr(), connectException.getMessage());
} catch (SocketTimeoutException socketTimeoutException) {
LOGGER.error("[NACOS SocketTimeoutException httpGet] currentServerAddr:{}， err : {}",
serverListMgr.getCurrentServerAddr(), socketTimeoutException.getMessage());
} catch (Exception ex) {
LOGGER.error("[NACOS Exception httpGet] currentServerAddr: " + serverListMgr.getCurrentServerAddr(),
ex);
throw ex;
}
if (serverListMgr.getIterator().hasNext()) {
currentServerAddr = serverListMgr.getIterator().next();
} else {
maxRetry--;
if (maxRetry < 0) {
throw new ConnectException(
"[NACOS HTTP-GET] The maximum number of tolerable server reconnection errors has been reached");
}
serverListMgr.refreshCurrentServerAddr();
}
} while (System.currentTimeMillis() <= endTime);
LOGGER.error("no available server");
throw new ConnectException("no available server");
}