前面说完了一些公共bean的配置引入，我们具体来介绍下git相关代码的实现。通过在EnvironmentRepositoryConfiguration类中，我们可以看到有两处实现git bean的地方，都是使用内部类的方式实现，分别是JGitFactoryConfig和DefaultRepositoryConfiguration，代码如下所示
@Configuration
@ConditionalOnClass(TransportConfigCallback.class)
static class JGitFactoryConfig {
@Bean
public MultipleJGitEnvironmentRepositoryFactory gitEnvironmentRepositoryFactory(
ConfigurableEnvironment environment, ConfigServerProperties server,
Optional jgitHttpConnectionFactory,
Optional customTransportConfigCallback) {
return new MultipleJGitEnvironmentRepositoryFactory(environment, server, jgitHttpConnectionFactory,
customTransportConfigCallback);
}
}
@Configuration
@ConditionalOnMissingBean(value = EnvironmentRepository.class)//, search = SearchStrategy.CURRENT)
class DefaultRepositoryConfiguration {
@Autowired
private ConfigurableEnvironment environment;
@Autowired
private ConfigServerProperties server;
@Autowired(required = false)
private TransportConfigCallback customTransportConfigCallback;
@Bean
public MultipleJGitEnvironmentRepository defaultEnvironmentRepository(
MultipleJGitEnvironmentRepositoryFactory gitEnvironmentRepositoryFactory,
MultipleJGitEnvironmentProperties environmentProperties) throws Exception {
return gitEnvironmentRepositoryFactory.build(environmentProperties);
}
}
从上面的代码中，我们可以看到都是通过MultipleJGitEnvironmentRepositoryFactory工厂类进行加载的，由于static类优先加载，所以首先执行的是前面部分代码来初始化工厂类
我们进入到MultipleJGitEnvironmentRepositoryFactory工厂类可以看到new MultipleJGitEnvironmentRepositoryFactory只是做了一个参数初始化工作，而真正起作用的是bulid()方法，bulid()方法的代码如下
public MultipleJGitEnvironmentRepository build(MultipleJGitEnvironmentProperties environmentProperties)
throws Exception {
if (connectionFactory.isPresent()) {
HttpTransport.setConnectionFactory(connectionFactory.get());
connectionFactory.get().addConfiguration(environmentProperties);
}
MultipleJGitEnvironmentRepository repository = new MultipleJGitEnvironmentRepository(environment,
environmentProperties);
repository.setTransportConfigCallback(customTransportConfigCallback
.orElse(buildTransportConfigCallback(environmentProperties)));
if (server.getDefaultLabel() != null) {
repository.setDefaultLabel(server.getDefaultLabel());
}
return repository;
}
首先判断ConfigurableHttpConnectionFactory对象是否存在，通过查看该对象类，我们可以了解到该类主要是读取配置文件中spring.cloud.config.server.git的perfix的值来组成HttpClientConnection连接信息，用于连接git服务器的基础信息，处理完HttpClientConnection信息再初始化MultipleJGitEnvironmentRepository类，一会我们在分析该类，然后给MultipleJGitEnvironmentRepository类设置回调类，回调类不存在的情况下则新增一个回调类用于与git仓库连接，分别使用SshSessionFactory和SshTransport两种方式与git仓库连接，最后判断是否有默认的标签(label，就是一个版本),有就设置。
接下来我们分析下MultipleJGitEnvironmentRepository类，我们先看下它的继承关系图
进入到这个类，我们首先可以看到它继承自JGitEnvironmentRepository类
public class MultipleJGitEnvironmentRepository extends JGitEnvironmentRepository
我们再次进入到JGitEnvironmentRepository类，可以看到该类继承了AbstractScmEnvironmentRepository抽象类和实现了EnvironmentRepository, SearchPathLocator, InitializingBean这3个接口类
public class JGitEnvironmentRepository extends AbstractScmEnvironmentRepository
implements EnvironmentRepository, SearchPathLocator, InitializingBean
进入到AbstractScmEnvironmentRepository类可以看到它继承了AbstractScmAccessor抽象类和实现了EnvironmentRepository, SearchPathLocator, Ordered这3个接口
public abstract class AbstractScmEnvironmentRepository extends AbstractScmAccessor
implements EnvironmentRepository, SearchPathLocator, Ordered
再进入到AbstractScmAccessor抽象类可以看到它实现了ResourceLoaderAware接口类
public abstract class AbstractScmAccessor implements ResourceLoaderAware
而ResourceLoaderAware接口是用于加载外部资源文件的接口，这里具体使用了DefaultResourceLoader类，这个在这里不多做介绍了，我们从上到下，从最基础的AbstractScmAccessor抽象类介绍到MultipleJGitEnvironmentRepository类的实现，这样有助于我们理解。
1.AbstractScmAccessor抽象类
从代码中可以看到该类主要定义一些在spring.cloud.config.server出现的属性，同时可以看到在没有定义basedir属性的时候，通过createBaseDir()方法自动生成一个临时文件路径
protected File createBaseDir() {
try {
final Path basedir = Files.createTempDirectory("config-repo-");
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
try {
FileSystemUtils.deleteRecursively(basedir);
}
catch (IOException e) {
AbstractScmAccessor.this.logger.warn(
"Failed to delete temporary directory on exit: " + e);
}
}
});
return basedir.toFile();
}
catch (IOException e) {
throw new IllegalStateException("Cannot create temp dir", e);
}
}
通过getSearchLocations()这个方法可以了解到主要是到创建配置文件的文件夹路径，把placeholder占位符替换为具体的配置prefix
protected String[] getSearchLocations(File dir, String application, String profile,
String label) {
String[] locations = this.searchPaths;
if (locations == null || locations.length == 0) {
locations = AbstractScmAccessorProperties.DEFAULT_LOCATIONS;
}
else if (locations != AbstractScmAccessorProperties.DEFAULT_LOCATIONS) {
locations = StringUtils.concatenateStringArrays(AbstractScmAccessorProperties.DEFAULT_LOCATIONS, locations);
}
Collection output = new LinkedHashSet();
for (String location : locations) {
String[] profiles = new String[] { profile };
if (profile != null) {
profiles = StringUtils.commaDelimitedListToStringArray(profile);
}
String[] apps = new String[] { application };
if (application != null) {
apps = StringUtils.commaDelimitedListToStringArray(application);
}
for (String prof : profiles) {
for (String app : apps) {
String value = location;
if (app != null) {
value = value.replace("{application}", app);
}
if (prof != null) {
value = value.replace("{profile}", prof);
}
if (label != null) {
value = value.replace("{label}", label);
}
if (!value.endsWith("/")) {
value = value + "/";
}
output.addAll(matchingDirectories(dir, value));
}
}
}
return output.toArray(new String[0]);
}
2.AbstractScmEnvironmentRepository
我们主要看findOne()方法
public synchronized Environment findOne(String application, String profile, String label) {
NativeEnvironmentRepository delegate = new NativeEnvironmentRepository(getEnvironment(),
new NativeEnvironmentProperties());
Locations locations = getLocations(application, profile, label);
delegate.setSearchLocations(locations.getLocations());
Environment result = delegate.findOne(application, profile, "");
result.setVersion(locations.getVersion());
result.setLabel(label);
return this.cleaner.clean(result, getWorkingDirectory().toURI().toString(),
getUri());
}
在这个方法的3个参数application,profile,lable分别来自客户端配置文件中定义的spring.cloud.config.name、spring.cloud.config.profile、spring.cloud.config.label，代码中首先定义了一个NativeEnvironmentRepository类对象，后一段代码是通过具体的getLocations()方法实现把placeholder占位符{application}、{profile}、{label}替换掉为具体的配置值，第4行的NativeEnvironmentRepository.findOne()方法
public Environment findOne(String config, String profile, String label) {
SpringApplicationBuilder builder = new SpringApplicationBuilder(
PropertyPlaceholderAutoConfiguration.class);
ConfigurableEnvironment environment = getEnvironment(profile);
builder.environment(environment);
builder.web(WebApplicationType.NONE).bannerMode(Mode.OFF);
if (!logger.isDebugEnabled()) {
// Make the mini-application startup less verbose
builder.logStartupInfo(false);
}
String[] args = getArgs(config, profile, label);
// Explicitly set the listeners (to exclude logging listener which would change
// log levels in the caller)
builder.application()
.setListeners(Arrays.asList(new ConfigFileApplicationListener()));
ConfigurableApplicationContext context = builder.run(args);
environment.getPropertySources().remove("profiles");
try {
return clean(new PassthruEnvironmentRepository(environment).findOne(config,
profile, label));
}
finally {
context.close();
}
}
进入到该方法，可以看到首先定义了SpringApplicationBuilder类对象builder，后一行代码获取当前的环境变量信息environment并把environment设置到builder中，设置builder在后端启动线程运行模式，在getArgs()方法中初始化一些配置项
private String[] getArgs(String application, String profile, String label) {
List list = new ArrayList();
String config = application;
if (!config.startsWith("application")) {
config = "application," + config;
}
list.add("--spring.config.name=" + config);
list.add("--spring.cloud.bootstrap.enabled=false");
list.add("--encrypt.failOnError=" + this.failOnError);
list.add("--spring.config.location=" + StringUtils.arrayToCommaDelimitedString(
getLocations(application, profile, label).getLocations()));
return list.toArray(new String[0]);
}
然后添加一个ConfigFileApplicationListener的监听类，该监听主要用于配置文件的覆盖的监听，再通过builder.run()方法启动一个新线程来连接rabbit mq,启动后再环境变量中删除propertySource属性的profile变量，最后处理环境变量中propertySources数组name的文件路径为形如file:/D:/baseConfig/publicConfig/merchant1-dev.properties这样的格式，同时取出merchant1-dev.properties文件中的键值对到propertySources属性为source的map集合中
public Environment findOne(String application, String env, String label) {
Environment result = new Environment(application,
StringUtils.commaDelimitedListToStringArray(env), label, null, null);
for (org.springframework.core.env.PropertySource source : this.environment
.getPropertySources()) {
String name = source.getName();
if (!this.standardSources.contains(name)
&& source instanceof MapPropertySource) {
result.add(new PropertySource(name, getMap(source)));
}
}
return result;
}
退出NativeEnvironmentRepository.findOne()方法后回到AbstractScmEnvironmentRepository.findOne()方法中，在环境变量environment中加入label和version，最后在EnvironmentCleaner.clean()方法中处理file:/D:/baseConfig/publicConfig/merchant1-dev.properties为https://github.com/422518490/orderSystem/publicConfig/merchant1-dev.properties这种格式的路径
protected Environment clean(Environment value) {
Environment result = new Environment(value.getName(), value.getProfiles(),
value.getLabel(), this.version, value.getState());
for (PropertySource source : value.getPropertySources()) {
String name = source.getName();
if (this.environment.getPropertySources().contains(name)) {
continue;
}
name = name.replace("applicationConfig: [", "");
name = name.replace("]", "");
if (this.searchLocations != null) {
boolean matches = false;
String normal = name;
if (normal.startsWith("file:")) {
normal = StringUtils
.cleanPath(new File(normal.substring("file:".length()))
.getAbsolutePath());
}
String profile = result.getProfiles() == null ? null
: StringUtils.arrayToCommaDelimitedString(result.getProfiles());
for (String pattern : getLocations(result.getName(), profile,
result.getLabel()).getLocations()) {
if (!pattern.contains(":")) {
pattern = "file:" + pattern;
}
if (pattern.startsWith("file:")) {
pattern = StringUtils
.cleanPath(new File(pattern.substring("file:".length()))
.getAbsolutePath())
+ "/";
}
if (logger.isTraceEnabled()) {
logger.trace("Testing pattern: " + pattern
+ " with property source: " + name);
}
if (normal.startsWith(pattern)
&& !normal.substring(pattern.length()).contains("/")) {
matches = true;
break;
}
}
if (!matches) {
// Don't include this one: it wasn't matched by our search locations
if (logger.isDebugEnabled()) {
logger.debug("Not adding property source: " + name);
}
continue;
}
}
logger.info("Adding property source: " + name);
result.add(new PropertySource(name, source.getSource()));
}
return result;
}
在此就讨论完AbstractScmEnvironmentRepository类的处理。
3.JGitEnvironmentRepository
这个类主要定义了一些初始化配置文件以及从git上获取配置文件的方法。从构造函数可以看出，初始化的信息主要来自配置文件的prefix
public JGitEnvironmentRepository(ConfigurableEnvironment environment, JGitEnvironmentProperties properties) {
super(environment, properties);
this.cloneOnStart = properties.isCloneOnStart();
this.defaultLabel = properties.getDefaultLabel();
this.forcePull = properties.isForcePull();
this.timeout = properties.getTimeout();
this.deleteUntrackedBranches = properties.isDeleteUntrackedBranches();
this.refreshRate = properties.getRefreshRate();
this.skipSslValidation = properties.isSkipSslValidation();
}
在getLocations()方法中，主要是定义Locations类信息以及刷新git提交的版本号,我们可以通过refresh()方法来发现是如何去git获取版本号的
public String refresh(String label) {
Git git = null;
try {
git = createGitClient();
if (shouldPull(git)) {
FetchResult fetchStatus = fetch(git, label);
if (deleteUntrackedBranches && fetchStatus != null) {
deleteUntrackedLocalBranches(fetchStatus.getTrackingRefUpdates(), git);
}
// checkout after fetch so we can get any new branches, tags, ect.
checkout(git, label);
tryMerge(git, label);
}
else {
// nothing to update so just checkout and merge.
// Merge because remote branch could have been updated before
checkout(git, label);
tryMerge(git, label);
}
// always return what is currently HEAD as the version
return git.getRepository().findRef("HEAD").getObjectId().getName();
}
catch (RefNotFoundException e) {
throw new NoSuchLabelException("No such label: " + label, e);
}
catch (NoRemoteRepositoryException e) {
throw new NoSuchRepositoryException("No such repository: " + getUri(), e);
}
catch (GitAPIException e) {
throw new NoSuchRepositoryException(
"Cannot clone or checkout repository: " + getUri(), e);
}
catch (Exception e) {
throw new IllegalStateException("Cannot load environment", e);
}
finally {
try {
if (git != null) {
git.close();
}
}
catch (Exception e) {
this.logger.warn("Could not close git repository", e);
}
}
}
从上面的代码中可以了解到是一个从git获取配置文件的过程，它是以的是eclipse提供的git api方法，先是初始化git的信息，具体初始化信息可以去代码查看，然后在满足重新获取git上的文件信息情况下，重新拉取和覆盖文件信息，删除不需要的分支。
在afterPropertiesSet()方法中，它是作为在properties信息加载完成后进行的一些初始化操作，在该方法中initClonedRepository()方法在满足启动的时候prefix属性设置为true是进入该方法
private void initClonedRepository() throws GitAPIException, IOException {
if (!getUri().startsWith(FILE_URI_PREFIX)) {
deleteBaseDirIfExists();
Git git = cloneToBasedir();
if (git != null) {
git.close();
}
git = openGitRepository();
if (git != null) {
git.close();
}
}
}
从该方法可以看出主要是在初始化的时候删除已经存在的文件，以及从git上面拉取配置文件路径下的文件信息到本地重新生成文件信息，具体的逻辑代码可以到代码里面查看。
在refresh()方法中通过new Locations()方法返回该对象，在new的过程中通过getSearchLocations()拆分形成了形如的file:/D:/baseConfig/和file:/D:/baseConfig/publicConfig/的数组String路径，这个路径是在配置bootstrap.properties中定义的。
4.MultipleJGitEnvironmentRepository
从构造函数可以看出，当有多个配置中心的时候会通过以下代码进行分解取值
properties.getRepos().entrySet().stream()
.map(e -> new AbstractMap.SimpleEntry<>(e.getKey(),
new PatternMatchingJGitEnvironmentRepository(environment, e.getValue())))
.collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue))
通过重写afterPropertiesSet()方法在加载完成prefix之后初始化信息。我们在来主要看一下findOne()方法
public Environment findOne(String application, String profile, String label) {
for (PatternMatchingJGitEnvironmentRepository repository : this.repos.values()) {
if (repository.matches(application, profile, label)) {
for (JGitEnvironmentRepository candidate : getRepositories(repository,
application, profile, label)) {
try {
if (label == null) {
label = candidate.getDefaultLabel();
}
Environment source = candidate.findOne(application, profile,
label);
if (source != null) {
return source;
}
}
catch (Exception e) {
if (logger.isDebugEnabled()) {
this.logger.debug(
"Cannot load configuration from " + candidate.getUri()
+ ", cause: (" + e.getClass().getSimpleName()
+ ") " + e.getMessage(),
e);
}
continue;
}
}
}
}
JGitEnvironmentRepository candidate = getRepository(this, application, profile,
label);
if (label == null) {
label = candidate.getDefaultLabel();
}
if (candidate == this) {
return super.findOne(application, profile, label);
}
return candidate.findOne(application, profile, label);
}
在方法中首先通过获取Map中的配置中心信息来循环进行获取配置信息，前提是已经赋值了Map集合信息，在for循环中经过getRepositories()方法进行了一系列的placeholder替换符合操作为正确的字符串以及赋值操作，具体可以在代码中查看，然后通过JGitEnvironmentRepository的findOne()方法获取Environment类信息，存在Environment信息就直接返回，在没有Map集合信息的情况下，直接通过application, profile,label三个参数去JGitEnvironmentRepository类调用findOne()方法，即AbstractScmEnvironmentRepository类的findOne()方法，返回获取到的Environment信息。
在下一篇文章我们将大体介绍server端的其他类，如ConfigServerEncryptionConfiguration、EncryptionAutoConfiguration。
