spring cloud config server源碼解析

##獲取配置

curl -i http://config-server-host:port/{application}/{proflie}

##主要過程

##ResourceController

@RequestMapping("/{name}/{profile}/{label}/**")
	public String resolve(@PathVariable String name, @PathVariable String profile,
			@PathVariable String label, HttpServletRequest request) throws IOException {
		String path = getFilePath(request, name, profile, label);
		return resolve(name, profile, label, path);
	}

###resolve方法

synchronized String resolve(String name, String profile, String label, String path)
			throws IOException {
		if (label != null && label.contains("(_)")) {
			// "(_)" is uncommon in a git branch name, but "/" cannot be matched
			// by Spring MVC
			label = label.replace("(_)", "/");
		}
		StandardEnvironment environment = prepareEnvironment(
				this.environmentRepository.findOne(name, profile, label));

		// ensure InputStream will be closed to prevent file locks on Windows
		try (InputStream is = this.resourceRepository.findOne(name, profile, label, path)
				.getInputStream()) {
			String text = StreamUtils.copyToString(is, Charset.forName("UTF-8"));
			return resolvePlaceholders(environment, text);
		}
	}

##GenericResourceRepository.findOne

public synchronized Resource findOne(String application, String profile, String label,
			String path) {
		String[] locations = this.service.getLocations(application, profile, label).getLocations();
		try {
			for (int i = locations.length; i-- > 0;) {
				String location = locations[i];
				for (String local : getProfilePaths(profile, path)) {
					Resource file = this.resourceLoader.getResource(location)
							.createRelative(local);
					if (file.exists() && file.isReadable()) {
						return file;
					}
				}
			}
		}
		catch (IOException e) {
			throw new NoSuchResourceException(
					"Error : " + path + ". (" + e.getMessage() + ")");
		}
		throw new NoSuchResourceException("Not found: " + path);
	}

##JGitEnvironmentRepository.getLocations

public synchronized Locations getLocations(String application, String profile,
			String label) {
		if (label == null) {
			label = this.defaultLabel;
		}
		String version = refresh(label);
		return new Locations(application, profile, label, version,
				getSearchLocations(getWorkingDirectory(), application, profile, label));
	}

##refresh

/**
	 * Get the working directory ready.
	 */
	private String refresh(String label) {
		initialize();
		Git git = null;
		try {
			git = createGitClient();
			if (shouldPull(git)) {
				fetch(git, label);
				//checkout after fetch so we can get any new branches, tags, ect.
				checkout(git, label);
				if(isBranch(git, label)) {
					//merge results from fetch
					merge(git, label);
					if (!isClean(git)) {
						logger.warn("The local repository is dirty. Resetting it to origin/"
								+ label + ".");
						resetHard(git, label, "refs/remotes/origin/" + label);
					}
				}
			}
			else{
				//nothing to update so just checkout
				checkout(git, label);
			}
			//always return what is currently HEAD as the version
			return git.getRepository().getRef("HEAD").getObjectId().getName();
		}
		catch (RefNotFoundException e) {
			throw new NoSuchLabelException("No such label: " + label);
		}
		catch (GitAPIException e) {
			throw new IllegalStateException("Cannot clone or checkout repository", 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);
			}
		}
	}

##shouldPull

public /*public for testing*/ boolean shouldPull(Git git) throws GitAPIException {
		boolean shouldPull;
		Status gitStatus = git.status().call();
		boolean isWorkingTreeClean = gitStatus.isClean();
		String originUrl = git.getRepository().getConfig().getString("remote", "origin",
				"url");

		if (this.forcePull && !isWorkingTreeClean) {
			shouldPull = true;
			logDirty(gitStatus);
		}
		else {
			shouldPull = isWorkingTreeClean && originUrl != null;
		}
		if (!isWorkingTreeClean && !this.forcePull) {
			this.logger.info("Cannot pull from remote " + originUrl
					+ ", the working tree is not clean.");
		}
		return shouldPull;
	}

##docs

• SpringCloud 分佈式配置
• Dive into Spring Cloud Config