context创建过程解析（三）之deployDirectories

HostConfig.deployApps()
//在监听到start事件类型，也就是StandardHost调用startInternal
protected void deployApps() {

        File appBase = host.getAppBaseFile();
//这个值是在触发before_start时间时生成的，默认是tomcat安装目录+engine名+host名
        File configBase = host.getConfigBaseFile();
//获取host上配置的webapp下的所有文件，默认是webapps目录下的所有文件
        String[] filteredAppPaths = filterAppPaths(appBase.list());
        // Deploy XML descriptors from configBase  发布xml描述文件
        deployDescriptors(configBase, configBase.list());
        // Deploy WARs
        deployWARs(appBase, filteredAppPaths);
        // Deploy expanded folders
        deployDirectories(appBase, filteredAppPaths);

    }

deployDirectories

protected void deployDirectories(File appBase, String[] files) {

        if (files == null)
            return;

        ExecutorService es = host.getStartStopExecutor();
        List<Future<?>> results = new ArrayList<>();

        for (int i = 0; i < files.length; i++) {

            if (files[i].equalsIgnoreCase("META-INF"))
                continue;
            if (files[i].equalsIgnoreCase("WEB-INF"))
                continue;
            File dir = new File(appBase, files[i]);
            if (dir.isDirectory()) {
                ContextName cn = new ContextName(files[i], false);

                if (isServiced(cn.getName()) || deploymentExists(cn.getName()))
                    continue;

                results.add(es.submit(new DeployDirectory(this, cn, dir)));
            }
        }

        for (Future<?> result : results) {
            try {
                result.get();
            } catch (Exception e) {
                log.error(sm.getString(
                        "hostConfig.deployDir.threaded.error"), e);
            }
        }
    }

HostConfig.deployDirectory(cn, dir);

protected void deployDirectory(ContextName cn, File dir) {

        long startTime = 0;
        // Deploy the application in this directory
        if( log.isInfoEnabled() ) {
            startTime = System.currentTimeMillis();
            log.info(sm.getString("hostConfig.deployDir",
                    dir.getAbsolutePath()));
        }

        Context context = null;
//Constants.ApplicationContextXml == META-INF/context.xml
        File xml = new File(dir, Constants.ApplicationContextXml);
//当允许copyxml的时候会使用到
        File xmlCopy =
                new File(host.getConfigBaseFile(), cn.getBaseName() + ".xml");

        DeployedApplication deployedApp;
        boolean copyThisXml = isCopyXML();
        boolean deployThisXML = isDeployThisXML(dir, cn);

        try {
            if (deployThisXML && xml.exists()) {
                synchronized (digesterLock) {
                    try {
                        context = (Context) digester.parse(xml);
                    } catch (Exception e) {
                        log.error(sm.getString(
                                "hostConfig.deployDescriptor.error",
                                xml), e);
                        context = new FailedContext();
                    } finally {
                        digester.reset();
                        if (context == null) {
                            context = new FailedContext();
                        }
                    }
                }

//这里有点疑问，为什么host配置的copyThisXml为false的时候才允许context进行覆盖？
                if (copyThisXml == false && context instanceof StandardContext) {
                    // Host is using default value. Context may override it.
                    copyThisXml = ((StandardContext) context).getCopyXML();
                }
//当允许copy时，进行复制，并把配置文件设置为新的目录
                if (copyThisXml) {
                    Files.copy(xml.toPath(), xmlCopy.toPath());
                    context.setConfigFile(xmlCopy.toURI().toURL());
                } else {
                    context.setConfigFile(xml.toURI().toURL());
                }
            } else if (!deployThisXML && xml.exists()) {//如果不允许发布这个配置文件并且对应的xml存在的话，构造失败context，why？？？即使存在context.xml也可以构造一个默认的context
                // Block deployment as META-INF/context.xml may contain security
                // configuration necessary for a secure deployment.
                log.error(sm.getString("hostConfig.deployDescriptor.blocked",
                        cn.getPath(), xml, xmlCopy));
                context = new FailedContext();
            } else {
                context = (Context) Class.forName(contextClass).getConstructor().newInstance();
            }
//下面的步骤和部署描述文件和部署war是一样的。不再赘述
            Class<?> clazz = Class.forName(host.getConfigClass());
            LifecycleListener listener = (LifecycleListener) clazz.getConstructor().newInstance();
            context.addLifecycleListener(listener);

            context.setName(cn.getName());
            context.setPath(cn.getPath());
            context.setWebappVersion(cn.getVersion());
            context.setDocBase(cn.getBaseName());
            host.addChild(context);
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("hostConfig.deployDir.error",
                    dir.getAbsolutePath()), t);
        } finally {
            deployedApp = new DeployedApplication(cn.getName(),
                    xml.exists() && deployThisXML && copyThisXml);

            // Fake re-deploy resource to detect if a WAR is added at a later
            // point
            deployedApp.redeployResources.put(dir.getAbsolutePath() + ".war",
                    Long.valueOf(0));
            deployedApp.redeployResources.put(dir.getAbsolutePath(),
                    Long.valueOf(dir.lastModified()));
            if (deployThisXML && xml.exists()) {
                if (copyThisXml) {
                    deployedApp.redeployResources.put(
                            xmlCopy.getAbsolutePath(),
                            Long.valueOf(xmlCopy.lastModified()));
                } else {
                    deployedApp.redeployResources.put(
                            xml.getAbsolutePath(),
                            Long.valueOf(xml.lastModified()));
                    // Fake re-deploy resource to detect if a context.xml file is
                    // added at a later point
                    deployedApp.redeployResources.put(
                            xmlCopy.getAbsolutePath(),
                            Long.valueOf(0));
                }
            } else {
                // Fake re-deploy resource to detect if a context.xml file is
                // added at a later point
                deployedApp.redeployResources.put(
                        xmlCopy.getAbsolutePath(),
                        Long.valueOf(0));
                if (!xml.exists()) {
                    deployedApp.redeployResources.put(
                            xml.getAbsolutePath(),
                            Long.valueOf(0));
                }
            }
            addWatchedResources(deployedApp, dir.getAbsolutePath(), context);
            // Add the global redeploy resources (which are never deleted) at
            // the end so they don't interfere with the deletion process
            addGlobalRedeployResources(deployedApp);
        }

        deployed.put(cn.getName(), deployedApp);

        if( log.isInfoEnabled() ) {
            log.info(sm.getString("hostConfig.deployDir.finished",
                    dir.getAbsolutePath(), Long.valueOf(System.currentTimeMillis() - startTime)));
        }
    }