context创建过程解析（二）之deployWARs

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);

    }

deployWARs

protected void deployWARs(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 war = new File(appBase, files[i]);
//处理war
            if (files[i].toLowerCase(Locale.ENGLISH).endsWith(".war") &&
                    war.isFile() && !invalidWars.contains(files[i]) ) {

                ContextName cn = new ContextName(files[i], true);

                if (isServiced(cn.getName())) {
                    continue;
                }
//如果已经发布
                if (deploymentExists(cn.getName())) {
                    DeployedApplication app = deployed.get(cn.getName());
                    boolean unpackWAR = unpackWARs;
                    if (unpackWAR && host.findChild(cn.getName()) instanceof StandardContext) {
                        unpackWAR = ((StandardContext) host.findChild(cn.getName())).getUnpackWAR();
                    }
//如果不需要解压，并且已经发布。那么判断对应的docBase是否已经存在
                    if (!unpackWAR && app != null) {
                        // Need to check for a directory that should not be
                        // there
                        File dir = new File(appBase, cn.getBaseName());
                        if (dir.exists()) {
                            if (!app.loggedDirWarning) {
                                log.warn(sm.getString(
                                        "hostConfig.deployWar.hiddenDir",
                                        dir.getAbsoluteFile(),
                                        war.getAbsoluteFile()));
                                app.loggedDirWarning = true;
                            }
                        } else {
                            app.loggedDirWarning = false;
                        }
                    }
                    continue;
                }

                // Check for WARs with /../ /./ or similar sequences in the name
                if (!validateContextPath(appBase, cn.getBaseName())) {
                    log.error(sm.getString(
                            "hostConfig.illegalWarName", files[i]));
                    invalidWars.add(files[i]);
                    continue;
                }

                results.add(es.submit(new DeployWar(this, cn, war)));
            }
        }

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

HostConfig.deployWAR(cn, war);

protected void deployWAR(ContextName cn, File war) {

// Constants.ApplicationContextXml == META-INF/context.xml
        File xml = new File(host.getAppBaseFile(),
                cn.getBaseName() + "/" + Constants.ApplicationContextXml);

        File warTracker = new File(host.getAppBaseFile(), cn.getBaseName() + Constants.WarTracker);

        boolean xmlInWar = false;
        try (JarFile jar = new JarFile(war)) {
            JarEntry entry = jar.getJarEntry(Constants.ApplicationContextXml);
//判断是否有context.xml在jar包里面
            if (entry != null) {
                xmlInWar = true;
            }
        } catch (IOException e) {
            /* Ignore */
        }

        // If there is an expanded directory then any xml in that directory
        // should only be used if the directory is not out of date and
        // unpackWARs is true. Note the code below may apply further limits
        boolean useXml = false;
        // If the xml file exists then expandedDir must exists so no need to
        // test that here
//如果对应xml存在，并且允许解压，也就是已经解压了，这个war包没有修改过
        if (xml.exists() && unpackWARs &&
                (!warTracker.exists() || warTracker.lastModified() == war.lastModified())) {
            useXml = true;
        }

        Context context = null;
//是否需要发布这个context.xml，通过校验
        boolean deployThisXML = isDeployThisXML(war, cn);

        try {
//允许发布这个xml并且仅仅是使用xml并且不允许copyxml到配置目录，如果允许copy到配置目录，那么这个xml可能不是最新的。
            if (deployThisXML && useXml && !copyXML) {
                synchronized (digesterLock) {
                    try {
                        context = (Context) digester.parse(xml);
                    } catch (Exception e) {
                        log.error(sm.getString(
                                "hostConfig.deployDescriptor.error",
                                war.getAbsolutePath()), e);
                    } finally {
                        digester.reset();
                        if (context == null) {
                            context = new FailedContext();
                        }
                    }
                }
//设置context.xml配置文件
                context.setConfigFile(xml.toURI().toURL());
//允许发布这个context.xml并且这个xml在war包里面
            } else if (deployThisXML && xmlInWar) {
                synchronized (digesterLock) {
                    try (JarFile jar = new JarFile(war)) {
                        JarEntry entry = jar.getJarEntry(Constants.ApplicationContextXml);
                        try (InputStream istream = jar.getInputStream(entry)) {
                            context = (Context) digester.parse(istream);
                        }
                    } catch (Exception e) {
                        log.error(sm.getString(
                                "hostConfig.deployDescriptor.error",
                                war.getAbsolutePath()), e);
                    } finally {
                        digester.reset();
                        if (context == null) {
                            context = new FailedContext();
                        }
                        context.setConfigFile(
                                UriUtil.buildJarUrl(war, Constants.ApplicationContextXml));
                    }
                }
//不允许发布这个context.xml并且这个xml在war包里面的，那么就直接new出一个StandardContext
            } else if (!deployThisXML && xmlInWar) {
                // 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(), Constants.ApplicationContextXml,
                        new File(host.getConfigBaseFile(), cn.getBaseName() + ".xml")));
            } else {
                context = (Context) Class.forName(contextClass).getConstructor().newInstance();
            }
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("hostConfig.deployWar.error",
                    war.getAbsolutePath()), t);
        } finally {
            if (context == null) {
                context = new FailedContext();
            }
        }

        boolean copyThisXml = false;//是否需要复制xml到配置文件夹中
        if (deployThisXML) {//允许发布
            if (host instanceof StandardHost) {
                copyThisXml = ((StandardHost) host).isCopyXML();
            }

            // If Host is using default value Context can override it. context指定的copyXml属性可以覆盖host级别的
            if (!copyThisXml && context instanceof StandardContext) {
                copyThisXml = ((StandardContext) context).getCopyXML();
            }
//如果context.xml在war中，并且允许复制这个xml到配置路径，那么就将此context.xml复制到配置文件夹中
            if (xmlInWar && copyThisXml) {
                // Change location of XML file to config base
                xml = new File(host.getConfigBaseFile(),
                        cn.getBaseName() + ".xml");
                try (JarFile jar = new JarFile(war)) {
                    JarEntry entry = jar.getJarEntry(Constants.ApplicationContextXml);
                    try (InputStream istream = jar.getInputStream(entry);
                            FileOutputStream fos = new FileOutputStream(xml);
                            BufferedOutputStream ostream = new BufferedOutputStream(fos, 1024)) {
                        byte buffer[] = new byte[1024];
                        while (true) {
                            int n = istream.read(buffer);
                            if (n < 0) {
                                break;
                            }
                            ostream.write(buffer, 0, n);
                        }
                        ostream.flush();
                    }
                } catch (IOException e) {
                    /* Ignore */
                }
            }
        }
//下面这部分代码基本和deployDescriptors差不多
        DeployedApplication deployedApp = new DeployedApplication(cn.getName(),
                xml.exists() && deployThisXML && copyThisXml);

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

        try {
            // Populate redeploy resources with the WAR file
            deployedApp.redeployResources.put
                (war.getAbsolutePath(), Long.valueOf(war.lastModified()));

            if (deployThisXML && xml.exists() && copyThisXml) {
//这个xml被复制到配置目录
                deployedApp.redeployResources.put(xml.getAbsolutePath(),
                        Long.valueOf(xml.lastModified()));
            } else {
                // In case an XML file is added to the config base later 如果配置加载配置目录中才会有效
                deployedApp.redeployResources.put(
                        (new File(host.getConfigBaseFile(),
                                cn.getBaseName() + ".xml")).getAbsolutePath(),
                        Long.valueOf(0));
            }

            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() + ".war");
     host.addChild(context);//与deployDescriptors一样的操作
        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("hostConfig.deployWar.error",
                    war.getAbsolutePath()), t);
        } finally {
            // If we're unpacking WARs, the docBase will be mutated after
            // starting the context
            boolean unpackWAR = unpackWARs;
            if (unpackWAR && context instanceof StandardContext) {
                unpackWAR = ((StandardContext) context).getUnpackWAR();
            }
//上面不是已经添加了docBase资源的监控了吗？这里是因为tomcat在解压了war之后会重新定义它的docBase目录，所以需要添加，不管原始的还是新的都要进行监控
            if (unpackWAR && context.getDocBase() != null) {
                File docBase = new File(host.getAppBaseFile(), cn.getBaseName());
                deployedApp.redeployResources.put(docBase.getAbsolutePath(),
                        Long.valueOf(docBase.lastModified()));
                addWatchedResources(deployedApp, docBase.getAbsolutePath(),
                        context);
                if (deployThisXML && !copyThisXml && (xmlInWar || xml.exists())) {
                    deployedApp.redeployResources.put(xml.getAbsolutePath(),
                            Long.valueOf(xml.lastModified()));
                }
            } else {
                // Passing null for docBase means that no resources will be
                // watched. This will be logged at debug level.
                addWatchedResources(deployedApp, null, 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.deployWar.finished",
                war.getAbsolutePath(), Long.valueOf(System.currentTimeMillis() - startTime)));
        }
    }