Hello Mr.J——Mycat加载用户配置，各种XML

上一篇中在初始化的时候，有读取用户配置的代码，这次我们进来看看。

这里的大部分初始化配置都是基于构造函数的。

MycatServer的构造函数中有个MycatConfig，这个类是保存读取的结果，具体的读取过程是ConfigInitializer来完成的。这里的注释很全，我就不要脸的直接贴了。

	public MycatConfig() {
		
		//读取schema.xml，rule.xml和server.xml
		ConfigInitializer confInit = new ConfigInitializer(true);
		this.system = confInit.getSystem();
		this.users = confInit.getUsers();
		this.schemas = confInit.getSchemas();
		this.dataHosts = confInit.getDataHosts();

		this.dataNodes = confInit.getDataNodes();
		for (PhysicalDBPool dbPool : dataHosts.values()) {
			dbPool.setSchemas(getDataNodeSchemasOfDataHost(dbPool.getHostName()));
		}
		
		this.firewall = confInit.getFirewall();
		this.cluster = confInit.getCluster();
		
		//初始化重加载配置时间
		this.reloadTime = TimeUtil.currentTimeMillis();
		this.rollbackTime = -1L;
		this.status = RELOAD;
		
		//配置加载锁
		this.lock = new ReentrantLock();
	}

    public ConfigInitializer(boolean loadDataHost) {

        //读取rule.xml和schema.xml
        SchemaLoader schemaLoader = new XMLSchemaLoader();

        //读取server.xml
        XMLConfigLoader configLoader = new XMLConfigLoader(schemaLoader);

        schemaLoader = null;

        //加载配置
        this.system = configLoader.getSystemConfig();
        this.users = configLoader.getUserConfigs();
        this.schemas = configLoader.getSchemaConfigs();

        //是否重新加载DataHost和对应的DataNode
        if (loadDataHost) {
            this.dataHosts = initDataHosts(configLoader);
            this.dataNodes = initDataNodes(configLoader);
        }

        //权限管理
        this.firewall = configLoader.getFirewallConfig();
        this.cluster = initCobarCluster(configLoader);

        //不同类型的全局序列处理器的配置加载
        if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_MYSQLDB) {
            IncrSequenceMySQLHandler.getInstance().load();
        }

        if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_LOCAL_TIME) {
            IncrSequenceTimeHandler.getInstance().load();
        }

        if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_ZK_DISTRIBUTED) {
            DistributedSequenceHandler.getInstance(system).load();
        }

        if (system.getSequnceHandlerType() == SystemConfig.SEQUENCEHANDLER_ZK_GLOBAL_INCREMENT) {
            IncrSequenceZKHandler.getInstance().load();
        }

        /**
         * 配置文件初始化， 自检
         */
        this.selfChecking0();
    }

    public XMLSchemaLoader(String schemaFile,String ruleFile) {
        //先读取rule.xml
        XMLRuleLoader ruleLoader = new XMLRuleLoader(ruleFile);
        //将tableRules拿出，用于这里加载Schema做rule有效判断，以及之后的分片路由计算
        this.tableRules = ruleLoader.getTableRules();
        //释放ruleLoader
        ruleLoader = null;
        this.dataHosts = new HashMap<String,DataHostConfig>();
        this.dataNodes = new HashMap<String,DataNodeConfig>();
        this.schemas = new HashMap<String,SchemaConfig>();
        //读取加载schema配置
        this.load(DEFAULT_DTD,schemaFile == null ? DEFAULT_XML : schemaFile);
    }

    public XMLRuleLoader(String ruleFile) {
        // this.rules = new HashSet<RuleConfig>();
        //rule名 -> rule
        this.tableRules = new HashMap<String,TableRuleConfig>();
        //function名 -> 具体分片算法
        this.functions = new HashMap<String,AbstractPartitionAlgorithm>();
        load(DEFAULT_DTD,ruleFile == null ? DEFAULT_XML : ruleFile);
    }

    private void load(String dtdFile,String xmlFile) {
        InputStream dtd = null;
        InputStream xml = null;
        try {
            dtd = XMLRuleLoader.class.getResourceAsStream(dtdFile);
            xml = XMLRuleLoader.class.getResourceAsStream(xmlFile);
            //读取出语意树
            Element root = ConfigUtil.getDocument(dtd,xml)
                    .getDocumentElement();
            //加载Function
            loadFunctions(root);
            //加载TableRule
            loadTableRules(root);
        } catch (ConfigException e) {
            throw e;
        } catch (Exception e) {
            throw new ConfigException(e);
        } finally {
            if (dtd != null) {
                try {
                    dtd.close();
                } catch (IOException e) {
                }
            }
            if (xml != null) {
                try {
                    xml.close();
                } catch (IOException e) {
                }
            }
        }
    }

（编辑：李大同）

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