RepositoryManager类

RepositoryManager类负责对RepositoryProvider进行管理，主要的功能为从配置文件中
“server/conf/sqoop.properties”读取RepositoryProvider的配置信息，并对RepositoryProvider进行实例化。在配置信息发生变动时，更新RepositoryProvider的信息。
RepositoryManager的初始化源代码如下：

public synchronized void initialize(boolean immutableRepository) {
        MapContext context = SqoopConfiguration.getInstance().getContext();
        Map repoSysProps = context.getNestedProperties("org.apache.sqoop.repository.sysprop.");
        LOG.info("Setting system properties: " + repoSysProps);
        Iterator repoProviderClassName = repoSysProps.entrySet().iterator();

        while(repoProviderClassName.hasNext()) {
            Entry repoProviderClass = (Entry)repoProviderClassName.next();
            System.setProperty((String)repoProviderClass.getKey(), (String)repoProviderClass.getValue());
        }

        String repoProviderClassName1 = context.getString("org.apache.sqoop.repository.provider");
        if(repoProviderClassName1 != null && repoProviderClassName1.trim().length() != 0) {
            if(LOG.isTraceEnabled()) {
                LOG.trace("Repository provider: " + repoProviderClassName1);
            }

            Class repoProviderClass1 = ClassUtils.loadClass(repoProviderClassName1);
            if(repoProviderClass1 == null) {
                throw new SqoopException(RepositoryError.REPO_0001, repoProviderClassName1);
            } else {
                try {
                    this.provider = (RepositoryProvider)repoProviderClass1.newInstance();
                } catch (Exception var7) {
                    throw new SqoopException(RepositoryError.REPO_0001, repoProviderClassName1, var7);
                }

                this.provider.initialize(context);
                if(!immutableRepository) {
                    LOG.info("Creating or updating respository at bootup");
                    this.provider.getRepository().createOrUpgradeRepository();
                }

                if(!this.provider.getRepository().isRepositorySuitableForUse()) {
                    throw new SqoopException(RepositoryError.REPO_0002);
                } else {
                    SqoopConfiguration.getInstance().getProvider().registerListener(new CoreConfigurationListener(this));
                    LOG.info("Repository Manager initialized: OK");
                }
            }
        } else {
            throw new SqoopException(RepositoryError.REPO_0001, "org.apache.sqoop.repository.provider");
        }
    }

RepositoryProvider类

RepositoryProvider类用于获取配置信息（上下文环境）， repository信息。
系统中的一个实现是：JdbcRepositoryProvider类。
JdbcRepositoryProvider类包含了配置信息（JdbcRepositoryContext），Repository信息（JdbcRepository )，以及用于处理事物的类（JdbcRepositoryHandler）。
其中主要包含了初始化handler的方法：

private void initializeRepositoryHandler() {
        String jdbcHandlerClassName = this.repoContext.getHandlerClassName();
        Class handlerClass = ClassUtils.loadClass(jdbcHandlerClassName);
        if(handlerClass == null) {
            throw new SqoopException(RepositoryError.JDBCREPO_0001, jdbcHandlerClassName);
        } else {
            try {
                this.handler = (JdbcRepositoryHandler)handlerClass.newInstance();
            } catch (Exception var9) {
                throw new SqoopException(RepositoryError.JDBCREPO_0001, jdbcHandlerClassName, var9);
            }

            String connectUrl = this.repoContext.getConnectionUrl();
            if(connectUrl != null && connectUrl.trim().length() != 0) {
                String jdbcDriverClassName = this.repoContext.getDriverClass();
                if(jdbcDriverClassName != null && jdbcDriverClassName.trim().length() != 0) {
                    Class driverClass = ClassUtils.loadClass(jdbcDriverClassName);
                    if(driverClass == null) {
                        throw new SqoopException(RepositoryError.JDBCREPO_0003, jdbcDriverClassName);
                    } else {
                        try {
                            this.driver = (Driver)driverClass.newInstance();
                        } catch (Exception var8) {
                            throw new SqoopException(RepositoryError.JDBCREPO_0003, jdbcDriverClassName, var8);
                        }

                        Properties jdbcProps = this.repoContext.getConnectionProperties();
                        DriverManagerConnectionFactory connFactory = new DriverManagerConnectionFactory(connectUrl, jdbcProps);
                        this.connectionPool = new GenericObjectPool();
                        this.connectionPool.setMaxActive(this.repoContext.getMaximumConnections());
                        this.statementPool = new GenericKeyedObjectPoolFactory((KeyedPoolableObjectFactory)null);
                        new PoolableConnectionFactory(connFactory, this.connectionPool, this.statementPool, this.handler.validationQuery(), false, false, this.repoContext.getTransactionIsolation().getCode());
                        this.dataSource = new PoolingDataSource(this.connectionPool);
                        this.txFactory = new JdbcRepositoryTransactionFactory(this.dataSource);
                        this.repoContext.initialize(this.dataSource, this.txFactory);
                        this.handler.initialize(this.repoContext);
                        this.repository = new JdbcRepository(this.handler, this.repoContext);
                        LOG.info("JdbcRepositoryProvider initialized");
                    }
                } else {
                    throw new SqoopException(RepositoryError.JDBCREPO_0003);
                }
            } else {
                throw new SqoopException(RepositoryError.JDBCREPO_0002);
            }
        }
    }

JdbcRepository类

JdbcRepository类代表了可以使用jdbc方式进行连接的reposity。其包含了两个对象

  private final JdbcRepositoryHandler handler;
    private final JdbcRepositoryContext repoContext;

其中JdbcRepositoryContext代表相关的配置信息，JdbcRepositoryHandler用于处理事务（这里采用了代理的设计模式）。

JdbcRepositoryContext类

JdbcRepositoryContext类从配置文件中(server/conf/sqoopproperties)读取配置信息。包括driver,userName, passwaord等。

JdbcRepositoryHandler抽象类

JdbcRepositoryHandler是真正实现各种事物处理的类，事物包括查询connector, link ,创建connector, link, 等。
系统中实现的JdbcRepositoryHandler类的有CommonRepositoryHandler类。
CommonRepositoryHandler利用sql查询语句从数据库中查询结果，并返回给用户。

RepositoryManager源码分析