solr dataimport 数据导入源码分析（九）

上文solr dataimport源码主要实现的是数据读取功能

下面我们接着看数据连接的实现的源码：

private Connection getConnection() throws Exception {
    long currTime = System.currentTimeMillis();
    if (currTime - connLastUsed > CONN_TIME_OUT) {
      synchronized (this) {
        Connection tmpConn = factory.call();
        closeConnection();
        connLastUsed = System.currentTimeMillis();
        return conn = tmpConn;
      }

    } else {
      connLastUsed = currTime;
      return conn;
    }

  } 

这里用到了synchronized关键字，使对成员变量 conn访问 线程安全 

其中factory 是一个Callable<Connection>类型的对象，是在初始化方法里面产生的

 java的Callable接口定义如下

public interface Callable<V> {
    V call() throws Exception;

} 

 factory 初始化

public void init(Context context, Properties initProps) {

//其他代码略



    factory = createConnectionFactory(context, initProps);

}

接下来看createConnectionFactory(context, initProps) 代码如下

  protected Callable<Connection> createConnectionFactory(final Context context,

                                       final Properties initProps) {

//    final VariableResolver resolver = context.getVariableResolver();

    resolveVariables(context, initProps);

    final String jndiName = initProps.getProperty(JNDI_NAME);

    final String url = initProps.getProperty(URL);

    final String driver = initProps.getProperty(DRIVER);



    if (url == null && jndiName == null)

      throw new DataImportHandlerException(SEVERE,

              "JDBC URL or JNDI name has to be specified");



    if (driver != null) {

      try {

        DocBuilder.loadClass(driver, context.getSolrCore());

      } catch (ClassNotFoundException e) {

        wrapAndThrow(SEVERE, e, "Could not load driver: " + driver);

      }

    } else {

      if(jndiName == null){

        throw new DataImportHandlerException(SEVERE, "One of driver or jndiName must be specified in the data source");

      }

    }



    String s = initProps.getProperty("maxRows");

    if (s != null) {

      maxRows = Integer.parseInt(s);

    }



    return factory = new Callable<Connection>() {

      public Connection call() throws Exception {

        LOG.info("Creating a connection for entity "

                + context.getEntityAttribute(DataImporter.NAME) + " with URL: "

                + url);

        long start = System.currentTimeMillis();

        Connection c = null;

        try {

          if(url != null){

            c = DriverManager.getConnection(url, initProps);

          } else if(jndiName != null){

            InitialContext ctx =  new InitialContext();

            Object jndival =  ctx.lookup(jndiName);

            if (jndival instanceof javax.sql.DataSource) {

              javax.sql.DataSource dataSource = (javax.sql.DataSource) jndival;

              String user = (String) initProps.get("user");

              String pass = (String) initProps.get("password");

              if(user == null || user.trim().equals("")){

                c = dataSource.getConnection();

              } else {

                c = dataSource.getConnection(user, pass);

              }

            } else {

              throw new DataImportHandlerException(SEVERE,

                      "the jndi name : '"+jndiName +"' is not a valid javax.sql.DataSource");

            }

          }

        } catch (SQLException e) {

          // DriverManager does not allow you to use a driver which is not loaded through

          // the class loader of the class which is trying to make the connection.

          // This is a workaround for cases where the user puts the driver jar in the

          // solr.home/lib or solr.home/core/lib directories.

          Driver d = (Driver) DocBuilder.loadClass(driver, context.getSolrCore()).newInstance();

          c = d.connect(url, initProps);

        }

        if (c != null) {

          if (Boolean.parseBoolean(initProps.getProperty("readOnly"))) {

            c.setReadOnly(true);

            // Add other sane defaults

            c.setAutoCommit(true);

            c.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);

            c.setHoldability(ResultSet.CLOSE_CURSORS_AT_COMMIT);

          }

          if (!Boolean.parseBoolean(initProps.getProperty("autoCommit"))) {

            c.setAutoCommit(false);

          }

          String transactionIsolation = initProps.getProperty("transactionIsolation");

          if ("TRANSACTION_READ_UNCOMMITTED".equals(transactionIsolation)) {

            c.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);

          } else if ("TRANSACTION_READ_COMMITTED".equals(transactionIsolation)) {

            c.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);

          } else if ("TRANSACTION_REPEATABLE_READ".equals(transactionIsolation)) {

            c.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);

          } else if ("TRANSACTION_SERIALIZABLE".equals(transactionIsolation)) {

            c.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);

          } else if ("TRANSACTION_NONE".equals(transactionIsolation)) {

            c.setTransactionIsolation(Connection.TRANSACTION_NONE);

          }

          String holdability = initProps.getProperty("holdability");

          if ("CLOSE_CURSORS_AT_COMMIT".equals(holdability)) {

            c.setHoldability(ResultSet.CLOSE_CURSORS_AT_COMMIT);

          } else if ("HOLD_CURSORS_OVER_COMMIT".equals(holdability)) {

            c.setHoldability(ResultSet.HOLD_CURSORS_OVER_COMMIT);

          }

        }

        LOG.info("Time taken for getConnection(): "

                + (System.currentTimeMillis() - start));

        return c;

      }

    };

  }

这里负责生成Connection对象