Package org.javalite.activejdbc

Class DB

java.lang.Object
org.javalite.activejdbc.DB
All Implemented Interfaces:
Closeable, AutoCloseable
public class DB extends Object implements Closeable
This class provides a number of convenience methods for opening/closing database connections, running various types of queries, and executing SQL statements. This class differs from Base such that in this class you can provide a logical name for a current connection. Use this class when you have more than one database in the system.
Author:
Igor Polevoy, Eric Nielsen

  • Field Details

  • Constructor Details

    • DB

      public DB​(String name)
      Creates a new DB object representing a connection to a DB.
      Parameters:
      name - logical name for a database.

    • DB

      public DB()
      Creates a new DB object representing a connection to a DB with default name. Calling this constructor is equivalent to new DB(DB.DEFAULT_NAME).

  • Method Details

    • name

      public String name()
      Return logical name for a database.
      Returns:
      logical name for a database.

    • open

      public DB open​(String driver, String url, String user, String password)
      Opens a new connection based on JDBC properties and attaches it to a current thread.
      Parameters:
      driver - class name of driver
      url - URL connection to DB
      user - user name.
      password - password.

    • open

      public DB open​(String driver, String url, Properties props)
      Opens a new connection in case additional driver-specific parameters need to be passed in.
      Parameters:
      driver - driver class name
      url - JDBC URL
      props - connection properties

    • open

      public DB open​(String jndiName)
      Opens a connection from JNDI based on a registered name. This assumes that there is a jndi.properties file with proper JNDI configuration in it.
      Parameters:
      jndiName - name of a configured data source.

    • open

      public DB open()
      This method will open a connection defined in the file 'database.properties' set by an initial previous call to DBConfiguration.loadConfiguration(String). The connection picked up from the file is defined by ACTIVE_ENV environment variable or active_env system property. If this variable is not defined, it defaults to 'development' environment.

      It is expected to find a single connection configuration in a current environment.
      See Also:
      AppConfig.activeEnv()

    • attach

      public void attach​(Connection connection)
      Attaches a database connection to current thread under a name provided to constructor.
      Parameters:
      connection - instance of connection to attach to current thread.

    • detach

      public Connection detach()
      Detaches a connection from current thread and returns an instance of it. This method does not close a connection. Use it for cases of advanced connection management, such as integration with Spring Framework.
      Returns:
      instance of a connection detached from current thread by name passed to constructor.

    • open

      public DB open​(DataSource datasource)
      Opens a connection from a datasource. This methods gives a high level control while sourcing a DB connection.
      Parameters:
      datasource - datasource will be used to acquire a connection.

    • open

      public DB open​(String jndiName, Properties jndiProperties)
      Opens a new connection from JNDI data source by name using explicit JNDI properties. This method can be used in cases when file jndi.properties cannot be easily updated.
      Parameters:
      jndiName - name of JNDI data source.
      jndiProperties - JNDI properties

    • open

      public DB open​(ConnectionConfig config)
      This method is used internally by the framework.
      Parameters:
      config - specification for a JDBC connection.

    • close

      public void close()
      Closes connection and detaches it from current thread.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable

    • close

      public void close​(boolean suppressWarning)
      Closes connection and detaches it from current thread.
      Parameters:
      suppressWarning - true to not display a warning in case of a problem (connection not there)

    • count

      public Long count​(String table)
      Returns count of rows in table.
      Parameters:
      table - name of table.
      Returns:
      count of rows in table.

    • count

      public Long count​(String table, String query, Object... params)
      Runs a count query, returns a number of matching records.
      Parameters:
      table - table in which to count rows.
      query - this is a filtering query for the count. If '*' provided, all records will be counted. Example: "age > 65 AND department = 'accounting'"
      params - parameters for placeholder substitution.
      Returns:
      count number of records found in a table.

    • firstCell

      public Object firstCell​(String query, Object... params)
      This method returns the value of the first column of the first row. If query results have more than one column or more than one row, they will be ignored.
      Parameters:
      query - query
      params - parameters
      Returns:
      fetched value, or null if query did not fetch anything.

    • all

      public List<Map<String,​Object>> all​(String query, Object... params)
      Alias to findAll(String, Object...)

    • findAll

      public List<Map<String,​Object>> findAll​(String query, Object... params)
      This method returns entire resultset as one list. Do not use it for large result sets. Example: 
       List<Map<String, Object>> people = Base.findAll("select * from people where first_name = ?", "John");
  for(Map person: people)
      System.out.println(person.get("first_name"));
      Parameters:
      query - raw SQL query. This query is parametrized.
      params - list of parameters for a parametrized query.
      Returns:
      entire result set corresponding to the query.

    • firstColumn

      public List firstColumn​(String query, Object... params)
      This method returns entire resultset with one column as a list. Do not use it for large result sets. Example: 
        List ssns = new DB("default").firstColumn("select ssn from people where first_name = ?", "John");
  for(Object ssn: ssns)
      System.out.println(ssn);
      This method collects the value of the first column of each row. If query results have more than one column, the remainder will be ignored.
      Parameters:
      query - raw SQL query. This query can be parametrized.
      params - list of parameters for a parametrized query.
      Returns:
      entire result set corresponding to the query.

    • all

      public List<Map<String,​Object>> all​(String query)
      Alias to findAll(String)

    • findAll

      public List<Map<String,​Object>> findAll​(String query)
      This method returns entire resultset as one list. Do not use it for large result sets.
      Parameters:
      query - raw SQL query. This query is not parametrized.
      Returns:
      entire result set corresponding to the query.

    • find

      public RowProcessor find​(String query, Object... params)
      Convenience method, same as find(RowProcessor.ResultSetType, RowProcessor.ResultSetConcur, int, String, Object...), but passes in default values: 
           RowProcessor.ResultSetType.FORWARD_ONLY, RowProcessor.ResultSetConcur.READ_ONLY, 0
      Executes a raw query and returns an instance of RowProcessor. Use it in the following pattern: 
       new DB("default").find("select first_name, last_name from really_large_table").with(new RowListenerAdapter() {
            public void onNext(Map row) {
                ///write your code here
                Object o1 = row.get("first_name");
                Object o2 = row.get("last_name");
            }
        });
      The JDBC fetch size defaults to 10 records. This means that the driver will fetch and accumulate 10 records in memory. Once you read them, the driver will fetch the next 10, and so on. If you want a finer control over a fetch size, use the find(RowProcessor.ResultSetType, RowProcessor.ResultSetConcur, int, String, Object...) method
      Parameters:
      query - raw SQL, parametrized if needed
      params - list of parameters if query is parametrized.
      Returns:
      instance of RowProcessor which has with() method for convenience.

    • find

      public RowProcessor find​(RowProcessor.ResultSetType type, RowProcessor.ResultSetConcur concur, int fetchSize, String query, Object... params)
      Executes a raw query and returns an instance of RowProcessor. Use it in the following pattern: 
         new DB("default").find("select first_name, last_name from really_large_table", ....).with(new RowListenerAdapter() {
         public void onNext(Map row) {
                 ///write your code here
                 Object o1 = row.get("first_name");
                 Object o2 = row.get("last_name");
             }
         });
      See ResultSet Docs
      Parameters:
      query - raw SQL.
      type - type of result set
      concur - concurrent mode of result set
      fetchSize - hint to the JDBC driver for the size of result set. Gives the JDBC driver a hint as to the number of rows that should be fetched from the database when more rows are needed for ResultSet objects generated by this Statement. If the value specified is zero, then the hint is ignored and an entire set maybe loaded into your heap space - be careful out there!
      params - list of parameters if query is parametrized.
      Returns:
      instance of RowProcessor which has with() method for convenience.

    • find

      public void find​(String sql, RowListener listener)
      Executes a raw query and calls instance of RowListener with every row found. Use this method for very large result sets.
      Parameters:
      sql - raw SQL query.
      listener - client listener implementation for processing individual rows.

    • exec

      public int exec​(String query)
      Executes DML. Use it for inserts and updates.
      Parameters:
      query - raw DML.
      Returns:
      number of rows afected by query.

    • exec

      public int exec​(String query, Object... params)
      Executes parametrized DML - will contain question marks as placeholders.
      Parameters:
      query - query to execute - will contain question marks as placeholders.
      params - query parameters.
      Returns:
      number of records affected.

    • openTransaction

      public void openTransaction()
      Opens local transaction.

    • commitTransaction

      public void commitTransaction()
      Commits local transaction.

    • rollbackTransaction

      public void rollbackTransaction()
      Rolls back local transaction.

    • connection

      public Connection connection()
      Provides connection from current thread.
      Returns:
      connection from current thread.

    • hasConnection

      public boolean hasConnection()
      Use to check if there is a connection present on current thread.
      Returns:
      true if finds connection on current thread, false if not.

    • getConnection

      public Connection getConnection()
      Synonym of connection() for people who like getters.
      Returns:
      connection from current thread.

    • getCurrrentConnectionNames

      public static List<String> getCurrrentConnectionNames()
      Provides a names' list of current connections.
      Returns:
      a names' list of current connections.

    • closeAllConnections

      public static void closeAllConnections()
      Closes all current connections.

    • connections

      public static Map<String,​Connection> connections()
      Provides connections available on current thread.
      Returns:
      connections available on current thread.

    • startBatch

      public PreparedStatement startBatch​(String parametrizedStatement)
      Creates a java.sql.PreparedStatement to be used in batch executions later.
      Parameters:
      parametrizedStatement - Example of a statement: INSERT INTO employees VALUES (?, ?).
      Returns:
      instance of java.sql.PreparedStatement with compiled query.

    • addBatch

      public void addBatch​(PreparedStatement ps, Object... params)
      Adds a batch statement using given java.sql.PreparedStatement and parameters.
      Parameters:
      ps - java.sql.PreparedStatement to add batch to.
      params - parameters for the query in java.sql.PreparedStatement. Parameters will be set on the statement in the same order as provided here.

    • executeBatch

      public int[] executeBatch​(PreparedStatement ps)
      Executes a batch on java.sql.PreparedStatement.
      Parameters:
      ps - java.sql.PreparedStatement to execute batch on.
      Returns:
      an array of update counts containing one element for each command in the batch. The elements of the array are ordered according to the order in which commands were added to the batch.
      See Also:
      Statement#executeBatch()

    • closePreparedStatement

      public void closePreparedStatement​(PreparedStatement ps)
      Quietly closes the java.sql.PreparedStatement used in a batch execution. The advantage over calling java.sql.PreparedStatement.close() directly is not having to explicitly handle a checked exception (java.sql.SQLException). This method should typically be called in a finally block. So as not to displace any exception (e.g. from a failed batch execution) that might already be in flight, this method swallows any exception that might arise from closing the statement. This is generally seen as a worthwhile trade-off, as it much less likely for a close to fail without a prior failure.
      Parameters:
      ps - java.sql.PreparedStatement with which a batch has been executed. If null, this is a no-op.

    • withDb

      public <T> T withDb​(String jndiName, Properties jndiProperties, Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Runnable and then will close the connection. The connection to open is the same as in open(String, Properties) method.

      Example of usage: 
           Object result = withDb("jndiName1", props, () -> {
        //place code here
        return res;
     });
      Parameters:
      jndiName - name of a configured data source.
      jndiProperties - JNDI properties.
      supplier - instance of Supplier to execute.

    • withDb

      public <T> T withDb​(DataSource dataSource, Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Runnable and then will close the connection. The connection to open is the same as in open(DataSource) method.

      Example of usage: 
           Object result = withDb(datasource, () -> {
        //place code here
        return res;
     });
      Parameters:
      dataSource - instance of DataSource to get a connection from.
      supplier - instance of Supplier to execute.

    • withDb

      public <T> T withDb​(String jndiName, Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Supplier and then will close the connection. The connection to open is the same as in open(String) method.

      Example of usage: 
           Object result = withDb(jndiName, () -> {
         //place code here
         return res;
     });
      Parameters:
      jndiName - name of a JNDI connection from container
      supplier - instance of Supplier to execute.

    • withDb

      public <T> T withDb​(String driver, String url, Properties properties, Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Supplier and then will close the connection. The connection to open is the same as in open(String, String, Properties) method.

      Example of usage: 
           Object results = withDb(driver, url, properties, () -> {
        //place code here
        return res;
     });
      The arguments to this method are the same as to open(String, String, Properties) method.
      Parameters:
      supplier - instance of Supplier to execute.

    • withDb

      public <T> T withDb​(String driver, String url, String user, String password, Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Supplier.get() and then will close the connection. The connection to open is the same as in open(String, String, String, String) method.

      Example of usage: 
           Object result = withDb(driver, url, user, password, () -> {
        //place code here
        return val;
     });
      The arguments to this method are the same as to open(String, String, String, String) method.
      Parameters:
      supplier - instance of Supplier to execute.

    • withDb

      public <T> T withDb​(Supplier<T> supplier)
      Convenience method to be used outside ActiveWeb. This method will open a connection, run the Supplier.get() and then will close the connection. The connection to open is the same as in open() method.

      Example of usage: 
           Object result = new DB("events").withDb(() -> {
        //place code here
        return res; // whatever it is
     });
      Parameters:
      supplier - instance of Supplier to execute.