Package org.apache.commons.configuration2

Class DatabaseConfiguration

java.lang.Object
org.apache.commons.configuration2.event.BaseEventSource
org.apache.commons.configuration2.AbstractConfiguration
org.apache.commons.configuration2.DatabaseConfiguration
All Implemented Interfaces:
Configuration, EventSource, ImmutableConfiguration, SynchronizerSupport
public class DatabaseConfiguration extends AbstractConfiguration
Configuration stored in a database. The properties are retrieved from a table containing at least one column for the keys, and one column for the values. It's possible to store several configurations in the same table by adding a column containing the name of the configuration. The name of the table and the columns have to be specified using the corresponding properties.

The recommended way to create an instance of DatabaseConfiguration is to use a configuration builder. The builder is configured with a special parameters object defining the database structures used by the configuration. Such an object can be created using the database() method of the Parameters class. See the examples below for more details.

Example 1 - One configuration per table 

 CREATE TABLE myconfig (
     `key`   VARCHAR NOT NULL PRIMARY KEY,
     `value` VARCHAR
 );

 INSERT INTO myconfig (key, value) VALUES ('foo', 'bar');

 BasicConfigurationBuilder<DatabaseConfiguration> builder =
     new BasicConfigurationBuilder<DatabaseConfiguration>(DatabaseConfiguration.class);
 builder.configure(
     Parameters.database()
         .setDataSource(dataSource)
         .setTable("myconfig")
         .setKeyColumn("key")
         .setValueColumn("value")
 );
 Configuration config = builder.getConfiguration();
 String value = config.getString("foo");

Example 2 - Multiple configurations per table 

 CREATE TABLE myconfigs (
     `name`  VARCHAR NOT NULL,
     `key`   VARCHAR NOT NULL,
     `value` VARCHAR,
     CONSTRAINT sys_pk_myconfigs PRIMARY KEY (`name`, `key`)
 );

 INSERT INTO myconfigs (name, key, value) VALUES ('config1', 'key1', 'value1');
 INSERT INTO myconfigs (name, key, value) VALUES ('config2', 'key2', 'value2');

 BasicConfigurationBuilder<DatabaseConfiguration> builder =
     new BasicConfigurationBuilder<DatabaseConfiguration>(DatabaseConfiguration.class);
 builder.configure(
     Parameters.database()
         .setDataSource(dataSource)
         .setTable("myconfigs")
         .setKeyColumn("key")
         .setValueColumn("value")
         .setConfigurationNameColumn("name")
         .setConfigurationName("config1")
 );
 Configuration config1 = new DatabaseConfiguration(dataSource, "myconfigs", "name", "key", "value", "config1");
 String value1 = conf.getString("key1");
The configuration can be instructed to perform commits after database updates. This is achieved by setting the commits parameter of the constructors to true. If commits should not be performed (which is the default behavior), it should be ensured that the connections returned by the DataSource are in auto-commit mode.

Note: Like JDBC itself, protection against SQL injection is left to the user.

Since:
1.0

  • Constructor Details

  • Method Details

    • addPropertyDirect

      protected void addPropertyDirect(String key, Object obj)
      Adds a property to this configuration. If this causes a database error, an error event will be generated of type ADD_PROPERTY with the causing exception. The event's propertyName is set to the passed in property key, the propertyValue points to the passed in value.
      Specified by:
      addPropertyDirect in class AbstractConfiguration
      Parameters:
      key - the property key
      obj - the value of the property to add

    • addPropertyInternal

      protected void addPropertyInternal(String key, Object value)
      Adds a property to this configuration. This implementation temporarily disables list delimiter parsing, so that even if the value contains the list delimiter, only a single record is written into the managed table. The implementation of getProperty() takes care about delimiters. So list delimiters are fully supported by DatabaseConfiguration, but internally treated a bit differently.
      Overrides:
      addPropertyInternal in class AbstractConfiguration
      Parameters:
      key - the key of the new property
      value - the value to be added

    • clearInternal

      protected void clearInternal()
      Removes all entries from this configuration. If this causes a database error, an error event will be generated of type CLEAR with the causing exception. Both the event's propertyName and the propertyValue will be undefined.
      Overrides:
      clearInternal in class AbstractConfiguration

    • clearPropertyDirect

      protected void clearPropertyDirect(String key)
      Removes the specified value from this configuration. If this causes a database error, an error event will be generated of type CLEAR_PROPERTY with the causing exception. The event's propertyName will be set to the passed in key, the propertyValue will be undefined.
      Specified by:
      clearPropertyDirect in class AbstractConfiguration
      Parameters:
      key - the key of the property to be removed

    • close

      protected void close(Connection conn, Statement stmt, ResultSet rs)
      Close the specified database objects. Avoid closing if null and hide any SQLExceptions that occur.
      Parameters:
      conn - The database connection to close
      stmt - The statement to close
      rs - the result set to close

    • containsKeyInternal

      protected boolean containsKeyInternal(String key)
      Checks whether this configuration contains the specified key. If this causes a database error, an error event will be generated of type READ with the causing exception. The event's propertyName will be set to the passed in key, the propertyValue will be undefined.
      Specified by:
      containsKeyInternal in class AbstractConfiguration
      Parameters:
      key - the key to be checked
      Returns:
      a flag whether this key is defined

    • containsValueInternal

      protected boolean containsValueInternal(Object value)
      Tests whether this configuration contains one or more matches to this value. This operation stops at first match but may be more expensive than the containsKey method.
      Specified by:
      containsValueInternal in class AbstractConfiguration
      Parameters:
      value - the value in question
      Returns:
      true if and only if some key maps to the value argument in this configuration as determined by the equals method; false otherwise.
      Since:
      2.11.0

    • extractPropertyValue

      protected Object extractPropertyValue(ResultSet rs) throws SQLException
      Extracts the value of a property from the given result set. The passed in ResultSet was created by a SELECT statement on the underlying database table. This implementation reads the value of the column determined by the valueColumn property. Normally the contained value is directly returned. However, if it is of type CLOB, text is extracted as string.
      Parameters:
      rs - the current ResultSet
      Returns:
      the value of the property column
      Throws:
      SQLException - if an error occurs

    • getConfigurationName

      public String getConfigurationName()
      Gets the name of this configuration instance.
      Returns:
      the name of this configuration

    • getConfigurationNameColumn

      public String getConfigurationNameColumn()
      Gets the name of the table column with the configuration name.
      Returns:
      the name of the configuration name column

    • getDatasource

      @Deprecated public DataSource getDatasource()
      Deprecated.
      Use getDataSource()
      Gets the used DataSource object.
      Returns:
      the data source
      Since:
      1.4

    • getDataSource

      public DataSource getDataSource()
      Gets the DataSource for obtaining database connections.
      Returns:
      the DataSource

    • getKeyColumn

      public String getKeyColumn()
      Gets the name of the column containing the configuration keys.
      Returns:
      the name of the key column

    • getKeysInternal

      protected Iterator<String> getKeysInternal()
      Returns an iterator with the names of all properties contained in this configuration. If this causes a database error, an error event will be generated of type READ with the causing exception. Both the event's propertyName and the propertyValue will be undefined.
      Specified by:
      getKeysInternal in class AbstractConfiguration
      Returns:
      an iterator with the contained keys (an empty iterator in case of an error)

    • getPropertyInternal

      protected Object getPropertyInternal(String key)
      Gets the value of the specified property. If this causes a database error, an error event will be generated of type READ with the causing exception. The event's propertyName is set to the passed in property key, the propertyValue is undefined.
      Specified by:
      getPropertyInternal in class AbstractConfiguration
      Parameters:
      key - the key of the desired property
      Returns:
      the value of this property

    • getTable

      public String getTable()
      Gets the name of the table containing configuration data.
      Returns:
      the name of the table to be queried

    • getValueColumn

      public String getValueColumn()
      Gets the name of the column containing the configuration values.
      Returns:
      the name of the value column

    • isAutoCommit

      public boolean isAutoCommit()
      Returns a flag whether this configuration performs commits after database updates.
      Returns:
      a flag whether commits are performed

    • isEmptyInternal

      protected boolean isEmptyInternal()
      Checks if this configuration is empty. If this causes a database error, an error event will be generated of type READ with the causing exception. Both the event's propertyName and propertyValue will be undefined.
      Specified by:
      isEmptyInternal in class AbstractConfiguration
      Returns:
      a flag whether this configuration is empty.

    • setAutoCommit

      public void setAutoCommit(boolean autoCommit)
      Sets the auto commit flag. If set to true, this configuration performs a commit after each database update.
      Parameters:
      autoCommit - the auto commit flag

    • setConfigurationName

      public void setConfigurationName(String configurationName)
      Sets the name of this configuration instance.
      Parameters:
      configurationName - the name of this configuration

    • setConfigurationNameColumn

      public void setConfigurationNameColumn(String configurationNameColumn)
      Sets the name of the table column with the configuration name.
      Parameters:
      configurationNameColumn - the name of the column with the configuration name

    • setDataSource

      public void setDataSource(DataSource dataSource)
      Sets the DataSource for obtaining database connections.
      Parameters:
      dataSource - the DataSource

    • setKeyColumn

      public void setKeyColumn(String keyColumn)
      Sets the name of the column containing the configuration keys.
      Parameters:
      keyColumn - the name of the key column

    • setTable

      public void setTable(String table)
      Sets the name of the table containing configuration data.
      Parameters:
      table - the table name

    • setValueColumn

      public void setValueColumn(String valueColumn)
      Sets the name of the column containing the configuration values.
      Parameters:
      valueColumn - the name of the value column