Package ch.autumo.beetroot.utils.bean

Class BeanProcessor

java.lang.Object
ch.autumo.beetroot.utils.bean.BeanProcessor
public class BeanProcessor extends Object
This bean processor operates with bean fields that hold information of beetRoot model beans with database annotation information generated by the beetRoot PLANT generator. There's no interpretation how table names are mapped to property names, it is simply defined by the 'Column'- annotation. We do not allow e.g. Java property camel case to database snake case conversion, because if we save or update objects, we don't know what database columns are present in the database; we would first have to get table meta data from the database and update the model with it, but this is inefficient! The method DB.updateModel(Entity, Map) would allow to update the model with database meta data, but for efficiency reasons Beans.updateModel(Entity, Map) us used. Originally from the 1.8 version of apache's common-dbutils: https://github.com/apache/commons-dbutils/blob/master/src/main/java/org/apache/commons/dbutils/BeanProcessor.java

BeanProcessor matches column names to bean property names and converts ResultSet columns into objects for those bean properties. Subclasses should override the methods in the processing chain to customize behavior.

This class is thread-safe.

Since:
1.1

  • Field Details

    • PROPERTY_NOT_FOUND

      protected static final int PROPERTY_NOT_FOUND
      Special array value used by mapColumnsToProperties that indicates there is no bean property that matches a column from a ResultSet.
      See Also:

  • Constructor Details

    • BeanProcessor

      public BeanProcessor()
      Constructor for BeanProcessor.

  • Method Details

    • toBean

      public Entity toBean(ResultSet rs, Class<?> type) throws SQLException
      Convert a ResultSet row into a JavaBean. This implementation uses reflection and BeanInfo classes to match column names to bean property names. Properties are matched to columns based on several factors: <br/> <ol> <li> The class has a writable property with the same name as a column. The name comparison is case insensitive. </li> <li> The column type can be converted to the property's set method parameter type with a ResultSet.get* method. If the conversion fails (ie. the property was an int and the column was a Timestamp) an SQLException is thrown. </li> </ol> <p> Primitive bean properties are set to their defaults when SQL NULL is returned from the ResultSet. Numeric fields are set to 0 and booleans are set to false. Object bean properties are set to null when SQL NULL is returned. This is the same behavior as the ResultSet get* methods. </p>
      Parameters:
      rs - ResultSet that supplies the bean data
      type - Class from which to create the bean instance
      Returns:
      the newly created bean
      Throws:
      SQLException - if a database access error occurs

    • toBeanList

      public List<Entity> toBeanList(ResultSet rs, Class<?> type) throws SQLException
      Convert a ResultSet into a List of JavaBeans. This implementation uses reflection and BeanInfo classes to match column names to bean property names. Properties are matched to columns based on several factors: <br/> <ol> <li> The class has a writable property with the same name as a column. The name comparison is case insensitive. </li> <li> The column type can be converted to the property's set method parameter type with a ResultSet.get* method. If the conversion fails (ie. the property was an int and the column was a Timestamp) an SQLException is thrown. </li> </ol>

      Primitive bean properties are set to their defaults when SQL NULL is returned from the ResultSet. Numeric fields are set to 0 and booleans are set to false. Object bean properties are set to null when SQL NULL is returned. This is the same behavior as the ResultSet get* methods. </p>

      Parameters:
      rs - ResultSet that supplies the bean data
      type - Class from which to create the bean instance
      Returns:
      the newly created List of beans
      Throws:
      SQLException - if a database access error occurs

    • populateBean

      public Entity populateBean(ResultSet rs, Entity entity) throws SQLException
      Initializes the fields of the provided bean from the ResultSet.
      Parameters:
      rs - The result set.
      entity - The bean to be populated.
      Returns:
      An initialized object.
      Throws:
      SQLException - if a database error occurs.

    • getWriteMethod

      protected Method getWriteMethod(Object target, BeanField beanField, Object value)
      Get the write method to use when setting value to the target.
      Parameters:
      target - Object where the write method will be called.
      beanField - Bean field information.
      value - The value that will be passed to the write method.
      Returns:
      The Method to call on target to write value or null if there is no suitable write method.

    • newInstance

      protected <T> T newInstance(Class<T> c) throws SQLException
      Factory method that returns a new instance of the given Class. This is called at the start of the bean creation process and may be overridden to provide custom behavior like returning a cached bean instance.
      Type Parameters:
      T - The type of object to create
      Parameters:
      c - The Class to create an object from.
      Returns:
      A newly created object of the Class.
      Throws:
      SQLException - if creation failed.

    • mapColumnsToProperties

      protected int[] mapColumnsToProperties(ResultSetMetaData rsmd, BeanField[] beanFields) throws SQLException
      The positions in the returned array represent column numbers. The values stored at each position represent the index in the BeanField[] for the bean property that matches the column name. If no bean property was found for a column, the position is set to PROPERTY_NOT_FOUND.
      Parameters:
      rsmd - The ResultSetMetaData containing column information.
      beanFields - The bean fields.
      Returns:
      An int[] with column index to property index mappings. The 0th element is meaningless because JDBC column indexing starts at 1.
      Throws:
      SQLException - if a database access error occurs

    • mapColumnsToPropertiesWithAllMethods

      protected int[] mapColumnsToPropertiesWithAllMethods(ResultSetMetaData rsmd, BeanField[] beanFields) throws SQLException
      The positions in the returned array represent column numbers. The values stored at each position represent the index in the BeanField[] for the bean property that matches the column name. If no bean property was found for a column, the position is set to PROPERTY_NOT_FOUND. This method tries not only to map properties by bean fields, it also tries to map properties by comparing property names to table column names (snake- to camel-case conversion) if no 'Column'-annotations are found!
      Parameters:
      rsmd - The ResultSetMetaData containing column information.
      beanFields - The bean fields.
      Returns:
      An int[] with column index to property index mappings. The 0th element is meaningless because JDBC column indexing starts at 1.
      Throws:
      SQLException - if a database access error occurs

    • processColumn

      protected Object processColumn(ResultSet rs, int index, Class<?> propType) throws SQLException
      Convert a ResultSet column into an object. Simple implementations could just call rs.getObject(index) while more complex implementations could perform type manipulation to match the column's type to the bean property type.

      This implementation calls the appropriate ResultSet getter method for the given property type to perform the type conversion. If the property type doesn't match one of the supported ResultSet types, getObject is called.

      Parameters:
      rs - The ResultSet currently being processed. It is positioned on a valid row before being passed into this method.
      index - The current column index being processed.
      propType - The bean property type that this column needs to be converted into.
      Returns:
      The object from the ResultSet at the given column index after optional type processing or null if the column value was SQL NULL.
      Throws:
      SQLException - if a database access error occurs