Package org.apache.commons.dbutils

Class BeanProcessor

  • Direct Known Subclasses:
    GenerousBeanProcessor
    public class BeanProcessor
extends java.lang.Object

    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
    See Also:
    BasicRowProcessor

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static java.util.List<ColumnHandler<?>> COLUMN_HANDLERS  
      private java.util.Map<java.lang.String,​java.lang.String> columnToPropertyOverrides
      ResultSet column to bean property name overrides.
      private static java.util.Map<java.lang.Class<?>,​java.lang.Object> PRIMITIVE_DEFAULTS
      Set a bean's primitive properties to these defaults when SQL NULL is returned.
      private static java.util.List<PropertyHandler> PROPERTY_HANDLERS  
      protected static int PROPERTY_NOT_FOUND
      Special array value used by mapColumnsToProperties that indicates there is no bean property that matches a column from a ResultSet.

    • Constructor Summary

      Constructors 
      Constructor Description
      BeanProcessor()
      Constructor for BeanProcessor.
      BeanProcessor​(java.util.Map<java.lang.String,​java.lang.String> columnToPropertyOverrides)
      Constructor for BeanProcessor configured with column to property name overrides.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private void callSetter​(java.lang.Object target, java.beans.PropertyDescriptor prop, java.lang.Object value)
      Calls the setter method on the target object for the given property.
      private <T> T createBean​(java.sql.ResultSet resultSet, java.lang.Class<T> type, java.beans.PropertyDescriptor[] props, int[] columnToProperty)
      Creates a new object and initializes its fields from the ResultSet.
      protected java.lang.reflect.Method getWriteMethod​(java.lang.Object target, java.beans.PropertyDescriptor prop, java.lang.Object value)
      Get the write method to use when setting value to the target.
      private boolean isCompatibleType​(java.lang.Object value, java.lang.Class<?> type)
      ResultSet.getObject() returns an Integer object for an INT column.
      protected int[] mapColumnsToProperties​(java.sql.ResultSetMetaData rsmd, java.beans.PropertyDescriptor[] props)
      The positions in the returned array represent column numbers.
      private boolean matchesPrimitive​(java.lang.Class<?> targetType, java.lang.Class<?> valueType)
      Check whether a value is of the same primitive type as targetType.
      protected <T> T newInstance​(java.lang.Class<T> c)
      Factory method that returns a new instance of the given Class.
      <T> T populateBean​(java.sql.ResultSet resultSet, T bean)
      Initializes the fields of the provided bean from the ResultSet.
      private <T> T populateBean​(java.sql.ResultSet resultSet, T bean, java.beans.PropertyDescriptor[] props, int[] columnToProperty)
      This method populates a bean from the ResultSet based upon the underlying meta-data.
      protected java.lang.Object processColumn​(java.sql.ResultSet resultSet, int index, java.lang.Class<?> propType)
      Convert a ResultSet column into an object.
      private java.beans.PropertyDescriptor[] propertyDescriptors​(java.lang.Class<?> c)
      Returns a PropertyDescriptor[] for the given Class.
      <T> T toBean​(java.sql.ResultSet rs, java.lang.Class<? extends T> type)
      Convert a ResultSet row into a JavaBean.
      <T> java.util.List<T> toBeanList​(java.sql.ResultSet resultSet, java.lang.Class<? extends T> type)
      Convert a ResultSet into a List of JavaBeans.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • 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:
        Constant Field Values

      • PRIMITIVE_DEFAULTS

        private static final java.util.Map<java.lang.Class<?>,​java.lang.Object> PRIMITIVE_DEFAULTS
        Set a bean's primitive properties to these defaults when SQL NULL is returned. These are the same as the defaults that ResultSet get* methods return in the event of a NULL column.

      • COLUMN_HANDLERS

        private static final java.util.List<ColumnHandler<?>> COLUMN_HANDLERS

      • PROPERTY_HANDLERS

        private static final java.util.List<PropertyHandler> PROPERTY_HANDLERS

      • columnToPropertyOverrides

        private final java.util.Map<java.lang.String,​java.lang.String> columnToPropertyOverrides
        ResultSet column to bean property name overrides.

    • Constructor Detail

      • BeanProcessor

        public BeanProcessor()
        Constructor for BeanProcessor.

      • BeanProcessor

        public BeanProcessor​(java.util.Map<java.lang.String,​java.lang.String> columnToPropertyOverrides)
        Constructor for BeanProcessor configured with column to property name overrides.
        Parameters:
        columnToPropertyOverrides - ResultSet column to bean property name overrides
        Since:
        1.5

    • Method Detail

      • callSetter

        private void callSetter​(java.lang.Object target,
                        java.beans.PropertyDescriptor prop,
                        java.lang.Object value)
                 throws java.sql.SQLException
        Calls the setter method on the target object for the given property. If no setter method exists for the property, this method does nothing.
        Parameters:
        target - The object to set the property on.
        prop - The property to set.
        value - The value to pass into the setter.
        Throws:
        java.sql.SQLException - if an error occurs setting the property.

      • createBean

        private <T> T createBean​(java.sql.ResultSet resultSet,
                         java.lang.Class<T> type,
                         java.beans.PropertyDescriptor[] props,
                         int[] columnToProperty)
                  throws java.sql.SQLException
        Creates a new object and initializes its fields from the ResultSet.
        Type Parameters:
        T - The type of bean to create
        Parameters:
        resultSet - The result set.
        type - The bean type (the return type of the object).
        props - The property descriptors.
        columnToProperty - The column indices in the result set.
        Returns:
        An initialized object.
        Throws:
        java.sql.SQLException - if a database error occurs.

      • getWriteMethod

        protected java.lang.reflect.Method getWriteMethod​(java.lang.Object target,
                                                  java.beans.PropertyDescriptor prop,
                                                  java.lang.Object value)
        Get the write method to use when setting value to the target.
        Parameters:
        target - Object where the write method will be called.
        prop - BeanUtils 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.

      • isCompatibleType

        private boolean isCompatibleType​(java.lang.Object value,
                                 java.lang.Class<?> type)
        ResultSet.getObject() returns an Integer object for an INT column. The setter method for the property might take an Integer or a primitive int. This method returns true if the value can be successfully passed into the setter method. Remember, Method.invoke() handles the unwrapping of Integer into an int.
        Parameters:
        value - The value to be passed into the setter method.
        type - The setter's parameter type (non-null)
        Returns:
        boolean True if the value is compatible (null => true)

      • mapColumnsToProperties

        protected int[] mapColumnsToProperties​(java.sql.ResultSetMetaData rsmd,
                                       java.beans.PropertyDescriptor[] props)
                                throws java.sql.SQLException
        The positions in the returned array represent column numbers. The values stored at each position represent the index in the PropertyDescriptor[] 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.
        props - The bean property descriptors.
        Returns:
        An int[] with column index to property index mappings. The 0th element is meaningless because JDBC column indexing starts at 1.
        Throws:
        java.sql.SQLException - if a database access error occurs

      • matchesPrimitive

        private boolean matchesPrimitive​(java.lang.Class<?> targetType,
                                 java.lang.Class<?> valueType)
        Check whether a value is of the same primitive type as targetType.
        Parameters:
        targetType - The primitive type to target.
        valueType - The value to match to the primitive type.
        Returns:
        Whether valueType can be coerced (e.g. autoboxed) into targetType.

      • newInstance

        protected <T> T newInstance​(java.lang.Class<T> c)
                     throws java.sql.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:
        java.sql.SQLException - if creation failed.

      • populateBean

        public <T> T populateBean​(java.sql.ResultSet resultSet,
                          T bean)
                   throws java.sql.SQLException
        Initializes the fields of the provided bean from the ResultSet.
        Type Parameters:
        T - The type of bean
        Parameters:
        resultSet - The result set.
        bean - The bean to be populated.
        Returns:
        An initialized object.
        Throws:
        java.sql.SQLException - if a database error occurs.

      • populateBean

        private <T> T populateBean​(java.sql.ResultSet resultSet,
                           T bean,
                           java.beans.PropertyDescriptor[] props,
                           int[] columnToProperty)
                    throws java.sql.SQLException
        This method populates a bean from the ResultSet based upon the underlying meta-data.
        Type Parameters:
        T - The type of bean
        Parameters:
        resultSet - The result set.
        bean - The bean to be populated.
        props - The property descriptors.
        columnToProperty - The column indices in the result set.
        Returns:
        An initialized object.
        Throws:
        java.sql.SQLException - if a database error occurs.

      • processColumn

        protected java.lang.Object processColumn​(java.sql.ResultSet resultSet,
                                         int index,
                                         java.lang.Class<?> propType)
                                  throws java.sql.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:
        resultSet - 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:
        java.sql.SQLException - if a database access error occurs

      • propertyDescriptors

        private java.beans.PropertyDescriptor[] propertyDescriptors​(java.lang.Class<?> c)
                                                     throws java.sql.SQLException
        Returns a PropertyDescriptor[] for the given Class.
        Parameters:
        c - The Class to retrieve PropertyDescriptors for.
        Returns:
        A PropertyDescriptor[] describing the Class.
        Throws:
        java.sql.SQLException - if introspection failed.

      • toBean

        public <T> T toBean​(java.sql.ResultSet rs,
                    java.lang.Class<? extends T> type)
             throws java.sql.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>
        Type Parameters:
        T - The type of bean to create
        Parameters:
        rs - ResultSet that supplies the bean data
        type - Class from which to create the bean instance
        Returns:
        the newly created bean
        Throws:
        java.sql.SQLException - if a database access error occurs

      • toBeanList

        public <T> java.util.List<T> toBeanList​(java.sql.ResultSet resultSet,
                                        java.lang.Class<? extends T> type)
                                 throws java.sql.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>

        Type Parameters:
        T - The type of bean to create
        Parameters:
        resultSet - ResultSet that supplies the bean data
        type - Class from which to create the bean instance
        Returns:
        the newly created List of beans
        Throws:
        java.sql.SQLException - if a database access error occurs