Class AbstractMappingStrategy<I, K extends Comparable<K>, C extends ComplexFieldMapEntry<I,K,T>, T>

java.lang.Object
com.opencsv.bean.AbstractMappingStrategy<I,K,C,T>
Type Parameters:
I - The initializer type used to build the internal many-to-one mapping
K - The type of the key used for internal indexing
C - The type of the internal many-to-one mapping
T - Type of object that is being processed.
All Implemented Interfaces:
MappingStrategy<T>
Direct Known Subclasses:
ColumnPositionMappingStrategy, HeaderNameBaseMappingStrategy
public abstract class AbstractMappingStrategy<I, K extends Comparable<K>, C extends ComplexFieldMapEntry<I,K,T>, T> extends Object implements MappingStrategy<T>
This class collects as many generally useful parts of the implementation of a mapping strategy as possible.

This mapping strategy knows of the existence of binding annotations, but assumes through getBindingAnnotations() they are not in use.

Anyone is welcome to use it as a base class for their own mapping strategies.

Since:
4.2

  • Field Details

    • FORBIDDEN_CLASSES_FOR_RECURSION

      private static final Set<Class> FORBIDDEN_CLASSES_FOR_RECURSION
      Set of classes where recursion is not allowed. Using HashSet because, given the large number of types, the contains method is quicker than an Array or ArrayList (Granted the number where Set is more efficient is different per Java release and system configuration). And being a Set we are noting that each value is unique.

    • type

      protected Class<? extends T> type
      This is the class of the bean to be manipulated.

    • headerIndex

      protected final HeaderIndex headerIndex
      Maintains a bi-directional mapping between column position(s) and header name.

    • recursiveTypeTree

      protected AbstractMappingStrategy.RecursiveType recursiveTypeTree
      A tree of the types encountered during recursion through the root bean type. These are only the types (and associated fields) specifically annotated with CsvRecurse.

    • ignoredFields

      private org.apache.commons.collections4.MultiValuedMap<Class<?>,Field> ignoredFields
      Storage for all manually excluded class/field pairs.

    • errorLocale

      protected Locale errorLocale
      Locale for error messages.

    • profile

      protected String profile
      The profile for configuring bean fields.

  • Constructor Details

    • AbstractMappingStrategy

      public AbstractMappingStrategy()

  • Method Details

    • chooseMultivaluedFieldIndexFromHeaderIndex

      protected abstract K chooseMultivaluedFieldIndexFromHeaderIndex(int index)
      For BeanField.indexAndSplitMultivaluedField(java.lang.Object, java.lang.Object) it is necessary to determine which index to pass in.
      Parameters:
      index - The current column position while transmuting a bean to CSV output
      Returns:
      The index to be used for this mapping strategy for BeanField.indexAndSplitMultivaluedField(java.lang.Object, java.lang.Object)

    • getFieldMap

      protected abstract FieldMap<I, K, ? extends C, T> getFieldMap()
      Returns the FieldMap associated with this mapping strategy.
      Returns:
      The FieldMap used by this strategy

    • getBindingAnnotations

      protected Set<Class<? extends Annotation>> getBindingAnnotations()
      Returns a set of the annotations that are used for binding in this mapping strategy. The default implementation returns the empty set.
      Returns:
      Annotations of the sort CsvBindByName or CsvBindByPosition that are relevant for binding input fields to bean members in this mapping strategy
      Since:
      5.0

    • loadAnnotatedFieldMap

      protected void loadAnnotatedFieldMap(org.apache.commons.collections4.ListValuedMap<Class<?>,Field> fields)
      Creates a map of annotated fields in the bean to be processed.

      This method is called by loadFieldMap() when at least one relevant annotation is found on a member variable.

      The default implementation assumes there are no annotations and does nothing.

      Parameters:
      fields - A list of fields annotated with a binding annotation in the bean to be processed
      Since:
      5.0

    • loadUnadornedFieldMap

      protected abstract void loadUnadornedFieldMap(org.apache.commons.collections4.ListValuedMap<Class<?>,Field> fields)
      Creates a map of fields in the bean to be processed that have no annotations. This method is called by loadFieldMap() when absolutely no annotations that are relevant for this mapping strategy are found in the type of bean being processed.
      Parameters:
      fields - A list of all non-synthetic fields in the bean to be processed
      Since:
      5.0

    • initializeFieldMap

      protected abstract void initializeFieldMap()
      Creates an empty binding-type-specific field map that can be filled in later steps.

      This method may be called multiple times and must erase any state information from previous calls.

      Since:
      5.0

    • findField

      protected abstract BeanField<T,K> findField(int col)
      Gets the field for a given column position.
      Parameters:
      col - The column to find the field for
      Returns:
      BeanField containing the field for a given column position, or null if one could not be found
      Throws:
      CsvBadConverterException - If a custom converter for a field cannot be initialized

    • verifyLineLength

      protected abstract void verifyLineLength(int numberOfFields) throws CsvRequiredFieldEmptyException
      Must be called once the length of input for a line/record is known to verify that the line was complete. Complete in this context means, no required fields are missing. The issue here is, as long as a column is present but empty, we can check whether the field is required and throw an exception if it is not, but if the data end prematurely, we never have this chance without indication that no more data are on the way. Another validation is that the number of fields must match the number of headers to prevent a data mismatch situation.
      Parameters:
      numberOfFields - The number of fields present in the line of input
      Throws:
      CsvRequiredFieldEmptyException - If a required column is missing
      Since:
      4.0

    • createBean

      protected Map<Class<?>,Object> createBean() throws CsvBeanIntrospectionException, IllegalStateException
      Implementation will return a bean of the type of object being mapped.
      Returns:
      A new instance of the class being mapped.
      Throws:
      CsvBeanIntrospectionException - Thrown on error creating object.
      IllegalStateException - If the type of the bean has not been initialized through setType(java.lang.Class)

    • createSubordinateBeans

      private static void createSubordinateBeans(AbstractMappingStrategy.RecursiveType typeTree, Map<Class<?>,Object> instanceMap, Object containingObject) throws InstantiationException, IllegalAccessException, InvocationTargetException
      Throws:
      InstantiationException
      IllegalAccessException
      InvocationTargetException

    • indexBean

      protected Map<Class<?>,Object> indexBean(T bean) throws IllegalAccessException, InvocationTargetException
      Creates an index of necessary types according to the mapping strategy and existing instances of (subordinate) beans.
      Parameters:
      bean - The root bean to be indexed
      Returns:
      The index from type to instance
      Throws:
      IllegalAccessException - If there are problems accessing a subordinate bean
      InvocationTargetException - If there are problems accessing a subordinate bean
      Since:
      5.0

    • indexSubordinateBeans

      private static void indexSubordinateBeans(AbstractMappingStrategy.RecursiveType typeTree, Map<Class<?>,Object> instanceMap, Object containingObject) throws IllegalAccessException, InvocationTargetException
      Throws:
      IllegalAccessException
      InvocationTargetException

    • findHeader

      public abstract String findHeader(int col)
      Gets the name (or position number) of the header for the given column number. The column numbers are zero-based.
      Parameters:
      col - The column number for which the header is sought
      Returns:
      The name of the header

    • generateHeader

      public String[] generateHeader(T bean) throws CsvRequiredFieldEmptyException
      This method generates a header that can be used for writing beans of the type provided back to a file.

      The ordering of the headers is determined by the FieldMap in use.

      This method should be called first by all overriding classes to make certain headerIndex is properly initialized.

      Specified by:
      generateHeader in interface MappingStrategy<I>
      Parameters:
      bean - One fully populated bean from which the header can be derived. This is important in the face of joining and splitting. If we have a MultiValuedMap as a field that is the target for a join on reading, that same field must be split into multiple columns on writing. Since the joining is done via regular expressions, it is impossible for opencsv to know what the column names are supposed to be on writing unless this bean includes a fully populated map.
      Returns:
      An array of column names for a header. This may be an empty array if no header should be written, but it must not be null.
      Throws:
      CsvRequiredFieldEmptyException - If a required header is missing while attempting to write. Since every other header is hard-wired through the bean fields and their associated annotations, this can only happen with multi-valued fields.

    • getColumnName

      protected String getColumnName(int col)
      Get the column name for a given column position.
      Parameters:
      col - Column position.
      Returns:
      The column name or null if the position is larger than the header array or there are no headers defined.

    • getType

      public Class<? extends T> getType()
      Get the class type that the strategy is mapping.
      Returns:
      Class of the object that this MappingStrategy will create.

    • populateNewBean

      public T populateNewBean(String[] line) throws CsvBeanIntrospectionException, CsvFieldAssignmentException, CsvChainedException
      Description copied from interface: MappingStrategy
      Takes a line of input from a CSV file and creates a bean out of it.
      Specified by:
      populateNewBean in interface MappingStrategy<I>
      Parameters:
      line - A line of input returned from CSVReader
      Returns:
      A bean containing the converted information from the input
      Throws:
      CsvBeanIntrospectionException - Generally, if some part of the bean cannot be accessed and used as needed
      CsvFieldAssignmentException - A more specific subclass of this exception is thrown for any problem decoding and assigning a field of the input to a bean field
      CsvChainedException - If multiple exceptions are thrown for the same input line

    • setType

      public void setType(Class<? extends T> type) throws CsvBadConverterException
      Sets the class type that is being mapped. Also initializes the mapping between column names and bean fields and attempts to create one example bean to be certain there are no fundamental problems with creation.
      Specified by:
      setType in interface MappingStrategy<I>
      Parameters:
      type - Class type.
      Throws:
      CsvBadConverterException - If a field in the bean is annotated with a custom converter that cannot be initialized. If you are not using custom converters that you have written yourself, it should be safe to catch this exception and ignore it.

    • setProfile

      public void setProfile(String profile)
      Sets the profile this mapping strategy will use when configuring bean fields.
      Specified by:
      setProfile in interface MappingStrategy<I>
      Parameters:
      profile - The profile to use

    • ignoreFields

      public void ignoreFields(org.apache.commons.collections4.MultiValuedMap<Class<?>,Field> fields) throws IllegalArgumentException
      Description copied from interface: MappingStrategy

      When processing a bean for reading or writing, ignore the given fields from the given classes completely, including all annotations and requirements. This method has two compelling applications:

      1. If you are not able to modify the source code of the beans you use, or
      2. If you use a mapping strategy without annotations and want to exclude a small number of fields from a bean with a large number of fields.

      Calling this method overwrites the fields passed in from any previous calls. It is legal to call this method before calling MappingStrategy.setType(Class), and it may be more efficient to do so.

      Caution must be exercised with this method when letting opencsv automatically determine the mapping strategy. When a field is ignored, opencsv pretends it does not exist at all. If, for instance, all fields annotated with opencsv binding annotations are ignored, opencsv will automatically switch to HeaderColumnNameMappingStrategy and assume header names exactly match field names.

      An implementation of this interface is not required to implement this method. The default implementation throws UnsupportedOperationException.

      Specified by:
      ignoreFields in interface MappingStrategy<I>
      Parameters:
      fields - All fields to be ignored, mapped from the classes of which they are members. These are the classes as opencsv encounters them, not necessarily the declaring classes if any fields are inherited. May be null.
      Throws:
      IllegalArgumentException - If any entry in the map has a null key, a null value, or if the value is not a field in the class represented by the key
      See Also:

    • filterIgnoredFields

      protected List<Field> filterIgnoredFields(Class<?> type, Field[] fields)
      Filters all fields that opencsv has been instructed to ignore and returns a list of the rest.
      Parameters:
      type - The class from which fields come. This must be the class as opencsv would seek to instantiate it, which in the case of inheritance is not necessarily the declaring class.
      fields - The fields to be filtered
      Returns:
      A list of fields that exist for opencsv

    • loadFieldMap

      protected void loadFieldMap() throws CsvBadConverterException
      Builds a map of columns from the input to fields of the bean type.
      Throws:
      CsvBadConverterException - If there is a problem instantiating the custom converter for an annotated field

    • isForbiddenClassForRecursion

      protected boolean isForbiddenClassForRecursion(Class<?> type)
      Parameters:
      type - Class to be checked
      Returns:
      Whether the type may be recursed into (false), or must be considered a leaf node for recursion (true). This implementation considers the boxed primitives forbidden.

    • loadRecursiveClasses

      protected AbstractMappingStrategy.RecursiveType loadRecursiveClasses(Class<?> newType, Set<Class<?>> encounteredTypes)
      Creates a tree of beans embedded in each other. These are the member variables annotated with CsvRecurse and their associated types. This method is used recursively.
      Parameters:
      newType - The type that is meant to be added to the tree
      encounteredTypes - A set of types already encountered during recursion, as types may not be recursed into more than once.
      Returns:
      A representation of this type and all of the types beneath it in a tree
      Throws:
      CsvRecursionException - If recursion is attempted into a primitive type or a previously encountered type is added again or a member variable annotated with CsvRecurse is also annotated with a binding annotation

    • assembleCompleteFieldList

      private void assembleCompleteFieldList(AbstractMappingStrategy.RecursiveType root, org.apache.commons.collections4.ListValuedMap<Class<?>,Field> encounteredFields)
      Creates a non-tree (fairly flat) representation of all of the fields bound from all types. This method is used recursively.
      Parameters:
      root - The root of the type tree at this level of recursion
      encounteredFields - A collection of all fields thus far included in the new representation. This collection will be added to and is the result of this method.

    • partitionFields

      protected Map<Boolean, org.apache.commons.collections4.ListValuedMap<Class<?>,Field>> partitionFields()
      Partitions all non-synthetic fields of the bean type being processed into annotated and non-annotated fields according to getBindingAnnotations().
      Returns:
      A multi-valued map (class to multiple fields in that class) in which all annotated fields are mapped under Boolean.TRUE, and all non-annotated fields are mapped under Boolean.FALSE.
      Since:
      5.0

    • instantiateCustomConverter

      protected BeanField<T,K> instantiateCustomConverter(Class<? extends AbstractBeanField<T,K>> converter) throws CsvBadConverterException
      Attempts to instantiate the class of the custom converter specified.
      Parameters:
      converter - The class for a custom converter
      Returns:
      The custom converter
      Throws:
      CsvBadConverterException - If the class cannot be instantiated

    • setErrorLocale

      public void setErrorLocale(Locale errorLocale)
      Description copied from interface: MappingStrategy
      Sets the locale for all error messages. The default implementation does nothing, as it is expected that most implementations of this interface will not support multiple languages.
      Specified by:
      setErrorLocale in interface MappingStrategy<I>
      Parameters:
      errorLocale - Locale for error messages. If null, the default locale is used.

    • setFieldValue

      protected void setFieldValue(Map<Class<?>,Object> beanTree, String value, int column) throws CsvDataTypeMismatchException, CsvRequiredFieldEmptyException, CsvConstraintViolationException, CsvValidationException
      Populates the field corresponding to the column position indicated of the bean passed in according to the rules of the mapping strategy. This method performs conversion on the input string and assigns the result to the proper field in the provided bean.
      Parameters:
      beanTree - Object containing the field to be set.
      value - String containing the value to set the field to.
      column - The column position from the CSV file under which this value was found.
      Throws:
      CsvDataTypeMismatchException - When the result of data conversion returns an object that cannot be assigned to the selected field
      CsvRequiredFieldEmptyException - When a field is mandatory, but there is no input datum in the CSV file
      CsvConstraintViolationException - When the internal structure of data would be violated by the data in the CSV file
      CsvValidationException - If a user-supplied validator determines that the input is invalid
      Since:
      4.2

    • transmuteBean

      public String[] transmuteBean(T bean) throws CsvFieldAssignmentException, CsvChainedException
      Description copied from interface: MappingStrategy
      Transmutes a bean instance into an array of Strings to be written to a CSV file.
      Specified by:
      transmuteBean in interface MappingStrategy<I>
      Parameters:
      bean - The bean to be transmuted
      Returns:
      The converted values of the bean fields in the correct order, ready to be passed to a CSVWriter
      Throws:
      CsvFieldAssignmentException - A more specific subclass of this exception is thrown for any problem decoding and assigning a field of the input to a bean field
      CsvChainedException - If multiple exceptions are thrown for the same input line

    • determineConverter

      protected CsvConverter determineConverter(Field field, Class<?> elementType, String locale, String writeLocale, Class<? extends AbstractCsvConverter> customConverter) throws CsvBadConverterException
      Given the information provided, determines the appropriate built-in converter to be passed in to the BeanField being created.
      Parameters:
      field - The field of the bean type in question
      elementType - The type to be generated by the converter (on reading)
      locale - The locale for conversion on reading. May be null or an empty string if a locale is not in use.
      writeLocale - The locale for conversion on writing. May be null or an empty string if a locale is not in use.
      customConverter - An optional custom converter
      Returns:
      The appropriate converter for the necessary conversion
      Throws:
      CsvBadConverterException - If the converter cannot be instantiated
      Since:
      4.2

    • selectAnnotationForProfile

      protected <A extends Annotation> A selectAnnotationForProfile(A[] annotations, Function<A,String[]> getProfiles)
      Determines which one of a list of annotations applies to the currently selected profile. If no annotation specific to the profile is found, the annotation for the default profile is returned. If neither is found, null is returned.
      Type Parameters:
      A - The annotation type being tested
      Parameters:
      annotations - All annotations of a given type
      getProfiles - A function mapping an annotation of type A to the list of profiles it applies to
      Returns:
      The annotation with the appropriate profile or null if nothing appropriate is found
      Since:
      5.4