com.opencsv.bean.ColumnPositionMappingStrategy Maven / Gradle / Ivy
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A simple library for reading and writing CSV in Java
package com.opencsv.bean;
import com.opencsv.CSVReader;
import com.opencsv.ICSVParser;
import com.opencsv.exceptions.CsvRequiredFieldEmptyException;
import org.apache.commons.collections4.ListValuedMap;
import org.apache.commons.lang3.ArrayUtils;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.*;
/**
* Allows for the mapping of columns with their positions. Using this strategy
* without annotations ({@link com.opencsv.bean.CsvBindByPosition} or
* {@link com.opencsv.bean.CsvCustomBindByPosition}) requires all the columns
* to be present in the CSV file and for them to be in a particular order. Using
* annotations allows one to specify arbitrary zero-based column numbers for
* each bean member variable to be filled. Also this strategy requires that the
* file does NOT have a header. That said, the main use of this strategy is
* files that do not have headers.
*
* @param Type of object that is being processed.
*/
public class ColumnPositionMappingStrategy extends AbstractMappingStrategy, T> {
/**
* Whether the user has programmatically set the map from column positions
* to field names.
*/
private boolean columnsExplicitlySet = false;
/**
* The map from column position to {@link BeanField}.
*/
private FieldMapByPosition fieldMap;
/**
* Holds a {@link java.util.Comparator} to sort columns on writing.
*/
private Comparator writeOrder;
/**
* Used to store a mapping from presumed input column index to desired
* output column index, as determined by applying {@link #writeOrder}.
*/
private Integer[] columnIndexForWriting = null;
/**
* Default constructor. Considered stable.
* @see ColumnPositionMappingStrategyBuilder
*/
public ColumnPositionMappingStrategy() {
}
/**
* There is no header per se for this mapping strategy, but this method
* checks the first line to determine how many fields are present and
* adjusts its field map accordingly.
*/
// The rest of the Javadoc is inherited
@Override
public void captureHeader(CSVReader reader) throws IOException {
// Validation
if (type == null) {
throw new IllegalStateException(ResourceBundle
.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale)
.getString("type.unset"));
}
String[] firstLine = ArrayUtils.nullToEmpty(reader.peek());
fieldMap.setMaxIndex(firstLine.length - 1);
if (!columnsExplicitlySet) {
headerIndex.clear();
for (FieldMapByPositionEntry entry : fieldMap) {
Field f = entry.getField().getField();
if (f.getAnnotation(CsvCustomBindByPosition.class) != null
|| f.getAnnotation(CsvBindAndSplitByPosition.class) != null
|| f.getAnnotation(CsvBindAndJoinByPosition.class) != null
|| f.getAnnotation(CsvBindByPosition.class) != null) {
headerIndex.put(entry.getPosition(), f.getName().toUpperCase().trim());
}
}
}
}
/**
* @return {@inheritDoc} For this mapping strategy, it's simply
* {@code index} wrapped as an {@link java.lang.Integer}.
*/
// The rest of the Javadoc is inherited
@Override
protected Integer chooseMultivaluedFieldIndexFromHeaderIndex(int index) {
return Integer.valueOf(index);
}
@Override
protected BeanField findField(int col) {
// If we have a mapping for changing the order of the columns on
// writing, be sure to use it.
if (columnIndexForWriting != null) {
return col < columnIndexForWriting.length ? fieldMap.get(columnIndexForWriting[col]) : null;
}
return fieldMap.get(col);
}
/**
* This method returns an empty array.
* The column position mapping strategy assumes that there is no header, and
* thus it also does not write one, accordingly.
*
* @return An empty array
*/
// The rest of the Javadoc is inherited
@Override
public String[] generateHeader(T bean) throws CsvRequiredFieldEmptyException {
String[] h = super.generateHeader(bean);
columnIndexForWriting = new Integer[h.length];
Arrays.setAll(columnIndexForWriting, i -> i);
// Create the mapping for input column index to output column index.
Arrays.sort(columnIndexForWriting, writeOrder);
return ArrayUtils.EMPTY_STRING_ARRAY;
}
/**
* Gets a column name.
*
* @param col Position of the column.
* @return Column name or null if col > number of mappings.
*/
@Override
public String getColumnName(int col) {
return headerIndex.getByPosition(col);
}
/**
* Retrieves the column mappings.
*
* @return String array with the column mappings.
*/
public String[] getColumnMapping() {
return headerIndex.getHeaderIndex();
}
/**
* Setter for the column mapping.
* This mapping is for reading. Use of this method in conjunction with
* writing is undefined.
*
* @param columnMapping Column names to be mapped.
*/
public void setColumnMapping(String... columnMapping) {
if (columnMapping != null) {
headerIndex.initializeHeaderIndex(columnMapping);
} else {
headerIndex.clear();
}
columnsExplicitlySet = true;
if(getType() != null) {
loadFieldMap(); // In case setType() was called first.
}
}
/**
* Register a binding between a bean field and a custom converter.
*
* @param annotation The annotation attached to the bean field
* @param localType The class/type in which the field resides
* @param localField The bean field
*/
private void registerCustomBinding(CsvCustomBindByPosition annotation, Class localType, Field localField) {
@SuppressWarnings("unchecked")
Class> converter = (Class>)annotation.converter();
BeanField bean = instantiateCustomConverter(converter);
bean.setType(localType);
bean.setField(localField);
bean.setRequired(annotation.required());
fieldMap.put(annotation.position(), bean);
}
/**
* Register a binding between a bean field and a collection converter that
* splits input into multiple values.
*
* @param annotation The annotation attached to the bean field
* @param localType The class/type in which the field resides
* @param localField The bean field
*/
private void registerSplitBinding(CsvBindAndSplitByPosition annotation, Class localType, Field localField) {
String fieldLocale = annotation.locale();
String fieldWriteLocale = annotation.writeLocaleEqualsReadLocale()
? fieldLocale
: annotation.writeLocale();
Class elementType = annotation.elementType();
CsvConverter converter = determineConverter(localField, elementType,
fieldLocale, fieldWriteLocale, annotation.converter());
fieldMap.put(annotation.position(), new BeanFieldSplit<>(
localType, localField, annotation.required(), errorLocale, converter,
annotation.splitOn(), annotation.writeDelimiter(),
annotation.collectionType(), elementType, annotation.capture(),
annotation.format()));
}
/**
* Register a binding between a bean field and a multi-valued converter
* that joins values from multiple columns.
*
* @param annotation The annotation attached to the bean field
* @param localType The class/type in which the field resides
* @param localField The bean field
*/
private void registerJoinBinding(CsvBindAndJoinByPosition annotation, Class localType, Field localField) {
String fieldLocale = annotation.locale();
String fieldWriteLocale = annotation.writeLocaleEqualsReadLocale()
? fieldLocale
: annotation.writeLocale();
CsvConverter converter = determineConverter(localField, annotation.elementType(),
fieldLocale, fieldWriteLocale, annotation.converter());
fieldMap.putComplex(annotation.position(), new BeanFieldJoinIntegerIndex<>(
localType, localField, annotation.required(), errorLocale, converter,
annotation.mapType(), annotation.capture(), annotation.format()));
}
/**
* Register a binding between a bean field and a simple converter.
*
* @param annotation The annotation attached to the bean field
* @param localType The class/type in which the field resides
* @param localField The bean field
*/
private void registerBinding(CsvBindByPosition annotation, Class localType, Field localField) {
String fieldLocale = annotation.locale();
String fieldWriteLocale = annotation.writeLocaleEqualsReadLocale()
? fieldLocale
: annotation.writeLocale();
CsvConverter converter = determineConverter(localField, localField.getType(), fieldLocale, fieldWriteLocale, null);
fieldMap.put(annotation.position(), new BeanFieldSingleValue<>(
localType, localField, annotation.required(), errorLocale,
converter, annotation.capture(), annotation.format()));
}
/**
* Creates a map of annotated fields in the bean to be processed.
* This method is called by {@link #loadFieldMap()} when at least one
* relevant annotation is found on a member variable.
*/
@Override
protected void loadAnnotatedFieldMap(ListValuedMap, Field> fields) {
for (Map.Entry, Field> classAndField : fields.entries()) {
Class localType = classAndField.getKey();
Field localField = classAndField.getValue();
// Custom converters always have precedence.
if (localField.isAnnotationPresent(CsvCustomBindByPosition.class)
|| localField.isAnnotationPresent(CsvCustomBindByPositions.class)) {
CsvCustomBindByPosition annotation = selectAnnotationForProfile(
localField.getAnnotationsByType(CsvCustomBindByPosition.class),
CsvCustomBindByPosition::profiles);
if (annotation != null) {
registerCustomBinding(annotation, localType, localField);
}
}
// Then check for a collection
else if (localField.isAnnotationPresent(CsvBindAndSplitByPosition.class)
|| localField.isAnnotationPresent(CsvBindAndSplitByPositions.class)) {
CsvBindAndSplitByPosition annotation = selectAnnotationForProfile(
localField.getAnnotationsByType(CsvBindAndSplitByPosition.class),
CsvBindAndSplitByPosition::profiles);
if (annotation != null) {
registerSplitBinding(annotation, localType, localField);
}
}
// Then check for a multi-column annotation
else if (localField.isAnnotationPresent(CsvBindAndJoinByPosition.class)
|| localField.isAnnotationPresent(CsvBindAndJoinByPositions.class)) {
CsvBindAndJoinByPosition annotation = selectAnnotationForProfile(
localField.getAnnotationsByType(CsvBindAndJoinByPosition.class),
CsvBindAndJoinByPosition::profiles);
if (annotation != null) {
registerJoinBinding(annotation, localType, localField);
}
}
// Then it must be a bind by position.
else {
CsvBindByPosition annotation = selectAnnotationForProfile(
localField.getAnnotationsByType(CsvBindByPosition.class),
CsvBindByPosition::profiles);
if (annotation != null) {
registerBinding(annotation, localType, localField);
}
}
}
}
@Override
protected void loadUnadornedFieldMap(ListValuedMap, Field> fields) {
for(Map.Entry, Field> classAndField : fields.entries()) {
Class localType = classAndField.getKey();
Field localField = classAndField.getValue();
CsvConverter converter = determineConverter(localField, localField.getType(), null, null, null);
int[] indices = headerIndex.getByName(localField.getName());
if(indices.length != 0) {
fieldMap.put(indices[0], new BeanFieldSingleValue<>(
localType, localField, false, errorLocale, converter, null, null));
}
}
}
/**
* Returns a set of the annotations that are used for binding in this
* mapping strategy.
* In this mapping strategy, those are currently:
* - {@link CsvBindByPosition}
* - {@link CsvCustomBindByPosition}
* - {@link CsvBindAndJoinByPosition}
* - {@link CsvBindAndSplitByPosition}
*
*/
@Override
protected Set> getBindingAnnotations() {
// With Java 9 this can be done more easily with Set.of()
return new HashSet<>(Arrays.asList(
CsvBindByPositions.class,
CsvCustomBindByPositions.class,
CsvBindAndJoinByPositions.class,
CsvBindAndSplitByPositions.class,
CsvBindByPosition.class,
CsvCustomBindByPosition.class,
CsvBindAndJoinByPosition.class,
CsvBindAndSplitByPosition.class));
}
@Override
protected void initializeFieldMap() {
fieldMap = new FieldMapByPosition<>(errorLocale);
fieldMap.setColumnOrderOnWrite(writeOrder);
}
@Override
protected void verifyLineLength(int numberOfFields) throws CsvRequiredFieldEmptyException {
if (!headerIndex.isEmpty()) {
BeanField f;
StringBuilder sb = null;
for (int i = numberOfFields; i <= headerIndex.findMaxIndex(); i++) {
f = findField(i);
if (f != null && f.isRequired()) {
if (sb == null) {
sb = new StringBuilder(ResourceBundle.getBundle(ICSVParser.DEFAULT_BUNDLE_NAME, errorLocale).getString("multiple.required.field.empty"));
}
sb.append(' ');
sb.append(f.getField().getName());
}
}
if (sb != null) {
throw new CsvRequiredFieldEmptyException(type, sb.toString());
}
}
}
/**
* Returns the column position for the given column number.
* Yes, they're the same thing. For this mapping strategy, it's a simple
* conversion from an integer to a string.
*/
// The rest of the Javadoc is inherited
@Override
public String findHeader(int col) {
return Integer.toString(col);
}
@Override
protected FieldMap, T> getFieldMap() {
return fieldMap;
}
/**
* Sets the {@link java.util.Comparator} to be used to sort columns when
* writing beans to a CSV file.
* Behavior of this method when used on a mapping strategy intended for
* reading data from a CSV source is not defined.
*
* @param writeOrder The {@link java.util.Comparator} to use. May be
* {@code null}, in which case the natural ordering is used.
* @since 4.3
*/
public void setColumnOrderOnWrite(Comparator writeOrder) {
this.writeOrder = writeOrder;
if (fieldMap != null) {
fieldMap.setColumnOrderOnWrite(this.writeOrder);
}
}
}
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