org.springframework.jdbc.core.BeanPropertyRowMapper.java Source code

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/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.core;

import java.beans.PropertyDescriptor;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.NotWritablePropertyException;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.beans.TypeMismatchException;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.dao.DataRetrievalFailureException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;

/**
 * {@link RowMapper} implementation that converts a row into a new instance
 * of the specified mapped target class. The mapped target class must be a
 * top-level class and it must have a default or no-arg constructor.
 *
 * <p>Column values are mapped based on matching the column name as obtained from result set
 * meta-data to public setters for the corresponding properties. The names are matched either
 * directly or by transforming a name separating the parts with underscores to the same name
 * using "camel" case.
 *
 * <p>Mapping is provided for fields in the target class for many common types, e.g.:
 * String, boolean, Boolean, byte, Byte, short, Short, int, Integer, long, Long,
 * float, Float, double, Double, BigDecimal, {@code java.util.Date}, etc.
 *
 * <p>To facilitate mapping between columns and fields that don't have matching names,
 * try using column aliases in the SQL statement like "select fname as first_name from customer".
 *
 * <p>For 'null' values read from the database, we will attempt to call the setter, but in the case of
 * Java primitives, this causes a TypeMismatchException. This class can be configured (using the
 * primitivesDefaultedForNullValue property) to trap this exception and use the primitives default value.
 * Be aware that if you use the values from the generated bean to update the database the primitive value
 * will have been set to the primitive's default value instead of null.
 *
 * <p>Please note that this class is designed to provide convenience rather than high performance.
 * For best performance, consider using a custom {@link RowMapper} implementation.
 *
 * @author Thomas Risberg
 * @author Juergen Hoeller
 * @since 2.5
 * @param <T> the result type
 */
public class BeanPropertyRowMapper<T> implements RowMapper<T> {

    /** Logger available to subclasses. */
    protected final Log logger = LogFactory.getLog(getClass());

    /** The class we are mapping to. */
    @Nullable
    private Class<T> mappedClass;

    /** Whether we're strictly validating. */
    private boolean checkFullyPopulated = false;

    /** Whether we're defaulting primitives when mapping a null value. */
    private boolean primitivesDefaultedForNullValue = false;

    /** ConversionService for binding JDBC values to bean properties. */
    @Nullable
    private ConversionService conversionService = DefaultConversionService.getSharedInstance();

    /** Map of the fields we provide mapping for. */
    @Nullable
    private Map<String, PropertyDescriptor> mappedFields;

    /** Set of bean properties we provide mapping for. */
    @Nullable
    private Set<String> mappedProperties;

    /**
     * Create a new {@code BeanPropertyRowMapper} for bean-style configuration.
     * @see #setMappedClass
     * @see #setCheckFullyPopulated
     */
    public BeanPropertyRowMapper() {
    }

    /**
     * Create a new {@code BeanPropertyRowMapper}, accepting unpopulated
     * properties in the target bean.
     * <p>Consider using the {@link #newInstance} factory method instead,
     * which allows for specifying the mapped type once only.
     * @param mappedClass the class that each row should be mapped to
     */
    public BeanPropertyRowMapper(Class<T> mappedClass) {
        initialize(mappedClass);
    }

    /**
     * Create a new {@code BeanPropertyRowMapper}.
     * @param mappedClass the class that each row should be mapped to
     * @param checkFullyPopulated whether we're strictly validating that
     * all bean properties have been mapped from corresponding database fields
     */
    public BeanPropertyRowMapper(Class<T> mappedClass, boolean checkFullyPopulated) {
        initialize(mappedClass);
        this.checkFullyPopulated = checkFullyPopulated;
    }

    /**
     * Set the class that each row should be mapped to.
     */
    public void setMappedClass(Class<T> mappedClass) {
        if (this.mappedClass == null) {
            initialize(mappedClass);
        } else {
            if (this.mappedClass != mappedClass) {
                throw new InvalidDataAccessApiUsageException("The mapped class can not be reassigned to map to "
                        + mappedClass + " since it is already providing mapping for " + this.mappedClass);
            }
        }
    }

    /**
     * Get the class that we are mapping to.
     */
    @Nullable
    public final Class<T> getMappedClass() {
        return this.mappedClass;
    }

    /**
     * Set whether we're strictly validating that all bean properties have been mapped
     * from corresponding database fields.
     * <p>Default is {@code false}, accepting unpopulated properties in the target bean.
     */
    public void setCheckFullyPopulated(boolean checkFullyPopulated) {
        this.checkFullyPopulated = checkFullyPopulated;
    }

    /**
     * Return whether we're strictly validating that all bean properties have been
     * mapped from corresponding database fields.
     */
    public boolean isCheckFullyPopulated() {
        return this.checkFullyPopulated;
    }

    /**
     * Set whether we're defaulting Java primitives in the case of mapping a null value
     * from corresponding database fields.
     * <p>Default is {@code false}, throwing an exception when nulls are mapped to Java primitives.
     */
    public void setPrimitivesDefaultedForNullValue(boolean primitivesDefaultedForNullValue) {
        this.primitivesDefaultedForNullValue = primitivesDefaultedForNullValue;
    }

    /**
     * Return whether we're defaulting Java primitives in the case of mapping a null value
     * from corresponding database fields.
     */
    public boolean isPrimitivesDefaultedForNullValue() {
        return this.primitivesDefaultedForNullValue;
    }

    /**
     * Set a {@link ConversionService} for binding JDBC values to bean properties,
     * or {@code null} for none.
     * <p>Default is a {@link DefaultConversionService}, as of Spring 4.3. This
     * provides support for {@code java.time} conversion and other special types.
     * @since 4.3
     * @see #initBeanWrapper(BeanWrapper)
     */
    public void setConversionService(@Nullable ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    /**
     * Return a {@link ConversionService} for binding JDBC values to bean properties,
     * or {@code null} if none.
     * @since 4.3
     */
    @Nullable
    public ConversionService getConversionService() {
        return this.conversionService;
    }

    /**
     * Initialize the mapping meta-data for the given class.
     * @param mappedClass the mapped class
     */
    protected void initialize(Class<T> mappedClass) {
        this.mappedClass = mappedClass;
        this.mappedFields = new HashMap<>();
        this.mappedProperties = new HashSet<>();
        PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
        for (PropertyDescriptor pd : pds) {
            if (pd.getWriteMethod() != null) {
                this.mappedFields.put(lowerCaseName(pd.getName()), pd);
                String underscoredName = underscoreName(pd.getName());
                if (!lowerCaseName(pd.getName()).equals(underscoredName)) {
                    this.mappedFields.put(underscoredName, pd);
                }
                this.mappedProperties.add(pd.getName());
            }
        }
    }

    /**
     * Convert a name in camelCase to an underscored name in lower case.
     * Any upper case letters are converted to lower case with a preceding underscore.
     * @param name the original name
     * @return the converted name
     * @since 4.2
     * @see #lowerCaseName
     */
    protected String underscoreName(String name) {
        if (!StringUtils.hasLength(name)) {
            return "";
        }
        StringBuilder result = new StringBuilder();
        result.append(lowerCaseName(name.substring(0, 1)));
        for (int i = 1; i < name.length(); i++) {
            String s = name.substring(i, i + 1);
            String slc = lowerCaseName(s);
            if (!s.equals(slc)) {
                result.append("_").append(slc);
            } else {
                result.append(s);
            }
        }
        return result.toString();
    }

    /**
     * Convert the given name to lower case.
     * By default, conversions will happen within the US locale.
     * @param name the original name
     * @return the converted name
     * @since 4.2
     */
    protected String lowerCaseName(String name) {
        return name.toLowerCase(Locale.US);
    }

    /**
     * Extract the values for all columns in the current row.
     * <p>Utilizes public setters and result set meta-data.
     * @see java.sql.ResultSetMetaData
     */
    @Override
    public T mapRow(ResultSet rs, int rowNumber) throws SQLException {
        Assert.state(this.mappedClass != null, "Mapped class was not specified");
        T mappedObject = BeanUtils.instantiateClass(this.mappedClass);
        BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
        initBeanWrapper(bw);

        ResultSetMetaData rsmd = rs.getMetaData();
        int columnCount = rsmd.getColumnCount();
        Set<String> populatedProperties = (isCheckFullyPopulated() ? new HashSet<>() : null);

        for (int index = 1; index <= columnCount; index++) {
            String column = JdbcUtils.lookupColumnName(rsmd, index);
            String field = lowerCaseName(StringUtils.delete(column, " "));
            PropertyDescriptor pd = (this.mappedFields != null ? this.mappedFields.get(field) : null);
            if (pd != null) {
                try {
                    Object value = getColumnValue(rs, index, pd);
                    if (rowNumber == 0 && logger.isDebugEnabled()) {
                        logger.debug("Mapping column '" + column + "' to property '" + pd.getName() + "' of type '"
                                + ClassUtils.getQualifiedName(pd.getPropertyType()) + "'");
                    }
                    try {
                        bw.setPropertyValue(pd.getName(), value);
                    } catch (TypeMismatchException ex) {
                        if (value == null && this.primitivesDefaultedForNullValue) {
                            if (logger.isDebugEnabled()) {
                                logger.debug("Intercepted TypeMismatchException for row " + rowNumber
                                        + " and column '" + column + "' with null value when setting property '"
                                        + pd.getName() + "' of type '"
                                        + ClassUtils.getQualifiedName(pd.getPropertyType()) + "' on object: "
                                        + mappedObject, ex);
                            }
                        } else {
                            throw ex;
                        }
                    }
                    if (populatedProperties != null) {
                        populatedProperties.add(pd.getName());
                    }
                } catch (NotWritablePropertyException ex) {
                    throw new DataRetrievalFailureException(
                            "Unable to map column '" + column + "' to property '" + pd.getName() + "'", ex);
                }
            } else {
                // No PropertyDescriptor found
                if (rowNumber == 0 && logger.isDebugEnabled()) {
                    logger.debug("No property found for column '" + column + "' mapped to field '" + field + "'");
                }
            }
        }

        if (populatedProperties != null && !populatedProperties.equals(this.mappedProperties)) {
            throw new InvalidDataAccessApiUsageException(
                    "Given ResultSet does not contain all fields " + "necessary to populate object of class ["
                            + this.mappedClass.getName() + "]: " + this.mappedProperties);
        }

        return mappedObject;
    }

    /**
     * Initialize the given BeanWrapper to be used for row mapping.
     * To be called for each row.
     * <p>The default implementation applies the configured {@link ConversionService},
     * if any. Can be overridden in subclasses.
     * @param bw the BeanWrapper to initialize
     * @see #getConversionService()
     * @see BeanWrapper#setConversionService
     */
    protected void initBeanWrapper(BeanWrapper bw) {
        ConversionService cs = getConversionService();
        if (cs != null) {
            bw.setConversionService(cs);
        }
    }

    /**
     * Retrieve a JDBC object value for the specified column.
     * <p>The default implementation calls
     * {@link JdbcUtils#getResultSetValue(java.sql.ResultSet, int, Class)}.
     * Subclasses may override this to check specific value types upfront,
     * or to post-process values return from {@code getResultSetValue}.
     * @param rs is the ResultSet holding the data
     * @param index is the column index
     * @param pd the bean property that each result object is expected to match
     * @return the Object value
     * @throws SQLException in case of extraction failure
     * @see org.springframework.jdbc.support.JdbcUtils#getResultSetValue(java.sql.ResultSet, int, Class)
     */
    @Nullable
    protected Object getColumnValue(ResultSet rs, int index, PropertyDescriptor pd) throws SQLException {
        return JdbcUtils.getResultSetValue(rs, index, pd.getPropertyType());
    }

    /**
     * Static factory method to create a new {@code BeanPropertyRowMapper}
     * (with the mapped class specified only once).
     * @param mappedClass the class that each row should be mapped to
     */
    public static <T> BeanPropertyRowMapper<T> newInstance(Class<T> mappedClass) {
        return new BeanPropertyRowMapper<>(mappedClass);
    }

}