/*
* Copyright 2002-2008 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
*
* http://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.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.dao.DataRetrievalFailureException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.util.Assert;
/**
* {@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
* metadata 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</code>, 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 RowMapper.
*
* @author Thomas Risberg
* @author Juergen Hoeller
* @since 2.5
*/
public class BeanPropertyRowMapper implements RowMapper {
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
/** The class we are mapping to */
private Class mappedClass;
/** Whether we're strictly validating */
private boolean checkFullyPopulated = false;
/** Whether we're defaulting primitives when mapping a null value */
private boolean primitivesDefaultedForNullValue = false;
/** Map of the fields we provide mapping for */
private Map mappedFields;
/** Set of bean properties we provide mapping for */
private Set mappedProperties;
/**
* Create a new BeanPropertyRowMapper for bean-style configuration.
* @see #setMappedClass
* @see #setCheckFullyPopulated
*/
public BeanPropertyRowMapper() {
}
/**
* Create a new BeanPropertyRowMapper, accepting unpopulated properties
* in the target bean.
* @param mappedClass the class that each row should be mapped to
*/
public BeanPropertyRowMapper(Class mappedClass) {
initialize(mappedClass);
}
/**
* Create a new 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 mappedClass, boolean checkFullyPopulated) {
initialize(mappedClass);
this.checkFullyPopulated = checkFullyPopulated;
}
/**
* Set the class that each row should be mapped to.
*/
public void setMappedClass(Class mappedClass) {
if (this.mappedClass == null) {
initialize(mappedClass);
}
else {
if (!this.mappedClass.equals(mappedClass)) {
throw new InvalidDataAccessApiUsageException("The mapped class can not be reassigned to map to " +
mappedClass + " since it is already providing mapping for " + this.mappedClass);
}
}
}
/**
* Initialize the mapping metadata for the given class.
* @param mappedClass the mapped class.
*/
protected void initialize(Class mappedClass) {
this.mappedClass = mappedClass;
this.mappedFields = new HashMap();
this.mappedProperties = new HashSet();
PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
for (int i = 0; i < pds.length; i++) {
PropertyDescriptor pd = pds[i];
if (pd.getWriteMethod() != null) {
this.mappedFields.put(pd.getName().toLowerCase(), pd);
String underscoredName = underscoreName(pd.getName());
if (!pd.getName().toLowerCase().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 string containing original name
* @return the converted name
*/
private String underscoreName(String name) {
StringBuffer result = new StringBuffer();
if (name != null && name.length() > 0) {
result.append(name.substring(0, 1).toLowerCase());
for (int i = 1; i < name.length(); i++) {
String s = name.substring(i, i + 1);
if (s.equals(s.toUpperCase())) {
result.append("_");
result.append(s.toLowerCase());
}
else {
result.append(s);
}
}
}
return result.toString();
}
/**
* Get the class that we are mapping to.
*/
public final Class 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</code>, 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</code>, throwing an exception when nulls are mapped to Java primitives.
*/
public boolean isPrimitivesDefaultedForNullValue() {
return primitivesDefaultedForNullValue;
}
/**
* Return whether we're defaulting Java primitives in the case of mapping a null value from corresponding
* database fields.
*/
public void setPrimitivesDefaultedForNullValue(boolean primitivesDefaultedForNullValue) {
this.primitivesDefaultedForNullValue = primitivesDefaultedForNullValue;
}
/**
* Extract the values for all columns in the current row.
* <p>Utilizes public setters and result set metadata.
* @see java.sql.ResultSetMetaData
*/
public Object mapRow(ResultSet rs, int rowNumber) throws SQLException {
Assert.state(this.mappedClass != null, "Mapped class was not specified");
Object mappedObject = BeanUtils.instantiateClass(this.mappedClass);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
initBeanWrapper(bw);
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
Set populatedProperties = (isCheckFullyPopulated() ? new HashSet() : null);
for (int index = 1; index <= columnCount; index++) {
String column = JdbcUtils.lookupColumnName(rsmd, index).toLowerCase();
PropertyDescriptor pd = (PropertyDescriptor) this.mappedFields.get(column);
if (pd != null) {
try {
Object value = getColumnValue(rs, index, pd);
if (logger.isDebugEnabled() && rowNumber == 0) {
logger.debug("Mapping column '" + column + "' to property '" +
pd.getName() + "' of type " + pd.getPropertyType());
}
try {
bw.setPropertyValue(pd.getName(), value);
}
catch (TypeMismatchException e) {
if (value == null && primitivesDefaultedForNullValue) {
logger.debug("Intercepted TypeMismatchException for row " + rowNumber +
" and column '" + column + "' with value " + value +
" when setting property '" + pd.getName() + "' of type " + pd.getPropertyType() +
" on object: " + mappedObject);
}
else {
throw e;
}
}
if (populatedProperties != null) {
populatedProperties.add(pd.getName());
}
}
catch (NotWritablePropertyException ex) {
throw new DataRetrievalFailureException(
"Unable to map column " + column + " to property " + pd.getName(), ex);
}
}
}
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 + "]: " + this.mappedProperties);
}
return mappedObject;
}
/**
* Initialize the given BeanWrapper to be used for row mapping.
* To be called for each row.
* <p>The default implementation is empty. Can be overridden in subclasses.
* @param bw the BeanWrapper to initialize
*/
protected void initBeanWrapper(BeanWrapper bw) {
}
/**
* 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</code>.
* @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
* (or <code>null</code> if none specified)
* @return the Object value
* @throws SQLException in case of extraction failure
* @see org.springframework.jdbc.support.JdbcUtils#getResultSetValue(java.sql.ResultSet, int, Class)
*/
protected Object getColumnValue(ResultSet rs, int index, PropertyDescriptor pd) throws SQLException {
return JdbcUtils.getResultSetValue(rs, index, pd.getPropertyType());
}
}