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public class BeanTransformerAdapter<T> implements ResultTransformer {
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
/** The class we are mapping to */
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;
/** Map of the fields we provide mapping for */
private Map<String, PropertyDescriptor> mappedFields;
/** Set of bean properties we provide mapping for */
private Set<String> mappedProperties;
/**
* Create a new BeanPropertyRowMapper for bean-style configuration.
* @see #setMappedClass
* @see #setCheckFullyPopulated
*/
public BeanTransformerAdapter() {
}
/**
* Create a new 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 BeanTransformerAdapter(Class<T> 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 BeanTransformerAdapter(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.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<T> mappedClass) {
this.mappedClass = mappedClass;
this.mappedFields = new HashMap<String, PropertyDescriptor>();
this.mappedProperties = new HashSet<String>();
PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
for (PropertyDescriptor pd : pds) {
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) {
if (!StringUtils.hasLength(name)) {
return "";
}
StringBuilder result = new StringBuilder();
result.append(name.substring(0, 1).toLowerCase());
for (int i = 1; i < name.length(); i++) {
String s = name.substring(i, i + 1);
String slc = s.toLowerCase();
if (!s.equals(slc)) {
result.append("_").append(slc);
} else {
result.append(s);
}
}
return result.toString();
}
/**
* Get the class that we are mapping to.
*/
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 primitivesDefaultedForNullValue;
}
/**
* 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}.
* @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} 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());
}
/**
* Static factory method to create a new 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) {
BeanPropertyRowMapper<T> newInstance = new BeanPropertyRowMapper<T>();
newInstance.setMappedClass(mappedClass);
return newInstance;
}
@Override
public Object transformTuple(Object[] tuple, String[] aliases) {
T mappedObject = BeanUtils.instantiate(this.mappedClass);
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);
initBeanWrapper(bw);
Set<String> populatedProperties = (isCheckFullyPopulated() ? new HashSet<String>() : null);
for (int i = 0; i < aliases.length; i++) {
String column = aliases[i];
PropertyDescriptor pd = this.mappedFields.get(column.replaceAll(" ", "").toLowerCase());
if (pd != null) {
try {
Object value = tuple[i];
try {
bw.setPropertyValue(pd.getName(), value);
} catch (TypeMismatchException e) {
if (value == null && primitivesDefaultedForNullValue) {
logger.debug("Intercepted TypeMismatchException for column " + column + " 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;
}
@Override
public List transformList(List list) {
return list;
}
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