/*
* 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 net.paoding.rose.jade.rowmapper;
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.BeanInstantiationException;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.NotWritablePropertyException;
import org.springframework.dao.DataRetrievalFailureException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.jdbc.core.RowMapper;
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>
* 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
* @author 王志亮 [qieqie.wang@gmail.com]
* @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 final Class<?> mappedClass;
/** Map of the fields we provide mapping for */
private Map<String, PropertyDescriptor> mappedFields;
private final boolean checkColumns;
private final boolean checkProperties;
/** Set of bean properties we provide mapping for */
private Set<String> mappedProperties;
/**
* 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, boolean checkColumns, boolean checkProperties) {
this.mappedClass = mappedClass;
Assert.state(this.mappedClass != null, "Mapped class was not specified");
this.checkProperties = checkProperties;
this.checkColumns = checkColumns;
initialize();
}
/**
* Initialize the mapping metadata for the given class.
*
* @param mappedClass the mapped class.
*/
protected void initialize() {
this.mappedFields = new HashMap<String, PropertyDescriptor>();
PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(mappedClass);
if (checkProperties) {
mappedProperties = new HashSet<String>();
}
for (int i = 0; i < pds.length; i++) {
PropertyDescriptor pd = pds[i];
if (pd.getWriteMethod() != null) {
if (checkProperties) {
this.mappedProperties.add(pd.getName());
}
this.mappedFields.put(pd.getName().toLowerCase(), pd);
for (String underscoredName : underscoreName(pd.getName())) {
if (underscoredName != null
&& !pd.getName().toLowerCase().equals(underscoredName)) {
this.mappedFields.put(underscoredName, pd);
}
}
}
}
}
/**
* 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 camelCaseName the string containing original name
* @return the converted name
*/
private String[] underscoreName(String camelCaseName) {
StringBuilder result = new StringBuilder();
if (camelCaseName != null && camelCaseName.length() > 0) {
result.append(camelCaseName.substring(0, 1).toLowerCase());
for (int i = 1; i < camelCaseName.length(); i++) {
char ch = camelCaseName.charAt(i);
if (Character.isUpperCase(ch)) {
result.append("_");
result.append(Character.toLowerCase(ch));
} else {
result.append(ch);
}
}
}
String name = result.toString();
// 当name为user1_name2时，使name2为user_1_name_2
// 这使得列user_1_name_2的列能映射到user1Name2属性
String name2 = null;
boolean digitFound = false;
for (int i = name.length() - 1; i >= 0; i--) {
if (Character.isDigit(name.charAt(i))) {
// 遇到数字就做一个标识并continue,直到不是时才不continue
digitFound = true;
continue;
}
// 只有上一个字符是数字才做下划线
if (digitFound && i < name.length() - 1 && i > 0) {
if (name2 == null) {
name2 = name;
}
name2 = name2.substring(0, i + 1) + "_" + name2.substring(i + 1);
}
digitFound = false;
}
return new String[] { name, name2 };
}
/**
* 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 {
// spring's : Object mappedObject = BeanUtils.instantiateClass(this.mappedClass);
// jade's : private Object instantiateClass(this.mappedClass);
// why: 经过简单的笔记本测试，mappedClass.newInstrance性能比BeanUtils.instantiateClass(mappedClass)快1个数量级
Object mappedObject = instantiateClass(this.mappedClass);
BeanWrapper bw = new BeanWrapperImpl(mappedObject);
ResultSetMetaData rsmd = rs.getMetaData();
int columnCount = rsmd.getColumnCount();
boolean warnEnabled = logger.isWarnEnabled();
boolean debugEnabled = logger.isDebugEnabled();
Set<String> populatedProperties = (checkProperties ? new HashSet<String>() : null);
for (int index = 1; index <= columnCount; index++) {
String column = JdbcUtils.lookupColumnName(rsmd, index).toLowerCase();
PropertyDescriptor pd = this.mappedFields.get(column);
if (pd != null) {
try {
Object value = JdbcUtils.getResultSetValue(rs, index, pd.getPropertyType());
if (debugEnabled && rowNumber == 0) {
logger.debug("Mapping column '" + column + "' to property '" + pd.getName()
+ "' of type " + pd.getPropertyType());
}
bw.setPropertyValue(pd.getName(), value);
if (populatedProperties != null) {
populatedProperties.add(pd.getName());
}
} catch (NotWritablePropertyException ex) {
throw new DataRetrievalFailureException("Unable to map column " + column
+ " to property " + pd.getName(), ex);
}
} else {
if (checkColumns) {
throw new InvalidDataAccessApiUsageException("Unable to map column '" + column
+ "' to any properties of bean " + this.mappedClass.getName());
}
if (warnEnabled && rowNumber == 0) {
logger.warn("Unable to map column '" + column + "' to any properties of bean "
+ this.mappedClass.getName());
}
}
}
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;
}
/**
*
* @param clazz
* @return
* @throws BeanInstantiationException
* @see {@link BeanUtils#instantiateClass(Class)}
*/
private static Object instantiateClass(Class<?> clazz) throws BeanInstantiationException {
/*- spring's BeanUtils.instantiateClass()
Assert.notNull(clazz, "Class must not be null");
if (clazz.isInterface()) {
throw new BeanInstantiationException(clazz, "Specified class is an interface");
}
try {
return instantiateClass(clazz.getDeclaredConstructor((Class[]) null), null);
}
catch (NoSuchMethodException ex) {
throw new BeanInstantiationException(clazz, "No default constructor found", ex);
}*/
try {
return clazz.newInstance();
} catch (Exception ex) {
throw new BeanInstantiationException(clazz, ex.getMessage(), ex);
}
}
}