【注】通常我们使用RowMapper（比如ParameterizedRowMapper），都需要定义好查询字段，，如果使用别名就没办法了。还要比如加入group，或者联合查询，也不能够使用，除非不想要非主体Bean之外的字段，那么只能用Map接收返回结果了，或者直接实现RowMapper。基于这一点，提出一个稍微通用的解决思路：所有的Bean都继承一个基类Bean，里面放一个Map（就是存放那些Bean没有指定的字段了，比如sum、count、avg … 各种查询字段或者别名），参考BeanPropertyRowMapper，在mapRow方法里面做些小调整，找不到的column就放到map里面，这样子的话，Bean有的字段就采用getxxx(),没有就从map里面取，好像会有点用。
#具体方法如下#
{private Map<String, Object> aliasFields = new HashMap<String, Object>();(String field, Object value) {aliasFields.put(field, value);}public Object getAliasFields(String field) {return aliasFields.get(field);}}
该类中只放一个map，存储Bean里面没有的字段，剩下的就是改造RowMapper实现类，可以拷贝BeanPropertyRowMapper，换个类名，直接修改mapRow方法，具体如下（改动量非常小，看注释）：
public T mapRow(ResultSet rs, int rowNumber) throws SQLException {Assert.state(this.mappedClass != null, “Mapped class was not specified”);T mappedObject = BeanUtils.instantiate(this.mappedClass);BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(mappedObject);initBeanWrapper(bw);ResultSetMetaData rsmd = rs.getMetaData();int columnCount = rsmd.getColumnCount();Set<String> populatedProperties = (isCheckFullyPopulated() ? new HashSet<String>() : null);for (int index = 1; index <= columnCount; index++) {String column = JdbcUtils.lookupColumnName(rsmd, index);PropertyDescriptor pd = this.mappedFields.get(column.replaceAll(” “, “”).toLowerCase());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);}} else {/// *****就是修改这个地方了！！！！Object value = JdbcUtils.getResultSetValue(rs, index);((BaseEntity)mappedObject).setAliasField(column, value);}}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;}
剩下的就是具体的Bean，继承BaseEntity，比如：
{serialVersionUID = 2233912281609962999L;private Integer id;private String name;private String password;private Date createTime;private Integer type;public Demo() {super.queryBuilder = new QueryBuilder(this);}(Integer id) {this.id = id;}public Integer getId () {return this.id;}(String name) {this.name = name;}public String getName () {return this.name;}(String password) {this.password = password;}public String getPassword () {return this.password;}(Date createTime) {this.createTime = createTime;}public Date getCreateTime () {return this.createTime;}(Integer type) {this.type = type;}public Integer getType () {return this.type;}}
查询的时候，就可以通过Demo Bean取出非表字段的数据，通过getAliasFields(String field)方法。个人感觉能够提高一定的便捷性，后续会加入sbrom中，关于sbrom可以查看，欢迎吐槽！
人生就像是一场旅行，遇到的既有感人的，
