自己写的一个对java bean自动进行rowMapper or handler的类

一般情况下在进行jdbc编程的时候避免不了的要写n多的bean类，用来封装数据库获取的查询结果集，同时又要写n多的rowMapper或者handler来操作装配结果集中的数据进入bean中，最近研究了下自己写了一个对java bean自动进行rowMapper or handler的类 AutoBoxingRowMapper(其实现了spring jdbc的rowMapper)，这是一个通用的rowMapper，大多数情况下可以帮助我们省去写n多的rowMapper类。(注：在应用该类之前应该约定你的java bean中的属性名字的与sql查询中列名不区分大小写匹配，该类保证结果集与bean之间满足toLowerCase(columnName) = toLowerCase(propertyName)时才自动装配)代码如下：

AutoBoxingRowMapper.javapackage com.test.beans.mapper;import java.beans.IntrospectionException;import java.beans.Introspector;import java.beans.PropertyDescriptor;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.HashMap;import java.util.Map;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.springframework.jdbc.core.RowMapper;import org.springframework.jdbc.support.JdbcUtils;/** * @pengle  * 对查询数据结果集进行bean自动装箱 * (注:结果集与bean之间满足toLowerCase(columnName) = toLowerCase(propertyName))时才自动装箱 */public class AutoBoxingRowMapper implements RowMapper {protected final Log logger = LogFactory.getLog(this.getClass());private boolean stringNotEmpty = true;//结果集中由字段值全部以string类型返回其值,并且为空时以空串""返回private Class<Object> beanClass;//即将要进行包装的bean的Classprivate Map<String,PropertyDescriptor> beanPropertyMap = new HashMap<String,PropertyDescriptor>();//即将要进行包装的bean的属性描述,以Map形式保存public boolean isStringNotEmpty() {return stringNotEmpty;}public void setStringNotEmpty(boolean stringNotEmpty) {this.stringNotEmpty = stringNotEmpty;}public Class<Object> getBeanClass() {return beanClass;}public void setBeanClass(Class<Object> beanClass) {this.beanClass = beanClass;}public Map<String, PropertyDescriptor> getBeanPropertyMap() {return beanPropertyMap;}public void setBeanPropertyMap(Map<String, PropertyDescriptor> beanPropertyMap) {this.beanPropertyMap = beanPropertyMap;}/** * 自动装配sql查询结果集的各列值到beanClass所指定的bean中的对应属性上,满足toLowerCase(columnName) = toLowerCase(propertyName)时进行装配 * @param beanClass - 要装配的bean的java.lang.Class */@SuppressWarnings({"rawtypes", "unchecked"})public AutoBoxingRowMapper(Class beanClass){super();this.beanClass = beanClass;//初始化beanClass对应的bean的所有属性PropertyDescriptor[] props = null;try {props = Introspector.getBeanInfo(this.getBeanClass(), Object.class).getPropertyDescriptors();if (props != null) {for (int i = 0; i < props.length; i++) {this.beanPropertyMap.put(props[i].getName().toLowerCase().trim(), props[i]);}}} catch (IntrospectionException e) {logger.error(e, e);}}/** * 自动装配sql查询结果集的各列值到beanClass所指定的bean中的对应属性上,满足toLowerCase(columnName) = toLowerCase(propertyName)时进行装配 * @param beanClass - 要装配的bean的java.lang.Class * @param stringNotEmpty - 是否将结果集中由字段值全部以string类型返回其值,并且为空时以空串""返回,default true */@SuppressWarnings({"rawtypes"})public AutoBoxingRowMapper(Class beanClass,boolean stringNotEmpty){this(beanClass);this.stringNotEmpty = stringNotEmpty;}public Object mapRow(ResultSet rs, int rowNum) throws SQLException {Object defaultInstance = null;try {defaultInstance = this.getBeanClass().newInstance();//获取bean的实例} catch (Exception e) {logger.error(e, e);}if(defaultInstance == null){logger.error("attempt to new a instance of class named : " + this.getBeanClass().getName() + " but failed!!!");return null;}//获取元数据ResultSetMetaData rsmd = rs.getMetaData();int columnCount = rsmd.getColumnCount();PropertyDescriptor propertyDescriptor = null;try {for (int i = 1; i <= columnCount; i++) {String key = getColumnKey(JdbcUtils.lookupColumnName(rsmd, i));//获取resultset结果集中第i列对应的列名Object obj = getColumnValue(rs, i, key);//获取resultset结果集中第i列对应的值propertyDescriptor = this.beanPropertyMap.get(key);if(propertyDescriptor == null){//当前列名key对应的属性在bean中找不到,给予警告logger.warn("no corresponding property defined in class : " + this.getBeanClass().getName() + " for sql query resultset column '" + key + "' !!!");continue;}else{////当前列名key对应的属性在bean中找到,则调用其setXxx方法设置其值propertyDescriptor.getWriteMethod().invoke(defaultInstance, obj);}}} catch (Exception e) {logger.error(e, e);} return defaultInstance;}protected String getColumnKey(String columnName) {return columnName == null ? null : columnName.toLowerCase().trim();}@SuppressWarnings("rawtypes")protected Object getColumnValue(ResultSet rs, int index, String columnName) throws SQLException {Object val = null;if(stringNotEmpty){//所有列以string类型解析(前提做到要约定你的bean中的所有属性都定义成string类型)val = rs.getString(index) == null ? "" : rs.getString(index);}else{//所有类型以其bean类中对应的属性类型进行解析PropertyDescriptor propertyDescriptor = this.beanPropertyMap.get(columnName);if(propertyDescriptor != null){Class propertyTypeClass = propertyDescriptor.getPropertyType();String className = propertyTypeClass.getName();if(className.equals("int") || className.equals(Integer.class.getName())){val = rs.getInt(index);return val;}else if(className.equals("short") || className.equals(Short.class.getName())){val = rs.getShort(index);return val;}else if(className.equals("byte") || className.equals(Byte.class.getName())){val = rs.getByte(index);return val;}else if(className.equals("long") || className.equals(Long.class.getName())){val = rs.getLong(index);return val;}else if(className.equals("float") || className.equals(Float.class.getName())){val = rs.getFloat(index);return val;}else if(className.equals("double") || className.equals(Double.class.getName())){val = rs.getDouble(index);return val;}else if(className.equals("char") || className.equals(Character.class.getName())){val = rs.getString(index);return val;}else if(className.equals(String.class.getName())){val = rs.getString(index);return val;}else if(className.equals(java.util.Date.class.getName())){val = rs.getDate(index);return val;}else if(className.equals(java.math.BigDecimal.class.getName())){val = rs.getBigDecimal(index);return val;}else{//Objectval = rs.getObject(index);return val;}}else{val = JdbcUtils.getResultSetValue(rs, index);}}return val;}}

应用时,DAO中类似代码示例：List<Object> list = this.getJdbcTemplate().query(sql, new AutoBoxingRowMapper(Department.class,false));Map<String,Object> map = this.callProcedure(procName, new Object[]{deptNo,0,5}, new AutoBoxingRowMapper(Employee.class,false),true);