irowprocessor.java

数据库的基本处理类

package com.neu.wrm.common;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.*;

import org.apache.commons.dbutils.RowProcessor;

/*
 * Created on 2005-4-12
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

/**
 * @author liuyuguang
 * 
 * TODO To change the template for this generated type comment go to Window -
 * Preferences - Java - Code Style - Code Templates
 */
public class IRowProcessor implements RowProcessor {
	public Object[] toArray(ResultSet rs) throws java.sql.SQLException {
		return null;
	}

	public Object toBean(ResultSet rs, Class type) throws java.sql.SQLException {
		Map property = propertyDescriptors(type);//获取property的集合
		ResultSetMetaData rsmd = rs.getMetaData();
		Map mapColumnProperties = MapColumnProperties(rsmd, property);//获取column与property之间的映射集合

		return createBean(rs, type, mapColumnProperties);//返回创建的bean
	}

	public List toBeanList(ResultSet rs, Class type)
			throws java.sql.SQLException {
		Map property = propertyDescriptors(type);//获取property的集合

		List list = new ArrayList();
		
		while (rs.next()) {
			ResultSetMetaData rsmd = rs.getMetaData();
			Map mapColumnProperties = MapColumnProperties(rsmd, property);//获取column与property之间的映射集合
			Object ob = createBean(rs, type, mapColumnProperties);
			list.add(ob);
		}
		return list;
	}

	public Map toMap(ResultSet rs) throws java.sql.SQLException {
		return null;
	}

	//通过column和property之间的映射map，将resultSet赋值到bean当中
	private Object createBean(ResultSet result, Class type, Map colp)
			throws java.sql.SQLException {
		Object target = newInstance(type);//实例化type类
		
		for (Iterator it = colp.entrySet().iterator(); it.hasNext();) {
		    String value = "";
			Map.Entry entry = (Map.Entry) it.next();
			if (result.getObject(entry.getKey().toString()) != null)
				value = result.getObject(entry.getKey().toString()).toString();//将指定的column的值赋给value
			PropertyDescriptor property = (PropertyDescriptor) entry.getValue();//取出映射map中的property
			callSetter(target, property, value);//调用callSetter将value装入到指定的property
		}
		return target;
	}

	//创建column和property之间的映射map
	private Map MapColumnProperties(ResultSetMetaData rsmd, Map pds)
			throws java.sql.SQLException {
		int s = rsmd.getColumnCount();
		Map colp = new HashMap();
		for (int i = 1; i <= s; i++) {
			//将property集中与columnName相同的property装入到map当中
			if (pds.containsKey(rsmd.getColumnName(i)))
				colp.put(rsmd.getColumnName(i), pds.get(rsmd.getColumnName(i)));
		}
		return colp;
	}

	//调用指定property的set方法，将value装入指定的类对象(target)
	private void callSetter(Object target, PropertyDescriptor property,
			Object value) throws java.sql.SQLException {
		Method method = property.getWriteMethod();
		try {

			method.invoke(target, new Object[] { value });
		} catch (IllegalArgumentException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

	private boolean isCompitableType(Object ob, Class type) {
		if (type.isInstance(ob))
			return true;
		else
			return false;
	}

	private Object newInstance(Class type) throws java.sql.SQLException {
		Object ob = null;
		try {
			ob = type.newInstance();
		} catch (InstantiationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return ob;
	}

	//将指定类的property装入map
	private Map propertyDescriptors(Class type) throws java.sql.SQLException {
		Map propertymap = new HashMap();
		try {

			BeanInfo beaninfo = Introspector.getBeanInfo(type);
			PropertyDescriptor[] p = beaninfo.getPropertyDescriptors();
			for (int i = 0; i < p.length; i++) {
				propertymap.put(p[i].getName().toUpperCase(), p[i]);//以属性名作为key值
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return propertymap;
	}
}