数据库增，删，改，查通用范形实现

package com.yunchow.util;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;

/**
 * 能用DaoSupport类, 支持常见的功能如下:
 * 1, 增加一条记录, 并且返回主键值
 * 2, 可以按照Id, 或是任意条件删除N条记录
 * 3, 修改一条记录
 * 4, 统计指定表中总的记录条数, 还可以根据条件统计记录条数
 * 5, 返回表中的所有数据
 * 6, 返回表中指定页的数据, 页码和每页条数可更改,
 * 7, 返回表中指定页的指定条件的数据, 并且还能为该记录集合进行排序
 * @author yunchow
 * @version 1.2  09/9/3	15:14
 */
public class DaoSupport<T> {	 
	/** 要操作的实体对象 */
	protected Class<T> entityClass;
	/** Jdbc操作模板 */
	protected JdbcTemplate template = new JdbcTemplate();
	/** 通用行映射器 */
	protected RowMapper<T> mapper;
	/** 得到配置文件的信息 */
	protected ConfigBean config = ConfigBean.getInstance("pk-mapping.ini");
	/** 所对应表的主键值 */
	private String pk;
	
	public DaoSupport(Class<T> clazz) {
		this.entityClass = clazz;
		mapper = new GenericRowMapper<T>(entityClass);
		pk = config.getProperty(this.entityClass.getSimpleName());
		if(pk == null) pk="cafebabe";
		init();
		// System.out.println(entityClass.getName());
	}	
	protected Class<T> getPersistenceClass() {
		return this.entityClass;
	}
	// 子类用于扩展.
	public void init() {
		System.out.println("DaoSupport 初始化!");
	}
	/**
	 * 更改行映射器.
	 */
	public void setMapper(RowMapper<T> mapper) {
		this.mapper = mapper;
	}
	/**
	 * 统计表中总共行数
	 * @return
	 */
	public int count() {
		return template.count(entityClass.getSimpleName());
	}
	/**
	 * 根据条件统计行数
	 * @param sqlwhere
	 * @return
	 */
	public int count(String sqlwhere) {
		return template.count(entityClass.getSimpleName(), sqlwhere);
	}
	/**
	 * 删除一个对象, 根据某个非空条件
	 */
	public boolean remove(T t) {
		try {
			StringBuffer sql = new StringBuffer();
			sql.append("delete from ").append(entityClass.getSimpleName());
			sql.append(" where ");
			List<Object> params = new ArrayList<Object>();
			for(Field field : entityClass.getDeclaredFields()) {
				String sql0 = field.getName() + "=? and ";
				Method getter = this.getReadMethod(field);
				Object value = getter.invoke(t);
				// System.out.println(field.getName() + " = " + value);
				if(value!=null && !"".equals(value)) {
					sql.append(sql0);
					params.add(value);
				}
			}
			int index = sql.lastIndexOf("and");
			if(index > 0)
				sql.delete(index, sql.length()-1);
			System.out.println("sql = " + sql);
			return (template.update(sql.toString(), params.toArray()) > 0 );
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}
	/**
	 * 根据ID删除一个对象
	 */
	public boolean remove(int id) {
		String sql = "delete from "+this.entityClass.getSimpleName()
					+" where " + pk + "=" + id;
		System.out.println(sql);
		return (template.update(sql) > 0);
	}
	/**
	 * 清空表
	 */
	public boolean clear() {
		String sql = "delete from "+this.entityClass.getSimpleName();
		System.out.println(sql);
		return (template.update(sql) > 0);
	}
	/**
	 * 查找所有的信息
	 */
	public List<T> findAll() {
		String sql = "select * from " + this.entityClass.getSimpleName();
		System.out.println(sql);
		return template.findList(sql, mapper);
	}
	/**
	 * 根据某个属性查找对象
	 */
	public List<T> find(String propertyName, Object value) {
		StringBuffer sql = new StringBuffer();
		sql.append("select * from ")
			.append(this.entityClass.getSimpleName());
		sql.append(" where ")
		    .append(propertyName)
		    .append("=")
		    .append(value);
		System.out.println(sql);
		return template.findList(sql.toString(), mapper);
	}
	/**
	 * 根据where子句查找对象的集合
	 */
	public List<T> find(String sqlwhere) {
		String sql = "select * from " + this.entityClass.getSimpleName();
		sql += " where " + sqlwhere;
		System.out.println(sql);
		return template.findList(sql, mapper);
	}
	/**
	 * 根据where子句查找指定页的对象的集合
	 * 并且根据传过来的orderby子句, 对结果进行排序
	 */
	public List<T> find(int pageSize, int pageNo, String sqlwhere, String orderby) {
		if(pageNo <= 0) pageNo = 1;
		if(pageSize <= 0) pageSize = 5;
		boolean boo = true;
		if(sqlwhere==null || "".equals(sqlwhere.trim())) {
			boo = false;
		}
		StringBuffer sql = new StringBuffer();
		sql.append("select top ").append(pageSize)
		   .append(" * from "+ entityClass.getSimpleName() +"  where ").append(sqlwhere);
		if(boo)
			sql.append(" and ");
		sql.append(pk +" not in( select top ")
		   .append(pageSize*(pageNo-1))
		   .append(" "+ pk +" from "+ entityClass.getSimpleName());
		if(boo)
			sql.append(" where ");
		sql.append(sqlwhere).append(")");
		if(orderby!=null && !"".equals(orderby.trim()))
			sql.append(" order by ")
				.append(orderby);
		System.out.println(sql);
		return template.findList(sql.toString(), mapper);
	}
	/**
	 * 查找符合条件的指定页记录
	 * @param pageSize
	 * @param pageNo
	 * @param sqlwhere
	 * @return
	 */
	public List<T> find(int pageSize, int pageNo, String sqlwhere){
		return find(pageSize, pageNo, sqlwhere, "");
	}
	/**
	 * 查找指定页记录
	 * @param pageSize
	 * @param pageNo
	 * @return
	 */
	public List<T> find(int pageSize, int pageNo){
		return find(pageSize, pageNo, "", "");
	}
	/**
	 * 保存一个对象, 并且插入主键值, 而不是由数据库产生.
	 * 返回数据库产生的主键值, 如果保存失败则返回-1
	 */
	public int save(T t) {
		return save(t, false);
	}
	/**
	 * 保存一个对象 
	 * 返回数据库产生的主键值, 如果保存失败则返回-1
	 * @param boo 为true时则插入主键值, 否则不插入
	 */
	public int save(T t, boolean boo) {
		try {
			StringBuffer sql = new StringBuffer("insert into ");
			StringBuffer values = new StringBuffer(" values( ");
			List<Object> params = new ArrayList<Object>();
			sql.append(entityClass.getSimpleName() + "(");
			for(Field field : t.getClass().getDeclaredFields()) {
				if(boo || !pk.equals(field.getName())) {
					Method getter = getReadMethod(field);
					Object value = getter.invoke(t);
					if(value!=null) {
						sql.append(field.getName() + ",");
						values.append("?,");
						params.add(value);
					}
				}
			}
			values.deleteCharAt(values.length()-1);
			values.append(")");
			sql.deleteCharAt(sql.length()-1);
			sql.append(")").append(values);		
			System.out.println(sql);
			/*for(Object obj : params) {
				System.out.println(obj);
			}*/
			return template.save(sql.toString(), params.toArray());
		} catch (Exception e) {
			e.printStackTrace();
		}
		return -1;
	}
	/**
	 * 更新一个对象
	 */
	public boolean update(T t) {
		try {
			StringBuffer sql = new StringBuffer("update ");
			sql.append(entityClass.getSimpleName() + " set ");
			List<Object> params = new ArrayList<Object>();	
			Object pkValue = "";
			for(Field field : t.getClass().getDeclaredFields()) {
				if(!pk.equals(field.getName())) {
					sql.append(field.getName() + "=?,");
					Method getter = getReadMethod(field);
					params.add(getter.invoke(t));
				} else {
					Method getter = getReadMethod(field);
					pkValue = getter.invoke(t);
				}
			}
			sql.deleteCharAt(sql.length()-1);
			sql.append(" where ")
				.append(pk + "=?");
			params.add(pkValue);
			System.out.println(sql);
			for(Object obj : params) {
				System.out.println(obj);
			}
			System.out.println(sql);
			return (template.update(sql.toString(), params.toArray()) > 0);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}
	/**
	 * 得到属性的read方法
	 * @param field
	 * @return
	 * @throws SecurityException
	 * @throws NoSuchMethodException
	 */
	protected Method getReadMethod(Field field) throws SecurityException, NoSuchMethodException {
		String name = field.getName();
		String firstLetter = name.substring(0,1).toUpperCase();
		String methodName = "get" + firstLetter + name.substring(1);
		// System.out.println("方法名为:" + methodName);
		return entityClass.getMethod(methodName);
	}
	/**
	 * 得到属性的write方法
	 * @param field
	 * @return
	 * @throws NoSuchMethodException 
	 * @throws SecurityException 
	 * @throws SecurityException
	 * @throws NoSuchMethodException
	 */
	protected Method getWriteMethod(Field field) throws SecurityException, NoSuchMethodException {
		String name = field.getName();
		String firstLetter = name.substring(0,1).toUpperCase();
		String methodName = "set" + firstLetter + name.substring(1);
		System.out.println("方法名为:" + methodName);
		return entityClass.getMethod(methodName, field.getType());
	}
}