jdbc的学习之 路（四）

对于dml操作

除了sql语句不一样其他都一样的

进行重构

对于get和getall也是一样

package com_xyit_shadow_Dao.imp;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com_xyit_shadow_Dao.IResultSetHandle;
import util.Jdbcutil;

public class JdbcTemplate {
	/*
	 * 本类为jdbc的模板
	 * 方法为dml和dql的操作*/
	/*
	 * 更新操作*/
	@SuppressWarnings("finally")
	public static long update(String sql,Object... params) {
	   Connection conn=null;
		PreparedStatement ps=null;
		ResultSet rs = null;
		Long id = null;
		try {
				conn=Jdbcutil.getconn();
				ps=conn.prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);
				for (int i = 0; i < params.length; i++) {
					ps.setObject(i+1, params[i]);
				}
				ps.executeUpdate();	
				rs=ps.getGeneratedKeys();					
				if(rs.next()) {				
					id=rs.getLong(1);
			}else {
				id=(Long) params[params.length-1];			
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			Jdbcutil.close(conn, ps, rs);
			return id;
		}
	}
	@SuppressWarnings("finally")
	public static <T>List<T> get(String sql,IResultSetHandle<T> IRS,Object... params){
		List<T> ts=new ArrayList<>();
		Connection conn=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		try {
			conn=Jdbcutil.getconn();
			ps=conn.prepareStatement(sql);
			for (int i = 0; i < params.length; i++) {
				ps.setObject(i+1, params[i]);
			}
			rs=ps.executeQuery();
			ts=IRS.handle(rs);
		} catch (Exception e) {
			// TODO: handle exception
		}finally {
			Jdbcutil.close(conn, ps, rs);
			return ts;
		}
		
		}
}

对于结果集的处理也可以提取出模板

创建IResultSetHandler接口来规范结果集的方法

package com_xyit_shadow_Dao;

import java.sql.ResultSet;
import java.util.List;

public interface IResultSetHandle<T> {
	//处理结果集的接口
	 List<T> handle(ResultSet rs)throws Exception;
}

一个通用模板 beaninfoHandler

package com_xyit_shadow_Dao.imp;

import java.beans.BeanInfo;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import com_xyit_shadow_Dao.IResultSetHandle;

public class BeanHandler<T> implements IResultSetHandle<T>{
	private Class<T> classtype;	
	public BeanHandler(Class<T> classtype) {
		this.classtype = classtype;
	}

	public List<T> handle(ResultSet rs) throws Exception {
		List<T> list=new ArrayList<>();
		while(rs.next()) {
		BeanInfo beanInfo=Introspector.getBeanInfo(classtype,Object.class);
		PropertyDescriptor[] pds=beanInfo.getPropertyDescriptors();
		T user=classtype.newInstance();
		list.add(user);
		for (PropertyDescriptor pd : pds) {			
			Method setter=pd.getWriteMethod();
			String name=pd.getName();
			Object val=rs.getObject(name);	
			setter.invoke(user,val);		
		}
		}
		return list;
		
	}


}