在查询时候有时候要一条数据，有时候要的是一个结果集，然而有时候返回就是一个统计值，通过对resultset和resultsetmetadata的变换得到各类所需的查询结果，因为没有利用连接池数据链接管理比较麻烦，所以谢了一个工具类，
package com.sky.connect;import java.lang.reflect.invocationtargetexception;import java.sql.resultset;import java.sql.sqlexception;import java.util.arraylist;import java.util.hashmap;import java.util.list;import java.util.map;import org.apache.commons.beanutils.beanutils;import com.mysql.jdbc.connection;import com.mysql.jdbc.preparedstatement;import com.mysql.jdbc.resultsetmetadata;/** * dao设计模式 * * @author 潘琢文 * */public class dao { /** * 更新数据库操作 * * @param sql * @param args */ public void update(string sql, object... args) { connection connection = null; preparedstatement preparedstatement = null; try { connection = jdbctools.getconnection(); preparedstatement = (preparedstatement) connection .preparestatement(sql); for (int i = 0; i t get(class clazz, string sql, object... args) { t entity = null; connection connection = null; preparedstatement preparedstatement = null; resultset result = null; try { connection = jdbctools.getconnection(); preparedstatement = (preparedstatement) connection .preparestatement(sql); for (int i = 0; i map = new hashmap(); resultsetmetadata rsmd = (resultsetmetadata) result.getmetadata(); if (result.next()) { for (int i = 0; i 0) { entity = clazz.newinstance(); for (map.entry entry : map.entryset()) { string filedname = entry.getkey(); object filedobject = entry.getvalue(); beanutils.setproperty(entity, filedname, filedobject); } } } catch (exception e) { e.printstacktrace(); } finally { jdbctools.release(result, preparedstatement, connection); } return entity; } /** * 通用查询方法，返回一个结果集 * * @param clazz * @param sql * @param args * @return */ public list getforlist(class clazz, string sql, object... args) { list list = new arraylist(); connection connection = null; preparedstatement preparedstatement = null; resultset result = null; try { connection = jdbctools.getconnection(); preparedstatement = (preparedstatement) connection .preparestatement(sql); for (int i = 0; i > values = handleresultsettomaplist(result); list = transftermaplisttobeanlist(clazz, values); } catch (exception e) { e.printstacktrace(); } finally { jdbctools.release(result, preparedstatement, connection); } return list; } /** * * @param clazz * @param values * @return * @throws instantiationexception * @throws illegalaccessexception * @throws invocationtargetexception */ public list transftermaplisttobeanlist(class clazz, list> values) throws instantiationexception, illegalaccessexception, invocationtargetexception { list result = new arraylist(); t bean = null; if (values.size() > 0) { for (map m : values) { bean = clazz.newinstance(); for (map.entry entry : m.entryset()) { string propertyname = entry.getkey(); object value = entry.getvalue(); beanutils.setproperty(bean, propertyname, value); } // 13. 把 object 对象放入到 list 中. result.add(bean); } } return result; } /** * * @param resultset * @return * @throws sqlexception */ public list> handleresultsettomaplist( resultset resultset) throws sqlexception { list> values = new arraylist>(); list columnlabels = getcolumnlabels(resultset); map map = null; while (resultset.next()) { map = new hashmap(); for (string columnlabel : columnlabels) { object value = resultset.getobject(columnlabel); map.put(columnlabel, value); } values.add(map); } return values; } /** * * @param resultset * @return * @throws sqlexception */ private list getcolumnlabels(resultset resultset) throws sqlexception { list labels = new arraylist(); resultsetmetadata rsmd = (resultsetmetadata) resultset.getmetadata(); for (int i = 0; i e getforvalue(string sql, object... args) { connection connection = null; preparedstatement preparedstatement = null; resultset resultset = null; try { connection = jdbctools.getconnection(); preparedstatement = (preparedstatement) connection .preparestatement(sql); for (int i = 0; i
package com.sky.connect;import java.io.ioexception;import java.io.inputstream;import java.sql.drivermanager;import java.sql.resultset;import java.sql.sqlexception;import java.util.properties;import com.mysql.jdbc.connection;import com.mysql.jdbc.driver;import com.mysql.jdbc.preparedstatement;import com.mysql.jdbc.statement;/** * jdbc操作的工具类 版本 1.0 * * @author 潘琢文 * */public class jdbctools { /** * 使用preparedstatement进行数据更新 * * @param sql * @param args */ public static void update(string sql, object ... args) { connection connection = null; preparedstatement preparedstatement = null; try { connection = jdbctools.getconnection(); preparedstatement = (preparedstatement) connection .preparestatement(sql); for (int i = 0; i