Java JDBC基础（一）
package com.yli.demo;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;/** * 创建与关闭JDBC连接 * @author yli * */public class ConnectionUtil {/** * 创建连接 * @return */ public static Connection getConnection() { String url = "jdbc:mysql://localhost:3306/world"; String user = "root"; String password = "123456"; Connection conn = null; try { Class.forName("com.mysql.jdbc.Driver"); conn = DriverManager.getConnection(url, user, password); } catch (SQLException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } return conn; } /** * 关闭连接 * @param conn */ public static void close(Connection conn){ if(null != conn) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } }}
?
?
1.3 为方便查询结果集ResultSet编写工具类RowMapper
?
package com.yli.dal.util;import java.lang.reflect.Field;import java.sql.ResultSet;import java.sql.ResultSetMetaData;import java.sql.SQLException;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;/** * 简单的结果集与Java对象转换 * @author yli * * @param <T> */public class RowMapper<T> {/** * 遍历结果集，将数据转换成指定的class类型<br> * 适合结果集包含多条记录 * @param classes * @param rs * @return */ public static <T> List<T> getForList(Class<T> classes, ResultSet rs) { List<T> resultList = new ArrayList<T>(); Field[] fileds = classes.getDeclaredFields(); try { T object; while (rs.next()) { object = getObject(classes, rs, fileds); if (null != object) { resultList.add(object); } } return resultList; } catch (SQLException e) { e.printStackTrace(); } return null; }/** * 遍历结果集，将数据转换成指定的class类型<br> * 适合结果集包含单条记录,如果不是则取第一条 * @param classes * @param rs * @return */ public static <T> T getForObject(Class<T> classes, ResultSet rs) { List<T> resultList = getForList(classes, rs); if (null != resultList && !resultList.isEmpty()) { return resultList.get(0); } return null; }/** * 遍历结果集，将数据转换成指定的List<Map<String, Object>>类型<br> * 适合结果集包含单条记录 * @param rs */ public static List<Map<String, Object>> getForList(ResultSet rs) { List<Map<String, Object>> resultList = null; try { resultList = new ArrayList<Map<String, Object>>(); ResultSetMetaData rsMeta = rs.getMetaData(); int columnCount = rsMeta.getColumnCount(); int index; String columnLabel; while (rs.next()) { Map<String, Object> resultMap = new HashMap<String, Object>(); for (index = 1; index <= columnCount; index++) { columnLabel = rsMeta.getColumnLabel(index); resultMap.put(columnLabel, rs.getObject(columnLabel)); } resultList.add(resultMap); } } catch (SQLException e) { e.printStackTrace(); } return resultList; }/** * 遍历结果集，将数据转换成指定的Map<String, Object>类型<br> * 适合结果集包含单条记录,如果不是则取第一条 * @param rs */ public static Map<String, Object> getForMap(ResultSet rs) { List<Map<String, Object>> resultList = getForList(rs); if (null != resultList && !resultList.isEmpty()) { return resultList.get(0); } return null; } private static <T> T getObject(Class<T> classes, ResultSet rs, Field[] fileds) { T object = null; try { object = classes.newInstance(); for (Field field : fileds) { String fieldName = field.getName(); field.setAccessible(true); field.set(object, rs.getObject(fieldName)); } } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } return object; }}?
1.4 为方便本例演示,编写与ES_T_SHOP_AFFICHE表结构字段对应的实体类
?
package com.yli.entity;/** * 简单实体,与数据表ES_T_SHOP_AFFICHE字段一一对应<br> * 方便将结果集ResultSet映射到该实体上 * @author yli * */public class ShopAffiche { private long afficheid; private String affichetitle; public long getAfficheid() { return afficheid; } public void setAfficheid(long afficheid) { this.afficheid = afficheid; } public String getAffichetitle() { return affichetitle; } public void setAffichetitle(String affichetitle) { this.affichetitle = affichetitle; } @Override public String toString() { return "[afficheid=" + afficheid + ";affichetitle=" + affichetitle + "]"; }}?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?