简易购物车项目，servlet

package com.sql; import java.rmi.StubNotFoundException; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; public class MysqlUtil { /** * 添加 * @param sql * @return */ public static int add(String sql) { int i=0; DBConnection db = new DBConnection(); try { PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(sql); preStmt.executeUpdate(); preStmt.close(); db.close(); i = 1; System.out.println("" + sql); } catch (Exception e) { e.printStackTrace(); } return i; } /** * 修改 * @param sql * @return */ public static int update(String sql) { int i =0; DBConnection db = new DBConnection(); try { PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(sql); preStmt.executeUpdate(); preStmt.close(); db.close(); i = 1; System.out.println(sql); } catch (SQLException e) { e.printStackTrace(); } return i; } /** * 删除 * @param delstr * @return */ public static int del(String delstr) { int i=0; DBConnection db = new DBConnection(); try { PreparedStatement preStmt = (PreparedStatement) db.conn.prepareStatement(delstr); preStmt.executeUpdate(); preStmt.close(); db.close(); i = 1; System.out.println(delstr); } catch (SQLException e){ e.printStackTrace(); } return i; } /** * 获取数量 * @param sql * @return */ public static int getCount(String sql) { int sum = 0; DBConnection db = new DBConnection(); try { Statement stmt = (Statement) db.conn.createStatement(); ResultSet rs = (ResultSet) stmt.executeQuery(sql); while (rs.next()) { sum += rs.getInt(1); } rs.close(); db.close(); } catch (Exception e) { // TODO: handle exception } return sum; } /** * 获取json * @author 闁厼绔� * @date 2021-03-22 10:30 * @param sqlcount 閺屻儴顕楅弫浼村櫤閻ㄥ墕ql * @param sql 閺屻儴顕楅崗铚傜秼閺佺増宓侀惃鍓唓l * @param colums 閺屻儴顕楅惃鍕摟濞堬拷 * @return java.lang.String */ public static String getJsonBySql( String sqlcount,String sql,String[] colums){ int count = getCount(sqlcount); System.err.println("閺嶅洨瀛╂穱鈩冧紖鐏炴洜銇歴ql:" + sql); ArrayList<String[]> result = new ArrayList<String[]>(); DBConnection db = new DBConnection(); try { Statement stmt = (Statement) db.conn.createStatement(); ResultSet rs = (ResultSet) stmt.executeQuery(sql); while(rs.next()){ String[] dataRow = new String[colums.length]; for( int i = 0; i < dataRow.length; i++ ) { dataRow[i] = rs.getString( colums[i] ); } result.add(dataRow); } rs.close(); db.close();// } catch (SQLException e) { e.printStackTrace(); } return listToJson(result,colums,count); } /** *閸旂喕鍏橀幓蹇氬牚 閺屻儴顕楅弫鐗堝祦 * @author 闁厼绔� * @date 2021-03-22 10:38 * @param sql 閺屻儴顕楅崗铚傜秼閺佺増宓侀惃鍓唓l * @param colums 閺屻儴顕楅惃鍕摟濞堬拷 * @return java.util.ArrayList<java.lang.String[]> */ public static ArrayList<String[]> showUtil( String sql, String[] colums){ System.out.println(sql); ArrayList<String[]> result = new ArrayList<String[]>(); DBConnection db = new DBConnection(); try { Statement stmt = (Statement) db.conn.createStatement(); ResultSet rs = (ResultSet) stmt.executeQuery(sql); while(rs.next()){ String[] dataRow = new String[colums.length]; for( int i = 0; i < dataRow.length; i++ ) { dataRow[i] = rs.getString( colums[i] ); } result.add(dataRow); } rs.close(); db.close();// } catch (SQLException e) { e.printStackTrace(); } return result; } /** * 鏉烆剙瀵叉稉绨�son閺佺増宓佺�涙顑佹稉锟� * @param * @return */ public static String listToJson( ArrayList<String[]> list,String[] colums,int count) { String jsonStr = "{\"code\":0,\"msg\":\"成功\",\"count\":"+count+",\"data\":["; for(int i = 0; i < list.size(); i++) { String arr = "{"; for( int j = 0; j < list.get(0).length; j++) { if( list.get(i)[j] == null || "NULL".equals(list.get(i)[j])) { arr += "\"" + colums[j] + "\":\"\""; }else { arr += "\"" + colums[j] + "\""+":" ; arr += "\"" + list.get(i)[j].replace("\"","\\\"") + "\""; } if( j < list.get(0).length - 1 ) { arr += ","; } } arr += "}"; if( i < list.size() - 1 ) { arr += ","; } jsonStr += arr; } jsonStr += "]}"; return jsonStr; } }