SSM项目中连接其他系统中的数据库

在项目开发中，本地系统需要连接其他系统中的数据库获取数据，此时采用jdbc连接数据库，代码为：

private Connection connection;
//jdbc连接数据库，init初始化方法
private void init() {
        if(!hasInit) {
            String driverName = "com.microsoft.sqlserver.jdbc.SQLServerDriver";
            String dbURL = "jdbc:sqlserver://172.18.199.214:1433; DatabaseName=VEG_SYS";
            String username = "DBW";
            String pwd = "123456";
            try {
                Class.forName(driverName);
                connection = DriverManager.getConnection(dbURL, username, pwd);
            }catch (Exception e) {
                e.printStackTrace();
            }
            hasInit = true;
        }
}
//拼接sql，返回结果集，将结果集转化成List<Map<String,Object>>格式返回
public List<Map<String, Object>> getCarInfoByCarNo(String where) throws Exception{
        init();
        List<Map<String, Object>> result = new ArrayList<Map<String,Object>>();
        Statement statement =  connection.createStatement();
        String sql1 = "select\r\n" + 
                "        top 10\r\n"+
                "        t.I_IntId  as Id\r\n"+
                "      ,t.C_CarsNo as CarsNo\r\n" + 
                "      ,t.C_InCarsNo as OutInCarsNo\r\n" + 
                "      ,t.C_PastName as PastName\r\n" + 
                "      ,t.C_RulesName as RulesName\r\n" + 
                "      ,t.I_InTime as OutInTime\r\n" + 
                "      ,t.C_CarsOwnerPhoneNo as Phone\r\n" + 
                "      ,t.C_InDepart as OutInDept\r\n" + 
                "      ,t.C_CustomNo as ICCard\r\n" + 
                "      ,t.C_AreaName as AreaName\r\n" + 
                "      ,t.C_CarsOwner as CarsOwner\r\n" + 
                "      ,t.C_PlateColor as PlateColor\r\n" + 
                "      ,t.I_InRulesId as OutInRulesId\r\n" + 
                "      from\r\n" + 
                "      (select\r\n" + 
                "        a.I_IntId\r\n" +
                "      ,a.C_CarsNo\r\n" + 
                "      ,a.C_InCarsNo\r\n" + 
                "      ,b.C_PastName\r\n" + 
                "      ,a.I_InTime\r\n" + 
                "      ,h.C_CarsOwnerPhoneNo\r\n" + 
                "      ,c.C_RulesName\r\n" + 
                "      ,a.C_InDepart\r\n" + 
                "      ,h.C_CustomNo\r\n" + 
                "      ,f.C_AreaName\r\n" + 
                "      ,h.C_CarsOwner\r\n" + 
                "      ,g.C_PlateColor\r\n" + 
                "      ,a.I_InRulesId\r\n" + 
                "      ,SUBSTRING(CONVERT(varchar(100),  a.I_InTime, 20),1,16) as ctine\r\n" + 
                "      from [CR].Cars_InRecord a\r\n" + 
                "      join [CA].Cars_Permissions_Rules_Main c on c.I_IntId = a.I_InRulesId\r\n" + 
                "      join [GI].Cars_Guard_Past b on b.I_IntId = a.I_InPastId\r\n" + 
                "      join  GI.Cars_Guard_Area f  on f.I_IntId =a.I_AreaId\r\n" + 
                "      join CI.Cars_Info h on h.I_IntId=a.I_CarsId\r\n" + 
                "      left join CR.Cars_PlateInfo g  on a.C_InCarsNo=g.C_CarsNo\r\n" + 
                "      left join CI.InStatePerson j on a.C_IdentityNo=j.C_IdentityNo "+where+") t ORDER BY OutInTime DESC";

        ResultSet rs = statement.executeQuery(sql1);
        System.out.println(sql1);
        while(rs.next()){
//            System.out.println(rs.getString("C_EngineeringNo"));
            Map<String, Object> car = new HashMap<String, Object>();
            car.put("Id", rs.getString("Id"));
            car.put("CarsNo", rs.getString("CarsNo"));
            car.put("OutInCarsNo", rs.getString("OutInCarsNo"));
            car.put("OutInDept", rs.getString("OutInDept"));
            car.put("PastName", rs.getString("PastName"));
            car.put("RulesName", rs.getString("RulesName"));
            car.put("OutInTime", rs.getString("OutInTime"));
            car.put("Phone", rs.getString("Phone"));
            car.put("ICCard", rs.getString("ICCard"));
            car.put("AreaName", rs.getString("AreaName"));
            car.put("CarsOwner", rs.getString("CarsOwner"));
            car.put("PlateColor", rs.getString("PlateColor"));
            car.put("OutInRulesId", rs.getString("OutInRulesId"));
            result.add(car);
        }
        statement =  connection.createStatement();
        return result;
}

插入数据方法：

public void createBlackInfo(String sql) throws Exception{
        init();
        Statement statement =  connection.createStatement();
        String sql1 = where;
　　　　　　//executeUpdate为插入语句
        statement.executeUpdate(sql1);
        System.out.println(sql1);
        statement =  connection.createStatement();
}