JDBC实现分页查询，同时使用动态数据源
方法是通过jdbc来实现分页的，这样做的目的是可以实现多数据库的情况下，都能使用的方法。
但是这个方法貌似会存在性能问题，因为结果集会全部数据查询出来...
public JSONObject query(JSONObject object, int pageIndex, int pageSize) { JSONObject result = new JSONObject(); if(object == null || object.getBoolean("success") == false) { result.put("success", false); if(object == null) { result.put("msg", "没有成功获取到基本对象"); } else if(object.getString("msg") != null) { result.put("msg", object.getString("msg")); } } else { Connection connection = null; PreparedStatement preparedStatement = null; //Statement statement = null; ResultSet rs = null; try { connection = createConnection(object.getString("className"), object.getString("url"), object.getString("user"), object.getString("pwd")); String sql = object.getString("sql"); System.out.println(sql); preparedStatement = connection.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY); if(pageIndex == 1 && pageSize == 1) { rs = preparedStatement.executeQuery(); } else { preparedStatement.setMaxRows(((pageIndex - 1) * pageSize) + pageSize);//查询的最大行数 //preparedStatement.setMaxRows(pageSize); rs = preparedStatement.executeQuery(); //rs.first(); rs.absolute((pageIndex - 1) * pageSize + 1);//利用绝对定位定位到结果集的每页第二条数据 rs.relative(-1);//利用结果集的相对定位定位到每页的第一条数据 } JSONArray datas = new JSONArray(); JSONArray data = null; ResultSetMetaData metaData = null; int colnumCount = 0; String colnumName = null; Object tmp = null; SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); Reader reader = null; BufferedReader bufferedReader = null; char[] chbTmp = null; StringBuffer sb = new StringBuffer(); while(rs.next()) { //获取数据 data = new JSONArray(); metaData = rs.getMetaData(); colnumCount = metaData.getColumnCount() + 1; for (int i = 1; i < colnumCount; i++) { colnumName = metaData.getColumnName(i); tmp = rs.getObject(colnumName); if(tmp == null) { data.add(""); } else { if(tmp.getClass() == Timestamp.class) { data.add(dateFormat.format(tmp)); } else if(tmp.getClass() == CLOB.class) { chbTmp = new char[20]; reader = rs.getClob(colnumName).getCharacterStream(); bufferedReader = new BufferedReader(reader); bufferedReader.read(chbTmp); sb.delete(0, chbTmp.length); sb.append(chbTmp); data.add(sb.toString() + "..."); } else { data.add(tmp); } } } datas.add(data);; } JSONArray colnums = new JSONArray(); if(datas.size() > 0) { //获取列名 metaData = rs.getMetaData(); colnumCount = metaData.getColumnCount() + 1; for (int i = 1; i < colnumCount; i++) { colnumName = metaData.getColumnName(i); colnums.add(colnumName); } } else { colnums.add("没有成功获取列的信息"); } result.put("colnum", colnums); result.put("datas", datas); result.put("success", true); } catch (ClassNotFoundException e) { e.printStackTrace(); result.put("success", false); result.put("msg", e.getMessage()); } catch (SQLException e) { e.printStackTrace(); result.put("success", false); result.put("msg", e.getMessage()); } catch (IOException e) { e.printStackTrace(); result.put("success", false); result.put("msg", e.getMessage()); } finally { close(connection, preparedStatement, rs); } } return result;}