JDBC实现分页查询，同时使用动态数据源

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);

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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;
}