private void _runSelect(Connection conn, DaoStatement st) throws SQLException {
Object[][] paramMatrix = st.getParamMatrix();
// -------------------------------------------------
// 以下代码,就为了该死的游标分页!!
// -------------------------------------------------
int startRow = -1;
int lastRow = -1;
if (st.getContext().getResultSetType() == ResultSet.TYPE_SCROLL_INSENSITIVE) {
Pager pager = st.getContext().getPager();
if (pager != null) {
startRow = pager.getOffset();
lastRow = pager.getOffset() + pager.getPageSize();
}
}
// -------------------------------------------------
// 生成 Sql 语句
String sql = st.toPreparedStatement();
// 打印调试信息
ResultSet rs = null;
Statement stat = null;
try {
// 木有参数，直接运行
if (null == paramMatrix || paramMatrix.length == 0 || paramMatrix[0].length == 0) {
if (log.isDebugEnabled()) log.debug(st);
stat = conn.createStatement(st.getContext().getResultSetType(), ResultSet.CONCUR_READ_ONLY);
if (lastRow > 0) stat.setMaxRows(lastRow); // 游标分页,现在总行数
if (st.getContext().getFetchSize() > 0) stat.setFetchSize(st.getContext().getFetchSize());
rs = stat.executeQuery(sql);
}
// 有参数，用缓冲语句
else {
// 打印调试信息
if (paramMatrix.length > 1) {
if (log.isWarnEnabled())
log.warnf("Drop last %d rows parameters for:\n%s", paramMatrix.length - 1, st);
}
if (log.isDebugEnabled()) {
log.debug(st);
}
// 准备运行语句
ValueAdaptor[] adaptors = st.getAdaptors();
// 创建语句并设置参数
stat =
conn.prepareStatement(
sql, st.getContext().getResultSetType(), ResultSet.CONCUR_READ_ONLY);
if (lastRow > 0) stat.setMaxRows(lastRow);
for (int i = 0; i < paramMatrix[0].length; i++) {
adaptors[i].set((PreparedStatement) stat, paramMatrix[0][i], i + 1);
}
rs = ((PreparedStatement) stat).executeQuery();
}
if (startRow > 0) rs.absolute(startRow);
// 执行回调
st.onAfter(conn, rs);
} finally {
Daos.safeClose(stat, rs);
}
// 打印更详细的调试信息
if (log.isTraceEnabled()) log.trace("...DONE");
}
public void exec(Connection conn, DaoStatement st) {
// 这个变量声明，后面两 case 要用到
Object[][] paramMatrix;
// 在这个块里执行语句
try {
/*
* 语句执行前的预操作
*/
st.onBefore(conn);
/*
* 开始执行语句
*/
switch (st.getSqlType()) {
// 查询
case SELECT:
_runSelect(conn, st);
break;
// 创建 & 删除 & 修改 & 清空
case ALTER:
case TRUNCATE:
case CREATE:
case DROP:
_runStatement(conn, st);
st.onAfter(conn, null);
break;
// 仅仅是运行回调
case RUN:
st.onAfter(conn, null);
break;
// 插入 & 删除 & 更新
// case DELETE:
// case UPDATE:
// case INSERT:
// 见鬼了，未知类型，也当作普通 SQL 运行吧，见 Issue#13
default:
if (st.getSqlType() == SqlType.OTHER && log.isInfoEnabled())
log.info("Can't indentify SQL type : " + st);
paramMatrix = st.getParamMatrix();
// 木有参数，直接运行
if (null == paramMatrix || paramMatrix.length == 0) {
_runStatement(conn, st);
}
// 有参数，用缓冲语句
else {
_runPreparedStatement(conn, st, paramMatrix);
}
// 运行回调
st.onAfter(conn, null);
}
}
// If any SQLException happend, throw out the SQL string
catch (SQLException e) {
if (log.isInfoEnabled()) log.debug("SQLException", e);
throw new DaoException(
format(
"!Nutz SQL Error: '%s'\nPreparedStatement: \n'%s'",
st.toString(), st.toPreparedStatement()),
e);
}
}