java tree 怎 取最后一个子节点

Question

怎在后台写代码，然后在前台显示tree ,代码可以显示了但是不知道怎取子节点的最后一个节点，和最前一个节点
private void readClientTree(Connection conn, int id, int level) 
throws SQLException {
String sql = "select * from t_client where pid=?";
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
rs = pstmt.executeQuery();
while (rs.next()) {
sbTreeHTML.append("<div>");
sbTreeHTML.append("\n");
for (int i=0; i<level; i++) {
sbTreeHTML.append("<img src=\"../images/white.gif\">");
sbTreeHTML.append("\n");
}
//if ("N".equals(rs.getString("is_leaf"))) {
if (Constants.NO.equals(rs.getString("is_leaf"))) {
sbTreeHTML.append("<img alt=\"展开\" style=\"cursor:hand;\" onClick=\"display('" + rs.getInt("id") + "');\" id=\"img" + rs.getInt("id") + "\" src=\"../images/plus.gif\">");
sbTreeHTML.append("\n");
sbTreeHTML.append("<img id=\"im" + rs.getInt("id") + "\" src=\"../images/closedfold.gif\">");
sbTreeHTML.append("\n");
sbTreeHTML.append("<a href=\"client_node_crud.jsp?id=" + rs.getInt("id") + "\" target=\"clientDispAreaFrame\">" + rs.getString("name") + "</a>");
sbTreeHTML.append("\n");
sbTreeHTML.append("<div style=\"display:none;\" id=\"div" + rs.getInt("id") + "\">");
sbTreeHTML.append("\n");
readClientTree(conn, rs.getInt("id"), level + 1);
sbTreeHTML.append("</div>");
sbTreeHTML.append("\n");
}else {
sbTreeHTML.append("<img src=\"../images/minus.gif\">");
sbTreeHTML.append("\n");
sbTreeHTML.append("<img src=\"../images/openfold.gif\">");
sbTreeHTML.append("\n");
//if ("Y1".equals(rs.getString("is_client"))) {
if (Constants.YES.equals(rs.getString("is_client"))) {
sbTreeHTML.append("<a href=\"client_crud.jsp?id=" + rs.getInt("id") + "\" target=\"clientDispAreaFrame\">" + rs.getString("name") +  "</a>");
}else {
sbTreeHTML.append("<a href=\"client_node_crud.jsp?id=" + rs.getInt("id") + "\" target=\"clientDispAreaFrame\">" + rs.getString("name") + "</a>");
}
sbTreeHTML.append("\n");

}
sbTreeHTML.append("</div>");
sbTreeHTML.append("\n");
}
}finally {
DbUtil.close(rs);
DbUtil.close(pstmt);
}
}

Answer 1

var first=document.body.firstChild,last=document.body.lastChild;//document.body换成你要查找最后一个子节点跟第一个子节点的子节点
while(first && first.nodeType==3){
    first = first.nextSibling
}
while(last && last.nodeType==3){
    last = last.previousSibling
}
console.log(first)
console.log(last)

Answer 2

var first=document.body.firstChild,last=document.body.lastChild;//document.body换成你要查找最后一个子节点跟第一个子节点的子节点
while(first && first.nodeType==3){
    first = first.nextSibling
}
while(last && last.nodeType==3){
    last = last.previousSibling
}
console.log(first)
console.log(last)