借助预编译防止sql注入攻击

可重用的sql操作类

 1 public ResultSet doQuery(String sql,Object[] params){
 2         ResultSet rs = null;
 3         conn = this.getConnection();
 4         try{
 5             PreparedStatement pstmt = conn.prepareStatement(sql);
 6             for(int i =0;i<params.length;i++){
 7                 pstmt.setObject(i+1, params[i]);
 8             }
 9             rs = pstmt.executeQuery();
10         }catch(Exception e){
11             e.printStackTrace();
12         }
13         return rs;
14     }

 1 public int doUpdate(String sql,Object[] params){
 2         int res = 0;
 3         conn  = this.getConnection();
 4         try{
 5             PreparedStatement pstmt = conn.prepareStatement(sql);
 6             for(int i=0;i<params.length;i++){
 7                 pstmt.setObject(i+1, params[i]);
 8             }
 9             res = pstmt.executeUpdate();
10         }catch(Exception e){
11             e.printStackTrace();
12         }
13         return res;
14     }

 1 public List<Object>  doQueryList(String sql,Object []params){
 2         List<Object> list = new ArrayList<Object>();
 3         ResultSet rs = this.doQuery(sql, params);
 4         try{
 5             ResultSetMetaData rsmd  = rs.getMetaData();
 6             int columnLength = rsmd.getColumnCount();
 7             while(rs.next()){
 8                 Map<String,Object> map = new HashMap<String,Object>();
 9                 for(int i = 1;i<=columnLength;i++){
10                     map.put(rsmd.getColumnLabel(i), rs.getObject(i));
11                 }
12                 list.add(map);
13             }
14         }catch(Exception e){ 
15             e.printStackTrace();
16         }
17         return list;
18     }

查询所有信息的jsp关键代码如下

 1 <%
 2     DBCon dbc = new DBCon();
 3     String sql  = "select * from schema.admin";
 4     List list = dbc.doQueryList(sql, new Object[]{});
 5     
 6     %>
 7     <table border="1">
 8     <%for(int i =0;i<list.size();i++){
 9         Map<String,Object> map = (Map<String,Object>)list.get(i);
10         %>
11         <tr>
12             <td><%=map.get("id") %></td>
13             <td><%=map.get("username") %></td>
14             <td><%=map.get("password") %></td>
15             <td><a href="do_delete.jsp?id=<%=map.get("id")%>">删除</a></td>
16             <td><a href="do_edit.jsp?id=<%=map.get("id")%>">编辑</a></td>
17         </tr>
18     <%}
19     dbc.close();
20     %>
21     </table>
22     <a href="addAdmin.jsp">添加用户</a>

更新、删除登操作同理，不再列出。