谁帮我写一个简单的放注入的代码嘛？

Question

Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
     conn=DriverManager.getConnection("jdbc:microsoft:sqlserver://localhost:1433;databaseName=xxx","sa", "123456");                                      
     sm=conn.createStatement();
             rs=sm.executeQuery("select top 1 * from tb3 where username='"+u+"' and passwd='"
              +p+"' "); 
if(rs.next()){
              String dbp=rs.getString(1);
             
              if(dbp.equals(p)){
             
              HttpSession hs=req.getSession(true);
                   hs.setMaxInactiveInterval(30);
                   hs.setAttribute("username",u);
                  
                 res.sendRedirect("L3?username="+u+"&passwd"+p);
              }
              }
             else{
              res.sendRedirect("L1");
              }我这个错在哪里呢！！！！！！！

Answer 1

异常不详.....送个底层给lz先玩玩...import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;public class DBCon {
    public static String driver="com.microsoft.jdbc.sqlserver.SQLServerDriver";
    public static String url="jdbc:microsoft:sqlserver://localhost:1433";
    public static String user="xxxxx";
    public static String pwd="xxxxxx";
    
    public static Connection getConnection(){
        try {
            Class.forName(driver);
            Connection con=DriverManager.getConnection(url, user, pwd);
            System.out.println("con success");
            return con;
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
    
    public static void close(Connection con,Statement stm,ResultSet rs){
        if(con!=null){
            try {
                con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(stm!=null){
            try {
                stm.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    
    public static void main(String[] args) {
        DBCon.getConnection();
    }
}

Answer 2

这里：passwd后面少了个等于 =
res.sendRedirect("L3?username="+u+"&passwd"+p); 

Answer 3

JAVA中防止SQL注入攻击类的源代码2008-05-03 12:29JAVA－字符串过滤类 
package cn.com.hbivt.util;
/**
* <p>Title: </p>
*
* <p>Description: </p>
*
* <p>Copyright: Copyright (c) 2005</p>
*
* <p>Company: </p>
*
* @author not attributable
* @version 1.0
*/
public class StringUtils {
       //过滤通过页面表单提交的字符
       private static String[][] FilterChars={{"<","&lt;"},{">","&gt;"},{" ","&nbsp;"},{"\"","&quot;"},{"&","&amp;"},
                                       {"/","&#47;"},{"\\","&#92;"},{"\n","<br>"}};
       //过滤通过javascript脚本处理并提交的字符
       private static String[][] FilterScriptChars={{"\n","\'+\'\\n\'+\'"},
                                                           {"\r"," "},{"\\","\'+\'\\\\\'+\'"},
                                                                   {"\'","\'+\'\\\'\'+\'"}};       /**
        * 用特殊的字符连接字符串
        * @param strings 要连接的字符串数组
        * @param spilit_sign 连接字符
        * @return 连接字符串
        */
       public static String stringConnect(String[] strings,String spilit_sign){
         String str="";
         for(int i=0;i<strings.length;i++){
           str+=strings[i]+spilit_sign;
         }
         return str;
       }       /**
        * 过滤字符串里的的特殊字符
        * @param str 要过滤的字符串
        * @return 过滤后的字符串
        */
       public static String stringFilter(String str){
         String[] str_arr=stringSpilit(str,"");
         for(int i=0;i<str_arr.length;i++){
           for(int j=0;j<FilterChars.length;j++){
             if(FilterChars[j][0].equals(str_arr[i]))
               str_arr[i]=FilterChars[j][1];
           }
         }
         return (stringConnect(str_arr,"")).trim();
       }       /**
* 过滤脚本中的特殊字符（包括回车符(\n)和换行符(\r)）
* @param str 要进行过滤的字符串
* @return 过滤后的字符串
* 2004-12-21 闫
*/
public static String stringFilterScriptChar(String str){
String[] str_arr=stringSpilit(str,"");
for(int i=0;i<str_arr.length;i++){
   for (int j = 0; j < FilterScriptChars.length; j++) {
     if (FilterScriptChars[j][0].equals(str_arr[i]))
       str_arr[i] = FilterScriptChars[j][1];
   }
}
return(stringConnect(str_arr,"")).trim();
}
       /**
        * 分割字符串
        * @param str 要分割的字符串
        * @param spilit_sign 字符串的分割标志
        * @return 分割后得到的字符串数组
        */
       public static String[] stringSpilit(String str,String spilit_sign){
         String[] spilit_string=str.split(spilit_sign);
         if(spilit_string[0].equals(""))
         {
           String[] new_string=new String[spilit_string.length-1];
           for(int i=1;i<spilit_string.length;i++)
             new_string[i-1]=spilit_string[i];
             return new_string;
         }
         else
           return spilit_string;
       }       /**
        * 字符串字符集转换
        * @param str 要转换的字符串
        * @return 转换过的字符串
        */
       public static String stringTransCharset(String str){
         String new_str=null;
         try{
             new_str=new String(str.getBytes("iso-8859-1"),"GBK");
         }
         catch(Exception e){
           e.printStackTrace();
         }
         return new_str;
       }       /**
        * 测试字符串处理类
        * @param args 控制台输入参数
        */
       public static void main(String[] args){         //测试字符串过滤
         String t_str1="<h1>StringDispose字符串 处理\n\r\'\"</h1>";
         System.out.println("过滤前："+t_str1);
         System.out.println("过滤后："+StringUtils.stringFilter(t_str1));
         //测试合并字符串
         String[] t_str_arr1={"PG_1","PG_2","PG_3"};
         String t_str2=StringUtils.stringConnect(t_str_arr1,",");
         System.out.println(t_str2);
         //测试拆分字符串
         String[] t_str_arr2=StringUtils.stringSpilit(t_str2,",");
         for(int i=0;i<t_str_arr2.length;i++){
           System.out.println(t_str_arr2[i]);
         }
       }
}