请问这个简单的JAVABEAN怎么写？？？？

胡说，怎么可能这样用？
用户输入密码后，要post，然后web服务器才能收到信息，去数据库里面查，不正确再返回信息，一般都是一个密码错误的页面，
为什么要用客户端的javascript程序，来显示一个对话框？
你见那个网站这么做了？奇了怪了。

如果找你说的，那这个JAVABEAN又怎么写呢？

这种判断程序，只会在登陆页面有，为什么非要写到javabean里面？
只用jsp也能实现，
如果你在jsp里面会写，javabean也是一样的。

我觉得大家好想没有理解他的意思,他说的是讲用户名和密码当作参数传进bean中,如果不正确则谈出对话框,其实很简单的,相信你在bean中怎么调数据库查询密码什么的肯定会了,如果迷吗不正确,这样就可以了out.print(<script language =\"JAVASCRIPT\">
alert(\"invalid password & username!!!\");
</script>),这样就可以轻松实现了,不用每次都写代码,不知道说的对不对,呵呵

最好买本书看看.
an classical example using isValidate() check validation in a JavaBean which can be reused in different jsp pages.
That's one of reasons why jsp is better than ASP(not ASP.net)

for detailed explaination, see www.jspin.com---tips and tutorial---form----advanced form processing
package forms;
import java.util.*;
import java.sql.*;
public class FormBean {
  private String firstName;
  private String lastName;
  private String email;
  private String userName;
  private String password1;
  private String password2;
  private String zip;
  private String[] faveMusic;
  private String notify;
  private Hashtable errors;



  String sDBDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
  String sConnStr = "jdbc:odbc:Customer";
  Connection conn = null;
  Statement stmt=null;
  ResultSet rs = null;
  int count=0;
  //private boolean isDouble=false;

  public void connect(){
  try {
    Class.forName(sDBDriver);
    conn = DriverManager.getConnection(sConnStr);
    checkForWarning (conn.getWarnings());
    stmt = conn.createStatement();
    System.out.println("connect to database :OK!");
    }catch (SQLException ex) {
System.out.println ("\n*** SQLException caught ***\n");
while (ex != null) {
         System.out.println("SQLState:" +ex.getSQLState());
         System.out.println(" Message :" +ex.getMessage());
         System.out.println(" Vendor  :" +ex.getErrorCode());
     ex = ex.getNextException ();
}
}catch (java.lang.Exception ex) {
ex.printStackTrace ();
}
  }
public int execUpdate(String sql) {
  try {
       count=stmt.executeUpdate(sql);
       if(count==0) {
             System.out.println("error!");
        }
     //   stmt.close();
     //   rs.close();
    }catch (SQLException ex) {
    System.out.println("Update error");
  System.out.println ("\n*** SQLException caught ***\n");
while (ex != null) {
       System.out.println("SQLState:" +ex.getSQLState());
       System.out.println(" Message :" +ex.getMessage());
       System.out.println(" Vendor  :" +ex.getErrorCode());
ex = ex.getNextException ();
}
}catch (java.lang.Exception ex) {
ex.printStackTrace ();

}
return count;
}
public ResultSet execQuery(String sql) {
try {
       rs=stmt.executeQuery(sql);
      /* if(rs.next()) {
        isDouble=true;
        System.out.println(" execQuery's result :"+rs.getString(1));}
       else{
       System.out.println("there is no record which you wanted!");
        }*/
     //   stmt.close();
     //   rs.close();
      }catch (SQLException ex) {
  System.out.println ("\n*** SQLException caught ***\n");
while (ex != null) {
       System.out.println("SQLState:" +ex.getSQLState());
       System.out.println(" Message :" +ex.getMessage());
       System.out.println(" Vendor  :" +ex.getErrorCode());
ex = ex.getNextException ();
}
}catch (java.lang.Exception ex) {
ex.printStackTrace ();
}
return rs;
}private boolean checkForWarning (SQLWarning warn) throws SQLException
{
// System.out.println("DBAccess checkForWarning");
boolean rc = false; if (warn != null) {
System.out.println ("\n *** Warning ***\n");
rc = true;
while (warn != null) {
           System.out.println("SQLState:" +warn.getSQLState());
           System.out.println("Message :" +warn.getMessage());
           System.out.println("Vendor :" +warn.getErrorCode());
warn = warn.getNextWarning ();
}
}
return rc;
}
public void disconnect() {
try {
    System.out.println("DBAccess disconnect");
    rs.close();
    stmt.close();
conn.close();
}catch (SQLException ex) {
System.out.println ("\n*** SQLException caught ***\n");
while (ex != null) {
System.out.println ("SQLState: " +ex.getSQLState());
System.out.println ("Message:  " +ex.getMessage());
System.out.println ("Vendor:   " +ex.getErrorCode());
ex = ex.getNextException ();
System.out.println ("");
}
}catch (java.lang.Exception ex) { ex.printStackTrace (); }
}  public String arrayToString(String[] arr){
   String temp="";
   int n=arr.length;
   for (int i=0;i<n;i++)
   {temp=temp+arr[i]+",";}
   temp=temp.substring(0,(temp.length()-1));
   return temp;
   }
  public boolean validate() {
   System.out.println(firstName+","+lastName+","+email+","+userName+","+password1+","+zip+","+arrayToString(faveMusic)+","+notify);
    boolean allOk=true;
    if (firstName.equals("")) {
      errors.put("firstName","Please enter your first name");
      firstName="";
      allOk=false;
    }
    if (lastName.equals("")) {
      errors.put("lastName","Please enter your last name");
      lastName="";
      allOk=false;
    }
    if (email.equals("") || (email.indexOf('@') == -1)) {
      errors.put("email","Please enter a valid email address");
      email="";
      allOk=false;
    }

    if (userName.equals("")) {
      errors.put("userName","Please enter a username");
      userName="";
      allOk=false;
    }else{
    System.out.println(userName);
    String querySQL="select * from register where username='"+userName+"'";
    try{
      rs=execQuery(querySQL);
      if(rs.next()) {
        errors.put("userName","The username has been exist,请换一个please change another");
     allOk=false;
       }
    }catch(SQLException ex){
    System.out.println ("\n*** SQLException caught ***\n");
while (ex != null) {
       System.out.println("SQLState:" +ex.getSQLState());
       System.out.println(" Message :" +ex.getMessage());
       System.out.println(" Vendor  :" +ex.getErrorCode());
ex = ex.getNextException ();
}
}catch (java.lang.Exception ex) {
ex.printStackTrace ();
}
    /*if(isDouble){
       errors.put("userName","The username has been exist,请换一个please change another");
     allOk=false;
        }*/
    }

    if (password1.equals("") ) {
      errors.put("password1","Please enter a valid password");
      password1="";
      allOk=false;
    }
    if (!password1.equals("") && (password2.equals("") ||
        !password1.equals(password2))) {
      errors.put("password2","Please confirm your password");
      password2="";
      allOk=false;
    }
    if (zip.equals("") || zip.length() !=5 ) {
      errors.put("zip","Please enter a valid zip code");
      zip="";
      allOk=false;
    } else {
      try {
        int x = Integer.parseInt(zip);
      } catch (NumberFormatException e) {
        errors.put("zip","Please enter a valid zip code");
        zip="";
        allOk=false;
      }
    }
    if (allOk){
    System.out.println("prepare to insert :");
    System.out.println(firstName+","+lastName+","+email+","+userName+","+password1+","+zip+","+notify);
    String strSQL="insert into register (username,password,firstname,lastname,email,zip,favorite,acception) " ;
           strSQL=strSQL+"values('"+userName+"','"+password1+"','"+firstName+"','"+lastName+"','"+email+"','"+zip+"','"+arrayToString(faveMusic)+ "'," +true +")";
//firstName+lastName+email+userName+password1+zip+notify
System.out.println("strSQl: "+strSQL);
int n=execUpdate(strSQL);
System.out.println("insert "+n+"record");
if (n==0){
allOk=false;
errors.put("DB Access","Sorry,DataBase access failed!");
}

    }
  return allOk;
  }
    public String getErrorMsg(String s) {
    String errorMsg =(String)errors.get(s.trim());
    return (errorMsg == null) ? "":errorMsg;
  }  public FormBean() {
    System.out.println("create FormBean ok");
    firstName="";
    lastName="";
    email="";
    userName="";
    password1="";
    password2="";
    zip="";
    faveMusic = new String[] { "1" };
    notify="";
    errors = new Hashtable();
    connect();

  }  public String getFirstName() {
    return firstName;
  }  public String getLastName() {
    return lastName;
  }  public String getEmail() {
    return email;
  }  public String getUserName() {
    return userName;
  }  public String getPassword1() {
    return password1;
  }  public String getPassword2() {
    return password2;
  }  public String getZip() {
    return zip;
  }  public String getNotify() {
    return notify;
  }  public String[] getFaveMusic() {
    return faveMusic;
  }  public String isCbSelected(String s) {
    boolean found=false;

    if (!faveMusic[0].equals("1"))
    {
      for (int i = 0; i < faveMusic.length; i++)
       {
        if (faveMusic[i].equals(s)) {
          found=true;
          break;
        }
      }
      if (found) return "checked";
    }
    return "";
  }  public String isRbSelected(String s) {
    return (notify.equals(s))? "checked" : "";
  }  public void setFirstName(String fname) {
    firstName =fname;
  }  public void setLastName(String lname) {
    lastName =lname;
  }  public void setEmail(String eml) {
    email=eml;
  }  public void setUserName(String u) {
    userName=u;
  }  public void setPassword1(String p1) {
    password1=p1;
  }  public void setPassword2(String p2) {
    password2=p2;
  }  public void setZip(String z) {
    zip=z;
  }  public void setFaveMusic(String[] music) {
    faveMusic=music;
  }  public void setErrors(String key, String msg) {
    errors.put(key,msg);
  }  public void setNotify(String n) {
    notify=n;
  }
}

这个也太多了吧。
package jb;
public class helloworld
{
  public String name="hello world!";
  public String hello()
{
  return name;
}
}

调试易

请问这个简单的JAVABEAN怎么写？？？？

解决方案 »