Java中的HttpServlet错误

我为登录屏幕编写了一个简单的java代码。
下面是代码：

Login.java

package Banking;

import java.io.*;
import javax.servlet.*;
import java.sql.*;
import javax.servlet.http.*;

public class Client extends HttpServlet
{
    Connection con;
    String s3="",s4="";

    public void init(ServletConfig sc)throws ServletException
    { 
     try{
          Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
          con=DriverManager.getConnection("jdbc:odbc:thin","sys","orcl as sysdba");
           }catch(Exception ee){System.out.println(ee);}
    }

   public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
   {
          PrintWriter pw=res.getWriter();
          res.setContentType("text/html");

          String s1=req.getParameter("user");
          String s2=req.getParameter("pwd");
  try{
                Statement st=con.createStatement();
             ResultSet rs=st.executeQuery("select name from pass where name=' "+s1+" ' ");      

     while(rs.next())
      {   
                s3=rs.getString(1);
                s4=rs.getString(2);   
    }


      if(s1.equals("")||s2.equals(""))
      {   
         pw.println("invalid");

      res.sendRedirect("http://localhost:8080p/tball.gif");
      }
          else 
       {
          PreparedStatement pst=con.prepareStatement("insert into pass values(?,?)" );
          pst.setString(1,s1);
          pst.setString(2,s2);
          pst.execute();
          res.sendRedirect("http://localhost:8080/welcome.html"); 
        }
  }catch(Exception e){res.sendRedirect("http://localhost:8080/invalid.html");} 
 }
}             

Data.java

package Banking;

import java.io.*;
import javax.servlet.*;
import java.sql.*;
import javax.servlet.http.*;

public class Client2 extends GenericServlet
{
  Connection con;
   public void init(ServletConfig sc)throws ServletException
   { 
    try{
     Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
    con=DriverManager.getConnection("jdbc:oracle:thin","sys","orcl as sysdba");
                    }catch(Exception ee){System.out.println(ee);}
}

   public void service(ServletRequest req,ServletResponse res)throws ServletException,IOException
{    boolean j=true;
      String s1=req.getParameter("t1");
      String s2=req.getParameter("t2");
      String s3=req.getParameter("t3");    
     String s4=req.getParameter("r");
     String s5=req.getParameter("s"); 
     String s6=req.getParameter("t4");
      String s7=req.getParameter("t5");
      String s8=req.getParameter("t6");
      String s9=req.getParameter("s1");
     String s10=req.getParameter("t7");
     String s11=req.getParameter("t8");
     String s12=req.getParameter("t9");


try{
            PreparedStatement pst=con.prepareStatement("insert into entry values(?,?,?,?,?,?,?,?,?,?,?,?)" );

pst.setString(1,s1);pst.setString(2,s2);pst.setString(3,s3);pst.setString(4,s4);
pst.setString(5,s5);pst.setString(6,s6);pst.setString(7,s7);pst.setString(8,s8);
pst.setString(9,s9);pst.setString(10,s10);pst.setString(11,s11);pst.setString(12,s12);
pst.execute();

}
catch(Exception e)
{System.out.println(e);}
PrintWriter pw=res.getWriter();
res.setContentType("text/html");
 pw.println("inserted.into table.."); 
 }
} 

我遇到了很多错误，比如：

GenericServlet cannot be resolved to a type data.java   /Myproject/src/Banking  line 8  Java Problem
HttpServlet cannot be resolved to a type    Login.java  /Myproject/src/Banking  line 7  Java Problem
HttpServlet cannot be resolved to a type    login.java  /banking/src/banking    line 9  Java Problem
HttpServletRequest cannot be resolved to a type Login.java  /Myproject/src/Banking  line 20 Java Problem
HttpServletRequest cannot be resolved to a type login.java  /banking/src/banking    line 22 Java Problem
HttpServletResponse cannot be resolved to a type    Login.java  /Myproject/src/Banking  line 20 Java Problem
HttpServletResponse cannot be resolved to a type    login.java  /banking/src/banking    line 22 Java Problem
ServletConfig cannot be resolved to a type  Login.java  /Myproject/src/Banking  line 12 Java Problem
ServletConfig cannot be resolved to a type  data.java   /Myproject/src/Banking  line 11 Java Problem
ServletConfig cannot be resolved to a type  login.java  /banking/src/banking    line 14 Java Problem
ServletException cannot be resolved to a type   Login.java  /Myproject/src/Banking  line 12 Java Problem
ServletException cannot be resolved to a type   Login.java  /Myproject/src/Banking  line 20 Java Problem
ServletException cannot be resolved to a type   data.java   /Myproject/src/Banking  line 11 Java Problem
ServletException cannot be resolved to a type   data.java   /Myproject/src/Banking  line 19 Java Problem
ServletException cannot be resolved to a type   login.java  /banking/src/banking    line 14 Java Problem
ServletException cannot be resolved to a type   login.java  /banking/src/banking    line 22 Java Problem
ServletRequest cannot be resolved to a type data.java   /Myproject/src/Banking  line 19 Java Problem
ServletResponse cannot be resolved to a type    data.java   /Myproject/src/Banking  line 19 Java Problem
The import javax.servlet cannot be resolved Login.java  /Myproject/src/Banking  line 3  Java Problem
The import javax.servlet cannot be resolved Login.java  /Myproject/src/Banking  line 5  Java Problem
The import javax.servlet cannot be resolved data.java   /Myproject/src/Banking  line 4  Java Problem
The import javax.servlet cannot be resolved data.java   /Myproject/src/Banking  line 6  Java Problem
The import javax.servlet cannot be resolved login.java  /banking/src/banking    line 4  Java Problem
The import javax.servlet cannot be resolved login.java  /banking/src/banking    line 6  Java Problem
The public type Client must be defined in its own file  Login.java  /Myproject/src/Banking  line 7  Java Problem
The public type Client2 must be defined in its own file data.java   /Myproject/src/Banking  line 8  Java Problem  

---

如何解决这些错误

您确定已添加LIB吗？检查您的构建路径

您需要按如下方式命名您的类：

public class Login extends HttpServlet
{
  // you
}



public class Data extends GenericServlet
{
   // .... you code here 
}

---

由于您的文件名为

Login.java

和

Data.java

，因此当您收到错误时，请将您的类名从

Login.java

更改为

Client.java

，并将

Data.java

更改为

Client2.java

。公共类应该在一个java文件中声明，该文件的名称与类的名称相同。因此，在您的情况下，客户机类必须位于

Client.java

中，而Client2类位于

Client2.java

中，您需要添加应用程序服务器提供的类路径库，如

j2ee.jar

（如果是websphere）或

servlet api.jar

（如果是tomcat），您的代码和IDE似乎没有引用servlet-api.jar。检查您的lib文件夹是否存在jar。您可以通过build path.Class命名添加它，正如Deepika所说，servlet-api.jar的jar看起来也没有被检测到。如果您是通过命令提示符编译此文件，请使用“-cp”，然后使用要包含的库的路径。