17-4.java

实例丰富经典

package check;
import java.io.PrintWriter;
import java.io.IOException;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckUserName extends HttpServlet
{
  private String msgStr="";
  //已注册名字列表
  public String[] usernameList;
  //响应Get请求函数
  protected void doGet(HttpServletRequest request,HttpServletResponse response) throws 
  ServletException
  {
    String oprate=(String)request.getParameter("oprate"); 
    String userName=(String)request.getParameter("userName");
    try
    {
      if(oprate.equals("chkUser"))
      {
        response.setContentType("text/html;charset=GB2312");
        if(userName.length()<6||userName.length()>20)
        {
	  msgStr="对不起,用户名必须为字母、数字或下划线，长度为6-20个字符!";
        }
        else
        {
          boolean bTmp=this.IsContain(userName); //找查数据库中有无该用户名
          if(bTmp) 
            msgStr="对不起,此用户名已经存在,请更换用户名注册!";
          else
	    msgStr="该用户名有效，可以使用！";
        }
        response.getWriter().write(msgStr);
      }  
    }//try
    catch(Exception ex){}
  }//doget
  //处理Post请求函数
  protected void doPost(HttpServletRequest request,HttpServletResponse response) throws   ServletException 
  {
     doGet(request,response);
  }
  //Servlet初始函数
  public void init(ServletConfig config) throws ServletException
  {
    //初始已注册用户名字列表
    usernameList=new String []{"Tomny","yangshuiqing","huoguangcheng"};
  }
  //判断用户名是否已经存在
  private boolean IsContain(String param)
  {
    for (int i=0;i<usernameList.length ;i++ )
    {
       if(usernameList[i].equals(param))
       {
         return true;
       }
       else
         continue;
    }
    return false;
  }
} //End of Class