java过滤器的类..也是100分,,好了立刻结贴,,(再开一个贴)

读入数据库就是乱码??应该如何解决呢??
于是找了个过滤器的类..为
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import java.io.IOException;/**
 *
 * Date: 2005-9-19
 * Time: 17:33:36
 *  @author Duzk
 */
public class MyFilter extends HttpServlet implements Filter {
    private FilterConfig filterConfig;
    //Handle the passed-in FilterConfig
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }    //Process the request/response pair
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain filterChain) {        try {
            request.setCharacterEncoding("GBK");
            filterChain.doFilter(request, response);        } catch (ServletException sx) {
            filterConfig.getServletContext().log(sx.getMessage());
        } catch (IOException iox) {
            filterConfig.getServletContext().log(iox.getMessage());
        }
    }    //Clean up resources
    public void destroy() {
    }
}
然后我把它另存为到C盘,,我将名保存为MyFilter.java  源代码不变
在编译时出现了以下的错误,,生成不到.class
C:\>javac MyFilter.java
MyFilter.java:1: package javax.servlet does not exist
import javax.servlet.*;
^
MyFilter.java:2: package javax.servlet.http does not exist
import javax.servlet.http.HttpServlet;
                          ^
MyFilter.java:11: cannot find symbol
symbol: class HttpServlet
public class MyFilter extends HttpServlet implements Filter {
                              ^
MyFilter.java:11: cannot find symbol
symbol: class Filter
public class MyFilter extends HttpServlet implements Filter {
                                                     ^
MyFilter.java:12: cannot find symbol
symbol  : class FilterConfig
location: class MyFilter
    private FilterConfig filterConfig;
            ^
MyFilter.java:14: cannot find symbol
symbol  : class FilterConfig
location: class MyFilter
    public void init(FilterConfig filterConfig) throws ServletException {
                     ^
MyFilter.java:14: cannot find symbol
symbol  : class ServletException
location: class MyFilter
    public void init(FilterConfig filterConfig) throws ServletException {
                                                       ^
MyFilter.java:19: cannot find symbol
symbol  : class ServletRequest
location: class MyFilter
    public void doFilter(ServletRequest request, ServletResponse response,
                         ^
MyFilter.java:19: cannot find symbol
symbol  : class ServletResponse
location: class MyFilter
    public void doFilter(ServletRequest request, ServletResponse response,
                                                 ^
MyFilter.java:20: cannot find symbol
symbol  : class FilterChain
location: class MyFilter
                         FilterChain filterChain) {
                         ^
MyFilter.java:26: cannot find symbol
symbol  : class ServletException
location: class MyFilter
        } catch (ServletException sx) {
                 ^
11 errors
是不是什么步骤作错了??