index.jsp

<form action="validateServlet" method="post">  
	  		  验证码：<input name="inputCode" value=""/>   
	    	
	   		<input name="button" type="submit" value="提交"/>  
	    </form>  

此处一定要在<form>表单中写入method标签，否则不好使

web.xml

 <servlet>
    <servlet-name>validate</servlet-name>
    <servlet-class>com.servlet.ValidateServlet</servlet-class>
  </servlet>
   
  <servlet-mapping>
        <servlet-name>validate</servlet-name>
        <url-pattern>/validateServlet</url-pattern>
  </servlet-mapping>

com.servlet.ValidateServlet.java

public class ValidateServlet extends HttpServlet{

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
		super.doPost(request, response);
	}

	@Override
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		.....相关实际操作
	}
}

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servlet中在doPost方法中实现跳转到里一个界面

response.sendRedirect("index.jsp");