JavaWeb????????????Servlet??

??Tomcat

??Tomcat

• ?????Tomcat?????????????????
  • bin????????Tomcat????????
  • conf???Tomcat????????????????????
  • lib???Tomcat??????JAR???
  • logs???Tomcat???????????
  • temp?????Tomcat????????????
  • webapps??????????????????Java????
  • work???JSP????Servlet???

???????????

Servlet???

Servlet???

• ???????Servlet??????????????????????HTML???
• ???????Servlet???????????????????????
• ?????Servlet????????????????????????????????

Servlet???

• ??????Java??
• ??Servlet?????????
• ??@WebServlet????Servlet??????

????????Servlet?????

@WebServlet("/demo")
public class MyServlet implements Servlet {
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        // ?????
    }
    @Override
    public ServletConfig getServletConfig() {
        return null;
    }
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse)
            throws ServletException, IOException {
        // ??????????
        String id = servletRequest.getParameter("id");
        System.out.println("????????" + id);
        servletResponse.setContentType("text/html");
        servletResponse.getWriter().write("????????????");
    }
    @Override
    public String getServletInfo() {
        return null;
    }
    @Override
    public void destroy() {
        // ????
    }
}

Servlet?????

• ??XML???????
  ?web.xml???Servlet??????

        
        
      
         
          
          
           myServlet
          
          
          
           com.lut.myservlet.MyServlet
          
      
         
      
         
          
          
           myServlet
          
          
          
           /demo
          
      
         
        

• ???????
  ??@WebServlet??????Servlet??????

  @WebServlet("/demo")
  public class MyServlet implements Servlet {
      // Servlet????????
  }

Servlet?????

• ??????init????????Servlet?????init???
• ?????service??????????????service???
• ?????destroy????????Servlet?????destroy???

????????????Servlet??????

@WebServlet("/demo")
public class MyServlet implements Servlet {
    public MyServlet() {
        System.out.println("????????Servlet??");
    }
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println("?Servlet?????????...");
    }
    @Override
    public void service(ServletRequest servletRequest, ServletResponse servletResponse)
            throws ServletException, IOException {
        System.out.println("???Servlet???????...");
    }
    @Override
    public void destroy() {
        System.out.println("???Servlet??...");
    }
}

ServletConfig

• getServletName()???Servlet????
• getInitParameter(String key)???????????
• getInitParameterNames()??????????????

ServletContext

• getServletContext()???ServletContext???
• getContextPath()?????????
• getServerInfo()??????????Tomcat????

???????ServletContext????

@WebServlet("/demo")
public class MyServlet implements Servlet {
    String username;
    public MyServlet() {
    }
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        System.out.println(servletConfig.getServletName());
        this.username = servletConfig.getInitParameter("username");
        Enumeration
    
      parameterNames = servletConfig.getInitParameterNames();
        while (parameterNames.hasMoreElements()) {
            String name = parameterNames.nextElement();
            String value = servletConfig.getInitParameter(name);
            System.out.println(name + ": " + value);
        }
        ServletContext servletContext = servletConfig.getServletContext();
        System.out.println(servletContext.getServletContextName());
        System.out.println(servletContext.getContextPath());
        System.out.println(servletContext.getServerInfo());
    }
    // ????...
}
    

Servlet?????

• Servlet
• GenericServlet
• HttpServlet

????????????HttpServlet????Servlet???????HttpServlet???????GET?POST??????????

???HTTP????

• GET???????
• POST???????
• PUT???????
• DELETE???????

???????HttpServlet??GET?POST??????

public class TestServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().write("GET????");
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().write("POST????");
    }
}

??Servlet?????

• ????Servlet??????????????
• ??GenericServlet????????Servlet????????
• ??HttpServlet????????HTTP??????GET?POST?????