servlet 篇 注解

servlet3.1 来提供了以下注解（在此之前，我们都是在web.xml配置的）

• HandlesTypes

            这个注解我们前面说过一个类是 ServletContainerInitializer ，这个注解用在这个初始化启动类上，这个注解主要提供注入类到我们set<Class<?>>set 中，这在我们在启动类中可以拿到，比如

@HandlesTypes(MyServlet.class)  //这样我们只能拿到MyServlet类
public class TestServletContainerInitializer implements ServletContainerInitializer{
    public void onStartup(Set<Class<?>> set, ServletContext servletContext) throws ServletException {
        System.out.println("=====================");
    }
}

• HttpMethodConstraint、ServletSecurity、HttpConstraint

            ServletSecurity这个注解是提供访问安全控制的，而HttpConstraint、HttpMethodConstraint配合这个安全注解使用的，也就是这个注解的属性，HttpConstraint提供了请求权限，而HttpMethonConstrain提供了方法访问控制

@WebServlet(urlPatterns = "/methodTest")
//@ServletSecurity(value = @HttpConstraint(transportGuarantee = ServletSecurity.TransportGuarantee.CONFIDENTIAL))
@ServletSecurity(httpMethodConstraints = @HttpMethodConstraint(value = "POST",emptyRoleSemantic = ServletSecurity.EmptyRoleSemantic.DENY))
public class methodTest extends HttpServlet {

    public void service(HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws ServletException, IOException {
        System.out.println("annotation ............."+servletRequest.getMethod());
    }
}

• WebFilter、WebServlet

        servlet提供一些注解在servlet注解，不需要在web.xml配置，比如WebFilter、WebServlet，项目会自动在classpath扫描这写注解，比如我们上面那个列子

• WebInitParam

        这个注解主要是配合上面两个注解使用，是注入我们初始化参数用的，比如

@WebFilter(urlPatterns = "/methodTest",initParams=@WebInitParam (name = "key",value = "value"))
public class TestFilter implements Filter {
    private FilterConfig filterConfig;
    public FilterConfig getFilterConfig() {
        return filterConfig;
    }
    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }
    public void init(FilterConfig filterConfig) throws ServletException {
        setFilterConfig(filterConfig);
    }
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        FilterConfig filterConfig =  this.getFilterConfig();
        System.out.println("================================"+filterConfig.getInitParameterNames());
    }
    
    public void destroy() {

    }
}

• WebListener

        webListener同样提供了我们使用主机的方式注入监听器，比如我们实现session监听器就可以如下

@WebListener
public class WebListerTest implements HttpSessionListener {
    public void sessionCreated(HttpSessionEvent httpSessionEvent) {
        
    }

    public void sessionDestroyed(HttpSessionEvent httpSessionEvent) {

    }
}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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转载于:https://my.oschina.net/chenping12/blog/1528109