SpringBoot中使用Servlet与更改DispatcherServlet默认Url

Springboot开发web应用过程中要用到过滤Filter和监听器Listener,
Springboot的主Servlet为 DispatcherServlet，其默认的url-pattern为“/”。也许我们在应用中还需要定义更多的Servlet，该如何使用SpringBoot来完成呢？

在spring boot中添加自己的Servlet有两种方法，代码注册Servlet和注解自动注册（Filter和Listener也是如此）。

一、代码注册通过ServletRegistrationBean、 FilterRegistrationBean 和 ServletListenerRegistrationBean 获得控制。

也可以通过实现 ServletContextInitializer 接口直接注册。

1.实现MyServlet.java

public class MyServlet extends HttpServlet{

[java] @Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println(">>>>>>>>>>doGet()<<<<<<<<<<<");
doPost(req, resp);
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println(">>>>>>>>>>doPost()<<<<<<<<<<<");
}
[/java]

}

2.SpringBoot启动时代码注入Servlet

[java]@SpringBootApplication
public class SpringBootSampleApplication {

public static void main(String[] args) {
SpringApplication.run(SpringBootSampleApplication.class, args);
}

/**
* 修改DispatcherServlet默认配置
*
*/
@Bean
public ServletRegistrationBean dispatcherRegistration(DispatcherServlet dispatcherServlet) {
ServletRegistrationBean registration = new ServletRegistrationBean(dispatcherServlet);
registration.getUrlMappings().clear();
registration.addUrlMappings("*.do");
registration.addUrlMappings("*.json");
return registration;
}

/**
* 使用代码注册Servlet（不需要@ServletComponentScan注解）
*/
@Bean
public ServletRegistrationBean servletRegistrationBean() {
return new ServletRegistrationBean(new MyServlet(), "/xs/*");// ServletName默认值为首字母小写，即myServlet
}
}[/java]

二、在 SpringBootApplication 上使用@ServletComponentScan 注解后，Servlet、Filter、Listener 可以直接通过 @WebServlet、@WebFilter、@WebListener 注解自动注册，无需其他代码。

1. 过滤器LoginFilter.java

[java]@WebFilter(value="/*")
public class LoginFilter implements Filter {

public LoginFilter() {
System.out.println("过滤器初始化");
}

public void destroy() {
System.out.println("过滤器销毁");
}

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
System.out.println("执行过滤操作>>>>>");
// pass the request along the filter chain

chain.doFilter(request, response);
}

public void init(FilterConfig fConfig) throws ServletException {
}

}[/java]

2.SpringBoot启动类添加组件扫描注解@ServletComponentScan

[java]@SpringBootApplication
@ServletComponentScan
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}[/java]

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