SpringBoot 无XML的相关配置
Setting context-params
在Servlet 2.0是在web.xml来设置context-params
<context-param>
<param-name>facelets.DEVELOPMENT</param-name>
<param-value>true</param-value>
</context-param>
在基于Servlet 3.0的SpringBoot上可使用
@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application implements ServletContextInitializer {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
@Override
public void onStartup(ServletContext servletContext)
throws ServletException {
servletContext.setInitParameter("facelets.DEVELOPMENT", "true");
}
}
添加Interceptor
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
@Configuration
public class MyWebAppConfigurer extends WebMvcConfigurerAdapter {
@Override
public void addInterceptors(InterceptorRegistry registry) {
// 多个拦截器组成一个拦截器链
// addPathPatterns 用于添加拦截规则
// excludePathPatterns 用户排除拦截
registry.addInterceptor(new MyInterceptor1()).addPathPatterns("/**");
registry.addInterceptor(new MyInterceptor2()).addPathPatterns("/**");
super.addInterceptors(registry);
}
}
Tips:Filter与Interceptor的区别
- 使用范围不同：Filter是Servlet规范规定的，只能用于Web程序中。而拦截器既可以用于Web程序，也可以用于Application、Swing程序中。
- 规范不同：Filter是在Servlet规范中定义的，是Servlet容器支持的。而拦截器是在Spring容器内的，是Spring框架支持的。
- 使用的资源不同：同其他的代码块一样，拦截器也是一个Spring的组件，归Spring管理，配置在Spring文件中，因此能使用Spring里的任何资源、对象，例如Service对象、数据源、事务管理等，通过IoC注入到拦截器即可；而Filter则不能。
- 深度不同：Filter在只在Servlet前后起作用。而拦截器能够深入到方法前后、异常抛出前后等，因此拦截器的使用具有更大的弹性。所以在Spring构架的程序中，要优先使用拦截器。
浏览器发起请求执行顺序
Client -> Listener -> ServletContainer -> Filter -> Servlet -> Interceptor
添加Servlet、Filer、Listener
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。
启动扫描
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
//这个就是扫描相应的Servlet包;
@ServletComponentScan
public class SiteConfig {
public static void main(String[] args) {
SpringApplication.run(SiteConfig.class, args);
}
}
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(urlPatterns="/myServlet/*", description="Servlet的说明")
public class MyServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@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()<<<<<<<<<<<");
resp.setContentType("text/html;charset=UTF-8");
PrintWriter out = resp.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Hello World</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>这是：MyServlet</h1>");
out.println("</body>");
out.println("</html>");
}
}
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
/**
* 使用注解标注过滤器
* @WebFilter将一个实现了javax.servlet.Filter接口的类定义为过滤器
* 属性filterName声明过滤器的名称,可选
* 属性urlPatterns指定要过滤的URL模式,也可使用属性value来声明.(指定要过滤的URL模式是必选属性)
*/
@WebFilter(filterName = "myFilter", urlPatterns = "/*")
public class MyFilter implements Filter {
@Override
public void init(FilterConfig config) throws ServletException {
System.out.println("过滤器初始化");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
System.out.println("执行过滤操作");
chain.doFilter(request, response);
}
@Override
public void destroy() {
System.out.println("过滤器销毁");
}
}
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
/**
* 使用@WebListener注解，实现ServletContextListener接口
*/
@WebListener
public class MyServletContextListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent arg0) {
System.out.println("ServletContex销毁");
}
@Override
public void contextInitialized(ServletContextEvent arg0) {
System.out.println("ServletContex初始化");
}
}
代码注册通过ServletRegistrationBean、FilterRegistrationBean和ServletListenerRegistrationBean获得控制。
@Bean
public FilterRegistrationBean sessionFilter() {
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(new HttpSessionFilter());
return bean;
}
可以通过实现ServletContextInitializer接口直接注册。
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
// Servlet
ServletRegistration.Dynamic dispatcher = servletContext.addServlet("dispatcher", new DispatcherServlet(dispatcherContext));
dispatcher.addMapping("/");
dispatcher.setLoadOnStartup(1);
dispatcher.setInitParameter("defaultHtmlEscape", "true");
// Filter
FilterRegistration.Dynamic filter = container.addFilter("encodingFilter", CharacterEncodingFilter.class);
filter.addMappingForUrlPatterns(null, false, "/*");
filter.setInitParameter("encoding", "UTF-8");
filter.setInitParameter("forceEncoding", "true");
// Listener
servletContext.addListener(TestServletContextListener.class);
super.onStartup(servletContext);
}
