Spring Boot配置過濾器的兩種方式
阿新 • • 發佈:2020-07-16
首先在介紹springboot實現過濾器之前,我們先來了解下sevlet的三大元件:
Spring Boot @ServletComponentScan 掃描 @WebServlet、@WebFilter、@WebListener
Servlet 三大元件 Servlet、Filter、Listener 在傳統專案中需要在 web.xml 中進行相應的配置。Servlet 3.0 開始在 javax.servlet.annotation 包下提供 3 個對應的 @WebServlet、@WebFilter、@WebListener 註解來簡化操作
@WebServlet、@WebFilter、@WebListener 寫在對應的 Servlet、Filter、Listener 類上作為標識,從而不需要在 web.xml 中進行配置了
Spring Boot 應用中這三個註解預設是不被掃描的,需要在專案啟動類上新增 @ServletComponentScan 註解, 表示對 Servlet 元件掃描
@WebServlet
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; /** * 標準的 Servlet ,實現 javax.servlet.http.HttpServlet. 重寫其 doGet 、doPost 方法 * name :表示 servlet 名稱,可以不寫,預設為空 * urlPatterns: 表示請求的路徑,如 http://ip:port/context-path/userServlet */ @WebServlet(name = "UserServlet", urlPatterns = {"/userServlet"}) public class UserServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { StringBuffer requestURL = req.getRequestURL(); System.out.println("com.wmx.servlet.UserServlet -- " + requestURL); resp.sendRedirect("/index.html");//瀏覽器重定向到伺服器下的 index.html 頁面 } }
@WebFilter
import javax.servlet.*; import javax.servlet.annotation.WebFilter; import javax.servlet.http.HttpServletRequest; import java.io.IOException; /** * 標準 Servlet 過濾器,實現 javax.servlet.Filter 介面,並重現它的 3 個方法 * filterName:表示過濾器名稱,可以不寫 * value:配置請求過濾的規則,如 "/*" 表示過濾所有請求,包括靜態資源,如 "/user/*" 表示 /user 開頭的所有請求 */ @WebFilter(filterName = "SystemFilter", value = {"/*"}) public class SystemFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { System.out.println("com.wmx.servlet.SystemFilter -- 系統啟動..."); } @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { //轉為 HttpServletRequest 輸出請求路徑 HttpServletRequest request = (HttpServletRequest) servletRequest; System.out.println("com.wmx.servlet.SystemFilter -- 過濾器放行前...." + request.getRequestURL()); filterChain.doFilter(servletRequest, servletResponse); System.out.println("com.wmx.servlet.SystemFilter -- 過濾器返回後...." + request.getRequestURL()); } @Override public void destroy() { System.out.println("com.wmx.servlet.SystemFilter -- 系統關閉..."); } }
@WebListener
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
/**
* 標準 Servlet 監聽器,實現 javax.servlet.ServletContextListener 介面,並重寫方法
* ServletContextListener 屬於 Servlet 應用啟動關閉監聽器,監聽容器初始化與銷燬。常用的監聽器還有:
* ServletRequestListener:HttpServletRequest 物件的建立和銷燬監聽器
* HttpSessionListener:HttpSession 資料物件建立和銷燬監聽器
* HttpSessionAttributeListener 監聽HttpSession中屬性變化
* ServletRequestAttributeListener 監聽ServletRequest中屬性變化
*/
@WebListener
public class SystemListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("com.wmx.servlet.SystemListener -- 伺服器啟動.");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
System.out.println("com.wmx.servlet.SystemListener -- 伺服器關閉.");
}
}
@ServletComponentScan
Spring Boot 應用中這三個註解預設是不被掃描的,需要在專案啟動類上新增 @ServletComponentScan 註解, 表示對 Servlet 元件掃描
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan //對 servlet 註解進行掃描
public class RedisStuWebApplication {
public static void main(String[] args) {
SpringApplication.run(RedisStuWebApplication.class, args);
}
}
在介紹完sevlet的三大元件之後,我們再來學習如何實現過濾器就不會那麼迷茫了……
Spring Boot配置過濾器的兩種方式
@WebFilter註解方式
使用@WebFilter註解為聲明當前類為filter,第一個引數為該filter起一個名字,第二個引數為說明要攔截的請求地址,當前類需要實現Filter介面,裡面有三個方法,分別為過濾器初始化、過濾方法和過濾器銷燬
@Slf4j
@WebFilter(filterName = "myFilter1", urlPatterns = "/*")
public class MyFilter1 implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
log.info(filterConfig.getFilterName() + " init");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
log.info("myFilter1 begin");
try {
log.info("業務方法執行");
chain.doFilter(request, response);
} catch (Exception e) {
log.error("error!", e);
}
log.info("myFilter1 end");
}
@Override
public void destroy() {
}
}
啟動類新增@ServletComponentScan註解,@ServletComponentScan註解所掃描的包路徑必須包含該Filter,程式碼如下:
之所以加這個註解,因為springboot預設不掃描Servlet的三大元件,所以需要加
@SpringBootApplication
@ServletComponentScan(basePackages = "com.example.demo.filter")
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
@Bean註解方式
新建MyFilter2.java類,不要加註解@WebFilter,程式碼如下:
@Slf4j
public class MyFilter2 implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
log.info(filterConfig.getFilterName() + " init");
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) {
log.info("myFilter2 begin");
try {
log.info("業務方法執行");
chain.doFilter(request, response);
} catch (Exception e) {
log.error("error!", e);
}
log.info("myFilter2 end");
}
@Override
public void destroy() {
}
}
新建配置類WebConfig.java,配置bean,程式碼如下:
@Configuration
public class WebConfig {
@Bean
public FilterRegistrationBean testFilterRegistration() {
//配置多個過濾規則
// List<String> urls = new ArrayList<>();
// urls.add("/order/*");
// urls.add("/user/*");
// registration.setUrlPatterns(urls);
FilterRegistrationBean registration = new FilterRegistrationBean(new MyFilter2());
registration.addUrlPatterns("/test"); //
registration.setName("myFilter2");
return registration;
}
}
檢視執行效果
專案啟動後瀏覽器訪問http://localhost:8080/test,可以看到過濾器已生效,後臺列印日誌如下:
[nio-8080-exec-1] com.example.demo.filter.MyFilter1 : myFilter1 begin
[nio-8080-exec-1] com.example.demo.filter.MyFilter1 : 業務方法執行
[nio-8080-exec-1] com.example.demo.filter.MyFilter1 : myFilter1 end
到此Spring Boot配置過濾器的兩種方式已經全部實現,有問題歡迎留言溝通哦!