Add Sentinel Spring Web MVC adapter module (alibaba#1104)

- Add sentinel-spring-webmvc-adapter module and demo

sentinel-adapter/pom.xml

@@ -24,6 +24,7 @@
         <module>sentinel-spring-webflux-adapter</module>
         <module>sentinel-api-gateway-adapter-common</module>
         <module>sentinel-spring-cloud-gateway-adapter</module>
+        <module>sentinel-spring-webmvc-adapter</module>
     </modules>
 
     <dependencyManagement>

sentinel-adapter/sentinel-spring-webmvc-adapter/README.md

@@ -0,0 +1,115 @@
+# Sentinel Spring MVC Interceptor
+
+Sentinel provides Spring MVC Interceptor integration to enable flow control for web requests, And support url like '/foo/{id}'
+
+Add the following dependency in `pom.xml` (if you are using Maven):
+
+```xml
+<dependency>
+    <groupId>com.alibaba.csp</groupId>
+    <artifactId>sentinel-spring-webmvc-adapter</artifactId>
+    <version>x.y.z</version>
+</dependency>
+```
+
+Configure interceptor
+
+```java
+@Configuration
+public class InterceptorConfig implements WebMvcConfigurer {
+
+    @Override
+    public void addInterceptors(InterceptorRegistry registry) {
+        //Add sentinel interceptor
+        addSpringMvcInterceptor(registry);
+        //If you want to sentinel the total flow, you can add total interceptor
+        addSpringMvcTotalInterceptor(registry);
+    }
+
+    private void addSpringMvcInterceptor(InterceptorRegistry registry) {
+        //Configure
+        SentinelWebMvcConfig config = new SentinelWebMvcConfig();
+        //Custom configuration if necessary
+        config.setHttpMethodSpecify(true);
+        config.setOriginParser(request -> request.getHeader("S-user"));
+        //Add sentinel interceptor
+        registry.addInterceptor(new SentinelInterceptor(config)).addPathPatterns("/**");
+    }
+
+    private void addSpringMvcTotalInterceptor(InterceptorRegistry registry) {
+        //Configure
+        SentinelWebMvcTotalConfig config = new SentinelWebMvcTotalConfig();
+        //Custom configuration if necessary
+        config.setRequestAttributeName("my_sentinel_spring_mvc_total_entity_container");
+        config.setTotalResourceName("my-spring-mvc-total-url-request");
+        //Add sentinel interceptor
+        registry.addInterceptor(new SentinelTotalInterceptor(config)).addPathPatterns("/**");
+    }
+}
+```
+
+Configure 'BlockException' handler, there are three options:
+1. Global exception handling in spring MVC. <Recommend>
+```java
+@ControllerAdvice
+@Order(0)
+public class SentinelSpringMvcBlockHandlerConfig {
+    private Logger logger = LoggerFactory.getLogger(this.getClass());
+    @ExceptionHandler(BlockException.class)
+    @ResponseBody
+    public String sentinelBlockHandler(BlockException e) {
+        AbstractRule rule = e.getRule();
+        logger.info("Blocked by sentinel, {}", rule.toString());
+        return "Blocked by Sentinel";
+    }
+}
+
+```
+2. Use `DefaultBlockExceptionHandler`
+```java
+//SentinelWebMvcTotalConfig config = new SentinelWebMvcTotalConfig();
+SentinelWebMvcConfig config = new SentinelWebMvcConfig();
+config.setBlockExceptionHandler(new DefaultBlockExceptionHandler());
+```
+3. `implements BlockExceptionHandler`
+```java
+//SentinelWebMvcTotalConfig config = new SentinelWebMvcTotalConfig();
+SentinelWebMvcConfig config = new SentinelWebMvcConfig();
+config.setBlockExceptionHandler((request, response, e) -> {
+    String resourceName = e.getRule().getResource();
+    //Depending on your situation, you can choose to process or throw
+    if ("/hello".equals(resourceName)) {
+        //Do something ......
+        //Write string or error page;
+        response.getWriter().write("Blocked by sentinel");
+    } else {
+        //Handle it in global exception handling
+        throw e;
+    }
+});
+```
+
+Configuration
+- Common configuration in `SentinelWebMvcConfig` and `SentinelWebMvcTotalConfig`
+
+| name | description | type | default value |
+|------|------------|------|-------|
+| blockExceptionHandler| The handler when blocked by sentinel, there are three options:<br/>1. The default value is null, you can hanlde `BlockException` in spring MVC;<br/>2.Use `DefaultBlockExceptionHandler`;<br/>3. `implements BlockExceptionHandler`  | `BlockExceptionHandler` | `null` |
+| originParser | `RequestOriginParser` interface is useful for extracting request origin (e.g. IP or appName from HTTP Header) from HTTP request | `RequestOriginParser` | `null` |
+
+- `SentinelWebMvcConfig` configuration
+
+| name | description | type | default value |
+|------|------------|------|-------|
+| urlCleaner | The `UrlCleaner` interface is designed for clean and unify the URL resource. For REST APIs, you can to clean the URL resource (e.g. `/api/user/getById` and `/api/user/getByName` -> `/api/user/getBy*`), avoid the amount of context and will exceed the threshold | `UrlCleaner` | `null` |
+| requestAttributeName | Attribute name in request used by sentinel, please check record log, if it is already used, please set | `String` | sentinel_spring_mvc_entry_container |
+| httpMethodSpecify | Specify http method, for example: GET:/hello | `boolean` | `false` |
+
+
+`SentinelWebMvcTotalConfig` configuration
+
+| name | description | type | default value |
+|------|------------|------|-------|
+| totalResourceName | The resource name in `SentinelTotalInterceptor` | `String` | spring-mvc-total-url-request |
+| requestAttributeName | Attribute name in request used by sentinel, please check record log, if it is already used, please set | `String` | sentinel_spring_mvc_total_entry_container |
+

sentinel-adapter/sentinel-spring-webmvc-adapter/pom.xml

@@ -0,0 +1,55 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>sentinel-adapter</artifactId>
+        <groupId>com.alibaba.csp</groupId>
+        <version>1.7.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>sentinel-spring-webmvc-adapter</artifactId>
+
+    <properties>
+        <spring.version>5.1.8.RELEASE</spring.version>
+        <spring.boot.version>2.1.3.RELEASE</spring.boot.version>
+        <servlet.api.version>3.1.0</servlet.api.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.alibaba.csp</groupId>
+            <artifactId>sentinel-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${servlet.api.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-webmvc</artifactId>
+            <version>${spring.version}</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>${spring.boot.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <version>${spring.boot.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.alibaba</groupId>
+            <artifactId>fastjson</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

sentinel-adapter/sentinel-spring-webmvc-adapter/src/main/java/com/alibaba/csp/sentinel/adapter/spring/webmvc/AbstractSentinelInterceptor.java

@@ -0,0 +1,138 @@
+/*
+ * Copyright 1999-2019 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.csp.sentinel.adapter.spring.webmvc;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.alibaba.csp.sentinel.Entry;
+import com.alibaba.csp.sentinel.EntryType;
+import com.alibaba.csp.sentinel.SphU;
+import com.alibaba.csp.sentinel.Tracer;
+import com.alibaba.csp.sentinel.adapter.spring.webmvc.config.BaseWebMvcConfig;
+import com.alibaba.csp.sentinel.context.ContextUtil;
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import com.alibaba.csp.sentinel.util.StringUtil;
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+/**
+ * @author kaizi2009
+ */
+public abstract class AbstractSentinelInterceptor implements HandlerInterceptor {
+
+    public static final String SPRING_MVC_CONTEXT_NAME = "spring_mvc_context";
+    private static final String EMPTY_ORIGIN = "";
+    protected static final String COLON = ":";
+    private BaseWebMvcConfig baseWebMvcConfig;
+
+    @Override
+    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
+            throws Exception {
+
+        try {
+            String resourceName = getResourceName(request);
+
+            if (StringUtil.isNotEmpty(resourceName)) {
+                // Parse the request origin using registered origin parser.
+                String origin = parseOrigin(request);
+                ContextUtil.enter(SPRING_MVC_CONTEXT_NAME, origin);
+                Entry entry = SphU.entry(resourceName, EntryType.IN);
+
+                setEntryInRequest(request, baseWebMvcConfig.getRequestAttributeName(), entry);
+            }
+            return true;
+        } catch (BlockException e) {
+            handleBlockException(request, response, e);
+            return false;
+        }
+    }
+
+    /**
+     * Get sentinel resource name.
+     * @param request
+     * @return
+     */
+    protected abstract String getResourceName(HttpServletRequest request);
+
+    @Override
+    public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
+                                Object handler, Exception ex) throws Exception {
+        Entry entry = getEntryInRequest(request, baseWebMvcConfig.getRequestAttributeName());
+        if (entry != null) {
+            traceExceptionAndExit(entry, ex);
+            removeEntryInRequest(request);
+        }
+        ContextUtil.exit();
+    }
+
+    @Override
+    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
+                           ModelAndView modelAndView) throws Exception {
+    }
+
+    protected void setEntryInRequest(HttpServletRequest request, String name, Entry entry) {
+        Object attrVal = request.getAttribute(name);
+        if (attrVal != null) {
+            RecordLog.warn(String.format("Already exist attribute name '%s' in request, please set `requestAttributeName`", name));
+        } else {
+            request.setAttribute(name, entry);
+        }
+    }
+
+    protected Entry getEntryInRequest(HttpServletRequest request, String attrKey) {
+        Object entryObject = request.getAttribute(attrKey);
+        return entryObject == null ? null : (Entry) entryObject;
+    }
+
+    protected void removeEntryInRequest(HttpServletRequest request) {
+        request.removeAttribute(baseWebMvcConfig.getRequestAttributeName());
+    }
+
+    protected void traceExceptionAndExit(Entry entry, Exception ex) {
+        if (entry != null) {
+            if (ex != null) {
+                Tracer.traceEntry(ex, entry);
+            }
+            entry.exit();
+        }
+    }
+
+    protected void handleBlockException(HttpServletRequest request, HttpServletResponse response, BlockException e) throws Exception {
+        if (baseWebMvcConfig.getBlockExceptionHandler() != null) {
+            baseWebMvcConfig.getBlockExceptionHandler().handle(request, response, e);
+        } else {
+            //Throw BlockException, handle it in spring mvc
+            throw e;
+        }
+    }
+
+    protected String parseOrigin(HttpServletRequest request) {
+        String origin = EMPTY_ORIGIN;
+        if (baseWebMvcConfig.getOriginParser() != null) {
+            origin = baseWebMvcConfig.getOriginParser().parseOrigin(request);
+            if (StringUtil.isEmpty(origin)) {
+                return EMPTY_ORIGIN;
+            }
+        }
+        return origin;
+    }
+
+    protected void setBaseWebMvcConfig(BaseWebMvcConfig config) {
+        this.baseWebMvcConfig = config;
+    }
+}