feat: implement custom @TimestampRequestBody annotation to enhance request body processing with timestamp injection

Author: helltractor

pattern-design/pattern-decorator/README.md

@@ -0,0 +1,11 @@
+## Decorator Pattern
+
+## 介绍
+
+实现一个自定义注解 `@TimestampRequestBody`，用于拦截并增强 `@RequestBody` 注解解析过程，
+在反序列化完成后，自动为请求体对象注入当前时间戳字段，无需客户端显式传递。
+
+## 参考
+
+> [Decorator Pattern](https://refactoringguru.cn/design-patterns/decorator)
+> [装饰模式](https://www.bilibili.com/video/BV1bgPBesENK)

pattern-design/pattern-decorator/pom.xml

@@ -0,0 +1,24 @@
+<?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">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.helltractor.demo</groupId>
+        <artifactId>pattern-design</artifactId>
+        <version>1.0-SNAPSHOT</version>
+        <relativePath>../pom.xml</relativePath>
+    </parent>
+
+    <artifactId>pattern-decorator</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+            <version>3.4.1</version>
+        </dependency>
+    </dependencies>
+
+</project>

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/Application.java

@@ -0,0 +1,13 @@
+package com.helltractor.demo;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+    
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+    
+}

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/config/MyArgumentResolverConfigurer.java

@@ -0,0 +1,33 @@
+package com.helltractor.demo.config;
+
+import org.springframework.beans.factory.SmartInitializingSingleton;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
+import org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Component
+public class MyArgumentResolverConfigurer implements SmartInitializingSingleton {
+    
+    @Autowired
+    private RequestMappingHandlerAdapter requestMappingHandlerAdapter;
+    
+    @Override
+    public void afterSingletonsInstantiated() {
+        List<HandlerMethodArgumentResolver> argumentResolvers = requestMappingHandlerAdapter.getArgumentResolvers();
+        List<HandlerMethodArgumentResolver> resolvers = new ArrayList<>(argumentResolvers.size() + 1);
+        for (HandlerMethodArgumentResolver resolver : argumentResolvers) {
+            resolvers.add(resolver);
+            if (resolver instanceof RequestResponseBodyMethodProcessor) {
+                resolvers.add(new TimestampRequestBodyMethodProcess(
+                        (RequestResponseBodyMethodProcessor) resolver));
+            }
+        }
+        requestMappingHandlerAdapter.setArgumentResolvers(resolvers);
+    }
+    
+}

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/config/MyWebMvcConfigurer.java

@@ -0,0 +1,32 @@
+package com.helltractor.demo.config;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
+import org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor;
+
+import java.util.List;
+
+/**
+ * This class will cause a circular dependency, instead, use MyArgumentResolverConfigurer.
+ */
+// @Configuration
+public class MyWebMvcConfigurer implements WebMvcConfigurer {
+    
+    @Autowired
+    private RequestMappingHandlerAdapter requestMappingHandlerAdapter;
+    
+    @Override
+    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> resolvers) {
+        List<HandlerMethodArgumentResolver> argumentResolvers = requestMappingHandlerAdapter.getArgumentResolvers();
+        for (HandlerMethodArgumentResolver resolver : argumentResolvers) {
+            if (resolver instanceof RequestResponseBodyMethodProcessor) {
+                resolvers.add(new TimestampRequestBodyMethodProcess(
+                        (RequestResponseBodyMethodProcessor) resolver));
+                return;
+            }
+        }
+    }
+    
+}

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/config/TimestampRequestBody.java

@@ -0,0 +1,14 @@
+package com.helltractor.demo.config;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.PARAMETER})
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface TimestampRequestBody {
+
+}

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/config/TimestampRequestBodyMethodProcess.java

@@ -0,0 +1,36 @@
+package com.helltractor.demo.config;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.web.bind.support.WebDataBinderFactory;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.method.support.ModelAndViewContainer;
+import org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor;
+
+import java.util.Map;
+
+public class TimestampRequestBodyMethodProcess implements HandlerMethodArgumentResolver {
+    
+    private final RequestResponseBodyMethodProcessor processor;
+    
+    TimestampRequestBodyMethodProcess(RequestResponseBodyMethodProcessor processor) {
+        this.processor = processor;
+    }
+    
+    @Override
+    public boolean supportsParameter(MethodParameter parameter) {
+        return parameter.hasParameterAnnotation(TimestampRequestBody.class);
+    }
+    
+    @Override
+    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
+        
+        Object result = processor.resolveArgument(parameter, mavContainer, webRequest, binderFactory);
+        if (!(result instanceof Map<?, ?>)) {
+            return result;
+        }
+        ((Map) result).put("timestamp", System.currentTimeMillis());
+        return result;
+    }
+    
+}

pattern-design/pattern-decorator/src/main/java/com/helltractor/demo/controller/MyController.java

@@ -0,0 +1,25 @@
+package com.helltractor.demo.controller;
+
+import com.helltractor.demo.config.TimestampRequestBody;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api")
+public class MyController {
+    
+    @PostMapping("/")
+    public Map<String, Object> origin(@RequestBody Map<String, Object> request) {
+        return request;
+    }
+    
+    @PostMapping("/timestamp")
+    public Map<String, Object> originWithTimestamp(@TimestampRequestBody Map<String, Object> request) {
+        return request;
+    }
+    
+}

pattern-design/pom.xml

@@ -13,6 +13,7 @@
         <module>pattern-proxy</module>
         <module>pattern-command</module>
         <module>pattern-memento</module>
+        <module>pattern-decorator</module>
     </modules>
 
     <properties>
@@ -24,4 +25,34 @@
         <mysql.version>8.1.0</mysql.version>
     </properties>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>flatten-maven-plugin</artifactId>
+                <version>1.1.0</version>
+                <configuration>
+                    <updatePomFile>true</updatePomFile>
+                    <flattenMode>resolveCiFriendliesOnly</flattenMode>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>flatten</id>
+                        <phase>process-resources</phase>
+                        <goals>
+                            <goal>flatten</goal>
+                        </goals>
+                    </execution>
+                    <execution>
+                        <id>flatten.clean</id>
+                        <phase>clean</phase>
+                        <goals>
+                            <goal>clean</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
 </project>