简介
现在项目中大部分采用前后端分离的架构，采用这种架构的项目，在返回数据时，几乎都是采用返回 json 格式的数据。而 spring 中返回 json 格式的数据一般采用 @RestController 或者 @ResponseBody 注解。代码样例
@ResponseBody @RequestMapping("/reqBody") public ResultInfo<Map<String, Object>> reqBody(){ ResultInfo<Map<String, Object>> resultInfo = new ResultInfo<>(); resultInfo.setCode(200); resultInfo.setMessage("success"); Map<String, Object> map = new HashMap<>(); map.put("userId", 100); map.put("tenantId", 1001); map.put("userName", "bug弄潮儿"); resultInfo.setBody(map); return resultInfo; }
今天定义一个注解读返回的 json 进行加密，来运用 HandlerMethodReturnValueHandler
pom.xml 文件引入依赖
<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> <groupId>com.olive</groupId> <artifactId>springmvc-response-body</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>springmvc-response-body</name> <url>http://maven.apache.org</url> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.14</version> <relativePath /> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>8</maven.compiler.source> <maven.compiler.target>8</maven.compiler.target> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>com.alibaba.fastjson2</groupId> <artifactId>fastjson2</artifactId> <version>2.0.14</version> </dependency> </dependencies> </project>
定义加密注解
package com.olive.annotation; import java.lang.annotation.*; @Target({ElementType.TYPE, ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface Encrypted { boolean value() default true; }
Encrypted 注解，该注解是一个标识注解；如果打上该注解标识加密
统一返回定义
主要包含 code、message 和 body 属性定义
package com.olive.dto; import lombok.Data; import java.io.Serializable; @Data public class ResultInfo<T> implements Serializable { public int code; public String message; private T body; private boolean encrypt; }
自定义 ResponseBodyHandler
该类实现 HandlerMethodReturnValueHandler 类，主要对 @RestController 或者 @ResponseBody 注解进行解析
package com.olive.config; import com.alibaba.fastjson2.JSON; import com.olive.annotation.Encrypted; import com.olive.dto.ResultInfo; import org.springframework.core.MethodParameter; import org.springframework.core.annotation.AnnotatedElementUtils; import org.springframework.util.Base64Utils; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.context.request.NativeWebRequest; import org.springframework.web.method.support.HandlerMethodReturnValueHandler; import org.springframework.web.method.support.ModelAndViewContainer; import java.nio.charset.StandardCharsets; public class ResponseBodyHandler implements HandlerMethodReturnValueHandler { protected final HandlerMethodReturnValueHandler handlerMethodReturnValueHandler; public ResponseBodyHandler(HandlerMethodReturnValueHandler handlerMethodReturnValueHandler){ this.handlerMethodReturnValueHandler = handlerMethodReturnValueHandler; } @Override public boolean supportsReturnType(MethodParameter returnType) { //如果被@ResponseBody注解修饰的 返回true return (AnnotatedElementUtils.hasAnnotation(returnType.getContainingClass(), ResponseBody.class) || returnType.hasMethodAnnotation(ResponseBody.class)) && returnType.hasMethodAnnotation(Encrypted.class); } @Override public void handleReturnValue(Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { if(returnValue instanceof ResultInfo){ ResultInfo<?> resultInfo = (ResultInfo<?>)returnValue; ResultInfo<String> newResultInfo = new ResultInfo<>(); newResultInfo.setCode(resultInfo.getCode()); newResultInfo.setMessage(resultInfo.getMessage()); newResultInfo.setEncrypt(true); newResultInfo.setBody(Base64Utils.encodeToString(JSON.toJSONString(resultInfo.getBody()).getBytes(StandardCharsets.UTF_8))); //ResponseBody注解执行器 handlerMethodReturnValueHandler.handleReturnValue(newResultInfo, returnType, mavContainer, webRequest); }else{ handlerMethodReturnValueHandler.handleReturnValue(returnValue, returnType, mavContainer, webRequest); } } }
注册 ResponseBodyHandler 到 controller 返回值处理器里，即添加自己的返回值处理器
package com.olive.config; import org.springframework.beans.factory.InitializingBean; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Configuration; import org.springframework.web.method.support.HandlerMethodReturnValueHandler; 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; @Configuration public class WebConfig implements InitializingBean { @Autowired private RequestMappingHandlerAdapter adapter; @Override public void afterPropertiesSet() throws Exception { List<HandlerMethodReturnValueHandler> unmodifiableList = adapter.getReturnValueHandlers(); List<HandlerMethodReturnValueHandler> list = new ArrayList<>(unmodifiableList.size()); for (HandlerMethodReturnValueHandler returnValueHandler : unmodifiableList) { if (returnValueHandler instanceof RequestResponseBodyMethodProcessor) { //将RequestResponseBodyMethodProcessor 实际返回值替换为自定义的，实际执行为RequestResponseBodyMethodProcessor //重要 HandlerMethodReturnValueHandler handler = new ResponseBodyHandler(returnValueHandler); list.add(handler); } else { list.add(returnValueHandler); } } adapter.setReturnValueHandlers(list); } }
测试
编写 Springboot 启动引导类
package com.olive; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; /** * https://cloud.tencent.com/developer/article/1616704 * * @author 2230 * */ @SpringBootApplication public class Application { public static void main(String[] args) { SpringApplication.run(Application.class); } }
编写测试 Controller
package com.olive.controller; import java.util.HashMap; import java.util.Map; import com.olive.annotation.Encrypted; import com.olive.dto.ResultInfo; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class TestController { @Encrypted @RequestMapping("/reqBody") public ResultInfo<Map<String, Object>> reqBody(){ ResultInfo<Map<String, Object>> resultInfo = new ResultInfo<>(); resultInfo.setCode(200); resultInfo.setMessage("success"); Map<String, Object> map = new HashMap<>(); map.put("userId", 100); map.put("tenantId", 1001); map.put("userName", "bug弄潮儿"); resultInfo.setBody(map); return resultInfo; } }
通过 HandlerMethodReturnValueHandler 可以对返回的数据进行进一步的封装，减少在业务代码中进行重复的返回值处理。例如，文章中的对返回数据进行统一加密。
