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。
标签：Springboot,HandlerMethodReturnValueHandler,springframework,resultInfo,org,import From： https://www.cnblogs.com/happyhuangjinjin/p/16748529.html