1. Problemdetails

错误信息返回新格式

package org.springframework.boot.autoconfigure.web.servlet;
......省略部分......
public class WebMvcAutoConfiguration {......省略部分......@Configuration(proxyBeanMethods = false)@ConditionalOnProperty(prefix = "spring.mvc.problemdetails",name = {"enabled"},havingValue = "true")static class ProblemDetailsErrorHandlingConfiguration {ProblemDetailsErrorHandlingConfiguration() {}@Bean@ConditionalOnMissingBean({ResponseEntityExceptionHandler.class})ProblemDetailsExceptionHandler problemDetailsExceptionHandler() {return new ProblemDetailsExceptionHandler();}}......省略部分......
}

1. 默认是关闭的。需要配置一个属性spring.mvc.problemdetails.enabled=true
2. ProblemDetailsExceptionHandler是一个@ControllerAdvice集中处理系统异常
3. 如果系统出现以下异常，会被SpringBoot支持以RFC 7807规范方式返回错误数据

	@ExceptionHandler({HttpRequestMethodNotSupportedException.class,    // 请求方式不支持HttpMediaTypeNotSupportedException.class,HttpMediaTypeNotAcceptableException.class,MissingPathVariableException.class,MissingServletRequestParameterException.class,MissingServletRequestPartException.class,ServletRequestBindingException.class,MethodArgumentNotValidException.class,NoHandlerFoundException.class,AsyncRequestTimeoutException.class,ErrorResponseException.class,ConversionNotSupportedException.class,TypeMismatchException.class,HttpMessageNotReadableException.class,HttpMessageNotWritableException.class,BindException.class})

4. 以HttpRequestMethodNotSupportedException来讲解开启的效果。不开启前，以post方式请求一个get url: http://localhost:8080/exception。显示如下。其中headers的Content-Type是application/json

{"timestamp": "2023-07-22T02:51:16.088+00:00","status": 405,"error": "Method Not Allowed","path": "/exception"
}

开启后。显示如下。。其中headers的Content-Type是application/problem+json。其中problem可以通过额外的拓展返回一些业务数据

{"type": "about:blank","title": "Method Not Allowed","status": 405,"detail": "Method 'POST' is not supported.","instance": "/exception"
}

2. 函数式Web

使用函数式的方式，定义Web的请求处理流程。使用的java8函数式接口

Web请求处理的方式：

1. @Controller + @RequestMapping：耦合式 （路由、业务耦合）
2. 函数式Web：分离式（路由、业务分离）

2.1 场景

以Restful方式，对User进行CRUD

• GET /user/1: 获取id=1的用户
• GET /users: 获取所有用户
• POST /user: 请求体携带json，新增一个用户
• PUT /user/1: 请求体携带json，修改id=1的用户
• DELETE /user/1: 删除id=1的用户

2.2 主要逻辑

1. 给容器中放一个Bean：类型是RouterFunction，集中所有路由信息
2. 每个业务准备一个的Handler

2.3 核心对象

1. RouterFunction：定义路由信息。发什么请求，谁来处理
2. RequestPredicate：定义请求规则：请求方式（GET、POST）和请求参数
3. ServerRequest：封装请求完整数据
4. ServerResponse：封装响应完整数据

2.4 示例程序

WebFunctionConfig.java

package com.hh.springboot3test.config;import com.hh.springboot3test.bean.User;
import com.hh.springboot3test.biz.UserBizHandler;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.web.servlet.function.RequestPredicates;
import org.springframework.web.servlet.function.RouterFunction;
import org.springframework.web.servlet.function.RouterFunctions;
import org.springframework.web.servlet.function.ServerResponse;@Configuration
public class WebFunctionConfig {@Beanpublic RouterFunction<ServerResponse> userRoute(UserBizHandler userBizHandler/*这个会被自动注入进来*/) {return RouterFunctions.route() // 开始定义路由信息.GET("/user/{id}", RequestPredicates.accept(MediaType.ALL).and(RequestPredicates.param("key1", "value1")/* 只有/user/n?key1=value1能查询出来结果 */), request -> {String id = request.pathVariable("id");System.out.println("查询的用户的id = " + id);// 模拟数据库查询出来的用户User user = new User(1, "jim", 28);// 构造响应。和@ResponseBody原理一样，利用HttpMessageConverter，可写出为jsonreturn ServerResponse.ok().body(user);}).GET("/users", userBizHandler::getUsers).POST("/user", RequestPredicates.accept(MediaType.APPLICATION_JSON), userBizHandler::saveUser).PUT("/user/{id}", RequestPredicates.accept(MediaType.APPLICATION_JSON), userBizHandler::updateUser).DELETE("/user/{id}", userBizHandler::deleteUser).build();}}

UserBizHandler.java

package com.hh.springboot3test.biz;import com.hh.springboot3test.bean.User;
import jakarta.servlet.ServletException;
import org.springframework.stereotype.Service;
import org.springframework.web.servlet.function.ServerRequest;
import org.springframework.web.servlet.function.ServerResponse;import java.io.IOException;
import java.util.Arrays;
import java.util.List;@Service
public class UserBizHandler {/*** 获取所有用户*/public ServerResponse getUsers(ServerRequest request) throws Exception {// 模拟数据库查询出来的所有用户List<User> users = Arrays.asList(new User(1, "jim", 28),new User(2, "lily", 18));return ServerResponse.ok().body(users);}/*** 保存用户*/public ServerResponse saveUser(ServerRequest request) throws ServletException, IOException {// 提取请求体User user = request.body(User.class);// 模拟保存用户System.out.println("保存的用户是: " + user);return ServerResponse.ok().build();}/*** 更新用户*/public ServerResponse updateUser(ServerRequest request) throws ServletException, IOException {// 提取请求体User user = request.body(User.class);// 模拟更新用户System.out.println("更新的用户是: " + user);return ServerResponse.ok().build();}/*** 删除用户*/public ServerResponse deleteUser(ServerRequest request) {String id = request.pathVariable("id");// 模拟删除用户System.out.println("删除的用户的id = " + id);return ServerResponse.ok().build();}
}