动力节点SpringBoot3第六章
6 远程访问@HttpExchange[SpringBoot 3]
远程访问是开发的常用技术，一个应用能够访问其他应用的功能。Spring Boot提供了多种远程访问的技术。 基于HTTP协议的远程访问是支付最广泛的。Spring Boot3提供了新的HTTP的访问能力，通过接口简化HTTP远程访问，类似Feign功能。Spring包装了底层HTTP客户的访问细节。 SpringBoot中定义接口提供HTTP服务。生成的代理对象实现此接口，代理对象实现HTTP的远程访问。需要理解：
[if !supportLists]· [endif]@HttpExchange
[if !supportLists]· [endif]WebClient
WebClient特性：我们想要调用其他系统提供的HTTP 服务，通常可以使用 Spring 提供的 RestTemplate 来访问，RestTemplate 是 Spring 3 中引入的同步阻塞式 HTTP 客户端，因此存在一定性能瓶颈。Spring 官方在 Spring 5 中引入了 WebClient 作为非阻塞式HTTP 客户端。
[if !supportLists]· [endif]非阻塞，异步请求
[if !supportLists]· [endif]它的响应式编程的基于Reactor
[if !supportLists]· [endif]高并发，硬件资源少。
[if !supportLists]· [endif]支持Java 8 lambdas 函数式编程
什么是异步非阻塞理解：异步和同步，非阻塞和阻塞上面都是针对对象不一样异步和同步针对调度者,调用者发送请求,如果等待对方回应之后才去做其他事情,就是同步,如果发送请求之后不等着对方回应就去做其他事情就是异步
阻塞和非阻塞针对被调度者,被调度者收到请求后,做完请求任务之后才给出反馈就是阻塞,收到请求之后马上给出反馈然后去做事情,就是非阻塞
1.安装GsonFormat插件，方便json和Bean的转换 2.介绍一个免费的、24h在线的Rest Http服务，每月提供近20亿的请求，关键还是免费的、可公开访问的。https://jsonplaceholder.typicode.com/
需求：访问https://jsonplaceholder.typicode.com/提供的todos服务。 基于RESTful风格，添加新的todo，修改todo，修改todo中的title，查询某个todo。声明接口提供对象https://jsonplaceholder.typicode.com/todos服务的访问
创建新的Spring Boot项目Lession18-HttpService, Maven构建工具，JDK19。 Spring Web, Spring Reactive Web , Lombok依赖。包名称：com.bjpowernode.http
step1：Maven依赖pom.xml
| org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-webflux
step2:声明Todo数据类
| /**
[if !supportLists]· [endif]根据https://jsonplaceholder.typicode.com/todos/1的结构创建的*/ public class Todo { private int userId; private int id; private String title; private boolean completed; //省略 set ， get方法 public boolean getCompleted() { return completed; } public void setCompleted(boolean completed) { this.completed = completed; }@Override public String toString() { return "Todo{" + "userId=" + userId + ", id=" + id + ", title='" + title + '\'' + ", completed=" + completed + '}'; } } | | --- |
step3:声明服务接口
| import org.springframework.http.HttpHeaders; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; //... public interface TodoService { @GetExchange("/todos/{id}") Todo getTodoById(@PathVariable Integer id); @PostExchange(value = "/todos",accept = MediaType.APPLICATION_JSON_VALUE) Todo createTodo(@RequestBodyTodo newTodo); @PutExchange("/todos/{id}") ResponseEntity modifyTodo(@PathVariable Integer id,@RequestBody Todo todo); @PatchExchange("/todos/{id}") HttpHeaders pathRequest(@PathVariable Integer id, @RequestParam String title); @DeleteExchange("/todos/{id}") void removeTodo(@PathVariable Integer id);
}
step4:创建HTTP服务代理对象
| @Configuration(proxyBeanMethods = false) public class HttpConfiguration {@Bean public TodoService requestService(){ WebClient webClient = WebClient.builder().baseUrl("https://jsonplaceholder.typicode.com/").build(); HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder(WebClientAdapter.forClient(webClient)).build();
return proxyFactory.createClient(TodoService.class);
}
}
step5:单元测试
| @SpringBootTest class HttpApplicationTests {@Resource private TodoService requestService;@Test void testQuery() { Todo todo = requestService.getTodoById(1); System.out.println("todo = " + todo); }@Test void testCreateTodo() { Todo todo = new Todo(); todo.setId(1001); todo.setCompleted(true); todo.setTitle("录制视频"); todo.setUserId(5001); Todo save = requestService.createTodo(todo); System.out.println(save); }@Test void testModifyTitle() {//org.springframework.http.HttpHeaders HttpHeaders entries = requestService.pathRequest(5, "homework"); entries.forEach( (name,vals)->{ System.out.println(name); vals.forEach(System.out::println); System.out.println("========================="); }); }@Test void testModifyTodo() { Todo todo = new Todo(); todo.setCompleted(true); todo.setTitle("录制视频!!!"); todo.setUserId(5002); ResponseEntity result = requestService.modifyTodo(2,todo); HttpStatusCode statusCode = result.getStatusCode(); HttpHeaders headers = result.getHeaders(); Todo modifyTodo = result.getBody(); System.out.println("statusCode = " + statusCode); System.out.println("headers = " + headers); System.out.println("modifyTodo = " + modifyTodo); }@Test void testRemove() { requestService.removeTodo(2); }
}
@HttpExchange注解用于声明接口作为HTTP远程服务。在方法、类级别使用。通过注解属性以及方法的参数设置HTTP请求的细节。
快捷注解简化不同的请求方式
[if !supportLists]· [endif]GetExchange
[if !supportLists]· [endif]PostExchange
[if !supportLists]· [endif]PutExchange
[if !supportLists]· [endif]PatchExchange
[if !supportLists]· [endif]DeleteExchange
@GetExchange就是@HttpExchange表示的GET请求方式
| @HttpExchange(method = "GET") public @interface GetExchange { @AliasFor(annotation = HttpExchange.class) String value() default "";@AliasFor(annotation = HttpExchange.class) String url() default "";@AliasFor(annotation = HttpExchange.class) String[] accept() default {};
}
作为HTTP服务接口中的方法允许使用的参数列表
参数说明
URI设置请求的url，覆盖注解的url属性
HttpMethod请求方式，覆盖注解的method属性
@RequestHeader 添加到请求中header。 参数类型可以为Map, MultiValueMap,单个值 或者 Collection
@PathVariable url中的占位符，参数可为单个值或Map<String,?>
@RequestBody 请求体，参数是对象
@RequestParam 请求参数，单个值或Map, MultiValueMap，Collection
@RequestPart 发送文件时使用
@CookieValue 向请求中添加cookie
接口中方法返回值
返回值类型说明
void执行请求，无需解析应答
HttpHeaders存储response应答的header信息
对象解析应答结果，转为声明的类型对象
ResponseEntity，ResponseEntity解析应答内容，得到ResponseEntity,从ResponseEntity可以获取http应答码，header，body内容。
反应式的相关的返回值包含Mono,Mono,Mono,Flux Mono,Mono,Mono。
@HttpExchange，@GetExchange等可以组合使用。 这次使用Albums远程服务接口，查询Albums信息
step1:创建Albums数据类
| public class Albums { private int userId; private int id; private String title; //省略 set ,get@Override public String toString() { return "Albums{" + "userId=" + userId + ", id=" + id + ", title='" + title + '\'' + '}'; }
}
step2:创建AlbumsService接口 接口声明方法，提供HTTP远程服务。在类级别应用@HttpExchange接口，在方法级别使用@HttpExchange , @GetExchange等
| @HttpExchange(url = " https://jsonplaceholder.typicode.com/") public interface AlbumsService { @GetExchange("/albums/{aid}") Albums getById(@PathVariable Integer aid); @HttpExchange(url= "/albums/{aid}",method = "GET", contentType = MediaType.APPLICATION_JSON_VALUE) Albums getByIdV2(@PathVariable Integer aid);
}
类级别的url和方法级别的url组合在一起为最后的请求url地址。
step3:声明代理
| @Configuration(proxyBeanMethods = true) public class HttpServiceConfiguration {@Bean public AlbumsService albumsService(){ WebClient webClient = WebClient.create(); HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder(WebClientAdapter.forClient(webClient)) .build(); return proxyFactory.createClient(AlbumsService.class); }
}
step4:单元测试
| @SpringBootTest public class TestHttpExchange {@Resource AlbumsService albumsService;@Test void getQuery() { Albums albums = albumsService.getById(1); System.out.println("albums = " + albums); }@Test void getQueryV2() { Albums albums = albumsService.getByIdV2(2); System.out.println("albums = " + albums); }
}
测试方法能正常完成远程方法调用。
测试Java Record作为返回类型，由框架的HTTP代理转换应该内容为Record对象 step1:创建Albums的Java Record
| public record AlbumsRecord(int userId, int id, String title) {
}
step2:AlbumsService接口增加新的远程访问方法，方法返回类型为Record
| @GetExchange("/albums/{aid}")
AlbumsRecord getByIdRecord(@PathVariable Integer aid);
step3:单元测试，Record接收结果
| @Test void getQueryV3() { AlbumsRecord albums = albumsService.getByIdRecord(1); System.out.println("albums = " + albums);
}
JavaRecord能够正确接收应该结果，转为AlbumsRecord对象。
设置HTTP远程的超时时间， 异常处理 在创建接口代理对象前，先设置WebClient的有关配置。
step1:设置超时，异常处理
| @Beanpublic AlbumsService albumsService(){ HttpClient httpClient = HttpClient.create() .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 30000) //连接超时 .doOnConnected(conn -> { conn.addHandlerLast(new ReadTimeoutHandler(10)); //读超时 conn.addHandlerLast(new WriteTimeoutHandler(10)); //写超时 }); WebClient webClient = WebClient.builder() .clientConnector(new ReactorClientHttpConnector(httpClient)) //定制4XX,5XX的回调函数 .defaultStatusHandler(HttpStatusCode::isError,clientResponse -> { System.out.println("WebClient请求异常**"); return Mono.error(new RuntimeException( "请求异常"+ clientResponse.statusCode().value())); }).build(); HttpServiceProxyFactory proxyFactory = HttpServiceProxyFactory.builder( WebClientAdapter.forClient(webClient)).build(); return proxyFactory.createClient(AlbumsService.class);
}
step2:单元测试超时和400异常
| @Test void testError() { Albums albums = albumsService.getById(111); System.out.println("albums = " + albums);
}
测试方法执行会触发异常代码。
