spring boot使用WebClient调用其他系统提供的HTTP服务

WebClient的请求模式属于异步非阻塞，能够以少量固定的线程处理高并发的HTTP请求

WebClient是Spring WebFlux模块提供的一个非阻塞的基于响应式编程的进行Http请求的客户端工具，从Spring5.0开始提供

在Spring Boot应用中

1.添加Spring WebFlux依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

2.使用

（1）Restful接口demoController.java

package com.example.demo.controller;

import com.example.demo.domain.MyData;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;

@RestController
@RequestMapping("/api")
public class demoController {

    @GetMapping(value = "/getHeader", produces = {MediaType.APPLICATION_JSON_UTF8_VALUE})
    public MyData getHeader(HttpServletRequest request) {

        int id = 0;
        if (request.getParameter("id") != null) {
            id = Integer.valueOf(request.getParameter("id"));
        }
        String name = request.getParameter("name");
        //header
        String userAgent = "USER_AGENT——" + request.getHeader(HttpHeaders.USER_AGENT);
        userAgent += " | ACCEPT_CHARSET——" + request.getHeader(HttpHeaders.ACCEPT_CHARSET);
        userAgent += " | ACCEPT_ENCODING——" + request.getHeader(HttpHeaders.ACCEPT_ENCODING);
        userAgent += " | ContextPath——" + request.getContextPath();
        userAgent += " | AuthType——" + request.getAuthType();
        userAgent += " | PathInfo——" + request.getPathInfo();
        userAgent += " | Method——" + request.getMethod();
        userAgent += " | QueryString——" + request.getQueryString();
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                System.out.println(cookie.getName() + "：" + cookie.getValue());
            }
        }
        MyData data = new MyData();
        data.setId(id);
        data.setName(name);
        data.setOther(userAgent);
        return data;
    }

    @PostMapping(value = "/getPost", produces = {MediaType.APPLICATION_JSON_UTF8_VALUE})
    public MyData getPost(HttpServletRequest request) {

        int id = 0;
        if (request.getParameter("id") != null) {
            id = Integer.valueOf(request.getParameter("id"));
        }
        String name = request.getParameter("name");
        System.out.println(name + "," + id);
        MyData data = new MyData();
        data.setId(id);
        data.setName(name);
        return data;

    }

    /**
     * POST传JSON请求
     */
    @PostMapping(value = "/getPostJson", produces = {MediaType.APPLICATION_JSON_UTF8_VALUE})
    public MyData getPostJson(@RequestBody(required = true) MyData data) {
        System.out.println(data.getId());
        System.out.println(data.getName());
        return data;
    }
}

MyData.java

package com.example.demo.domain;

public class MyData {
    private int id;
    private String name;
    private String other;
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getOther() {
        return other;
    }

    public void setOther(String other) {
        this.other = other;
    }
}

（2）WebClient使用

DemoApplicationTests.java

package com.example.demo;

import com.example.demo.domain.MyData;
import org.junit.Test;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Mono;

import java.time.Duration;
import java.time.temporal.ChronoUnit;

public class DemoApplicationTests {

    private WebClient webClient = WebClient.builder()
            .baseUrl("http://127.0.0.1:8080")
            .defaultHeader(HttpHeaders.USER_AGENT, "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko)")
            .defaultCookie("ACCESS_TOKEN", "test_token").build();

    @Test
    public void WebGetDemo() {

        try {
            Mono<MyData> resp = webClient.method(HttpMethod.GET).uri("api/getHeader?id={id}&name={name}", 123, "abc")
                    .retrieve()
                    .bodyToMono(MyData.class);
            MyData data = resp.block();
            System.out.println("WebGetDemo result----- " + data.getString());
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    @Test
    public void WebPostDemo() {
        MultiValueMap<String, String> formData = new LinkedMultiValueMap<>(2);
        formData.add("id", "456");
        formData.add("name", "xyz");

        Mono<MyData> response = webClient.method(HttpMethod.POST).uri("/api/getPost")
                .contentType(MediaType.APPLICATION_FORM_URLENCODED)
                .body(BodyInserters.fromFormData(formData))
                .retrieve()
                .bodyToMono(MyData.class).timeout(Duration.of(10, ChronoUnit.SECONDS));
        System.out.println(response);
        MyData data = response.block();
        System.out.println("WebPostDemo result----- " + data.getString());
    }

    @Test
    public void WebPostJson() {
        MyData requestData = new MyData();
        requestData.setId(789);
        requestData.setName("lmn");

        Mono<MyData> response = webClient.post().uri("/api/getPostJson")
                .contentType(MediaType.APPLICATION_JSON_UTF8)
                .syncBody(requestData)
                .retrieve()
                .bodyToMono(MyData.class).timeout(Duration.of(10, ChronoUnit.SECONDS));

        MyData data = response.block();
        System.out.println("WebPostJson result----- " + data.getString());
    }

}