最简WebClient 同步、异步调用示例

一，序言

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WebClient作为RestTemplete的替代品，有更好的响应式能力，支持异步调用，可以在Spring项目中实现网络请求。

二，简单示例

1. 引入依赖

pom.xml

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0modelVersion>
	<groupId>com.flygroupId>
	<artifactId>web-clientartifactId>
	<version>0.0.1version>
	<name>basename>
	<properties>
		<project.build.sourceEncoding>UTF-8project.build.sourceEncoding>
		<java.version>1.8java.version>
		<skipTests>trueskipTests>
	properties>
	<dependencies>
		<dependency>
			<groupId>org.springframeworkgroupId>
			<artifactId>spring-webfluxartifactId>
			<version>5.2.3.RELEASEversion>
		dependency>
		<dependency>
			<groupId>io.projectreactor.nettygroupId>
			<artifactId>reactor-nettyartifactId>
			<version>0.9.4.RELEASEversion>
		dependency>
		<dependency>
			<groupId>org.apache.logging.log4jgroupId>
			<artifactId>log4j-slf4j-implartifactId>
			<version>2.12.1version>
		dependency>
		<dependency>
			<groupId>org.apache.commonsgroupId>
			<artifactId>commons-lang3artifactId>
			<version>3.10version>
		dependency>
		<dependency>
			<groupId>org.projectlombokgroupId>
			<artifactId>lombokartifactId>
			<version>1.18.12version>
			<scope>providedscope>
		dependency>
	dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.pluginsgroupId>
				<artifactId>maven-compiler-pluginartifactId>
				<version>3.10.1version>
				<configuration>
					<source>1.8source>
					<target>1.8target>
					<encoding>UTF-8encoding>
				configuration>
			plugin>
		plugins>
	build>
project>

2. 日志配置

log4j2.xml

<configuration status="off" monitorInterval="0">
	<appenders>
		<console name="Console" target="system_out">
			<patternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
		console>
	appenders>
	<loggers>
		<root level="INFO">
			<appender-ref ref="Console" />
		root>
	loggers>
configuration>

3. 调用代码

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.concurrent.TimeUnit;

import org.apache.commons.lang3.StringUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.client.WebClient;

import lombok.extern.slf4j.Slf4j;
import reactor.core.publisher.Mono;

/**
 * WebClient是RestTemplete的替代品，有更好的响应式能力，支持异步调用

 * 
 * https://blog.csdn.net/zzhongcy/article/details/105412842
 * 
 */
@Slf4j
public class RunWebClient
{
    public static void main(String[] args)
        throws InterruptedException
    {
        // 默认使用netty
        WebClient webClient = WebClient.builder()
            .codecs(configurer -> configurer.defaultCodecs().maxInMemorySize(-1)) // 缓冲区默认256k，解决报错Exceeded limit on max bytes to buffer : 262144
            .build();
        
        // block转换为同步调用
        Mono<String> resp = WebClient.create().get().uri("https://00fly.online/upload/ids").acceptCharset(StandardCharsets.UTF_8).accept(MediaType.TEXT_HTML).retrieve().bodyToMono(String.class);
        String[] idArray = StringUtils.split(resp.block(), "\r\n");
        log.info("★★★★★★★★ ids: {}", Arrays.asList(idArray));
        
        // 异步调用
        for (String id : idArray)
        {
            Mono<String> result = webClient.get()
                .uri("https://blog.csdn.net/qq_16127313/article/details/{id}", id)
                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                .acceptCharset(StandardCharsets.UTF_8)
                .accept(MediaType.TEXT_HTML)
                .retrieve()
                .bodyToMono(String.class);
            result.subscribe(body -> log.info("{} process complted", id), e -> log.error(e.getMessage()));
        }
        log.info("异步请求已提交...");
        TimeUnit.SECONDS.sleep(10); // 重要，等待异步调用完成
    }
}

4. 运行结果

三，完整代码

如何使用下面的备份文件恢复成原始的项目代码，请移步查阅：神奇代码恢复工具

//goto pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.fly</groupId>
	<artifactId>web-client</artifactId>
	<version>0.0.1</version>
	<name>base</name>
	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<java.version>1.8</java.version>
		<skipTests>true</skipTests>
	</properties>
	<dependencies>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webflux</artifactId>
			<version>5.2.3.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>io.projectreactor.netty</groupId>
			<artifactId>reactor-netty</artifactId>
			<version>0.9.4.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.apache.logging.log4j</groupId>
			<artifactId>log4j-slf4j-impl</artifactId>
			<version>2.12.1</version>
		</dependency>
		<dependency>
			<groupId>org.apache.commons</groupId>
			<artifactId>commons-lang3</artifactId>
			<version>3.10</version>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.18.12</version>
			<scope>provided</scope>
		</dependency>
	</dependencies>
	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.10.1</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
					<encoding>UTF-8</encoding>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>
//goto src\main\java\com\fly\http\RunWebClient.java
package com.fly.http;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.concurrent.TimeUnit;

import org.apache.commons.lang3.StringUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.client.WebClient;

import lombok.extern.slf4j.Slf4j;
import reactor.core.publisher.Mono;

/**
 * WebClient是RestTemplete的替代品，有更好的响应式能力，支持异步调用

 * 
 * https://blog.csdn.net/zzhongcy/article/details/105412842
 * 
 */
@Slf4j
public class RunWebClient
{
    public static void main(String[] args)
        throws InterruptedException
    {
        // 默认使用netty
        WebClient webClient = WebClient.builder()
            .codecs(configurer -> configurer.defaultCodecs().maxInMemorySize(-1)) // 缓冲区默认256k，解决报错Exceeded limit on max bytes to buffer : 262144
            .build();
        
        // block转换为同步调用
        Mono<String> resp = WebClient.create().get().uri("https://00fly.online/upload/ids").acceptCharset(StandardCharsets.UTF_8).accept(MediaType.TEXT_HTML).retrieve().bodyToMono(String.class);
        String[] idArray = StringUtils.split(resp.block(), "\r\n");
        log.info("★★★★★★★★ ids: {}", Arrays.asList(idArray));
        
        // 异步调用
        for (String id : idArray)
        {
            Mono<String> result = webClient.get()
                .uri("https://blog.csdn.net/qq_16127313/article/details/{id}", id)
                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                .acceptCharset(StandardCharsets.UTF_8)
                .accept(MediaType.TEXT_HTML)
                .retrieve()
                .bodyToMono(String.class);
            result.subscribe(body -> log.info("{} process complted", id), e -> log.error(e.getMessage()));
        }
        log.info("异步请求已提交...");
        TimeUnit.SECONDS.sleep(10); // 重要，等待异步调用完成
    }
}
//goto src\main\resources\log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<configuration status="off" monitorInterval="0">
	<appenders>
		<console name="Console" target="system_out">
			<patternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
		</console>
	</appenders>
	<loggers>
		<root level="INFO">
			<appender-ref ref="Console" />
		</root>
	</loggers>
</configuration>

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