RestTemplate StringHttpMessageConverter 中文乱码

解决方案

版本：org.springframework.boot:spring-boot-starter-web:2.1.6.RELEASE

import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.client.RestTemplate;

import java.nio.charset.StandardCharsets;

@Bean
public RestTemplate restTemplate(RestTemplateBuilder restTemplateBuilder) {
    RestTemplate restTemplate = restTemplateBuilder.build();
    restTemplate.getMessageConverters().forEach(httpMessageConverter -> {
        if (httpMessageConverter instanceof StringHttpMessageConverter) {
            ((StringHttpMessageConverter) httpMessageConverter).setDefaultCharset(StandardCharsets.UTF_8);
        }
    });
    return restTemplate;
}

问题原因

版本：org.springframework:spring-web:5.1.8.RELEASE

org.springframework.web.client.RestTemplate

import org.springframework.http.converter.StringHttpMessageConverter;

/**
 * Create a new instance of the {@link RestTemplate} using default settings.
 * Default {@link HttpMessageConverter HttpMessageConverters} are initialized.
 */
public RestTemplate() {
	{...}
	this.messageConverters.add(new StringHttpMessageConverter());
	{...}
}

org.springframework.http.converter.StringHttpMessageConverter

import java.nio.charset.StandardCharsets;

/**
 * Thedefault charset used by the converter.
 */
public static final Charset DEFAULT_CHARSET = StandardCharsets.ISO_8859_1;

/**
 * A default constructor that uses {@code "ISO-8859-1"} as the default charset.
 * @see #StringHttpMessageConverter(Charset)
 */
public StringHttpMessageConverter() {
	this(DEFAULT_CHARSET);
}

（完）