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【WEB系列】RestTemplate之中文乱码问题fix

在RestTemplate基础用法博文中，post json表单时，会发现存在中文乱码问题，本文主要介绍对应的解决方案

I. 中文乱码Fix

1. “罪魁祸首”

场景复现

/**
 * json表单
 */
public void jsonPost() {
    RestTemplate restTemplate = new RestTemplate();

    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);

    JSONObject params = new JSONObject();
    params.put("name", "一灰灰Blog");
    params.put("age", 20);

    HttpEntity<String> request = new HttpEntity<>(params.toJSONString(), headers);

    String response = restTemplate.postForObject("http://127.0.0.1:8080/body", request, String.class);
    log.info("json post res: {}", response);
}

输出结果如下:

(json post res: params: {} | DemoRest.ReqBody(name=???Blog, age=20)
headers: {"content-length":"27","host":"127.0.0.1:8080","content-type":"application/json","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Java/1.8.0_171"}
cookies:

原因定位

RestTemplate中存在一个 HttpMessageConverter 列表的属性成员，而 HttpMessageConverter 主要的职责就是消息转码

导致我们中文乱码的一个关键点在于 StringHttpMessageConverter 采用的默认编码格式为 StandardCharsets.ISO_8859_1

2. 指定StringHttpMessageConverter编码

既然是因为 StringHttpMessageConverter 的默认编码不是UTF-8，那么将它手动改成utf-8不就over了么

/**
 * 中文乱码问题fix
 */
public void chinese() {
    RestTemplate restTemplate = new RestTemplate();

    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);

    JSONObject params = new JSONObject();
    params.put("name", "一灰灰Blog");
    params.put("age", 20);

    HttpEntity<String> request = new HttpEntity<>(params.toJSONString(), headers);

    // 中文乱码，主要是 StringHttpMessageConverter的默认编码为ISO导致的
    List<HttpMessageConverter<?>> list = restTemplate.getMessageConverters();
    for (HttpMessageConverter converter : list) {
        if (converter instanceof StringHttpMessageConverter) {
            ((StringHttpMessageConverter) converter).setDefaultCharset(Charset.forName("UTF-8"));
            break;
        }
    }

    String response = restTemplate.postForObject("http://127.0.0.1:8080/body", request, String.class);
    log.info("json post res: {}", response);
}

测试输出如:

(json post res: params: {} | DemoRest.ReqBody(name=一灰灰Blog, age=20)
headers: {"content-length":"33","host":"127.0.0.1:8080","content-type":"application/json","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Java/1.8.0_171"}
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3. 传参POJO

在看 RestTemplate 的 HttpMessageConvert 时，会看到默认提供了一个 MappingJackson2HttpMessageConverter ，那么我们直接传参POJO，走Jackson序列化，是不是也可以解决中文乱码呢?

@Data
@NoArgsConstructor
@AllArgsConstructor
public static class InnerParam implements Serializable {
    private static final long serialVersionUID = -3693060057697231136L;
    private String name;
    private Integer age;
}


// 直接传一个POJO
public void chinese() {
    HttpHeaders headers = new HttpHeaders();
    headers.setContentType(MediaType.APPLICATION_JSON);

    RestTemplate restTemplate = new RestTemplate();
    InnerParam innerParam = new InnerParam("一灰灰Blog", 20);
    String HttpEntity<InnerParam> entity = new HttpEntity<>(innerParam, headers);
    response = restTemplate.postForObject("http://127.0.0.1:8080/body", entity, String.class);
    log.info("json post DO res: {}", response);
}

输出结果如下

(json post DO res: params: {} | DemoRest.ReqBody(name=一灰灰Blog, age=20)
headers: {"content-length":"33","host":"127.0.0.1:8080","content-type":"application/json","connection":"keep-alive","accept":"text/plain, application/json, application/*+json, */*","user-agent":"Java/1.8.0_171"}
cookies: