Springboot-RestTemplate调用服务实战记录

springboot内自带的resttemplate可以帮助我们实现远程调用其他服务接口的作用,实际封装了httpclient,将httpclient繁琐的

配置用springboot特有的配置类来配置,并交给sprinng管理.

避免在一个项目中频繁创建httpclient对象,造成的堆内存浪费,确保连接对象的单例性.

优点:配置简单,请求参数灵活.

缺点:报错需要try-catch手动捕获,不看日志不容易发现问题.没有熔断器,可以根据熔断器状态返回指定错误码,及时发现.

配置类RestTemplateConfig:

@Configuration
public class RestTemplateConfig {

    @Bean
    public RestTemplate httpRestTemplate() {
        ClientHttpRequestFactory factory = httpRequestFactory();
        RestTemplate restTemplate = new RestTemplate(factory);
        // 可以添加消息转换
        //restTemplate.setMessageConverters(...);
        // 可以增加拦截器
        //restTemplate.setInterceptors(...);
        return restTemplate;
    }

    public ClientHttpRequestFactory httpRequestFactory() {
        return new HttpComponentsClientHttpRequestFactory(restTemplateConfigHttpClient());
    }

    public HttpClient restTemplateConfigHttpClient() {
        Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", SSLConnectionSocketFactory.getSocketFactory())
                .build();
        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(registry);
        // 设置整个连接池最大连接数 根据自己的场景决定
        connectionManager.setMaxTotal(200);
        // 路由是对maxTotal的细分
        connectionManager.setDefaultMaxPerRoute(100);
        RequestConfig requestConfig = RequestConfig.custom()
                // 服务器返回数据(response)的时间，超过该时间抛出read timeout
                .setSocketTimeout(10000)
                // 连接上服务器(握手成功)的时间，超出该时间抛出connect timeout
                .setConnectTimeout(5000)
                // 从连接池中获取连接的超时时间，超过该时间未拿到可用连接，
                // 会抛出org.apache.http.conn.ConnectionPoolTimeoutException:
                // Timeout waiting for connection from pool
                .setConnectionRequestTimeout(5000)
                .build();
        return HttpClientBuilder.create()
                .setDefaultRequestConfig(requestConfig)
                .setConnectionManager(connectionManager)
                .build();
    }
}

注入:

@Autowired
RestTemplateConfig restTemplateConfig;

发请求:

RestTemplate httpRestTemplate = restTemplateConfig.httpRestTemplate();
try {
    List<Integer> requestBean = new ArrayList<>();
    result.stream().map(a -> {
        requestBean.add(a.getId());
        return a;
    }).collect(Collectors.toList());
    Map map = httpRestTemplate.postForObject(服务url, requestBean, Map.class);
    result = result.stream().map(a -> {
        Iterator iterator = map.keySet().iterator();
        while (iterator.hasNext()) {
            String key = (String) iterator.next();
            Object obj = map.get(key);
            if (String.valueOf(a.getId()).equals(key)) {
                Integer i = (Integer) obj;
                a.setCourseCount(i);
                return a;
            }
        }
        return a;
    }).collect(Collectors.toList());
} catch (Exception e) {
    System.err.println("调用服务:" + metel2ApiUrl + "查询课程数量异常");
    e.printStackTrace();
}
return result;

get请求方式:用占位符的方式,getForObject后面对应请求头参数顺序
application.properties如下:

baidu.translate.api=http://xxxx:80080/translation/add?keyword={1}&product={2}&from={3}&to={4}

//调百度api转为英文

private String constructEn(String bucketKey) {
    RestTemplate httpRestTemplate = restTemplateConfig.httpRestTemplate();
    try {
        TransResult requestBean = new TransResult();
        requestBean.setSrc(bucketKey);
        requestBean.setCode("auto");
        requestBean.setMsg("en");
        String transResult = httpRestTemplate.getForObject(baiDuTranslateApi, String.class, bucketKey, "metel", "zh", "en");
        TransResult result = GsonUtil.GsonToBean(transResult, TransResult.class);
        return result.getDst();
    } catch (Exception e) {
        System.err.println("调用服务:" + baiDuTranslateApi + "转换为英文异常");
        e.printStackTrace();
    }
    return null;
}