RestTemplate是Spring提供的一个基于restful风格的http调用的API，使用简单、方便，让我们摆脱了写繁杂的HttpURLConnection代码。本文记录通过RestTemplate发起带header的http请求。

1.配置RestTemplate

我们可以通过Java config模式简单快速的配置RestTemplate，即利用注解@Configuration在配置类中声明bean，详见如下代码：

import com.alibaba.fastjson.parser.Feature;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.alibaba.fastjson.support.config.FastJsonConfig;
import com.alibaba.fastjson.support.spring.FastJsonHttpMessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.web.client.RestTemplate;
import java.util.Arrays;

@Configuration
public class AppConfig {

    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        //添加RestTemplate的报文转换器
        restTemplate.getMessageConverters().add(this.getFastJsonConverter());
        return restTemplate;
    }

    //自定义报文转换器
    FastJsonHttpMessageConverter getFastJsonConverter(){

        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        // 设置feature
        fastJsonConfig.setFeatures(Feature.AllowISO8601DateFormat);
        // 设置日期格式、关闭循环引用检测
        fastJsonConfig.setSerializerFeatures(SerializerFeature.WriteDateUseDateFormat,
                SerializerFeature.DisableCircularReferenceDetect);
        //指定全局日期格式
        fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss");
        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);

        //设定MediaType
        fastJsonHttpMessageConverter.setSupportedMediaTypes(Arrays.asList(MediaType.APPLICATION_JSON,MediaType.APPLICATION_JSON_UTF8));
        return fastJsonHttpMessageConverter;
    }

}

2.发起带header的http请求

配置好RestTemplate后我们就可以使用它发起http请求了，这里我们演示带请求头的请求示例，详见如下代码（代码中有详细注释）：

import com.alibaba.fastjson.JSON;
import io.swagger.annotations.ApiModelProperty;
import lombok.*;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

import java.util.*;
import java.util.stream.Collectors;


@Service
@Slf4j
public class FooService {

    private static final String FOO_HEADER_NAME = "Foo";
    private static final String TOKEN_HEADER_NAME = "AccessToken";
    private static final int SUCCESS_CODE = 200;

    @Autowired
    private RestTemplate restTemplate;


    public Map<String, ResultBO> getInfo(Set<String> argSet) {

        if (CollectionUtils.isEmpty(argSet)) {
            return Collections.emptyMap();
        }

        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON_UTF8);
        headers.add(DEPT_HEADER_NAME, "项目中配置的具体值");
        headers.add(TOKEN_HEADER_NAME, "项目中配置的具体值");

        RequestBody request = new RequestBody(StringUtils.join(argSet, ","));
        log.info("request RequestBody: {}", request);
        HttpEntity<RequestBody> requestParam = new HttpEntity<>(request, headers);
        ResponseEntity<ResponseBody> responseEntity = restTemplate.postForEntity("urlAddress", requestParam, ResponseBody.class);

        log.info("responseEntity: {}", JSON.toJSONString(responseEntity));
        if (Objects.isNull(responseEntity)) {
            throw new RuntimeException("查询失败, response is null");
        }
        if (SUCCESS_CODE != responseEntity.getStatusCodeValue()) {
            throw new RuntimeException("查询失败, status: " + responseEntity.getStatusCodeValue());
        }

        ResponseBody responseBody = responseEntity.getBody();
        if (Objects.isNull(responseBody)) {
            log.info("responseEntity_body is null");
            return Collections.emptyMap();
        }

        List<ResultBO> resultBOS = responseBody.getResult();

        return resultBOS.stream().collect(Collectors.toMap(k -> String.valueOf(k.getId()), v -> v, (f,s) -> s));
    }

    @Getter
    @Setter
    @ToString
    @AllArgsConstructor
    @NoArgsConstructor
    public static class RequestBody {
        @ApiModelProperty("业务数据id 多个时逗号连接")
        private String ids;
    }

    @Getter
    @Setter
    @ToString
    @AllArgsConstructor
    @NoArgsConstructor
    public static class ResponseBody {
        @ApiModelProperty("0成功")
        private Integer code;
        @ApiModelProperty("结果信息")
        private List<ResultBO> result;
    }


}

OK，回聊~