【自用】java Http请求

工具类

import com.alibaba.fastjson.JSONObject;
import com.smcv.yjapp.common.base.ResultData;
import com.smcv.yjapp.common.exception.AppException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.*;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.http.converter.FormHttpMessageConverter;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.ResponseErrorHandler;
import org.springframework.web.client.RestTemplate;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RestTemplateUtils {

    private Logger logger = LoggerFactory.getLogger(RestTemplateUtils.class);

    /**
     *
     */
    private static class DefaultResponseErrorHandler implements ResponseErrorHandler {
        private Logger logger = LoggerFactory.getLogger(RestTemplateUtils.class);

        @Override
        public boolean hasError(ClientHttpResponse response) throws IOException {
            return response.getStatusCode().value() != HttpServletResponse.SC_OK;
        }

        @Override
        public void handleError(ClientHttpResponse response) throws IOException {

            logger.error(JSONObject.toJSONString(response));
            HttpStatus responseStatus = response.getStatusCode();

            if (HttpStatus.UNAUTHORIZED.value() == responseStatus.value() || HttpStatus.FORBIDDEN.value() == responseStatus.value()) {

                throw new AppException();
            }


            BufferedReader br = new BufferedReader(new InputStreamReader(response.getBody()));
            StringBuilder sb = new StringBuilder();
            String str = null;
            while ((str = br.readLine()) != null) {
                sb.append(str);
            }
            try {
                throw new Exception(sb.toString());
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * @param url
     * @param params
     * @return
     */
    public static <T> T get(String url, JSONObject params, Class<T> clz) {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
        url = expandURL(url, params.keySet());
        T response = restTemplate.getForObject(url, clz, params);
        return response;
    }

    /**
     * @param url
     * @param requestHeaders
     * @param params
     * @return
     */
    public static ResultData get(String url, HttpHeaders requestHeaders, JSONObject params) {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
        url = expandURL(url, params.keySet());

        HttpEntity<String> requestEntity = new HttpEntity<String>(null, requestHeaders);
        ResponseEntity<ResultData> response = restTemplate.exchange(url, HttpMethod.GET, requestEntity, ResultData.class, params);
        return response.getBody();
    }

    /**
     * @param url
     * @param requestHeaders
     * @param params
     * @param mediaType
     * @return
     */
    public static String post(String url, HttpHeaders requestHeaders, JSONObject params, MediaType mediaType) {
        RestTemplate restTemplate = new RestTemplate();
        // 拿到header信息
        requestHeaders.setContentType(mediaType);
        HttpEntity<JSONObject> requestEntity = (mediaType == MediaType.APPLICATION_JSON
                || mediaType == MediaType.APPLICATION_JSON_UTF8) ? new HttpEntity<JSONObject>(params, requestHeaders)
                : new HttpEntity<JSONObject>(null, requestHeaders);
        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
        String result = (mediaType == MediaType.APPLICATION_JSON || mediaType == MediaType.APPLICATION_JSON_UTF8)
                ? restTemplate.postForObject(url, requestEntity, String.class)
                : restTemplate.postForObject(expandURL(url, params.keySet()), requestEntity, String.class, params);
        return result;
    }


    /**
     * @param url
     * @param requestHeaders
     * @param params
     * @param mediaType
     * @param clz
     * @param <T>
     * @return
     */
    public static <T> T post(String url, HttpHeaders requestHeaders, JSONObject params, MediaType mediaType, Class<T> clz) {
        RestTemplate restTemplate = new RestTemplate();
        //这是为 MediaType.APPLICATION_FORM_URLENCODED 格式HttpEntity 数据 添加转换器
        //还有就是，如果是APPLICATION_FORM_URLENCODED方式发送post请求，
        //也可以直接HttpHeaders requestHeaders = new HttpHeaders(createMultiValueMap(params)，true)，就不用增加转换器了
        restTemplate.getMessageConverters().add(new FormHttpMessageConverter());
        // 设置header信息
        requestHeaders.setContentType(mediaType);

        HttpEntity<?> requestEntity = (
                mediaType == MediaType.APPLICATION_JSON
                        || mediaType == MediaType.APPLICATION_JSON_UTF8)
                ? new HttpEntity<JSONObject>(params, requestHeaders)
                : (mediaType == MediaType.APPLICATION_FORM_URLENCODED
                ? new HttpEntity<MultiValueMap>(createMultiValueMap(params), requestHeaders)
                : new HttpEntity<>(null, requestHeaders));

        restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
        T result = (mediaType == MediaType.APPLICATION_JSON || mediaType == MediaType.APPLICATION_JSON_UTF8)
                ? restTemplate.postForObject(url, requestEntity, clz)
                : restTemplate.postForObject(mediaType == MediaType.APPLICATION_FORM_URLENCODED
                ? url
                : expandURL(url, params.keySet()), requestEntity, clz, params);

        return result;
    }

    private static MultiValueMap<String, String> createMultiValueMap(JSONObject params) {
        MultiValueMap<String, String> map = new LinkedMultiValueMap<>();
        for (String key : params.keySet()) {
            if (params.get(key) instanceof List) {
                for (Iterator<String> it = ((List<String>) params.get(key)).iterator(); it.hasNext(); ) {
                    String value = it.next();
                    map.add(key, value);
                }
            } else {
                map.add(key, params.getString(key));
            }
        }
        return map;
    }

    /**
     * @param url
     * @param keys
     * @return
     */
    public static String expandURL(String url, Set<?> keys) {
        final Pattern QUERY_PARAM_PATTERN = Pattern.compile("([^&=]+)(=?)([^&]+)?");
        Matcher mc = QUERY_PARAM_PATTERN.matcher(url);
        StringBuilder sb = new StringBuilder(url);
        if (mc.find()) {
            sb.append("?");
        } else {
            sb.append("&");
        }

        for (Object key : keys) {
            sb.append(key).append("=").append("{").append(key).append("}").append("&");
        }
        return sb.deleteCharAt(sb.length() - 1).toString();
    }


    public static RestTemplate restTemplate;

    public void setRestTemplate(RestTemplate restTemplate) {
        this.restTemplate = restTemplate;
    }

    public static String get(ServletRequest req, String url, HttpHeaders requestHeaders, Map json, Map<String, ?> params) {
        ResponseEntity<String> rss = request(req, url, requestHeaders, HttpMethod.GET, params);
        return rss.getBody();
    }


    /**
     * @param req
     * @param url
     * @param method
     * @param params maybe null
     * @return
     */
    public static ResponseEntity<String> request(ServletRequest req, String url, HttpHeaders requestHeaders, HttpMethod method, Map<String, ?> params) {
        HttpServletRequest request = (HttpServletRequest) req;
        //获取header信息
        Enumeration<String> headerNames = request.getHeaderNames();
        while (headerNames.hasMoreElements()) {
            String key = (String) headerNames.nextElement();
            String value = request.getHeader(key);
            requestHeaders.add(key, value);
        }
        //获取parameter信息
        if (params == null) {
            params = request.getParameterMap();
        }

        HttpEntity<String> requestEntity = new HttpEntity<String>(null, requestHeaders);
        ResponseEntity<String> rss = restTemplate.exchange(url, method, requestEntity, String.class, params);
        return rss;
    }


}

请求post示例

import com.alibaba.fastjson.JSONObject;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;

JSONObject param = JSONObject.parseObject(JSONObject.toJSONString(请求入参));
//也可以直接用json对象
返回实体 名字= RestTemplateUtils.post(url, new HttpHeaders(), param, MediaType.APPLICATION_JSON_UTF8, 返回实体.class);

get同理