使用RestTemplate訪問https請求 並獲取返回的輸入流

代碼

package com.hyzs.szcg.doc.utils;

import com.hyzs.intelligentgateway.core.service.IntelligentGatewayService;
import lombok.extern.slf4j.Slf4j;
import org.apache.http.util.EntityUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.Resource;
import org.springframework.http.*;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.stereotype.Component;
import org.springframework.web.client.RestTemplate;

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

@Slf4j
@Component
public class TencentApiUtil {
    @Value("${apiUrl}")
    private String apiUrl;
    @Autowired
    IntelligentGatewayService intelligentGatewayService;
    /**
     * GET
     *
     * @date 2019年11月28日
     */
    public  byte[] doGetHttps(String params) {
        // HttpHeaders  自己另外創建
        HttpHeaders httpHeaders = this.intelligentGatewayService.buildHttpHeaders();
        HttpEntity<String> requestEntity = new  HttpEntity<>(httpHeaders);
        RestTemplate restTemplate=new RestTemplate();
//如果返回的是String 則改用 String 若爲文件流 則改用 Resource
        ResponseEntity<Resource> responseEntity = restTemplate.exchange(apiUrl+params, HttpMethod.GET,requestEntity, Resource.class);
        if (responseEntity.getStatusCodeValue()!= HttpStatus.OK.value()){
            return null;
        }
        if (responseEntity != null) {
            String contentType=responseEntity.getHeaders().getContentType().toString();
            if("image/png".equals(contentType)){
                InputStream responseInputStream=null;
                try {
                    responseInputStream = responseEntity.getBody().getInputStream();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (responseInputStream == null) {
                    return null;
                } else {
                    try {
                        return toByteArray(responseInputStream);
                    } catch (IOException e) {
                        log.error("圖片數據轉化爲byte[]失敗");
                        return null;
                    }
                }
            }else
            {
                log.error("調用騰訊api失敗="+ responseEntity.getBody());
            }
        }
        return null;
    }
    public static byte[] toByteArray(InputStream input) throws IOException {
        ByteArrayOutputStream output = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024*4];
        int n = 0;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
        }
        return output.toByteArray();
    }
}