第一種方式,使用HttpURLConnection

使用HttpURlConnection傳送一個get請求,開啟一個連線,從連接獲取到流,將流轉成byte陣列

/**
   * 發起Get請求
   *
   * @param urlStr
   * @return
   */
  public final static byte[] doGetRequestForFile(String urlStr) {

    InputStream is = null;
    ByteArrayOutputStream os = null;
    byte[] buff = new byte[1024
 
];
    int len = 0;
    try {
      URL url = new URL(UriUtils.encodePath(urlStr, DEFAULT_CHARSET));
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();
      conn.setRequestProperty("Content-Type", "plain/text;charset=" + DEFAULT_CHARSET);
      conn.setRequestProperty("charset", DEFAULT_CHARSET);
      conn.setDoInput(true
 
);
      conn.setDoOutput(true);
      conn.setRequestMethod("GET");
      conn.setReadTimeout(DEFAULT_TIME_OUT);
      conn.connect();
      is = conn.getInputStream();
      os = new ByteArrayOutputStream();
      while ((len = is.read(buff)) != -1) {
        os.write(buff, 0, len);
      }
      return
 
 os.toByteArray();
    } catch (IOException e) {
      log.error("發起請求出現異常:", e);
       return null;
    } finally {
      if (is != null) {
        try {
          is.close();
        } catch (IOException e) {
          log.error("【關閉流異常】");
        }
      }
      if (os != null) {
        try {
          os.close();
        } catch (IOException e) {
          log.error("【關閉流異常】");
        }
      }
    }
    return result;
  }

引入的類:

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

　第二種，使用OkHttpClient傳送get請求

使用OkHttpClient直接模擬request請求和response

public final static byte[] sendGetForFile(String url) {
    InputStream inputStream = null;
    Request req = (new Request.Builder()).url(url).get().build();
    Response response = null;
    try {
      response = new OkHttpClient().newCall(req).execute();
      if (!response.isSuccessful()) {
        log.error("【呼叫HTTP請求異常】 code:{},message:{}", response.code(), response.message());
        return null;
      }

      inputStream = response.body().byteStream();
      return inputToByte(inputStream);
    } catch (IOException e) {
      log.error("發起請求出現異常:", e);
      return null;
    } finally {
      try {
        inputStream.close();
      } catch (IOException var12) {
        log.error("【關閉流異常】");
      }
    }
    return result;
  }

inputToByte方法:

/**
   * 流轉byte陣列
   *
   * @param inputStream
   * @return
   * @throws IOException
   */
  private static byte[] inputToByte(InputStream inputStream) throws IOException {
    ByteArrayOutputStream swapStream = new ByteArrayOutputStream();
    byte[] buff = new byte[1024];
    int rc;
    while ((rc = inputStream.read(buff, 0, 1024)) > 0) {
      swapStream.write(buff, 0, rc);
    }
    byte[] in2b = swapStream.toByteArray();
    return in2b;
  }

OkHttpClient傳送post請求

public static byte sendPostForFile(String url, String json) {

    InputStream inputStream = null;

    try {
      RequestBody requestBody = RequestBody.create(JSON, json);
      Request request = (new Builder()).url(url).post(requestBody).build();

      Response response =  new OkHttpClient().newCall(request).execute() ;
      if (!response.isSuccessful()) {
        log.error("【呼叫HTTP請求異常】 code:{},message:{}", response.code(), response.message());
        return null;
      }

      inputStream = response.body().byteStream();
      return inputToByte(inputStream);

    } catch (IOException var13) {
      logger.error("【post請求異常】", var13);
      return null;
    } finally {
      try {
        inputStream.close();
      } catch (IOException var12) {
        log.error("【關閉流異常】");
      }

    }

    return result;
  }