HttpClient 如何设置请求接口等待时间

我们在请求接口的时候容易出现请求超时的现象，出现这一问题的原因可能是接口确实挂了，也可能是接口还没有来的及响应，我们程序里面已经出现了请求超时的现象

问题描述：

通常会出现以下的报错：

java.net.SocketTimeoutException: Read timed out
  at java.net.SocketInputStream.socketRead0(SocketInputStream.java)
  at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
  at java.net.SocketInputStream.read(SocketInputStream.java:170)
  at java.net.SocketInputStream.read(SocketInputStream.java:141)
  at org.apache.http.impl.conn.LoggingInputStream.read(LoggingInputStream.java:84)
  at org.apache.http.impl.io.SessionInputBufferImpl.streamRead(SessionInputBufferImpl.java:137)
  at org.apache.http.impl.io.SessionInputBufferImpl.fillBuffer(SessionInputBufferImpl.java:153)
  at org.apache.http.impl.io.SessionInputBufferImpl.readLine(SessionInputBufferImpl.java:282)
  at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:138)
  at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:56)
  at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:259)
  at org.apache.http.impl.DefaultBHttpClientConnection.receiveResponseHeader(DefaultBHttpClientConnection.java:163)
  at org.apache.http.impl.conn.CPoolProxy.receiveResponseHeader(CPoolProxy.java:165)
  at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:273)
  at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:125)
  at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:272)
  at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
  at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
  at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
  at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
  at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)

 结合接口日志的打印，我判断是第二种现象，就是接口还没有返回信息，我程序这边就出现了超时的报错。那么如何解决，我们只有增加接口的请求等待时间

问题解决：

  private static Logger logger = LoggerFactory.getLogger(HttpUtil.class);

  public static String postGeneralUrl(String url, String contentType, String jsonParam, String encoding, int reSend) {
    
    logger.info("当前请求接口地址:{}",jsonParam.toString());
    // 声明返回结果
    String result = "";
    // 开始请求API接口时间
    long startTime = System.currentTimeMillis();
    // 请求API接口的响应时间
    long endTime = 0L;
    HttpEntity httpEntity = null;
    HttpResponse httpResponse = null;
    HttpClient httpClient = null;
    try {

      contentType = contentType == null ? "application/x-www-form-urlencoded" : contentType;
      // 创建连接
      httpClient = HttpClientFactory.getInstance().getHttpClient();
      // 设置请求头和报文
      HttpPost httpPost = HttpClientFactory.getInstance().httpPost(url);
      Header header = new BasicHeader("Accept-Encoding", null);
      RequestConfig requestConfig =  RequestConfig.custom().setSocketTimeout(20000).setConnectTimeout(20000).build();
      httpPost.setConfig(requestConfig);
      httpPost.addHeader(header);
      httpPost.addHeader("Content-Type", contentType);
      List<NameValuePair> list = new LinkedList<>();
      list.add(new BasicNameValuePair("params", jsonParam));// pageHelper放在body中传过去
      // 使用URL实体转换工具
      UrlEncodedFormEntity entityParam = new UrlEncodedFormEntity(list, "UTF-8"); // 使用 UrlEncodedFormEntity 来设置
      // // body,消息体内容
      httpPost.setEntity(entityParam);
      logger.info("请求{}接口的参数为{}", url, jsonParam);
      httpResponse = httpClient.execute(httpPost);
      httpEntity = httpResponse.getEntity();
      result = EntityUtils.toString(httpEntity);
    } catch (SocketTimeoutException es) {
      endTime = System.currentTimeMillis();
      result = "网络连接异常，请检查网络或者开票服务是否正常启动";
      logger.info("请求{}接口的响应报文内容为{},本次请求API接口的响应时间为:{}毫秒", url, result, (endTime - startTime));
      logger.error("请求{}接口出现异常", url, es);
      return result;
    } catch (Exception e) {
      logger.error("请求{}接口出现异常", url, e);
    } finally {
      try {
        EntityUtils.consume(httpEntity);
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    // 请求接口的响应时间
    endTime = System.currentTimeMillis();

    logger.info("请求{}接口的响应报文内容为{},本次请求API接口的响应时间为:{}毫秒", url, result, (endTime - startTime));
    return result;

  }

其中主要是这部分代码：

      RequestConfig requestConfig =  RequestConfig.custom().setSocketTimeout(20000).setConnectTimeout(20000).build();
      httpPost.setConfig(requestConfig);

当然这个设置和使用的 http.client 版本也有一定的关系

当前我使用的版本是：

    <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpcore -->
    <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpcore</artifactId>
      <version>4.4.10</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.apache.httpcomponents/httpclient -->
    <dependency>
      <groupId>org.apache.httpcomponents</groupId>
      <artifactId>httpclient</artifactId>
      <version>4.5.6</version>
      <exclusions>
        <exclusion>
          <groupId>commons-codec</groupId>
          <artifactId>commons-codec</artifactId>
        </exclusion>
        <exclusion>
          <groupId>commons-logging</groupId>
          <artifactId>commons-logging</artifactId>
        </exclusion>
      </exclusions>
    </dependency>

希望对你有所帮助