利用java实现发送http或get请求的方法有哪些

public static String httpGet(String url, String charset)   throws HttpException, IOException {  String json = null;  HttpGet httpGet = new HttpGet();  // 设置参数  try {   httpGet.setURI(new URI(url));  } catch (URISyntaxException e) {   throw new HttpException("请求url格式错误。"+e.getMessage());  }  // 发送请求  HttpResponse httpResponse = client.execute(httpGet);  // 获取返回的数据  HttpEntity entity = httpResponse.getEntity();  byte[] body = EntityUtils.toByteArray(entity);  StatusLine sL = httpResponse.getStatusLine();  int statusCode = sL.getStatusCode();  if (statusCode == 200) {   json = new String(body, charset);   entity.consumeContent();  } else {   throw new HttpException("statusCode="+statusCode);  }  return json;}