对于httpClient4.3访问指定页面，可以从下面的demo抽取方法使用。
注意：对于URL必须使用 http://开始，否则会有如下报错信息：
Caused by: org.apache.http.ProtocolException: Target host is not specified
at org.apache.http.impl.conn.DefaultRoutePlanner.determineRoute(DefaultRoutePlanner.java:69)
at org.apache.http.impl.client.InternalHttpClient.determineRoute(InternalHttpClient.java:124)
at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:183)
... 5 more
demo代码：
public class ClientWithResponseHandler {
public static String url = "http://www.baidu.com";
public final static void main(String[] args) throws Exception {
CloseableHttpClient httpclient = HttpClients.createDefault();
try {
HttpGet httpget = new HttpGet(url);
System.out.println("Executing request " + httpget.getRequestLine());
// Create a custom response handler
ResponseHandler<String> responseHandler = new ResponseHandler<String>() {
public String handleResponse(
final HttpResponse response) throws ClientProtocolException, IOException {
int status = response.getStatusLine().getStatusCode();
if (status >= 200 && status < 300) {
HttpEntity entity = response.getEntity();
return entity != null ? EntityUtils.toString(entity) : null;
} else {
throw new ClientProtocolException("Unexpected response status: " + status);
}
}
};
String responseBody = httpclient.execute(httpget, responseHandler);
System.out.println("----------------------------------------");
System.out.println(responseBody);
} finally {
httpclient.close();
}
}
}