Cannot instantiate the type HttpClient问题

时间:2023-03-10 01:37:45
Cannot instantiate the type HttpClient问题

看自己动手写爬虫,没想到一上来就跪了。

里面提到用的jar包是apache的http客户端开源项目---HttpClient

就去官网下载了一个版本4.3

当按书上代码敲时

HttpClient httpclient = new HttpClient();

敲完这句,就给跪了

提示Cannot instantiate the type HttpClient,

google 了下,在*上面说是应该

HttpClient httpclient = new DefaultHttpClient();

这样写,不过得先import org.apache.http.impl.client.DefaultHttpClient;

试了一下。。。果然可以,但是后面的GetMethod啥的都有,

最后才特么发现从4.×版本后,它的用法就变了不能这么使用了

给个官网示例看看就知道咋回事了

package spider;

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils; public class Spider {
public static void main(String[] args) throws Exception{
CloseableHttpClient httpclient = HttpClients.createDefault();
try{
String url = "http://www.baidu.com";
HttpGet httpGet = new HttpGet(url);
System.out.println("executing request " + httpGet.getURI()); 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);
System.out.println("-------------------------------------------");
}finally{
httpclient.close();
}
}
}