想copy個爬蟲玩玩，結果提到用的jar包是apache的http客戶端開源專案---HttpClient

就下載了一個版本4.3

HttpClient httpclient = new HttpClient();

結果遇到這句就給跪了

提示Cannot instantiate the type HttpClient，

google 了下，在stackoverflow上面說是應該

HttpClient httpclient = new DefaultHttpClient();

這樣寫，不過得先import org.apache.http.impl.client.Defaul

tHttpClient;

據說從4.×版本後，它的用法就變了不能這麼使用了

最後把爬到的html程式碼儲存成html格式就行了

這個程式碼比較正常：

import java.io.IOException;

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.methods.GetMethod;

public class Spider {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		// 相當於開啟瀏覽器
		HttpClient httpClient = new HttpClient();
		// 相當於在瀏覽器中輸入網址
		GetMethod getMethod = new GetMethod("http://www.baidu.com");
		try {
			// 返回HTTP狀態碼，在後面用到。
			int statusCode = httpClient.executeMethod(getMethod);
			// 此處輸出的是html語言
			System.out.println("response=" + getMethod.getResponseBodyAsString());
		} catch (HttpException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			// 關閉網路連線，防止造成資源浪費
			getMethod.releaseConnection();
		}
	}

}
 

不太正常的程式碼：

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();
		}
	}
}