Posted on 2006-12-11 15:55
Fisher 閱讀(10035)
評論(10) 編輯 收藏 所屬分類:
Java應用
在用Java的HttpURLConnection 來下載網頁，發現訪問google的網站時，會被google拒絕掉。
?????? try
??????? {
??????????? url = new URL(urlStr);
??????????? httpConn = (HttpURLConnection) url.openConnection();
??????????? HttpURLConnection.setFollowRedirects(true);
??????????? // logger.info(httpConn.getResponseMessage());
??????????? in = httpConn.getInputStream();
??????????? out = new FileOutputStream(new File(outPath));
??????????? chByte = in.read();
??????????? while (chByte != -1)
??????????? {
??????????????? out.write(chByte);
??????????????? chByte = in.read();
??????????? }
??????? }
??????? catch (MalformedURLException e)
????????{
?????????}
??????? }
經過一段時間的研究和查找資料，發現是由于上面的代碼缺少了一些必要的信息導致，增加更加詳細的屬性
??????????? httpConn.setRequestMethod("GET");
??????????? httpConn.setRequestProperty("User-Agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)");
完整代碼如下：
?? public static void DownLoadPages(String urlStr, String outPath)
??? {
??????? int chByte = 0;
??????? URL url = null;
??????? HttpURLConnection httpConn = null;
??????? InputStream in = null;
??????? FileOutputStream out = null;
??????? try
??????? {
??????????? url = new URL(urlStr);
??????????? httpConn = (HttpURLConnection) url.openConnection();
??????????? HttpURLConnection.setFollowRedirects(true);
??????????? httpConn.setRequestMethod("GET");
??????????? httpConn.setRequestProperty("User-Agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)");
???????????
??????????? // logger.info(httpConn.getResponseMessage());
??????????? in = httpConn.getInputStream();
??????????? out = new FileOutputStream(new File(outPath));
??????????? chByte = in.read();
??????????? while (chByte != -1)
??????????? {
??????????????? out.write(chByte);
??????????????? chByte = in.read();
??????????? }
??????? }
??????? catch (MalformedURLException e)
??????? {
??????????? e.printStackTrace();
??????? }
??????? catch (IOException e)
??????? {
??????????? e.printStackTrace();
??????? }
??????? finally
??????? {
??????????? try
??????????? {
??????????????? out.close();
??????????????? in.close();
??????????????? httpConn.disconnect();
??????????? }
??????????? catch (Exception ex)
??????????? {
??????????????? ex.printStackTrace();
??????????? }
??????? }
??? }
此外，還有第二種方法可以訪問Google的網站，就是用apache的一個工具HttpClient 模仿一個瀏覽器來訪問Google
??????? Document document = null;
??????? HttpClient httpClient = new HttpClient();
???????
??????? GetMethod getMethod = new GetMethod(url);
??????? getMethod.setFollowRedirects(true);
??????? int statusCode = httpClient.executeMethod(getMethod);
???????
??????? if (statusCode == HttpStatus.SC_OK)
??????? {
??????????? InputStream in = getMethod.getResponseBodyAsStream();
??????????? InputSource is = new InputSource(in);
??????????? DOMParser domParser = new DOMParser();?? //nekoHtml 將取得的網頁轉換成dom
??????????? domParser.parse(is);
??????????? document = domParser.getDocument();
???????????
??????????? System.out.println(getMethod.getURI());
???????????
??????? }
??????? return document;
推薦使用第一種方式，使用HttpConnection 比較輕量級，速度也比第二種HttpClient 的快。