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前言 :
要達到基本的Http get與post方法取得網站內容，Java內的URLConnection就可以達成。
但我實作時發現它太過於底層，以致於我不知該如何做到關於Session狀態的延續，也就是不能夠在完成登入後，保留住登入狀態然後進入下個動作。
於是就尋求別的作法，最後發現了Apache有提供了HttpClient套件的JAR檔，能讓我們用更簡單的方式達成工作。
在此參考網路上的文章：用HttpClient來模擬瀏覽器GET,POST，加上可自動轉導的功能，包成函式。
另外再加上可用三種類型來設定傳遞的參數，並控制其連線與中斷狀態.

下載套件 :
到 HttpClient Download 下載套件，選擇Binary with dependencies的版本(如4.0.1.zip)，
我們需要的JAR在該壓縮檔中的lib目錄下。會用到的JAR檔有三個：

- commons-logging-1.1.1.jar
- httpclient-4.0.1.jar
- httpcore-4.0.1.jar

範例代碼 :

- HTTPBaseIO.java 代碼 :

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package john.net;



import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.UnsupportedEncodingException;

import java.net.URLEncoder;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;



import org.apache.http.Header;

import org.apache.http.HttpEntity;

import org.apache.http.HttpHost;

import org.apache.http.HttpResponse;

import org.apache.http.HttpStatus;

import org.apache.http.NameValuePair;

import org.apache.http.client.ClientProtocolException;

import org.apache.http.client.entity.UrlEncodedFormEntity;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.client.methods.HttpPost;

import org.apache.http.client.methods.HttpUriRequest;

import org.apache.http.conn.params.ConnRoutePNames;

import org.apache.http.entity.StringEntity;

import org.apache.http.impl.client.DefaultHttpClient;

import org.apache.http.message.BasicNameValuePair;

import org.apache.http.protocol.HTTP;



public class HTTPBaseIO {

public enum Method {

  get, post

}



private DefaultHttpClient httpclient = null;

private boolean isClosedConn = false;

private String newuri = null;

private int statuscode = HttpStatus.SC_NO_CONTENT;



private HttpHost proxy = null;



public HTTPBaseIO(){



}

public HTTPBaseIO(String proxyIP,int proxyPort){

  setProxy(proxyIP,proxyPort);

}

public HTTPBaseIO(HttpHost proxy){

  setProxy(proxy);

}



/**

  * 取得使用的proxy

  */

public HttpHost getProxy() {

  return proxy;

}



/**

  * 設定proxy

  */

public void setProxy(HttpHost proxy) {

  this.proxy = proxy;

}



/**

  * 設定proxy

  *

  * @param ip

  *            proxy的IP(hostname)

  * @param port

  *            proxy的Port

  */

public void setProxy(String ip, int port) {

  if(ip!=null)

   proxy = new HttpHost(ip, port);

}



/**

  * 取得回應後所得到的代碼，可參考org.apache.http.HttpStatus類別

  *

  * @return org.apache.http.HttpStatus

  */

public int getStatuscode() {

  return statuscode;

}



/**

  * 如果是轉導的狀態所得到的URI

  *

  * @return

  */

public String getNewuri() {

  return newuri;

}



public void resetNewuri() {

  newuri = null;

}



/**

  * 取得連線物件

  *

  * @return

  */

public DefaultHttpClient getHttpclient() {

  return httpclient;

}



/**

  * 設定連線物件

  *

  * @param httpclient

  */

public void setHttpclient(DefaultHttpClient httpclient) {

  this.httpclient = httpclient;

}



/**

  * 是否已關閉連線

  *

  * @return

  */

public boolean isClosedConn() {

  return isClosedConn;

}



/**

  * 關閉連線

  */

public void closeConn() {

  closeConn(true);

}



/**

  * 關閉連線

  *

  * @param isCloseConn

  *            是否關閉

  */

public void closeConn(boolean isCloseConn) {

  if (isCloseConn && httpclient != null && !isClosedConn) {

   httpclient.getConnectionManager().shutdown();

   httpclient = null;

   isClosedConn = true;

  }

}



/**

  * 取得網頁內容

  *

  * @param urlpath

  *            網址

  * @param method

  *            Method.get or Method.post

  * @param params

  *            參數

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @param isAutoRedirect

  *            如果網頁回應狀態為轉導到新網頁，且Header的location有值，則自己以location所指網址取得內容

  * @param isCloseConn

  *            是否關閉連線

  * @return 失敗回傳null，成功回傳網頁HTML

  * @throws ClientProtocolException

  * @throws IOException

  */

public String doSend(String urlpath, Method method, String params,

   String charset, boolean isAutoRedirect, boolean isCloseConn)

   throws ClientProtocolException, IOException {

  return doSendBase(urlpath, method, StringToHttpEntity(params, charset),

    charset, isAutoRedirect, isCloseConn);

}



/**

  * 取得網頁內容

  *

  * @param urlpath

  *            網址

  * @param method

  *            Method.get or Method.post

  * @param params

  *            參數

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @param isAutoRedirect

  *            如果網頁回應狀態為轉導到新網頁，且Header的location有值，則自己以location所指網址取得內容

  * @param isCloseConn

  *            是否關閉連線

  * @return 失敗回傳null，成功回傳網頁HTML

  * @throws ClientProtocolException

  * @throws IOException

  */

public String doSend(String urlpath, Method method,

   List params, String charset, boolean isAutoRedirect,

   boolean isCloseConn) throws ClientProtocolException, IOException {

  return doSendBase(urlpath, method, ListToHttpEntity(params, charset),

    charset, isAutoRedirect, isCloseConn);

}



/**

  * 取得網頁內容

  *

  * @param urlpath

  *            網址

  * @param method

  *            Method.get or Method.post

  * @param params

  *            參數

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @param isAutoRedirect

  *            如果網頁回應狀態為轉導到新網頁，且Header的location有值，則自己以location所指網址取得內容

  * @param isCloseConn

  *            是否關閉連線

  * @return 失敗回傳null，成功回傳網頁HTML

  * @throws ClientProtocolException

  * @throws IOException

  */

public String doSend(String urlpath, Method method,

   HashMap params, String charset,

   boolean isAutoRedirect, boolean isCloseConn)

   throws ClientProtocolException, IOException {

  return doSendBase(urlpath, method,

    HashMapToHttpEntity(params, charset), charset, isAutoRedirect,

    isCloseConn);

}



/**

  * 取得網頁內容

  *

  * @param urlpath

  *            網址

  * @param method

  *            Method.get or Method.post

  * @param params

  *            參數

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @param isAutoRedirect

  *            如果網頁回應狀態為轉導到新網頁，且Header的location有值，則自己以location所指網址取得內容

  * @param isCloseConn

  *            是否關閉連線

  * @return 失敗回傳null，成功回傳網頁HTML

  * @throws ClientProtocolException

  * @throws IOException

  */

public String doSendBase(String urlpath, Method method, HttpEntity params,

   String charset, boolean isAutoRedirect, boolean isCloseConn)

   throws ClientProtocolException, IOException {

  String responseBody = null;

  HttpUriRequest httpgetpost = null;



  statuscode = HttpStatus.SC_NO_CONTENT;

  try {

   if (httpclient == null || isClosedConn())

    httpclient = new DefaultHttpClient();



   if (proxy != null)

    httpclient.getParams().setParameter(

      ConnRoutePNames.DEFAULT_PROXY, proxy);



   if (method == Method.post) {

    httpgetpost = new HttpPost(urlpath);

    if (params != null) {

     ((HttpPost) httpgetpost).setEntity(params);

    }

   } else {

    if (params != null) {

     urlpath += "?"

       + inputStream2String(params.getContent(), charset);

    }

    httpgetpost = new HttpGet(urlpath);

   }



   HttpResponse response = httpclient.execute(httpgetpost);

   statuscode = response.getStatusLine().getStatusCode();

   if ((statuscode == HttpStatus.SC_MOVED_TEMPORARILY)

     || (statuscode == HttpStatus.SC_MOVED_PERMANENTLY)

     || (statuscode == HttpStatus.SC_SEE_OTHER)

     || (statuscode == HttpStatus.SC_TEMPORARY_REDIRECT)) {

    Header header = response.getFirstHeader("location");



    if (header != null) {

     newuri = header.getValue();

     if ((newuri == null) || (newuri.equals("")))

      newuri = "/";

     if (isAutoRedirect) {

      httpgetpost.abort();

      httpgetpost = null;

      responseBody = doSendBase(newuri, Method.get, null,

        charset, true, false);

     }

    }

   } else if (statuscode == HttpStatus.SC_OK) {

    responseBody = inputStream2String(response.getEntity()

      .getContent(), charset);

   }

  } catch (ClientProtocolException e) {

   throw e;

  } catch (IOException e) {

   throw e;

  } catch (Exception e) {

   e.printStackTrace();

  } finally {

   if (httpgetpost != null) {

    httpgetpost.abort();

    httpgetpost = null;

   }

   closeConn(isCloseConn);

  }

  return responseBody;

}



/**

  * 將inputStream轉為String

  *

  * @param is

  *            inputStream

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @return inputStream的內容

  * @throws UnsupportedEncodingException

  */

public static String inputStream2String(InputStream is, String charset)

   throws UnsupportedEncodingException {

  BufferedReader in = new BufferedReader(new InputStreamReader(is,

    charset));

  StringBuffer buffer = new StringBuffer();

  String line = "";

  try {

   boolean isfirst = true;

   while ((line = in.readLine()) != null) {

    if (!isfirst) {

     buffer.append("\n");

    } else {

     isfirst = false;

    }

    buffer.append(line);

   }

  } catch (IOException e) {

   e.printStackTrace();

  }



  return buffer.toString();

}



/**

  * List轉為HttpEntity

  *

  * @param nvps

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @return

  * @throws UnsupportedEncodingException

  */

public static HttpEntity ListToHttpEntity(List nvps,

   String charset) throws UnsupportedEncodingException {

  HttpEntity result = null;

  if (nvps != null && nvps.size() > 0) {

   result = new UrlEncodedFormEntity(nvps, charset);



  }

  return result;

}



/**

  * String to HttpEntity(

  *

  * @param nvps

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @return

  * @throws UnsupportedEncodingException

  */

public static HttpEntity StringToHttpEntity(String nvps, String charset)

   throws UnsupportedEncodingException {

  HttpEntity result = null;

  if (nvps != null) {

   StringEntity reqEntity = new StringEntity(nvps, charset);

   reqEntity.setContentType("application/x-www-form-urlencoded");

   result = reqEntity;

  }

  return result;

}



/**

  * HashMap To HttpEntity

  *

  * @param nvps

  * @param charset

  *            編碼，如HTTP.UTF_8

  * @return

  * @throws UnsupportedEncodingException

  */

public static HttpEntity HashMapToHttpEntity(HashMap nvps,

   String charset) throws UnsupportedEncodingException {

  HttpEntity result = null;

  if (nvps != null) {

   result = new StringEntity(hashMapToString(nvps, charset), charset);

   try {

    result = StringToHttpEntity(inputStream2String(result

      .getContent(), charset), charset);

   } catch (IllegalStateException e) {

    e.printStackTrace();

   } catch (IOException e) {

    e.printStackTrace();

   }

  }

  return result;

}



/**

  * hashMapToString

  *

  * @param map

  * @param charset編碼

  *            ，如HTTP.UTF_8

  * @return

  * @throws UnsupportedEncodingException

  */

@SuppressWarnings("unchecked")

public static String hashMapToString(HashMap map,

   String charset) throws UnsupportedEncodingException {

  StringBuffer result = new StringBuffer();

  java.util.Iterator it = map.entrySet().iterator();

  boolean isfirst = true;

  while (it.hasNext()) {

   java.util.Map.Entry entry = (java.util.Map.Entry) it.next();

   if (isfirst) {

    isfirst = false;

   } else {

    result.append("&");

   }

   result

     .append(URLEncoder.encode(entry.getKey().toString(),

       charset));

   result.append("=");

   result.append(URLEncoder.encode(entry.getValue().toString(),

     charset));

  }

  return result.toString();

}



public static ArrayList paramToArray(String param)

   throws UnsupportedEncodingException {

  ArrayList arr = null;

  if(param!=null){

      String[] p = param.split("&");

      if (param.toLowerCase().contains("&")) {

       ArrayList p2 = new ArrayList();

       int j = 0;

       for (int i = 0; i < p.length; i++) {

        if (p[i].toLowerCase().startsWith("amp;")) {

         p2.set(j - 1, p2.get(j - 1) + "&" + p[i].substring(4));

         j--;

        }

        p2.add(p[i]);

        j++;

       }

       p2.toArray(p);

      }



      for (int i = 0; i < p.length; i++) {

       String[] item = p[i].split("=");

       if (item.length == 2) {

        if (arr == null)

         arr = new ArrayList();

        // item[0]=URLDecoder.decode(item[0],charset);

        // item[1]=URLDecoder.decode(item[1],charset);

        arr.add(item);

       }

      }

  }

  return arr;

}

}

- 測試 Http GET 的範例代碼 :

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public void testDoGet() {

  String urltest = "http://www.google.com.tw" ;

  String charset="UTF-8";

  HTTPBaseIO.Method method = HTTPBaseIO.Method.get;

  HTTPBaseIO reqClient = new HTTPBaseIO();

  try {

   String html=reqClient.doSendBase(urltest,method, null,charset,false, false);

   System.out.println(html);

   if(html==null) System.out.println("Client get nothing");

  } catch (Exception e) {

   e.printStackTrace();

  } finally {

   reqClient.closeConn();

  }

}

執行結果 :
取得 Google 首頁的 html 代碼.

This message was edited 1 time. Last update was at 03/09/2010 18:42:39

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2010年9月10日星期五

[ Java 代碼範本 ] Java 模擬 Http Get 與 Post query

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