java httpclient访问某些网页报403错误

应该是某些网站对这种“网络收集器”类的东西进行了过滤，你设置请求头伪装成浏览器应该可以的

就是需要setheader

代码如下:

httpclient 模拟浏览器动作需注意的cookie和HTTP头等信息

commons-httpclient是apache下的一个开源项目，提供了一个纯java实现的http客户端，使用它可以很方便发送HTTP请求，接受HTTP应答，自动管理Cookie等等。

对于contact-list类库来说，需要使用的功能有，自动管理Cookie，设置HTTP头，发送HTTP请求，接受HTTP应答，转发HTTP重定向，还有输出HTTP请求/应答日志，下面对这些功能的实现进行解释：

1. 自动管理Cookie

public EmailImporter(String email, String password, String encoding) { 
   ...... 
   client = new HttpClient(); 
    client.getParams().setCookiePolicy(CookiePolicy.BROWSER_COMPATIBILITY); 
    client.getParams().setParameter("http.protocol.single-cookie-header", true); 
}

其中将HttpClient的Cookie策略设置为CookiePolicy.BROWSER_COMPATIBILITY，即表示java client将按照浏览器的方式来自动处理Cookie。当然你也可以在运行过程中手动调整cookie，比如：

hotmail登录之前需要设置当前时间的Cookie：

client.getState().addCookie(new Cookie("login.live.com", "CkTst", "G" + new Date().getTime()));

不过，httpclient似乎没有提供删除cookie的功能，于是我增加了两个cookie管理的接口，一个是保留指定的cookies，一个是删除指定的cookies：

protected void retainCookies(String[] cookieNames) { 
    Cookie[] cookies = client.getState().getCookies(); 
    ArrayList<Cookie> retainCookies = new ArrayList<Cookie>(); 
    for (Cookie cookie : cookies) { 
      if (Arrays.binarySearch(cookieNames, cookie.getName()) >= 0) { 
            retainCookies.add(cookie); 
       } 
    } 
    client.getState().clearCookies(); 
    client.getState().addCookies(retainCookies.toArray(new Cookie[0])); 
} 
 
protected void removeCookies(String[] cookieNames) { 
    Cookie[] cookies = client.getState().getCookies(); 
    ArrayList<Cookie> retainCookies = new ArrayList<Cookie>(); 
    for (Cookie cookie : cookies) { 
       if (Arrays.binarySearch(cookieNames, cookie.getName()) < 0) { 
            retainCookies.add(cookie); 
        } 
    } 
    client.getState().clearCookies(); 
   client.getState().addCookies(retainCookies.toArray(new Cookie[0])); 
}

2. 设置HTTP头：

http头的设置，可以让邮件服务器认为是在和浏览器打交道，而避免被refuse的可能：

private void setHeaders(HttpMethod method) { 
    method.setRequestHeader("Accept", "text/html,application/xhtml+xml,application/xml;"); 
    method.setRequestHeader("Accept-Language", "zh-cn"); 
    method.setRequestHeader("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3"); 
    method.setRequestHeader("Accept-Charset", encoding); 
    method.setRequestHeader("Keep-Alive", "300"); 
    method.setRequestHeader("Connection", "Keep-Alive"); 
    method.setRequestHeader("Cache-Control", "no-cache"); 
}

另外，在GET和POST的时候设置referer值，以及在POST的时候设置Content-Type：

protected String doPost(String actionUrl, NameValuePair[] params, String referer) throws HttpException, IOException { 
    ...... 
    method.setRequestHeader("Referer", referer); 
    method.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); 
    ...... 
}

3. 发送HTTP请求，接收HTTP应答。在contact-list中只使用了GET和POST请求，我也做了简单的封装：

protected String doGet(String url, String referer) throws HttpException, IOException { 
    GetMethod method = new GetMethod(url); 
    setHeaders(method); 
    method.setRequestHeader("Referer", referer); 
    // log request 
    client.executeMethod(method); 
    String responseStr = readInputStream(method.getResponseBodyAsStream()); 
    // log response 
    method.releaseConnection(); 
   lastUrl = method.getURI().toString(); 
    return responseStr; 
} 
 
protected String doPost(String actionUrl, NameValuePair[] params, String referer) throws HttpException, IOException { 
    PostMethod method = new PostMethod(actionUrl); 
    setHeaders(method); 
    method.setRequestHeader("Referer", referer); 
    method.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); 
    method.setRequestBody(params); 
   // log request 
    client.executeMethod(method); 
    String responseStr = readInputStream(method.getResponseBodyAsStream()); 
    // log response 
   method.releaseConnection(); 
    if (method.getResponseHeader("Location") != null) { 
       // do redirect 
    } else { 
       lastUrl = method.getURI().toString(); 
        return responseStr; 
    } 
}

4. HTTP重定向，主要是两种，一种是根据HTTP头的Location

if (method.getResponseHeader("Location").getValue().startsWith("http")) { 
    return doGet(method.getResponseHeader("Location").getValue()); 
} else { 
    return doGet("http://" + getResponseHost(method) + method.getResponseHeader("Location").getValue()); 
}

另一种是根据javascript中的window.location.replace。

5. 输出请求/应答日志，这个对调试非常重要：

private void logGetRequest(GetMethod method) throws URIException { 
    logger.debug("do get request: " + method.getURI().toString()); 
    logger.debug("header:/n" + getHeadersStr(method.getRequestHeaders())); 
    logger.debug("cookie:/n" + getCookieStr()); 
} 
 
private void logGetResponse(GetMethod method, String responseStr) throws URIException { 
    logger.debug("do get response: " + method.getURI().toString()); 
    logger.debug("header: /n" + getHeadersStr(method.getResponseHeaders())); 
    logger.debug("body: /n" + responseStr); 
} 
 
private void logPostRequest(PostMethod method) throws URIException { 
    logger.debug("do post request: " + method.getURI().toString()); 
    logger.debug("header:/n" + getHeadersStr(method.getRequestHeaders())); 
   logger.debug("body:/n" + getPostBody(method.getParameters())); 
    logger.debug("cookie:/n" + getCookieStr()); 
} 


private void logPostResponse(PostMethod method, String responseStr) throws URIException { 
    logger.debug("do post response:" + method.getURI().toString()); 
    logger.debug("header:/n" + getHeadersStr(method.getResponseHeaders())); 
    logger.debug("body:/n" + responseStr); 
} 
 
private String getHeadersStr(Header[] headers) { 
   StringBuilder builder = new StringBuilder(); 
    for (Header header : headers) { 
       builder.append(header.getName()).append(": ").append(header.getValue()).append("/n"); 
    } 
    return builder.toString(); 
} 


private String getPostBody(NameValuePair[] postValues) { 
    StringBuilder builder = new StringBuilder(); 
    for (NameValuePair pair : postValues) { 
        builder.append(pair.getName()).append(":").append(pair.getValue()).append("/n"); 
    } 
    return builder.toString(); 
} 
 
private String getCookieStr() { 
    Cookie[] cookies = client.getState().getCookies(); 
    StringBuilder builder = new StringBuilder(); 
    for (Cookie cookie : cookies) { 
        builder.append(cookie.getDomain()).append(":") 
              .append(cookie.getName()).append("=").append(cookie.getValue()).append(";") 
              .append(cookie.getPath()).append(";") 
               .append(cookie.getExpiryDate()).append(";") 
               .append(cookie.getSecure()).append(";/n"); 
    } 
    return builder.toString(); 
}

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