HttpClient學習整理 (一)

參考：http://www.blogjava.net/alpha/archive/2007/01/22/95216.html

           http://www.360doc.com/content/09/1201/18/203871_10149531.shtml

HttpClient是apache設計實現，用來簡化http客戶端與服務器端的網絡通信編程接口。目前，有commons-httpclient和httpclient倆個版本，前者最後版本是3.1，後者分爲HttpClient和HttpCore兩個部分，同時包含server和client端的API，版本號從4.0開始。我們儘量優先使用最新版本的httpclient。

commons-httpclient

1、GET/POST

a、get/post

private static final String host = "localhost";
private static final int port = 8080;

HttpClient client = new HttpClient();
client.getHostConfiguration.setHost(host,port,"http");

//get方式提交信息
GetMethod getMethod = new GetMethod("/index.jsp?key=520");
//獲取流
InputStream in = getMethod.getResponseBodyAsStream();
//post方式提交信息
PostMethod postMethod = new PostMethod("/index.jsp");
NameValuePair value1 = new NameValuePair("name","felix");
NameValuePair value2 = new NameValuePair("age",18);
postMethod.setRequestBody(new NameValuePair[][value1,value2]);

client.executeMethod(getMethod);
client.executeMethod(postMethod);

//記得釋放連接哦
getMethod.releaseConnection();
postMethod.releaseConnection();

b、head

HeadMethod head = new HeadMethod("http://www.csdn.net");
// 執行方法，並處理失敗的請求.
...
// 取回應答包的頭字段信息.
Header[] headers = head.getResponseHeaders();
 
// 只取回最後修改日期字段的信息.
String lastModified = head.getResponseHeader("last-modified").getValue();

c、post (使用HttpPost)

DefaultHttpClient httpclient = new DefaultHttpClient();
HttpPost postMethod = new HttpPost("http://reg.csdn.net");    //注意用post
        
//參數
List<NameValuePair> list = new ArrayList<NameValuePair>(); 
list.add(new BasicNameValuePair("username", "felix"));  
list.add(new BasicNameValuePair("password", "****"));
list.add(new BasicNameValuePair("age", "22"));
list.add(new BasicNameValuePair("address", "beijing"));
list.add(new BasicNameValuePair("sex", "male"));

        
postMethod.setEntity(new UrlEncodedFormEntity(list, HTTP.UTF_8));  
HttpResponse response = httpclient.execute(postMethod);    

2、重定向

狀態碼    HttpServletResponse常量 詳細

301 SC_MOVED_PERMANENTLY 頁面已經永久移動到另外一個新地址

302 SC_MOVED_TEMPORARILY 頁面暫時移動到另外一個新地址

303 SC_SEE_OTHER 客戶端請求的地址必須通過另外的URL來訪問

307 SC_TEMPORARY_REDIRECT 同SC_MOVED_TEMPORARILY

client.executeMethod(postMethod);
postMethod.releaseConnection():

int status=postMethod.getStatusCode();
//是否重定向
if((statuscode == HttpStatus.SC_MOVED_TEMPORARILY) || 
 (statuscode == HttpStatus.SC_MOVED_PERMANENTLY) || 
 (statuscode == HttpStatus.SC_SEE_OTHER) ||
 (statuscode == HttpStatus.SC_TEMPORARY_REDIRECT)){
	   //新地址
    Header header = postMethod.getResponseHeader("location");
    String uri = header.getValue()==null?header.getValue():"";
}

3、超時和重試（retry）

a、設置超時

client.setConnectionTimeout(SysGlobals.TIMEOUT);
或者
client.setTimeOut(SysGlobals.TIMEOUT);

這兩個方法已經@Deprecated

b、設置get/post請求超時

getMethod.getParams().setParameter(HttpParams.SO_TIMEOUT,10000);

postMethod.getParams().setParameter(HttpParams.SO_TIMEOUT,10000);

c、設置http連接超時5s

client.getHttpConnectionManager().getParams().setConnectionTimeout(5000);

d、設置retry

DefaultMethodRetryHandler retry = new DefaultMethodRetryHandler();
retry.setRequestSentRetryEnabled(true);
retry.setRetryCount(4);
method.setMethodRetryHandler(retry);
client.executeMethod(method);

4、提交xml格式參數

import java.io.File; 
import java.io.FileInputStream; 
import org.apache.commons.httpclient.HttpClient; 
import org.apache.commons.httpclient.methods.EntityEnclosingMethod; 
import org.apache.commons.httpclient.methods.PostMethod;
/** 
 *用來演示提交XML格式數據的例子
*/
public class PostXMLClient {

   public static void main(String[] args) throws Exception {
      File input = new File("/home/lrq1988/test.xml");
      PostMethod post = new PostMethod(“http://localhost:8080/httpclient/xml.jsp”);

      // 設置請求的內容直接從文件中讀取
      post.setRequestBody( new FileInputStream(input)); 
      if (input.length() < Integer.MAX_VALUE)
         post.setRequestContentLength(input.length());
      else
         post.setRequestContentLength(EntityEnclosingMethod.CONTENT_LENGTH_CHUNKED);

      // 指定請求內容的類型
      post.setRequestHeader( "Content-type" , "text/xml; charset=GBK" );
      HttpClient httpclient = new HttpClient();
      int result = httpclient.executeMethod(post);
      System.out.println( "Response status code: " + result);
      System.out.println( "Response body: " );
      System.out.println(post.getResponseBodyAsString()); 
      post.releaseConnection(); 
   } 
}

5、文件上傳

MultipartPostMethod filePost = new MultipartPostMethod(targetURL); 
filePost.addParameter( "fileName" , targetFilePath); 
HttpClient client = new HttpClient();
// 由於要上傳的文件可能比較大 , 因此在此設置最大的連接超時時間 
client.getHttpConnectionManager(). getParams().setConnectionTimeout(5000); 
int status = client.executeMethod(filePost); 

6、多線程模式

多線程同時訪問httpclient，例如同時從一個站點上下載多個文件。對於同一個HttpConnection同一個時間只能有一個線程訪問，爲了保證多線程工作環境下不產生衝突，httpclient使用了一個多線程連接管理器的類：MultiThreadedHttpConnectionManager，要使用這個類很簡單，只需要在構造HttpClient實例的時候傳入即可，代碼如下：

MultiThreadedHttpConnectionManager connectionManager = 
	new MultiThreadedHttpConnectionManager();
HttpClient client = new HttpClient(connectionManager);

以後儘管訪問client實例即可。

7、Cookie

HttpClient client = new HttpClient();
client.getParams().setCookiePolicy(CookiePolicy.RFC_2109);//RFC_2109之外，還有其他cookie協議
HttpState state = new HttpState();
Cookie cookie = new Cookie();
cookie.setDomain("www.csdn.net");
cookie.setPath("/");
cookie.setName("name");
cookie.setValue("value");
state.addCookie(cookie);
client.setState(state);

Cookie[] cookies = client.getState().getCookies();
for(){}

8、代理

client.getHostConfiguration().setProxy("192.168.0.1",9527);
client.getParams.setAuthenticationPreemptive(true);//使用搶先認證，否則沒有資格
/*
   MyProxyCredentialsProvider實現了CredentialsProvider接口，返回代理的credential(username/password)
*/
client.setParams.setParameter(CredentialsProvider.PROVIDER,
new MyProxyCredentialsProvider());
client.getState().setProxyCredentials(new AuthScop("192.168.0.1",
AuthScope.ANY_PORT,//任意端口
AuthScope.ANY_REALM,//任意域
new UsernamePasswordCredentials("username","password")));//代理的用戶名、密碼

9、https

Class EasySSLProtocolSocketFactory ： http://juliusdavies.ca/commons-ssl/javadocs/org/apache/commons/httpclient/contrib/ssl/EasySSLProtocolSocketFactory.html

針對特定主機使用自定義協議套接字工廠

Protocol easyhttps = 
	new Protocol("https", new EasySSLProtocolSocketFactory(), 443);
HttpClient client = new HttpClient();
client.getHostConfiguration().setHost("localhost", 443, easyhttps);
// use relative url only
GetMethod httpget = new GetMethod("/");
client.executeMethod(httpget);

使用http method之前，先註冊https，下面的請求都將默認使用這個

Protocol easyhttps = 
	new Protocol("https", new EasySSLProtocolSocketFactory(), 443);
Protocol.registerProtocol("https", easyhttps); 
HttpClient client = new HttpClient();
GetMethod httpget = new GetMethod("https://localhost/");
client.executeMethod(httpget);