关于HttpClient的总结

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(1)当HttpClient的实例不再需要时，可以使用连接管理器关闭
httpclient.getConnectionManager().shutdown();  

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(2)针对HTTPs的协议的HttpClient请求必须用户和密码
 httpclient.getCredentialsProvider()
            .setCredentials(new AuthScope("localhost", 443), 
                new UsernamePasswordCredentials("username", "password"));

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(3)如果不想获取HTTPClient返回的信息
   httpclient.abort();

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(4)httpclient传送文件的方式
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://www.apache.org");
        File file = new File(args[0]);
        InputStreamEntity reqEntity = new InputStreamEntity(
                new FileInputStream(file), -1);
        reqEntity.setContentType("binary/octet-stream");
        reqEntity.setChunked(true);
        // It may be more appropriate to use FileEntity class in this particular 
        // instance but we are using a more generic InputStreamEntity to demonstrate
        // the capability to stream out data from any arbitrary source
        // 
        // FileEntity entity = new FileEntity(file, "binary/octet-stream"); 
        httppost.setEntity(reqEntity);
        System.out.println("executing request " + httppost.getRequestLine());
        HttpResponse response = httpclient.execute(httppost);

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(5)获取Cookie的信息
        HttpClient httpclient = new DefaultHttpClient();
        // 创建一个本地Cookie存储的实例
        CookieStore cookieStore = new BasicCookieStore();
        //创建一个本地上下文信息
        HttpContext localContext = new BasicHttpContext();
        //在本地上下问中绑定一个本地存储
        localContext.setAttribute(ClientContext.COOKIE_STORE, cookieStore);
        //设置请求的路径
        HttpGet httpget = new HttpGet("http://www.google.com/"); 
        //传递本地的http上下文给服务器
        HttpResponse response = httpclient.execute(httpget, localContext);
        //获取本地信息
        HttpEntity entity = response.getEntity();
        System.out.println(response.getStatusLine());
        if (entity != null) {
            System.out.println("Response content length: " + entity.getContentLength());
        }
        //获取cookie中的各种信息
        List<Cookie> cookies = cookieStore.getCookies();
        for (int i = 0; i < cookies.size(); i++) {
            System.out.println("Local cookie: " + cookies.get(i));
        }
        //获取消息头的信息
        Header[] headers = response.getAllHeaders();
        for (int i = 0; i<headers.length; i++) {
            System.out.println(headers[i]);
        }

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(6)针对典型的SSL请求的处理
        DefaultHttpClient httpclient = new DefaultHttpClient();
        //获取默认的存储密钥类
        KeyStore trustStore  = KeyStore.getInstance(KeyStore.getDefaultType()); 
        //加载本地的密钥信息       
        FileInputStream instream = new FileInputStream(new File("my.keystore")); 
        try {
            trustStore.load(instream, "nopassword".toCharArray());
        } finally {
            instream.close();
        }
        //创建SSLSocketFactory，创建相关的Socket
        SSLSocketFactory socketFactory = new SSLSocketFactory(trustStore);
        //设置协议的类型和密钥信息，以及断开信息
        Scheme sch = new Scheme("https", socketFactory, 443);
        //在连接管理器中注册中信息
        httpclient.getConnectionManager().getSchemeRegistry().register(sch);