Android网络编程总结（一）

首先记得添加网络访问许可：<use-permission android:name="ANDROID.PERMISSION.INTERNET" />

1  URL获取网络资源
     URL即一个资源定位符，包含协议，主机，端口，资源，如http://127.0.0.1: 8080/meishimeike/index.jsp。获取到URL后可以通过一系列方法获取到对应的部分.
     String getFile(); //资源名
     String getHost(); //主机
     String getPath(); //资源的路径
     int getPort(); //端口
     String getProtocol(); //获取协议名称
     String getQuery(); //获取URL的查询字符串部分
     URLConnection openConnection(); //返回URLConnection对象， 表示URL所引用的远程对象的链接
     InputStream openStream(); //打开于此URL的连接，表示返回一个用于读取该URL的inputstream

     对文件操作完后记得关闭流。

2  使用URLConnection提交请求
     通过URL的getConnection()方法，可以获得一个URLConnection对象， 表示应用程序和目标URL的通信资源链接，应用程序可以通过URLConnection向目标主机发送链接,      

    基本步骤：

     

 

    常用设置：

      

   注意：如果既要使用输入流又要使用输出流，一定要先使用输出流发送请求，再使用输入流。

下面提供一个实:

public class GetPostUtil
{
	/**
	 * 向指定URL发送GET方法的请求
	 * 
	 * @param url
	 *            发送请求的URL
	 * @param params
	 *            请求参数，请求参数应该是name1=value1&name2=value2的形式。
	 * @return URL所代表远程资源的响应
	 */
	public static String sendGet(String url, String params)
	{
		String result = "";
		BufferedReader in = null;
		try
		{
			String urlName = url + "?" + params;
			URL realUrl = new URL(urlName);
			// 打开和URL之间的连接
			URLConnection conn = realUrl.openConnection();
			// 设置通用的请求属性
			conn.setRequestProperty("accept", "*/*");
			conn.setRequestProperty("connection", "Keep-Alive");
			conn.setRequestProperty("user-agent",
				"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
			
			// 建立实际的连接
			conn.connect();
			// 获取所有响应头字段
			
			Map<String, List<String>> map = conn.getHeaderFields();
			// 遍历所有的响应头字段
			for (String key : map.keySet())
			{
				System.out.println(key + "--->" + map.get(key));
			}
			
			// 定义BufferedReader输入流来读取URL的响应
			in = new BufferedReader(
				new InputStreamReader(conn.getInputStream()));
			String line;
			while ((line = in.readLine()) != null)
			{
				result += "\n" + line;
			}
		}
		catch (Exception e)
		{
			System.out.println("发送GET请求出现异常！" + e);
			e.printStackTrace();
		}
		// 使用finally块来关闭输入流
		finally
		{
			try
			{
				if (in != null)
				{
					in.close();
				}
			}
			catch (IOException ex)
			{
				ex.printStackTrace();
			}
		}
		return result;
	}

	/**
	 * 向指定URL发送POST方法的请求
	 * 
	 * @param url
	 *            发送请求的URL
	 * @param params
	 *            请求参数，请求参数应该是name1=value1&name2=value2的形式。
	 * @return URL所代表远程资源的响应
	 */
	public static String sendPost(String url, String params)
	{
		PrintWriter out = null;
		BufferedReader in = null;
		String result = "";
		try
		{
			URL realUrl = new URL(url);
			// 打开和URL之间的连接
			URLConnection conn = realUrl.openConnection();
			// 设置通用的请求属性
			conn.setRequestProperty("accept", "*/*");
			conn.setRequestProperty("connection", "Keep-Alive");
			conn.setRequestProperty("user-agent",
				"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
			
			// 发送POST请求必须设置如下两行
			conn.setDoOutput(true);
			conn.setDoInput(true);
			// 获取URLConnection对象对应的输出流
			out = new PrintWriter(conn.getOutputStream());
			// 发送请求参数
			out.print(params);
			// flush输出流的缓冲
			out.flush();
			
			// 定义BufferedReader输入流来读取URL的响应
			in = new BufferedReader(
				new InputStreamReader(conn.getInputStream()));
			String line;
			while ((line = in.readLine()) != null)
			{
				result += "\n" + line;
			}
		}
		catch (Exception e)
		{
			System.out.println("发送POST请求出现异常！" + e);
			e.printStackTrace();
		}
		// 使用finally块来关闭输出流、输入流
		finally
		{
			try
			{
				if (out != null)
				{
					out.close();
				}
				if (in != null)
				{
					in.close();
				}
			}
			catch (IOException ex)
			{
				ex.printStackTrace();
			}
		}
		return result;
	}
}

3  使用HttpURLConnection访问网络

     实例： 通过HttpURLConnection完成多线程下载的基本步骤和核心代码：

  

     

4  使用Apache HttpClient

    

   使用HttpClient的基本步骤：

    

下面是github上eoecn客户端的网络访问组件：

public class CustomHttpClient {
	private static String TAG = "CustomHttpClient";
	private static final String CHARSET_UTF8 = HTTP.UTF_8;
	private static final String CHARSET_GB2312 = "GB2312";
	private static HttpClient customerHttpClient;

	private CustomHttpClient() {
	}

	/**
	 * HttpClient post方法
	 * 
	 * @param url
	 * @param nameValuePairs
	 * @return
	 */
	public static String PostFromWebByHttpClient(Context context, String url,
			NameValuePair... nameValuePairs) {
		try {
			List<NameValuePair> params = new ArrayList<NameValuePair>();
			if (nameValuePairs != null) {
				for (int i = 0; i < nameValuePairs.length; i++) {
					params.add(nameValuePairs[i]);
				}
			}
			UrlEncodedFormEntity urlEncoded = new UrlEncodedFormEntity(params,
					CHARSET_UTF8);
			HttpPost httpPost = new HttpPost(url);
			httpPost.setEntity(urlEncoded);
			HttpClient client = getHttpClient(context);
			HttpResponse response = client.execute(httpPost);
			if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
				throw new RuntimeException("请求失败");
			}
			HttpEntity resEntity = response.getEntity();
			return (resEntity == null) ? null : EntityUtils.toString(resEntity,
					CHARSET_UTF8);
		} catch (UnsupportedEncodingException e) {
			return null;
		} catch (ClientProtocolException e) {
			return null;
		} catch (IOException e) {
			throw new RuntimeException(context.getResources().getString(
					R.string.httpError), e);
		} 
	}

	public static String getFromWebByHttpClient(Context context, String url,
			NameValuePair... nameValuePairs) throws Exception{
			log.d("getFromWebByHttpClient url = " + url);
		try {
			// http地址
			// String httpUrl =
			// "http://192.168.1.110:8080/httpget.jsp?par=HttpClient_android_Get";
			StringBuilder sb = new StringBuilder();
			sb.append(url);
			if (nameValuePairs != null && nameValuePairs.length > 0) {
				sb.append("?");
				for (int i = 0; i < nameValuePairs.length; i++) {
					if (i > 0) {
						sb.append("&");
					}
					sb.append(String.format("%s=%s",
							nameValuePairs[i].getName(),
							nameValuePairs[i].getValue()));
				}
			}
			// HttpGet连接对象
			HttpGet httpRequest = new HttpGet(sb.toString());
			// 取得HttpClient对象
			HttpClient httpclient = getHttpClient(context);
			// 请求HttpClient，取得HttpResponse
			HttpResponse httpResponse = httpclient.execute(httpRequest);
			// 请求成功
			if (httpResponse.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
				throw new RuntimeException(context.getResources().getString(
						R.string.httpError));
			}
			return EntityUtils.toString(httpResponse.getEntity());
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			throw new RuntimeException(context.getResources().getString(
					R.string.httpError),e);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			throw new RuntimeException(context.getResources().getString(
					R.string.httpError),e);
		} 	
	}

	/**
	 * 创建httpClient实例
	 * 
	 * @return
	 * @throws Exception
	 */
	private static synchronized HttpClient getHttpClient(Context context) {
		if (null == customerHttpClient) {
			HttpParams params = new BasicHttpParams();
			// 设置一些基本参数
			HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
			HttpProtocolParams.setContentCharset(params, CHARSET_UTF8);
			HttpProtocolParams.setUseExpectContinue(params, true);
			HttpProtocolParams
					.setUserAgent(
							params,
							"Mozilla/5.0(Linux;U;Android 2.2.1;en-us;Nexus One Build.FRG83) "
									+ "AppleWebKit/553.1(KHTML,like Gecko) Version/4.0 Mobile Safari/533.1");
			// 超时设置
			/* 从连接池中取连接的超时时间 */
			ConnManagerParams.setTimeout(params, 1000);
			/* 连接超时 */
			int ConnectionTimeOut = 3000;
			if (!HttpUtils.isWifiDataEnable(context)) {
				ConnectionTimeOut = 10000;
			}
			HttpConnectionParams
					.setConnectionTimeout(params, ConnectionTimeOut);
			/* 请求超时 */
			HttpConnectionParams.setSoTimeout(params, 4000);
			// 设置我们的HttpClient支持HTTP和HTTPS两种模式
			SchemeRegistry schReg = new SchemeRegistry();
			schReg.register(new Scheme("http", PlainSocketFactory
					.getSocketFactory(), 80));
			schReg.register(new Scheme("https", SSLSocketFactory
					.getSocketFactory(), 443));

			// 使用线程安全的连接管理来创建HttpClient
			ClientConnectionManager conMgr = new ThreadSafeClientConnManager(
					params, schReg);
			customerHttpClient = new DefaultHttpClient(conMgr, params);
		}
		return customerHttpClient;
	}
}