android 网络编程

Android中提供的HttpURLConnection和HttpClient接口可以用来开发HTTP程序。以下是本人在学习中的总结与归纳。
1. HttpURLConnection接口
      首先需要明确的是，Http通信中的POST和GET请求方式的不同。GET可以获得静态页面，也可以把参数放在URL字符串后面，传递给服务器。而POST方法的参数是放在Http请求中。因此，在编程之前，应当首先明确使用的请求方法，然后再根据所使用的方式选择相应的编程方式。

      HttpURLConnection是继承于URLConnection类，二者都是抽象类。其对象主要通过URL的openConnection方法获得。创建方法如下代码所示：

URL url = new URL("http://www.51cto.com/index.jsp?par=123456");  
HttpURLConnection urlConn=(HttpURLConnection)url.openConnection();

    通过以下方法可以对请求的属性进行一些设置，如下所示

  

//设置输入和输出流  
urlConn.setDoOutput(true);  
urlConn.setDoInput(true);  
//设置请求方式为POST  
urlConn.setRequestMethod("POST");  
//POST请求不能使用缓存  
urlConn.setUseCaches(false); 
//关闭连接  
urlConn.disConnection(); 

Manifest文件中权限的设定：

<uses-permission android:name="android.permission.INTERNET" /> 

  

HttpURLConnection默认使用GET方式，例如下面代码所示：

//以Get方式上传参数
public class Activity03 extends Activity
{
	private final String DEBUG_TAG = "Activity03"; 
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.http);	
		TextView mTextView = (TextView)this.findViewById(R.id.TextView_HTTP);
		//http地址"?par=abcdefg"是我们上传的参数
		String httpUrl = "http://192.168.1.110:8080/httpget.jsp?par=abcdefg";
		//获得的数据
		String resultData = "";
		URL url = null;
		try
		{
			//构造一个URL对象
			url = new URL(httpUrl); 
		}
		catch (MalformedURLException e)
		{
			Log.e(DEBUG_TAG, "MalformedURLException");
		}
		if (url != null)
		{
			try
			{
				// 使用HttpURLConnection打开连接
				HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
				//得到读取的内容(流)
				InputStreamReader in = new InputStreamReader(urlConn.getInputStream());
				// 为输出创建BufferedReader
				BufferedReader buffer = new BufferedReader(in);
				String inputLine = null;
				//使用循环来读取获得的数据
				while (((inputLine = buffer.readLine()) != null))
				{
					//我们在每一行后面加上一个"\n"来换行
					resultData += inputLine + "\n";
				}		  
				//关闭InputStreamReader
				in.close();
				//关闭http连接
				urlConn.disconnect();
				//设置显示取得的内容
				if ( resultData != null )
				{
					mTextView.setText(resultData);
				}
				else 
				{
					mTextView.setText("读取的内容为NULL");
				}
			}
			catch (IOException e)
			{
				Log.e(DEBUG_TAG, "IOException");
			}
		}
		else
		{
			Log.e(DEBUG_TAG, "Url NULL");
		}
}

  如果需要使用POST方式，则需要setRequestMethod设置。代码如下：

//以post方式上传参数
public class Activity04  extends Activity
{
	private final String DEBUG_TAG = "Activity04"; 
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.http);
		
		TextView mTextView = (TextView)this.findViewById(R.id.TextView_HTTP);
		//http地址"?par=abcdefg"是我们上传的参数
		String httpUrl = "http://192.168.1.110:8080/httpget.jsp";
		//获得的数据
		String resultData = "";
		URL url = null;
		try
		{
			//构造一个URL对象
			url = new URL(httpUrl); 
		}
		catch (MalformedURLException e)
		{
			Log.e(DEBUG_TAG, "MalformedURLException");
		}
		if (url != null)
		{
			try
			{
				// 使用HttpURLConnection打开连接
				HttpURLConnection urlConn = (HttpURLConnection) url.openConnection();
				//因为这个是post请求,设立需要设置为true
				urlConn.setDoOutput(true);
				urlConn.setDoInput(true);
		        // 设置以POST方式
				urlConn.setRequestMethod("POST");
		        // Post 请求不能使用缓存
				urlConn.setUseCaches(false);
				urlConn.setInstanceFollowRedirects(true);
		        // 配置本次连接的Content-type，配置为application/x-www-form-urlencoded的
				urlConn.setRequestProperty("Content-Type","application/x-www-form-urlencoded");
		        // 连接，从postUrl.openConnection()至此的配置必须要在connect之前完成，
		        // 要注意的是connection.getOutputStream会隐含的进行connect。
				urlConn.connect();
				//DataOutputStream流
		        DataOutputStream out = new DataOutputStream(urlConn.getOutputStream());
		        //要上传的参数
		        String content = "par=" + URLEncoder.encode("ABCDEFG", "gb2312");
		        //将要上传的内容写入流中
		        out.writeBytes(content); 
		        //刷新、关闭
		        out.flush();
		        out.close(); 
		        //获取数据
		        BufferedReader reader = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));
				String inputLine = null;
				//使用循环来读取获得的数据
				while (((inputLine = reader.readLine()) != null))
				{
					//我们在每一行后面加上一个"\n"来换行
					resultData += inputLine + "\n";
				}		  
				reader.close();
				//关闭http连接
				urlConn.disconnect();
				//设置显示取得的内容
				if ( resultData != null )
				{
					mTextView.setText(resultData);
				}
				else 
				{
					mTextView.setText("读取的内容为NULL");
				}
			}
			catch (IOException e)
			{
				Log.e(DEBUG_TAG, "IOException");
			}
		}
		else
		{
			Log.e(DEBUG_TAG, "Url NULL");
		}
	}
}

 2. HttpClient接口
 使用Apache提供的HttpClient接口同样可以进行HTTP操作。
 对于GET和POST请求方法的操作有所不同。GET方法的操作代码示例如下：

public class Activity02 extends Activity
{
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.http);
		TextView mTextView = (TextView) this.findViewById(R.id.TextView_HTTP);
		// http地址
		String httpUrl = "http://192.168.1.110:8080/httpget.jsp?par=HttpClient_android_Get";
		//HttpGet连接对象
		HttpGet httpRequest = new HttpGet(httpUrl);
		try
		{
			//取得HttpClient对象
			HttpClient httpclient = new DefaultHttpClient();
			//请求HttpClient，取得HttpResponse
			HttpResponse httpResponse = httpclient.execute(httpRequest);
			//请求成功
			if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK)
			{
				//取得返回的字符串
				String strResult = EntityUtils.toString(httpResponse.getEntity());
				mTextView.setText(strResult);
			}
			else
			{
				mTextView.setText("请求错误!");
			}
		}
		catch (ClientProtocolException e)
		{
			mTextView.setText(e.getMessage().toString());
		}
		catch (IOException e)
		{
			mTextView.setText(e.getMessage().toString());
		}
		catch (Exception e)
		{
			mTextView.setText(e.getMessage().toString());
		}  
	
			}
}

  使用POST方法进行参数传递时，需要使用NameValuePair来保存要传递的参数，另外，还需要设置所使用的字符集。代码如下所示：

public class Activity03 extends Activity
{
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.http);
		TextView mTextView = (TextView) this.findViewById(R.id.TextView_HTTP);
		// http地址
		String httpUrl = "http://192.168.1.110:8080/httpget.jsp";
		//HttpPost连接对象
		HttpPost httpRequest = new HttpPost(httpUrl);
		//使用NameValuePair来保存要传递的Post参数
		List<NameValuePair> params = new ArrayList<NameValuePair>();
		//添加要传递的参数
		params.add(new BasicNameValuePair("par", "HttpClient_android_Post"));
		try
		{
			//设置字符集
			HttpEntity httpentity = new UrlEncodedFormEntity(params, "gb2312");
			//请求httpRequest
			httpRequest.setEntity(httpentity);
			//取得默认的HttpClient
			HttpClient httpclient = new DefaultHttpClient();
			//取得HttpResponse
			HttpResponse httpResponse = httpclient.execute(httpRequest);
			//HttpStatus.SC_OK表示连接成功
			if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK)
			{
				//取得返回的字符串
				String strResult = EntityUtils.toString(httpResponse.getEntity());
				mTextView.setText(strResult);
			}
			else
			{
				mTextView.setText("请求错误!");
			}
		}
		catch (ClientProtocolException e)
		{
			mTextView.setText(e.getMessage().toString());
		}
		catch (IOException e)
		{
			mTextView.setText(e.getMessage().toString());
		}
		catch (Exception e)
		{
			mTextView.setText(e.getMessage().toString());
		}  
	}
}

 

     HttpClient实际上是对Java提供方法的一些封装，在HttpURLConnection中的输入输出流操作，在这个接口中被统一封装成了HttpPost(HttpGet)和HttpResponse，这样，就减少了操作的繁琐性。

    另外，在使用POST方式进行传输时，需要进行字符编码。

评论

3 楼 zhangchunyu275 2011-11-01  

中权限的设定：我也想要源码。。。能给发一个不 [e-mail]

2 楼 guozhigang 2011-10-20  

很详细的哈，注释详细，易于入门。顶下版主！

1 楼 flyering 2011-09-01  

能不能给我发一个源码，谢谢。[e-mail]