转载 Android之网络与通信

2.三种网络接口简述
2.1 标准Java接口

           java.net.*提供与联网有关的类，包括流和数据包套接字、Internet协议、常见HTTP处理。

           使用java.net.*包连接网络代码：
Java代码  收藏代码

    try {  
                //定义地址  
                URL url=new URL("http://www.google.com");  
                //打开连接  
                HttpURLConnection http=(HttpURLConnection)url.openConnection();  
                //得到连接状态  
                int nRC=http.getResponseCode();  
                if(nRC==HttpURLConnection.HTTP_OK)  
                {  
                    //取得数据  
                    InputStream is = http.getInputStream();  
                    //处理数据  
                      
                }  
            } catch (Exception e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  

2.2 Apache接口

          org. apache.http.* 提供的HttpClient对HTTP的请求做了比较好的封装。示例代码如下：
Java代码  收藏代码

    //创建HttpClient  
            //这里使用DefaultHttpClient表示默认属性  
            HttpClient hc = new DefaultHttpClient();  
            //HttpGet实例  
            HttpGet get = new HttpGet("http://www.google.com");  
            //连接  
            try {  
                HttpResponse rp = hc.execute(get);  
                if(rp.getStatusLine().getStatusCode()==HttpStatus.SC_OK)  
                {  
                    InputStream is = rp.getEntity().getContent();  
                    //处理数据  
                }  
            } catch (ClientProtocolException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            } catch (IOException e) {  
                // TODO Auto-generated catch block  
                e.printStackTrace();  
            }  

 
2.3 Android 网络接口

          android.net.*包实际上是通过对Apache中HttpClient的封装来实现的一个HTTP编程接口，同时还提供了HTTP请求队列管理以及HTTP连接池管理，以提高并发请求情况下的处理效率，除此之外还有网络状态监视等接口、网络访问的Socket、常用的Uri类以及有关Wifi相关的类等等。
3. HTTP通信

         在上面的介绍中我们可以看出http的通信方式，有2种方式可以实现HttpURLConnection和HttpClient。
3.1 HttpURLConnection实现HTTP通信

          我们知道在http的请求中主要有2种方式，GET 和 POST。下面我们通过代码看看如何实现的。

          Get方式的HTTP请求，代码如下：
Java代码  收藏代码

    //GET获取数据  
    public class HttpGetActivity extends Activity  
    {  
        private final String DEBUG_TAG = "Activity02";   
        /** 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/http1.jsp？name=bigboy";  
            //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");  
            }  
            //设置按键事件监听  
            Button button_Back = (Button) findViewById(R.id.Button_Back);  
            /* 监听button的事件信息 */  
            button_Back.setOnClickListener(new Button.OnClickListener()   
            {  
                public void onClick(View v)  
                {  
                    /* 新建一个Intent对象 */  
                    Intent intent = new Intent();  
                    /* 指定intent要启动的类 */  
                    intent.setClass(Activity02.this, Activity01.class);  
                    /* 启动一个新的Activity */  
                    startActivity(intent);  
                    /* 关闭当前的Activity */  
                    Activity02.this.finish();  
                }  
            });  
        }  
    }  

         POST请求的方式稍有不同，代码如下：
Java代码  收藏代码

    //以post方式上传参数  
    public class HttpPOSTActivity 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");  
            }  
              
            Button button_Back = (Button) findViewById(R.id.Button_Back);  
            /* 监听button的事件信息 */  
            button_Back.setOnClickListener(new Button.OnClickListener()   
            {  
                public void onClick(View v)  
                {  
                    /* 新建一个Intent对象 */  
                    Intent intent = new Intent();  
                    /* 指定intent要启动的类 */  
                    intent.setClass(Activity04.this, Activity01.class);  
                    /* 启动一个新的Activity */  
                    startActivity(intent);  
                    /* 关闭当前的Activity */  
                    Activity04.this.finish();  
                }  
            });  
        }  
    }  

 默认是使用GET方式。
3.2 HttpClient实现HTTP通信

          HttpClient实现GET请求方式，代码如下：
Java代码  收藏代码

    public class ClientGETActivity 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());  
            }    
          
            //设置按键事件监听  
            Button button_Back = (Button) findViewById(R.id.Button_Back);  
            /* 监听button的事件信息 */  
            button_Back.setOnClickListener(new Button.OnClickListener()   
            {  
                public void onClick(View v)  
                {  
                    /* 新建一个Intent对象 */  
                    Intent intent = new Intent();  
                    /* 指定intent要启动的类 */  
                    intent.setClass(Activity02.this, Activity01.class);  
                    /* 启动一个新的Activity */  
                    startActivity(intent);  
                    /* 关闭当前的Activity */  
                    Activity02.this.finish();  
                }  
            });  
        }  
    }  

    HttpClient实现POST请求方式稍有复杂，要求使用NameValuePair保存传递参数,代码如下:
Java代码  收藏代码

    public class ClientPOSTActivity 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());  
            }    
            //设置按键事件监听  
            Button button_Back = (Button) findViewById(R.id.Button_Back);  
            /* 监听button的事件信息 */  
            button_Back.setOnClickListener(new Button.OnClickListener()   
            {  
                public void onClick(View v)  
                {  
                    /* 新建一个Intent对象 */  
                    Intent intent = new Intent();  
                    /* 指定intent要启动的类 */  
                    intent.setClass(Activity03.this, Activity01.class);  
                    /* 启动一个新的Activity */  
                    startActivity(intent);  
                    /* 关闭当前的Activity */  
                    Activity03.this.finish();  
                }  
            });  
        }  
    }  

4.Socket通信

        在Android中完全可以使用Java标准APilai开发Socket程序。

        下面是一个服务器和客户端通信的例子。

        服务器断代码：
Java代码  收藏代码

    public class Server implements Runnable  
    {  
        public void run()  
        {  
            try  
            {  
                //创建ServerSocket  
                ServerSocket serverSocket = new ServerSocket(54321);  
                while (true)  
                {  
                    //接受客户端请求  
                    Socket client = serverSocket.accept();  
                    System.out.println("accept");  
                    try  
                    {  
                        //接收客户端消息  
                        BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));  
                        String str = in.readLine();  
                        System.out.println("read:" + str);    
                        //向服务器发送消息  
                        PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(client.getOutputStream())),true);        
                        out.println("server message");   
                        //关闭流  
                        out.close();  
                        in.close();  
                    }  
                    catch (Exception e)  
                    {  
                        System.out.println(e.getMessage());  
                        e.printStackTrace();  
                    }  
                    finally  
                    {  
                        //关闭  
                        client.close();  
                        System.out.println("close");  
                    }  
                }  
            }  
            catch (Exception e)  
            {  
                System.out.println(e.getMessage());  
            }  
        }  
        //main函数，开启服务器  
        public static void main(String a[])  
        {  
            Thread desktopServerThread = new Thread(new Server());  
            desktopServerThread.start();  
        }  
    }  

 

   客户端代码：
Java代码  收藏代码

    public class ClientActivity  extends Activity  
    {  
        private final String        DEBUG_TAG   = "Activity01";  
          
        private TextView    mTextView=null;  
        private EditText    mEditText=null;  
        private Button      mButton=null;  
        /** Called when the activity is first created. */  
        @Override  
        public void onCreate(Bundle savedInstanceState)  
        {  
            super.onCreate(savedInstanceState);  
            setContentView(R.layout.main);  
              
            mButton = (Button)findViewById(R.id.Button01);  
            mTextView=(TextView)findViewById(R.id.TextView01);  
            mEditText=(EditText)findViewById(R.id.EditText01);  
              
            //登陆  
            mButton.setOnClickListener(new OnClickListener()  
            {  
                public void onClick(View v)  
                {  
                    Socket socket = null;  
                    String message = mEditText.getText().toString() + "\r\n";   
                    try   
                    {     
                        //创建Socket  
                        socket = new Socket("192.168.1.110",54321);   
                        //向服务器发送消息  
                        PrintWriter out = new PrintWriter( new BufferedWriter( new OutputStreamWriter(socket.getOutputStream())),true);        
                        out.println(message);   
                          
                        //接收来自服务器的消息  
                        BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));   
                        String msg = br.readLine();   
                          
                        if ( msg != null )  
                        {  
                            mTextView.setText(msg);  
                        }  
                        else  
                        {  
                            mTextView.setText("数据错误!");  
                        }  
                        //关闭流  
                        out.close();  
                        br.close();  
                        //关闭Socket  
                        socket.close();   
                    }  
                    catch (Exception e)   
                    {  
                        // TODO: handle exception  
                        Log.e(DEBUG_TAG, e.toString());  
                    }  
                }  
            });  
        }  
    }  

5.乱码问题

        网络通信中，产生乱码的主要原因是通信过程中使用了不同的编码方式：服务器中的编码方式，传输过程中的编码方式，传输到达终端设备的编码方式。

        解决中文乱码的两个步骤：

 1.使用getBytes("编码方式")来对汉字进行重编码，得到它的字节数组。

 2.再使用new String(Bytes[],"解码方式")来对字节数组进行相应的解码。

 

至此Android的网络通信篇基本结束了。