Android中的Http请求

程序的核心可以说是分为算法和数据结构两部分，说到底就是使用一定的方法（算法）处理数据（数据结构），算法是一种能力，需要不断的学习积累，而数据则需要获取，在移动设备上，不可能存储大量数据，所以就需要从服务器获取数据，和服务器进行数据交互，也就要用到Http请求。

Android4.0后所有网络方面的操作都不能在主线程执行 ! ! !

Android目前提供两种Http通信方式：HttpClient (org.appache.http) 和 HttpURLConnection (java.net)

• HttpClient : 是Android SDK集成自Apache中，比较完善，全面支持Http协议，；（常用）

• HttpURLConnection : 多用于发送和接收数据流形式的数据，传输数据量大，适合上传/下载文件；（用于简单的基于URL的请求、响应功能）

请 求 方 式又分为： HttpGet 请求和 HttpPost 请求

• get方式 ： 将参数连接在URL后面，各个参数之间用&连接；

• post方式 ： 使用根URL，将参数信息放在请求实体中发送；

HttpURLConnection实例

参考链接：http://blog.csdn.net/yanzi1225627/article/details/22222735

private String getURLResponse(String urlString){  
        HttpURLConnection conn = null; //连接对象 
        InputStream is = null;  
        String resultData = "";  
        try {  
            URL url = new URL(urlString); //URL对象 
            conn = (HttpURLConnection)url.openConnection(); //使用URL打开一个链接 
            conn.setDoInput(true); //允许输入流，即允许下载 
            conn.setDoOutput(true); //允许输出流，即允许上传 
            conn.setUseCaches(false); //不使用缓冲 
            conn.setRequestMethod("GET"); //使用get请求 
            is = conn.getInputStream();   //获取输入流，真正建立链接 
            InputStreamReader isr = new InputStreamReader(is);  
            BufferedReader bufferReader = new BufferedReader(isr);  
            String inputLine  = "";  
            while((inputLine = bufferReader.readLine()) != null){  
                resultData += inputLine + "\n";  
            }  
        } catch (MalformedURLException e) {  
            e.printStackTrace();  
        }catch (IOException e) {  
            e.printStackTrace();  
        }finally{  
            if(is != null){  
                try {  
                    is.close();  
                } catch (IOException e) {  
                    e.printStackTrace();  
                }  
            }  
            if(conn != null){  
                conn.disconnect();  
            }  
        }  

        return resultData;  
    }  

HttpClient (Get) 实例

链接：http://www.cnblogs.com/mengdd/p/3142442.html

// 使用GET方法发送请求,需要把参数加在URL后面，用？连接，参数之间用&分隔
String url = baseURL + "?username=" + name + "&age=" + age;
HttpGet httpGet = new HttpGet(url);// 生成请求对象
HttpClient httpClient = new DefaultHttpClient();
try{
    // 发送请求
    HttpResponse response = httpClient.execute(httpGet);//显示响应
    showResponseResult(response);// 一个私有方法，将响应结果显示出来
}catch (Exception e){
     e.printStackTrace();
 }

HttpClient (Post) 实例

链接：http://www.cnblogs.com/mengdd/p/3142442.html

try{
   HttpEntity requestHttpEntity = 
   new UrlEncodedFormEntity(pairList);
   // URL使用基本URL即可，其中不需要加参数
   HttpPost httpPost = new HttpPost(baseURL);
   // 将请求体内容加入请求中
   httpPost.setEntity(requestHttpEntity);
   // 需要客户端对象来发送请求
   HttpClient httpClient = new DefaultHttpClient();
   // 发送请求
   HttpResponse response = httpClient.execute(httpPost);
   // 显示响应
   showResponseResult(response);
   }catch (Exception e){
        e.printStackTrace();
    }

HttpClient (Post) 封装类

链接：http://www.cnblogs.com/hrlnw/p/4118480.html

/** * * 用于封装&简化http通信 * */
public class PostRequest implements Runnable {

    private static final int NO_SERVER_ERROR=1000;
    //服务器地址
    public static final String URL = "fill your own url";
    //一些请求类型
    public final static String ADD = "/add";
    public final static String UPDATE = "/update";
    public final static String PING = "/ping";
    //一些参数
    private static int connectionTimeout = 60000;
    private static int socketTimeout = 60000;
    //类静态变量
    private static HttpClient httpClient=new DefaultHttpClient();
    private static ExecutorService executorService=Executors.newCachedThreadPool();
    private static Handler handler = new Handler();
    //变量
    private String strResult;
    private HttpPost httpPost;
    private HttpResponse httpResponse;
    private OnReceiveDataListener onReceiveDataListener;
    private int statusCode;

    /** * 构造函数，初始化一些可以重复使用的变量 */
    public PostRequest() {
        strResult = null;
        httpResponse = null;
        httpPost = new HttpPost();
    }

    /** * 注册接收数据监听器 * @param listener */
    public void setOnReceiveDataListener(OnReceiveDataListener listener) {
        onReceiveDataListener = listener;
    }

    /** * 根据不同的请求类型来初始化httppost * * @param requestType * 请求类型 * @param nameValuePairs * 需要传递的参数 */
    public void iniRequest(String requestType, JSONObject jsonObject) {
        httpPost.addHeader("Content-Type", "text/json");
        httpPost.addHeader("charset", "UTF-8");

        httpPost.addHeader("Cache-Control", "no-cache");
        HttpParams httpParameters = httpPost.getParams();
        HttpConnectionParams.setConnectionTimeout(httpParameters,
                connectionTimeout);
        HttpConnectionParams.setSoTimeout(httpParameters, socketTimeout);
        httpPost.setParams(httpParameters);
        try {
            httpPost.setURI(new URI(URL + requestType));
            httpPost.setEntity(new StringEntity(jsonObject.toString(),
                    HTTP.UTF_8));
        } catch (URISyntaxException e1) {
            e1.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
    }

    /** * 新开一个线程发送http请求 */
    public void execute() {
        executorService.execute(this);
    }

    /** * 检测网络状况 * * @return true is available else false */
    public static boolean checkNetState(Activity activity) {
        ConnectivityManager connManager = (ConnectivityManager) activity
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if (connManager.getActiveNetworkInfo() != null) {
            return connManager.getActiveNetworkInfo().isAvailable();
        }
        return false;
    }

    /** * 发送http请求的具体执行代码 */
    @Override
    public void run() {
        httpResponse = null;
        try {
            httpResponse = httpClient.execute(httpPost);
            strResult = EntityUtils.toString(httpResponse.getEntity());
        } catch (ClientProtocolException e1) {
            strResult = null;
            e1.printStackTrace();
        } catch (IOException e1) {
            strResult = null;
            e1.printStackTrace();
        } finally {
            if (httpResponse != null) {
                statusCode = httpResponse.getStatusLine().getStatusCode();
            }
            else
            {
                statusCode=NO_SERVER_ERROR;
            }
            if(onReceiveDataListener!=null)
            {
                //将注册的监听器的onReceiveData方法加入到消息队列中去执行
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        onReceiveDataListener.onReceiveData(strResult, statusCode);
                    }
                });
            }
        }
    }

    /** * 用于接收并处理http请求结果的监听器 * */
    public interface OnReceiveDataListener {
        /** * the callback function for receiving the result data * from post request, and further processing will be done here * @param strResult the result in string style. * @param StatusCode the status of the post */
        public abstract void onReceiveData(String strResult,int StatusCode);
    }

}