HttpClient

HttpClient是Apache對java中的HttpURLClient介面的封裝，主要引用org.apache.http.**。Google在2.3版本之前推薦使用HttpClient，因為這個封裝包安全性高，bug較少。

使用方法：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import
 
 org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import
 
 org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;



public class HttpClientUtils {
    private static HttpClient httpClient;
    private static HttpClientUtils instance = null;

    public static synchronized
 
 HttpClientUtils getInstance() {
        if (instance == null) {
            instance = new HttpClientUtils();
        }
        return instance;
    }

    private HttpClientUtils() {
        // 學習volley請求佇列，HttpClient使用單例模式
        if (httpClient == null) {
            httpClient = new DefaultHttpClient();
        }
    }
    /**
     * 以get方式傳送請求，訪問介面
     * @param uri連結地址
     * @return 響應資料
     */
    private static String doHttpGet(String uri) {
        BufferedReader reader = null;
        StringBuffer sb = null;
        String result = "";
        HttpGet request = new HttpGet(uri);
        try {
            // 傳送請求，得到響應
            HttpResponse response = httpClient.execute(request);
            // 請求成功，statuscode返回200
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
                sb = new StringBuffer();
                String line = "";
                while ((line = reader.readLine()) != null) {
                    sb.append(line);
                }
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != reader) {
                    reader.close();
                    reader = null;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (null != sb) {
            result = sb.toString();
        }
        return result;
    }

    /**
     * 以post方式傳送請求，訪問介面
     * @param uri連結地址
     * @return 響應資料
     */
    private static String doHttpPost(String uri) {
        BufferedReader reader = null;
        StringBuffer sb = null;
        String result = "";
        HttpPost request = new HttpPost(uri);

        // 儲存要傳遞的引數
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // 新增引數
        params.add(new BasicNameValuePair("parameter", "以Post方式傳送請求"));

        try {
            // 設定字符集
            HttpEntity entity = new UrlEncodedFormEntity(params, "utf-8");
            // 請求物件
            request.setEntity(entity);
            // 傳送請求
            HttpResponse response = httpClient.execute(request);
            // 請求成功
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                System.out.println("post success");
                reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
                sb = new StringBuffer();
                String line = "";
                while ((line = reader.readLine()) != null) {
                    sb.append(line);
                }
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                // 關閉流
                if (null != reader) {
                    reader.close();
                    reader = null;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (null != sb) {
            result = sb.toString();
        }
        return result;
    }

}

HttpURLConnection

HttpURLConnection在java.NET下，繼承自URLConnection類，相對於HttpClient具有擴充套件性高、靈活性高，更輕量級的優點，所以Google在2.3版本之後推薦大家使用HttpURLConnection來操作網路請求。

使用方法：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;


public class HttpURLConnectUtils {

    private static HttpURLConnectUtils instance = null;

    public static synchronized HttpURLConnectUtils getInstance() {
        if (instance == null) {
            instance = new HttpURLConnectUtils();
        }
        return instance;
    }

    private HttpURLConnectUtils() {
    }

    // post
    public String dohttppost(String mUrl) throws IOException {

        URL url = new URL(mUrl);
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();//初始化建立HttpURLConnection例項
        httpURLConnection.setConnectTimeout(5000);//推薦設定網路延時
        httpURLConnection.setDoOutput(true);
        httpURLConnection.setDoInput(true);
        httpURLConnection.setUseCaches(false);
        httpURLConnection.setRequestProperty("Content-type", "application/x-java-serialized-object");
        httpURLConnection.setRequestMethod("POST");
        //設定引數
        OutputStream outputStream = httpURLConnection.getOutputStream();
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
        String params = new String();//這裡簡單設定引數
        params = "name=" + URLEncoder.encode("高冉", "GBK");
        objectOutputStream.writeBytes(params);
        objectOutputStream.flush();
        objectOutputStream.close();
        //接收返回值
        //String msg = httpURLConnection.getResponseMessage();// 接收簡單string
        InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream());
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        StringBuilder builder = new StringBuilder();
        for (String s = bufferedReader.readLine(); s != null; s = bufferedReader.readLine()) {
            builder.append(s);
        }
        return builder.toString();
    }

    // get
    public String dohttpget(String mUrl) throws IOException {
        URL url = new URL(mUrl);
        HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
        httpURLConnection.setConnectTimeout(5000);//推薦設定網路延時
        httpURLConnection.setRequestMethod("GET");
        httpURLConnection.connect();

        // String msg = httpURLConnection.getResponseMessage();

        InputStreamReader inputStreamReader = new InputStreamReader(httpURLConnection.getInputStream());
        BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
        StringBuilder builder = new StringBuilder();
        for (String s = bufferedReader.readLine(); s != null; s = bufferedReader.readLine()) {
            builder.append(s);
        }

        return builder.toString();
    }
}

還需要注意一些細節：

1、post與get區別在於post將引數置於請求資料中，get則跟在url連結後面。
2、大檔案下載操作要置於sd卡中，不要放在手機記憶體中操作，而且需要邊讀邊寫，不要使用Buffered做快取。

三、我們看一個簡單的socket程式設計，實現伺服器回發客戶端資訊。

下面用個例子來說明：

A、客戶端：

新建Android專案工程：SocketForAndroid（這個隨意起名字了吧，我是以這個建立的！）

下面是main_activity.xml的程式碼：

MainActivity.java的程式碼入下：

最後別忘記新增訪問網路許可權：

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

B、服務端：

C、啟動伺服器，控制檯會打印出“start...”字串！

D、執行Android專案檔案，如下圖：

在輸入框裡輸入如下字串，點發送按鈕：

伺服器收到客戶端發來的訊息並列印到控制檯：