1.初步认识HTTP

HTTP(Hypertext Transfer Protocol超文本传输协议)是网络应用层协议，建立在TCP/IP基础上，HTTP使用可靠的TCP连接，默认端口是80。

较常用的HTTP为GET和POST，不同在于GET通过在请求URL中设定参数来查询，POST则是以表单的形式将数据发送给web端

2.Android下HTTP操作

package org.tonny.httpUtil;import java.util.List;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;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.util.EntityUtils;public class HttpService {    private HttpClient _httpClient = null;    private HttpGet _httpGet = null;    private HttpPost _httpPost = null;    private HttpResponse _httpResponse = null;    private HttpEntity _responseEntity = null;    private HttpEntity _requestEntity = null;    public HttpService() {        _httpClient = new DefaultHttpClient();    }    public String get(String url) throws Exception {        // http请求对象        _httpGet = new HttpGet(url);        // 执行GET请求        _httpResponse = _httpClient.execute(_httpGet);        // 200表示请求成功        if (_httpResponse.getStatusLine().getStatusCode() == 200) {            _responseEntity = _httpResponse.getEntity();            return EntityUtils.toString(_responseEntity);        } else {            return null;        }    }    /**     *      * @param url     *            请求的URL地址     * @param params     *            POST的参数，使用键值对的方式传入     * @return     * @throws Exception     */    public String post(String url, List
     
       params) throws Exception {        _httpPost = new HttpPost(url);                //注意这里需要请求实体        _requestEntity = new UrlEncodedFormEntity(params);        _httpPost.setEntity(_requestEntity);        _httpResponse = _httpClient.execute(_httpPost);        if (_httpResponse.getStatusLine().getStatusCode() == 200) {                        //数据返回还是使用实体            _responseEntity = _httpResponse.getEntity();            return EntityUtils.toString(_responseEntity);        } else {            return null;        }    }}
     

这里封装了POST和GET请求，这里只处理了返回字符形式的，对于字节形式（如图片文件）还需要修改一下

package org.tonnny.httptest;import java.util.ArrayList;import java.util.List;import org.apache.http.NameValuePair;import org.apache.http.message.BasicNameValuePair;import org.tonny.httpUtil.HttpService;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.app.Activity;public class MainActivity extends Activity {    private EditText _txtUrl = null;    private TextView _lblInfo = null;    private Handler _handler = null;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        this._txtUrl = (EditText) this.findViewById(R.id.txtUrl);        this._lblInfo = (TextView) this.findViewById(R.id.lblInfo);        // 这里使用handler实现work线程和UI线程的通信，主要是work线程向UI发送消息，所以在这里定了了消息的处理方法        this._handler = new Handler() {            @Override            public void handleMessage(Message msg) {                String content = String.valueOf(msg.obj);                Log.d("Main in UI ", content);                _lblInfo.setText(content);            }        };    }    /**     * 这里没有采用定义类的方式，而是直接在activity_main中定义onclick属性来实现     * @param v     */    public void OnBtnGetClick(View v) {        // String url = this._txtUrl.getText().toString().trim();        String url = "http://www.baidu.com";        GetThread work = new GetThread(url);        work.start();    }    /**     * 这里POST的参数需要设置好     * @param v     */    public void OnBtnPostClick(View v) {        // String url = this._txtUrl.getText().toString().trim();        String url = "http://mail.163.com/";        List
     
       params = new ArrayList
      
       ();        params.add(new BasicNameValuePair("savelogin", "0"));        params.add(new BasicNameValuePair("url2",                "http://mail.163.com/errorpage/error163.htm"));        params.add(new BasicNameValuePair("username", "***"));        params.add(new BasicNameValuePair("passowrd", "***"));        PostThread work = new PostThread(url, params);        work.start();    }    /**     * Get work线程类     * @author Tinny Cheung     *     */    private final class GetThread extends Thread {        private String _url;        public GetThread(String url) {            _url = url;        }        @Override        public void run() {            HttpService getMethod = new HttpService();            try {                String res = getMethod.get(_url);                Message msg = _handler.obtainMessage();                msg.obj = res;                _handler.sendMessage(msg);            } catch (Exception e) {                e.printStackTrace();            }        }    }    /**     * Post work线程类     * @author Tinny Cheung     *     */    private final class PostThread extends Thread {        private String _url;        private List
       
         _params;        public PostThread(String url, List
        
          params) {            _url = url;            _params = params;        }        @Override        public void run() {            HttpService postMethod = new HttpService();            try {                String res = postMethod.post(_url, _params);                Message msg = _handler.obtainMessage();                msg.obj = res;                _handler.sendMessage(msg);            } catch (Exception e) {                e.printStackTrace();            }        }    }}
        
       
      
     

这里实现对上面封装类的使用，由于邮箱涉及个人隐私问题，所以没有写上去。读者可以通过Http Analyzer之类的工具简单的分析就可以获取到相关的数据。

另外要说的是，此处设计用到了线程间的通信，使用的loop-handler方法来实现，具体细节代码中已有体现。最后记得在清单文件加入许可，如下：

 

3.总结

个人觉得以后项目中Http的操作肯定是比较多的，与具体的业务结合起来，那还是相当复杂，这一块还是要重点掌握，多学多练。事情要做好还有很需要下一番功夫，哎，我就是这样一个懒散的人，以后再完善吧。