7.1.4 Android HTTP请求方式:HttpClient

本节引言：

在上一节中我们对HttpURLConnection进行了学习，本节到第二种方式：HttpClient，尽管被Google 弃用了，但是我们我们平时也可以拿HttpClient来抓下包，配合Jsoup解析网页效果更佳！HttpClient 用于接收/发送Http请求/响应，但不缓存服务器响应，不执行HTML页面潜入的JS代码，不会对页面内容 进行任何解析，处理！开始本节内容！

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1.HttpClient使用流程

基本流程：

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2.HttpClient使用示例

1）使用HttpClient发送GET请求

直接贴下简单的发送Get请求的代码：

public class MainActivity extends Activity implements OnClickListener {



    private Button btnGet;

    private WebView wView;

    public static final int SHOW_DATA = 0X123;

    private String detail = "";



    private Handler handler = new Handler() {

        public void handleMessage(Message msg) {

            if(msg.what == SHOW_DATA)

            {

                wView.loadDataWithBaseURL("",detail, "text/html","UTF-8","");

            }

        };

    };

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initView();

        setView();

    }



    private void initView() {

        btnGet = (Button) findViewById(R.id.btnGet);

        wView = (WebView) findViewById(R.id.wView);

    }



    private void setView() {

        btnGet.setOnClickListener(this);

        wView.getSettings().setDomStorageEnabled(true);

    }

    @Override

    public void onClick(View v) {

        if (v.getId() == R.id.btnGet) {

            GetByHttpClient();

        }

    }

    private void GetByHttpClient() {

        new Thread()

        {

            public void run() 

            {

                    try {

                        HttpClient httpClient = new DefaultHttpClient();

                        HttpGet httpGet = new HttpGet("http://www.w3cschool.cc/python/python-tutorial.html");

                        HttpResponse httpResponse = httpClient.execute(httpGet);

                        if (httpResponse.getStatusLine().getStatusCode() == 200) {

                            HttpEntity entity = httpResponse.getEntity();

                            detail = EntityUtils.toString(entity, "utf-8");

                            handler.sendEmptyMessage(SHOW_DATA);

                        }

                    } catch (Exception e) {

                        e.printStackTrace();

                    }

            };

        }.start();

    }



}

运行截图

另外，如果是带有参数的GET请求的话，我们可以将参数放到一个List集合中，再对参数进行URL编码， 最后和URL拼接下就好了：

List<BasicNameValuePair> params = new LinkedList<BasicNameValuePair>();  

params.add(new BasicNameValuePair("user", "猪小弟"));  

params.add(new BasicNameValuePair("pawd", "123"));

String param = URLEncodedUtils.format(params, "UTF-8"); 

HttpGet httpGet = new HttpGet("http://www.baidu.com"+"?"+param);

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2）使用HttpClient发送POST请求

POST请求比GET稍微复杂一点，创建完HttpPost对象后，通过NameValuePair集合来存储等待提交 的参数，并将参数传递到UrlEncodedFormEntity中，最后调用setEntity(entity)完成， HttpClient.execute(HttpPost)即可；这里就不写例子了，暂时没找到Post的网站，又不想 自己写个Servlet，So,直接贴核心代码吧~

核心代码:

private void PostByHttpClient(final String url)

{

    new Thread()

    {

        public void run() 

        {

            try{

                HttpClient httpClient = new DefaultHttpClient();

                HttpPost httpPost = new HttpPost(url);

                List<NameValuePair> params = new ArrayList<NameValuePair>();

                params.add(new BasicNameValuePair("user", "猪大哥"));

                params.add(new BasicNameValuePair("pawd", "123"));

                UrlEncodedFormEntity entity = new UrlEncodedFormEntity(params,"UTF-8");

                httpPost.setEntity(entity);

                HttpResponse httpResponse =  httpClient.execute(httpPost);

                if (httpResponse.getStatusLine().getStatusCode() == 200) {

                    HttpEntity entity2 = httpResponse.getEntity();

                    detail = EntityUtils.toString(entity2, "utf-8");

                    handler.sendEmptyMessage(SHOW_DATA);

                }

            }catch(Exception e){e.printStackTrace();}

        };

    }.start();

}

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3.HttpClient抓数据示例(教务系统数据抓取)

其实关于HttpClient的例子有很多，比如笔者曾经用它来抓学校教务系统上学生的课程表: 这就涉及到Cookie，模拟登陆的东西，说到抓数据(爬虫)，一般我们是搭配着JSoup来解析 抓到数据的，有兴趣可以自己查阅相关资料，这里贴下笔者毕设app里获取网页部分的关键 代码！大家可以体会下：

HttpClient可以通过下述代码获取与设置Cookie： HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin); 获得Cookie:cookie = loginResponse.getFirstHeader("Set-Cookie").getValue(); 请求时带上Cookie:httpPost.setHeader("Cookie", cookie);

//获得链接,模拟登录的实现:

public int getConnect(String user, String key) throws Exception {

    // 先发送get请求 获取cookie值和__ViewState值

    HttpGet getLogin = new HttpGet(true_url);

    // 第一步:主要的HTML:

    String loginhtml = "";

    HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin);

    if (loginResponse.getStatusLine().getStatusCode() == 200) {

        HttpEntity entity = loginResponse.getEntity();

        loginhtml = EntityUtils.toString(entity);

        // 获取响应的cookie值

        cookie = loginResponse.getFirstHeader("Set-Cookie").getValue();

        System.out.println("cookie= " + cookie);

    }



    // 第二步:模拟登录

    // 发送Post请求,禁止重定向

    HttpPost httpPost = new HttpPost(true_url);

    httpPost.getParams().setParameter(ClientPNames.HANDLE_REDIRECTS, false);



    // 设置Post提交的头信息的参数

    httpPost.setHeader("User-Agent",

            "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko");

    httpPost.setHeader("Referer", true_url);

    httpPost.setHeader("Cookie", cookie);



    // 设置请求数据

    List<NameValuePair> params = new ArrayList<NameValuePair>();



    params.add(new BasicNameValuePair("__VIEWSTATE",

            getViewState(loginhtml)));// __VIEWSTATE参数，如果变化可以动态抓取获取

    params.add(new BasicNameValuePair("Button1", ""));

    params.add(new BasicNameValuePair("hidPdrs", ""));

    params.add(new BasicNameValuePair("hidsc", ""));

    params.add(new BasicNameValuePair("lbLanguage", ""));

    params.add(new BasicNameValuePair("RadioButtonList1", "%D1%A7%C9%FA"));

    params.add(new BasicNameValuePair("txtUserName", user));

    params.add(new BasicNameValuePair("TextBox2", key));

    params.add(new BasicNameValuePair("txtSecretCode", "")); // ( ╯□╰ )逗比正方,竟然不需要验证码



    // 设置编码方式,响应请求,获取响应状态码:

    httpPost.setEntity(new UrlEncodedFormEntity(params, "gb2312"));

    HttpResponse response = new DefaultHttpClient().execute(httpPost);

    int Status = response.getStatusLine().getStatusCode();

    if(Status == 200)return Status;

    System.out.println("Status= " + Status);



    // 重定向状态码为302

    if (Status == 302 || Status == 301) {

        // 获取头部信息中Location的值

        location = response.getFirstHeader("Location").getValue();

        System.out.println(location);

        // 第三步:获取管理信息的主页面

        // Get请求

        HttpGet httpGet = new HttpGet(ip_url + location);// 带上location地址访问

        httpGet.setHeader("Referer", true_url);

        httpGet.setHeader("Cookie", cookie);



        // 主页的html

        mainhtml = "";

        HttpResponse httpResponseget = new DefaultHttpClient()

                .execute(httpGet);

        if (httpResponseget.getStatusLine().getStatusCode() == 200) {

            HttpEntity entity = httpResponseget.getEntity();

            mainhtml = EntityUtils.toString(entity);

        }



    }

    return Status;

}

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4.使用HttpPut发送Put请求

示例代码如下：

public static int PutActCode(String actCode, String licPlate, Context mContext) {

    int resp = 0;

    String cookie = (String) SPUtils.get(mContext, "session", "");

    HttpPut httpPut = new HttpPut(PUTACKCODE_URL);

    httpPut.setHeader("Cookie", cookie);

    try {



        List<NameValuePair> params = new ArrayList<NameValuePair>();

        params.add(new BasicNameValuePair("activation_code", actCode));

        params.add(new BasicNameValuePair("license_plate", licPlate));

        httpPut.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));

        HttpResponse course_response = new DefaultHttpClient().execute(httpPut);

        if (course_response.getStatusLine().getStatusCode() == 200) {

            HttpEntity entity2 = course_response.getEntity();

            JSONObject jObject = new JSONObject(EntityUtils.toString(entity2));

            resp = Integer.parseInt(jObject.getString("status_code"));

            return resp;

        }

    } catch (Exception e) {

        e.printStackTrace();

    }

    return resp;

}

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本节小结：

好的，本节关于Android HTTP的第二种请求方式:HttpClient就到这里， 下节开始我们来学习XML以及Json的解析，本节就到这里，谢谢~