Android HTTP請求方式:HttpClient
本節引言：
在上一節中我們對HttpURLConnection進行了學習，本節到第二種方式：HttpClient，儘管被Google 棄用了，但是我們我們平常也可以拿HttpClient來抓下包，配合Jsoup解析網頁效果更佳！ HttpClient 用於接收/傳送Http請求/回應，但不快取伺服器回應，不執行HTML頁面潛入的JS程式碼，不會對頁面內容 進行任何解析，處理！開始本節內容！
1.HttpClient使用流程
基本流程：
2.HttpClient使用範例
1）使用HttpClient發送GET請求
直接貼下簡單的發送Get請求的程式碼：
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();
}
}另外，如果是帶有參數的GET請求的話，我們可以將參數放到一個List集合中，再對參數進行URL編碼， 最後和URL拼接下就好了：
List params = new LinkedList();
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);2）使用HttpClient發送POST請求
POST請求比GET稍微複雜一點，創建完HttpPost物件後，透過NameValuePair集合來儲存等待提交 的參數，並將參數傳遞到UrlEncodedFormEntity中，最後呼叫setEntity(entity)完成， HttpClient.execute(HttpPost)即可；這裡就不寫範例了，暫時沒找到Post的網站，又不想 自己寫個Servlet，So,直接貼核心程式碼吧~
核心程式碼:
private void PostByHttpClient(final String url)
{
new Thread()
{
public void run()
{
try{
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
List params = new ArrayList();
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();
}3.HttpClient抓資料範例(教學系統資料抓取)
其實關於HttpClient的例子很多，例如筆者曾經用它來抓學校教務系統上學生的課程表: 這就牽涉到Cookie，模擬登陸的東西，說到抓數據(爬蟲)，一般我們是搭配著JSoup來解析 抓到數據的，有興趣可以自己查閱相關資料，這裡貼下筆者畢設app裡獲取網頁部分的關鍵 代碼！大家可以體會下：
HttpClient可以透過下述程式碼取得與設定Cookie：HttpResponse loginResponse = new DefaultHttpClient().execute(getLogin);取得Cookie: cookie = loginResponse.getFirstHeader("Set-Cookie").getValue();請求時帶上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 params = new ArrayList();
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;
}4.使用HttpPut發送Put請求
範例程式碼如下：
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 params = new ArrayList();
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;
}本節小結：
好的，本節關於Android HTTP的第二種請求方式:HttpClient就到這裡， 下節開始我們來學習XML以及Json的解析，本節就到這裡，謝謝~
