Android HTTP请求方式

1.HttpClient使用流程
基本流程：

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","");        }    };};@Overrideprotected 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);}@Overridepublic 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 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 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 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302if (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 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;

}