7.1.4 Android HTTP请求方式:HttpClient
最后更新于：2022-04-01 05:27:58
## 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~