Android之Http沟通——4.Android HTTP索取信息:HttpClient

本节介绍:

HttpClient使用流程:

基本流程:

HttpClient使用演示样例:

1.发送GET请求

嗯，就写个简单的发送GET请求的代码吧:

package com.example.httpclientdemo;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.View.OnClickListener;
import android.webkit.WebView;
import android.widget.Button;

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。假设是带有參数的GET请求的话，我们能够把參数放到List集合中，在对參数进行URL编码:

然后和URL拼接

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);

接着贴下执行截图:

2.发送POST请求

POST请求比GET略微复杂一点。创建完HttpPost对象后，通过NameValuePair集合来存储等待提交

的參数。并将參数传递到UrlEncodedFormEntity中，最后调用setEntity(entity)完毕，

HttpClient.execute(HttpPost)就可以。这里就不写样例了。临时没找到Post的站点，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();
}

3.胡说八道

事实上关于HttpClient的样例有非常多。比方笔者以前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，有兴趣能够自己查阅相关文档。至于笔者的毕设，代码非常烂的说。兴许有时间

整理在公布出来吧。这里贴下模拟登陆教务系统部分的代码。大家能够体会下HttpClient：

//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:基本的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提交的头信息的參数
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參数，假设变化能够动态抓取获取
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,居然不须要验证码

// 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地址訪问
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;
}

总结: