Android---如何利用API实时获取各频道新闻？

基本上万事俱备了，博主我把开发新闻阅读器的相关知识都整理好了，接下来几天我要搞一个新闻阅读器(*^__^*) ~

本次实例包含了利用API（从“百度APIStore”上找的），从网络上实时获取各种频道的新闻。

接下来，我们首先建一个Layout，上面放一个Spinner，用来展现各种新闻频道，而下面，我们放一个TextView，当选中Spinner中相应的频道时，TextView中则会加载从网络获取的该频道实时新闻。

[b]这里先给大家贴个工具类，用来从网络获取信息:
[/b]

public class UrlUtil {
//获取频道的网络接口
public static String channelUrl = "http://apis.baidu.com/showapi_open_bus/channel_news/channel_news";
//获取频道对应新闻的网络接口
/*
get 请求参数
*channelId 新闻频道id，必须精确匹配
channelName 新闻频道名称，可模糊匹配
title 新闻标题，模糊匹配
page 页数，默认1。每页最多20条记录
*needContent 是否需要返回正文，1为需要，其他为不需要
*needHtml 是否需要返回正文的html格式，1为需要，其他为不需要
*/
public static String newsUrl = "http://apis.baidu.com/showapi_open_bus/channel_news/search_news";

}
Layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
tools:context="jerehdu.com.jerehdu04.HttpNewsActivity"
android:orientation="vertical">

<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbars="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingRight="12dp">
<Spinner
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/channel"
android:gravity="center">
</Spinner>
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/news"/>
</LinearLayout>

</ScrollView>

</LinearLayout>

Activity:

public class HttpNewsActivity extends AppCompatActivity {

private Spinner channel;
private TextView show;
private SimpleAdapter sa;
private List<Map<String,String>> channelList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_http_news);
channel = (Spinner) findViewById(R.id.channel);
show = (TextView) findViewById(R.id.news);
channelList = new ArrayList<>();
sa = new SimpleAdapter(this,channelList,
android.R.layout.simple_list_item_1,
new String[]{"name"},new int[]{android.R.id.text1});
channel.setAdapter(sa);
String httpUrl = UrlUtil.channelUrl;
new GetNewsChannel().execute(httpUrl);

//Spinner监听
channel.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
Map map = channelList.get(position);
String channelName = (String) map.get("name");
String channelId = (String) map.get(channelName);
String[] strings = new String[]{channelId,channelName};
new GetNews().execute(strings);
}

@Override
public void onNothingSelected(AdapterView<?> parent) {

}
});
}

//获取新闻频道
public class GetNewsChannel extends AsyncTask<String,Void,String>{

@Override
protected void onPreExecute() {
super.onPreExecute();
}

@Override
protected String doInBackground(String... strings) {
return HttpUtil.HttpGet(strings[0]);
}

//在UI线程(主线程)中执行命令
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
if(s.equals("")){
Toast.makeText(getBaseContext(),"没有数据",Toast.LENGTH_SHORT).show();
return;
}
try {
JSONObject obj = new JSONObject(s);
JSONObject body = obj.getJSONObject("showapi_res_body");
JSONArray ja = body.getJSONArray("channelList");
for(int i = 0;i<ja.length();i++){
JSONObject channelObj = (JSONObject) ja.get(i);
String id = channelObj.getString("channelId");
String name = channelObj.getString("name");
Map map = new HashMap();
map.put("name",name);
map.put(name,id);
channelList.add(map);
}
sa.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}

}
}

//获取新闻内容
public class GetNews extends AsyncTask<String,Void,String>{
@Override
protected String doInBackground(String... params) {
String httpUrl = UrlUtil.newsUrl;
String httpArg = "channelId="+params[0]+"&" +
"channelName="+params[1]+"&" +
"title=&" +
"page=1&" +
"needContent=1&" +
"needHtml=1";
String jsonResult = httpUrl + "?" + httpArg;
return HttpUtil.HttpGet(jsonResult);
}

@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
if(s.equals("")){
show.setText("没有数据或无网络连接");
}else {
jsonHandle(s);
}
}

}

//解析Json
public void jsonHandle(String s){
InputStream is ;
BufferedReader reader = null;
StringBuilder sbd = new StringBuilder();
try {
JSONObject obj = new JSONObject(s);
JSONObject body = obj.getJSONObject("showapi_res_body");
JSONObject body2 = body.getJSONObject("pagebean");
JSONArray ja = body2.getJSONArray("contentlist");
for(int i = 0;i<ja.length();i++){
JSONObject newsObj = (JSONObject) ja.get(i);
String news1 = newsObj.getString("content");
sbd.append(news1);
sbd.append("\t\n");
}
} catch (JSONException e) {
e.printStackTrace();
}

show.setText(sbd.toString());
}

}
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