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。

这里先给大家贴个工具类，用来从网络获取信息:

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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