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AsyncTask、Json、Spinner练习
练习题
main_activity.xml文件：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android=""
xmlns:app=""
xmlns:tools=""
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.mrzhao.examdemo.MainActivity">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onClick"
android:text="点击下载"
tools:ignore="OnClick" />
<Spinner
android:id="@+id/spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></Spinner>
</LinearLayout>
MainActivity：
public class MainActivity extends AppCompatActivity {private String path = ".php?stage_id=1&limit=20&page=1";
private Spinner spinner;
private List<String> list = new ArrayList<>();
private ArrayAdapter<String> adapter;
private MyTask myTask;
@Override
protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spinner = (Spinner) findViewById(R.id.spinner);
/**
* 数组适配器
* 参数1 上下文对象
* 参数2 条目布局id
* 参数3 数据源
*/
adapter = new ArrayAdapter<>(this, android.R.layout.simple_dropdown_item_1line, list);
//设置适配器
spinner.setAdapter(adapter);
// 设置选中事件！
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {// 弹出 展示的数据
Toast.makeText(MainActivity.this, list.get(position), Toast.LENGTH_SHORT).show();
}@Override
public void onNothingSelected(AdapterView<?> parent) {}});
}/**
* 点击下载网络数据
*
* @param view
*/
public void onClick(View view) {//执行异步任务
myTask = new MyTask();
//执行异步任务 相当于线程的start方法
myTask.execute();
}@Override
protected void onDestroy() {super.onDestroy();
//当页面销毁的时候 取消任务
myTask.cancel(true);
}class MyTask extends AsyncTask<String, Void, String> {//子线程 用来下载数据
@Override
protected String doInBackground(String... strings) {return getDataFromNet();
}//主线程用来更新UI
@Override
protected void onPostExecute(String s) {super.onPostExecute(s);
if (!TextUtils.isEmpty(s)){//解析数据
Gson gson = new Gson();
FoodEntity foodEntity = gson.fromJson(s, FoodEntity.class);
List<FoodEntity.DataBean> data = foodEntity.getData();
for (int i = 0; i < data.size(); i++) {String title = data.get(i).getTitle();
list.add(title);
}//数据更新刷新适配器
adapter.notifyDataSetChanged();
}}}/**
* 从网络获取数据
*
* @return
*/
private String getDataFromNet() {InputStream inputStream = null;
ByteArrayOutputStream outputStream= null;
try {//将 路径转换成为 URL对象
URL url = new URL(path);
// 使用URL打开一个链接
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
//设置请求方式
conn.setRequestMethod("GET");
//设置链接超时
conn.setConnectTimeout(20 * 1000);
//设置读取超时
conn.setReadTimeout(20 * 1000);
//开始链接
conn.connect();
//判断响应吗
if (conn.getResponseCode() == 200) {inputStream = conn.getInputStream();
outputStream = new ByteArrayOutputStream();
int len = 0;
byte[] bytes= new byte[1024];
while ((len = inputStream.read(bytes))!=-1){outputStream.write(bytes,0,len);
}return outputStream.toString();
}} catch (MalformedURLException e) {e.printStackTrace();
} catch (ProtocolException e) {e.printStackTrace();
} catch (IOException e) {e.printStackTrace();
}finally {if (inputStream!=null){try {inputStream.close();
} catch (IOException e) {e.printStackTrace();
}}if (outputStream!=null){try {outputStream.close();
} catch (IOException e) {e.printStackTrace();
}}}return null;
}}
FoodEntity：
public class FoodEntity {/**
* ret : 1
* data : [{"id":"8289","title":"油焖大虾","pic":".jpg","collect_num":"1659","food_str":"大虾 葱 生姜 植物油 料酒","num":1659},{"id":"2127","title":"四川回锅肉","pic":".jpg","collect_num":"1585","food_str":"猪肉 青蒜 青椒 红椒 姜片","num":1585},{"id":"30630","title":"超简单芒果布丁","pic":".jpg","collect_num":"1528","food_str":"QQ糖 牛奶 芒果","num":1528},{"id":"9073","title":"家常红烧鱼","pic":".jpg","collect_num":"1419","food_str":"鲜鱼 姜 葱 蒜 花椒","num":1419},{"id":"10097","title":"家常煎豆腐","pic":".jpg","collect_num":"1405","food_str":"豆腐 新鲜红椒 青椒 葱花 油","num":1405},{"id":"10509","title":"水煮肉片","pic":".jpg","collect_num":"1336","food_str":"瘦猪肉 生菜 豆瓣酱 干辣椒 花椒","num":1336},{"id":"46968","title":"红糖苹果银耳汤","pic":".jpg","collect_num":"1245","food_str":"银耳 苹果 红糖","num":1245},{"id":"10191","title":"麻婆豆腐","pic":".jpg","collect_num":"1214","food_str":"豆腐 肉末 生抽 白糖 芝麻油","num":1214},{"id":"2372","title":"皮蛋瘦肉粥","pic":".jpg","collect_num":"1147","food_str":"大米 皮蛋 猪肉 油条 香葱","num":1147},{"id":"2166","title":"蚂蚁上树","pic":".jpg","collect_num":"1140","food_str":"红薯粉 肉 姜 蒜 花椒","num":1140},{"id":"2262","title":"糖醋肉","pic":".jpg","collect_num":"1074","food_str":"猪肉 红椒 黄椒 洋葱 蛋清","num":1074},{"id":"9971","title":"鱼香豆腐","pic":".jpg","collect_num":"1004","food_str":"豆腐 木耳 胡萝卜 香葱 番茄酱","num":1004},{"id":"10172","title":"干煸四季豆","pic":".jpg","collect_num":"988","food_str":"四季豆 干辣椒 蒜头 酱油 糖","num":988},{"id":"2685","title":"胡萝卜肉末蒸蛋","pic":".jpg","collect_num":"918","food_str":"胡萝卜 肉 蛋 生抽 盐","num":918},{"id":"9972","title":"虎皮青椒","pic":".jpg","collect_num":"889","food_str":"青辣椒 大蒜 香醋 白糖 生抽","num":889},{"id":"10437","title":"叉烧排骨","pic":".jpg","collect_num":"797","food_str":"排骨 李锦记叉烧酱 植物油 清水 油菜","num":797},{"id":"2892","title":"\u201c五行\u201d彩蔬汤","pic":".jpg","collect_num":"756","food_str":"黑木耳 玉米 牛蒡 胡萝卜 西兰花","num":756},{"id":"33783","title":"美人豆浆","pic":".jpg","collect_num":"753","food_str":"黄豆 红豆 绿豆 黑豆 黑米","num":753},{"id":"2348","title":"麻辣肉丝面","pic":".jpg","collect_num":"753","food_str":"面条 肉丝 淀粉 酱油 辣椒","num":753},{"id":"10044","title":"土豆炖翅根","pic":".jpg","collect_num":"752","food_str":"土豆 翅根 葱 姜 料酒","num":752}]
*/
private int ret;
private List<DataBean> data;
public int getRet() {return ret;
}public void setRet(int ret) {this.ret = ret;
}public List<DataBean> getData() {return data;
}public void setData(List<DataBean> data) {this.data = data;
}public static class DataBean {/**
* id : 8289
* title : 油焖大虾
* pic : .jpg
* collect_num : 1659
* food_str : 大虾 葱 生姜 植物油 料酒
* num : 1659
*/
private String id;
private String title;
private String pic;
private String collect_num;
private String food_str;
private int num;
public String getId() {return id;
}public void setId(String id) {this.id = id;
}public String getTitle() {return title;
}public void setTitle(String title) {this.title = title;
}public String getPic() {return pic;
}public void setPic(String pic) {this.pic = pic;
}public String getCollect_num() {return collect_num;
}public void setCollect_num(String collect_num) {this.collect_num = collect_num;
}public String getFood_str() {return food_str;
}public void setFood_str(String food_str) {this.food_str = food_str;
}public int getNum() {return num;
}public void setNum(int num) {this.num = num;
}}
}
本文标签： AsyncTaskJsonSpinner练习
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