AsyncTask 异步任务 + json 解析 网络数据

package com.qf.day07_asynctask_04;

import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ProgressBar;
import android.widget.Spinner;
import android.widget.Toast;

public class MainActivity extends Activity {

private ProgressBar progressBar;

private Spinner spinner;

private MyTask myTask;

private String path = "http://m2.qiushibaike.com/article/list/suggest?page=1";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

progressBar = (ProgressBar) findViewById(R.id.progress_id);
spinner = (Spinner) findViewById(R.id.spinner_id);

}

// 按钮点击事件
public void clickButton(View v) {
switch (v.getId()) {
case R.id.start:
// 开启异步任务, 下载内容
myTask = new MyTask();

myTask.execute(path);

break;

case R.id.stop:
// 停止异步任务
myTask.cancel(true);

break;
}
}

/**
* 自定义异步任务, 加载数据(json)
*
* @author Administrator
*
*/
public class MyTask extends AsyncTask<String, Integer, List<String>> {
@Override
protected void onPreExecute() {
// TODO 事前方法, 初始化工作
super.onPreExecute();

// 进度条显示
progressBar.setVisibility(View.VISIBLE);

// 当前的进度值=0
progressBar.setProgress(0);

}

@Override
protected List<String> doInBackground(String... params) {
// TODO 后台运行, 执行耗时的操作

try {

// 向网络获取数据json
URL url = new URL(params[0]);

HttpURLConnection conn = (HttpURLConnection) url
.openConnection();

conn.setRequestMethod("GET");

// 请求数据时不能以压缩的方式返回
conn.setRequestProperty("Accept-Encoding", "identity");

conn.connect();

if (conn.getResponseCode() == 200) {
InputStream is = conn.getInputStream();

// 得到数据的总长度
long maxLen = conn.getContentLength();

Log.i("info", "maxLen = " + maxLen);

// 得到数据当前的加载长度
long curLen = 0;

// 读取数据
byte[] buffer = new byte[1024];
int len = 0;

StringBuilder sBuilder = new StringBuilder();

while ((len = is.read(buffer)) != -1) {

sBuilder.append(new String(buffer, 0, len));

// 计算当前加载的进度值 百分比
// int progress = (int)(当前加载的长度 *100 / 总长度);

curLen += len;

int progress = (int) (curLen * 100 / maxLen);

// 异步更新进度条(onProgressUpdate(Integer... values))
publishProgress(progress);

Thread.sleep(500);
}

// 解析数据,并且返回
return ParseJson.parseJson(sBuilder.toString());
}
} catch (Exception e) {
// TODO: handle exception
}

return null;
}

@Override
protected void onProgressUpdate(Integer... values) {
// TODO 实时更新进度
super.onProgressUpdate(values);

// 实时更新进度条
progressBar.setProgress(values[0]);

}

@Override
protected void onPostExecute(List<String> result) {
// TODO 事后方法: 更新UI
super.onPostExecute(result);
// 进度条消失
progressBar.setVisibility(View.GONE);

// 通过适配器, 将获取到的数据填充到Spinner中
if (result != null && result.size() > 0) {

// 控件 spinner
// 数据源 result
// 适配器

ArrayAdapter<String> adapter = new ArrayAdapter<String>(
MainActivity.this,
android.R.layout.simple_spinner_item, result);

spinner.setAdapter(adapter);

} else {
Toast.makeText(MainActivity.this, "网络异常", Toast.LENGTH_LONG)
.show();
}
}
}

}

package com.qf.day07_asynctask_04;

import java.util.ArrayList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
* 解析json数据
* @author Administrator
*
*/
public class ParseJson {

public static List<String> parseJson(String jsonStr) throws JSONException {

List<String> data = new ArrayList<String>();

if(jsonStr!=null)
{
JSONObject jsonObject = new JSONObject(jsonStr);

JSONArray jsonArray = jsonObject.getJSONArray("items");

for(int i=0;i<jsonArray.length();i++)
{
JSONObject jsonObject2 = jsonArray.getJSONObject(i);

String content = jsonObject2.getString("content");

data.add(content);
}
}
return data;
}

}

<RelativeLayout 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"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<Button
android:id="@+id/start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="获取数据"
android:onClick="clickButton" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/stop"
android:text="停止获取"
android:layout_toRightOf="@id/start"
android:onClick="clickButton"
/>

<ProgressBar
android:layout_width="match_parent"
android:layout_height="20dp"
android:id="@+id/progress_id"
android:layout_below="@id/start"
android:layout_marginTop="20dp"
style="?android:attr/progressBarStyleHorizontal"
android:visibility="gone"
/>

<Spinner
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/spinner_id"
android:layout_below="@id/progress_id"
android:layout_marginTop="20dp"
/>

</RelativeLayout>