package com.example.android02;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Activity01 extends Activity{
      private TextView text=null;
      private ProgressDialog dialog=null;
      private Button button=null;
      @Override
      protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity01);
            text=(TextView)findViewById(R.id.view1);
            //点击按钮后开始下载文件
            button=(Button)findViewById(R.id.button1);
            button.setOnClickListener(new OnClickListener() {
                  @Override
                  public void onClick(View arg0) {
                        Down down=new Down();
                        try {
                              //输入url值，异步下载文件。
                              down.execute(new URL("http://192.168.1.100/Mp3Player/log.txt"));
                        } catch (MalformedURLException e) {
                              e.printStackTrace();
                        }
                  }
            });
      }
      class Down extends AsyncTask<URL, Integer, String>{
            int progress=0;
            //在后台运行的代码~~ 也就是去url下载文件的关键代码
            @Override
            protected String doInBackground(URL... url) {
                  try {
                        HttpURLConnection conn=(HttpURLConnection)url[0].openConnection();
                        //假设读取文本文件
                        BufferedReader br=new BufferedReader(new InputStreamReader(conn.getInputStream()));
                        String buff="";
                        StringBuilder sb=new StringBuilder();
                        while((buff=br.readLine())!=null){
                              progress++;
                              publishProgress(progress);//调用onProgressUpdate 更新dialog的进度条
                              sb.append(buff);
                        }
                        return sb.toString();
                  } catch (IOException e) {
                        e.printStackTrace();
                  }
                  return null;
            }
            //在后台下载的代码执行好后得到一个String，作为参数传入
            @Override
            protected void onPostExecute(String result) {
                  super.onPostExecute(result);
                  //把读取得到的文本内容显示
                  text.setText(result);
                  //关闭进度条的框框
                  dialog.dismiss();
            }
            //在进行异步下载前的一些准备措施
            @Override
            protected void onPreExecute() {
                  super.onPreExecute();
                  dialog=new ProgressDialog(Activity01.this);
                  dialog.setTitle("任务正在执行中");
                  dialog.setMessage("请稍等===");
                  dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                  dialog.setCancelable(true);
                  //这里我直接写死，文本内容一共1009行，所以进度条的最大值为1009
                  dialog.setMax(1009);
                  dialog.show();
            }
            //
            @Override
            protected void onProgressUpdate(Integer... values) {
                  super.onProgressUpdate(values);
                  dialog.setProgress(values[0]);
            }
      }
}