Android 读sys/class/power_supply/battery/cureent_now的值

package com.example.readsysclass;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class MainActivity extends Activity { Button button01; TextView text01; private int TIME = 2000;   static final String TAG="readsysclass";  private static final String CHARGER_CURRENT_NOW =             "/sys/class/power_supply/battery/current_now";  /**      * Read a text file into a String, optionally limiting the length.      *      * @param file     to read (will not seek, so things like /proc files are OK)      * @param max      length (positive for head, negative of tail, 0 for no limit)      * @param ellipsis to add of the file was truncated (can be null)      * @return the contents of the file, possibly truncated      * @throws IOException if something goes wrong reading the file      */     public static String readTextFile(File file, int max, String ellipsis) throws IOException {         InputStream input = new FileInputStream(file);         try {             long size = file.length();             if (max > 0 || (size > 0 && max == 0)) {  // "head" mode: read the first N bytes                 if (size > 0 && (max == 0 || size < max)) max = (int) size;                 byte[] data = new byte[max + 1];                 int length = input.read(data);                 if (length <= 0) return "";                 if (length <= max) return new String(data, 0, length);                 if (ellipsis == null) return new String(data, 0, max);                 return new String(data, 0, max) + ellipsis;             } else if (max < 0) {  // "tail" mode: keep the last N                 int len;                 boolean rolled = false;                 byte[] last = null, data = null;                 do {                     if (last != null) rolled = true;                     byte[] tmp = last;                     last = data;                     data = tmp;                     if (data == null) data = new byte[-max];                     len = input.read(data);                 } while (len == data.length);                 if (last == null && len <= 0) return "";                 if (last == null) return new String(data, 0, len);                 if (len > 0) {                     rolled = true;                     System.arraycopy(last, len, last, 0, last.length - len);                     System.arraycopy(data, 0, last, last.length - len, len);                 }                 if (ellipsis == null || !rolled) return new String(last);                 return ellipsis + new String(last);             } else {  // "cat" mode: size unknown, read it all in streaming fashion                 ByteArrayOutputStream contents = new ByteArrayOutputStream();                 int len;                 byte[] data = new byte[1024];                 do {                     len = input.read(data);                     if (len > 0) contents.write(data, 0, len);                 } while (len == data.length);                 return contents.toString();             }         } finally {             input.close();         }     } @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  button01 = (Button)findViewById(R.id.button01);  text01 = (TextView)findViewById(R.id.text01);      button01.setOnClickListener(new OnClickListener() {      public void onClick(View arg0) {    // TODO Auto-generated method stub    handler.postDelayed(runnable, TIME); //每隔1s执行    }  }); } Handler handler = new Handler();      Runnable runnable = new Runnable() {  @Override  public void run() {   // TODO Auto-generated method stub   handler.postDelayed(this, TIME);     try {    String mode1 = readTextFile(new File(CHARGER_CURRENT_NOW), 0, null).trim();    text01.setText(mode1);    Log.e(TAG,mode1);   } catch (IOException e) {    // TODO Auto-generated catch block    e.printStackTrace();   }  }      };}