InputStream inputStream = getResources().openRawResource(R.raw.a);

public static String getString(InputStream inputStream) {
  InputStreamReader inputStreamReader = null;
  try {
    inputStreamReader = new InputStreamReader(inputStream, "gbk");
  } catch (UnsupportedEncodingException e1) {
    e1.printStackTrace();
  }
  BufferedReader reader = new BufferedReader(inputStreamReader);
  StringBuffer sb = new StringBuffer("");
  String line;
  try {
    while ((line = reader.readLine()) != null) {
      sb.append(line);
      sb.append("\n");
    }
  } catch (IOException e) {
    e.printStackTrace();
  }
  return sb.toString();
}

inputStreamReader = new InputStreamReader(inputStream, "gbk");

package com.example.ReadAsset;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import java.io.IOException;
import java.io.InputStream;
public class ReadAsset extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.read_asset);
    try {
//Return an AssetManager instance for your application's package
      InputStream is = getAssets().open("index.txt");
      int size = is.available();
      // Read the entire asset into a local byte buffer.
      byte[] buffer = new byte[size];
      is.read(buffer);
      is.close();
      // Convert the buffer into a string.
      String text = new String(buffer, "GB2312");
      // Finally stick the string into the text view.
      TextView tv = (TextView) findViewById(R.id.text);
      tv.setText(text);
    } catch (IOException e) {
      // Should never happen!
      throw new RuntimeException(e);
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<ScrollView android:layout_width="fill_parent"
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_height="fill_parent" android:paddingTop="50dip">
  <TextView android:id="@+id/text" android:layout_width="fill_parent"
    android:layout_height="wrap_content" android:textStyle="normal" />
</ScrollView>