Android手机读取大文本文件源码

package dingq.BigTxtReader; // Android大TXT文本文档读取 import java.io.FileInputStream; import java.io.IOException; import java.io.InputStreamReader; import java.nio.CharBuffer; import android.app.Activity; import android.net.Uri; import android.os.AsyncTask; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.text.TextUtils; import android.util.Log; import android.widget.ScrollView; public class BigTxtReader extends Activity implements SwanTextView.OnPreDrawListener { private static final String LOG_TAG = "BigTxtReader"; private static final int BUF_SIZE = 1024 * 2; private static final int BUF_SHOW = 3; private static final int ARROW_UP = 1; private static final int ARROW_DOWN = 2; private static String ENCODING = "GB2312"; private InputStreamReader mIsReader = null; private Uri mUri = null; private SwanTextView mTextShow; private ScrollView mScrollView; private String mStringShow = null; private StringBuilder mStringBuilder = null; private boolean mReadNext = true; private boolean mReadBack = false; private boolean mStopThread = false; private int mPreBottom = -1; private int mCurBottom = -1; private int mReadBufNum = 0; private int mBuffHeight = -1; private int mPreScrollY = -1; private final Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case ARROW_DOWN: mTextShow.setText((CharBuffer) msg.obj); break; case ARROW_UP: mTextShow.setText((CharBuffer) msg.obj); mScrollView.scrollTo(0, mBuffHeight); break; default: super.handleMessage(msg); } } }; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mUri = getIntent().getData(); mScrollView = (ScrollView) findViewById(R.id.text_show_scroll); mTextShow = (SwanTextView) findViewById(R.id.text_show); mTextShow.setOnPreDrawListener(this); new TextShowTask().execute(mUri); } private void showText(Uri uri) throws IOException, InterruptedException { mIsReader = new InputStreamReader(new FileInputStream( uri.getPath()), ENCODING); mStringBuilder = new StringBuilder(); int initBufSize = BUF_SIZE * (BUF_SHOW - 1); char[] buf = new char[BUF_SIZE]; while (!mStopThread) { int scrollY = mScrollView.getScrollY(); if (mCurBottom == scrollY && mPreScrollY < scrollY) { mReadNext = true; mReadBack = false; } else if (mReadBufNum > BUF_SHOW && 0 == scrollY && mPreScrollY != scrollY) { mReadNext = false; mReadBack = true; } mPreScrollY = scrollY; int len = -1; if (mReadNext && (len = mIsReader.read(buf)) > 0) { mReadNext = false; mReadBufNum++; if (mStringBuilder.length() > initBufSize) { mStringBuilder.delete(0, BUF_SIZE); mPreBottom = mCurBottom; Message msg = mHandler.obtainMessage(ARROW_DOWN); msg.obj = CharBuffer.wrap(mStringBuilder.toString()); mHandler.sendMessage(msg); mStringShow = mStringBuilder.append(buf, 0, len).toString(); } else { while (mStringBuilder.length() < initBufSize) { mStringBuilder.append(buf); mIsReader.read(buf); mReadBufNum++; } mStringBuilder.append(buf); Message msg = mHandler.obtainMessage(ARROW_DOWN); msg.obj = CharBuffer.wrap(mStringBuilder.toString()); mHandler.sendMessage(msg); } } else if (mReadBack && mReadBufNum > BUF_SHOW) { Log.d(LOG_TAG, "Prepare to read back"); mReadBack = false; mIsReader.close(); new BackBufReadThread(mStringBuilder).start(); } } } private class TextShowTask extends AsyncTask<Object, Object, Object> { @Override protected void onPostExecute(Object param) { Log.d(LOG_TAG, "Send broadcast"); } @Override protected Object doInBackground(Object... params) { Uri uri = (Uri) params[0]; uri = Uri.parse("/sdcard/Books/readme.txt"); try { showText(uri); } catch (Exception e) { Log.d(LOG_TAG, "Exception", e); } return null; } } private class BackBufReadThread extends Thread { StringBuilder mSbPre = null; public BackBufReadThread(StringBuilder sb) { mSbPre = sb.delete(0, sb.length()); } @Override public void run() { try { mIsReader = new InputStreamReader(new FileInputStream( mUri.getPath()), ENCODING); char[] buf = new char[BUF_SIZE]; int i = 0; while((mReadBufNum - BUF_SHOW) > ++i && mIsReader.read(buf) > 0) { // Just to skip the inputstream. Any better methods? } mReadBufNum--; for (i = 0; i < BUF_SHOW; i++) { mIsReader.read(buf); mSbPre.append(buf); } // mSbPre.delete(mSbPre.length() - BUF_SIZE, mSbPre.length()).insert(0, buf); Message msg = mHandler.obtainMessage(ARROW_UP); msg.obj = CharBuffer.wrap(mSbPre.toString()); mHandler.sendMessage(msg); } catch (Exception e) { Log.d(LOG_TAG, "Exception", e); } } } public void onPreDraw(int bottom) { mCurBottom = bottom - mScrollView.getHeight(); if (!TextUtils.isEmpty(mStringShow)) { // Use the last deleted buff to evaluate the height mBuffHeight = mPreBottom - mScrollView.getScrollY(); // Set the text to add new content without flash the view Message msg = mHandler.obtainMessage(ARROW_DOWN); msg.obj = CharBuffer.wrap(mStringShow); mHandler.sendMessage(msg); mStringShow = null; } } @Override public void finish() { mStopThread = true; super.finish(); } }