android 大文本读取

向虚拟机sk卡复制文件  adb push aaa.txt /sdcard/book.txt

BigTextReader代码：

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/aaa.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();    }}

SwanTextView

package dingq.BigTxtReader;import android.content.Context;import android.graphics.Canvas;import android.util.AttributeSet;import android.widget.TextView;public class SwanTextView extends TextView {    private int mPreBottom = -1;    private OnPreDrawListener preDrawListener = null;        public SwanTextView(Context context) {        super(context);    }    public SwanTextView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public SwanTextView(Context context, AttributeSet attrs,            int defStyle) {        super(context, attrs, defStyle);    }    @Overrideprotected void onDraw(Canvas canvas) {        if (mPreBottom != getBottom()) {        mPreBottom = getBottom();        if (preDrawListener != null)            preDrawListener.onPreDraw(mPreBottom);    }    super.onDraw(canvas);}public static interface OnPreDrawListener {    public void onPreDraw(int bottom);}public void setOnPreDrawListener(OnPreDrawListener listener) {    preDrawListener = listener;}}

布局main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/text_show_linear" android:layout_width="wrap_content"    android:layout_height="wrap_content">    <ScrollView android:id="@+id/text_show_scroll"        android:layout_width="fill_parent" android:layout_height="fill_parent">        <dingq.BigTxtReader.SwanTextView            android:id="@+id/text_show" android:layout_width="fill_parent"            android:layout_height="wrap_content" android:scrollbars="none">        </dingq.BigTxtReader.SwanTextView>    </ScrollView></LinearLayout>

Mainfest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"      package="dingq.BigTxtReader"      android:versionCode="1"      android:versionName="1.0">    <application android:icon="@drawable/icon" android:label="@string/app_name">        <activity android:name=".BigTxtReader"                  android:label="@string/app_name">            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>