ScrollView向下滑动阅读少量文本；ProgressDialog子线程读取文本

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff" >


    <TextView
        android:id="@+id/detail_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="14sp" />

</ScrollView>

package com.kane.filemanager;


import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;


import java.io.InputStreamReader;


import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.app.ProgressDialog;


import android.widget.TextView;


public class DetailActivity extends Activity {
private TextView tView;
private Handler handler;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_detail);
tView = (TextView) findViewById(R.id.detail_text);
//进度条
final ProgressDialog dialog=new ProgressDialog(this);
dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
dialog.setTitle("提示");
dialog.setMessage("正在读取数据...........");

//一边显示进度条，一边读数据，如果只是读数据将显示黑屏
//主线程显示界面 ，子线程读数据
//进度条属性
dialog.setMax((int)(new File(getIntent().getStringExtra("fullPath")).length()));
dialog.show();
handler=new Handler(){
@Override
public void handleMessage(Message msg){
// 当接收到子线程发送的消息时,自动调用这个方法.
// 从子线程传递的消息中取得内容,并设置
tView.setText(msg.obj.toString());
}
};
Thread t=new Thread(){
@Override
public void run(){
//取得数据
String path=getIntent().getStringExtra("fullPath");
//建立文件
File file=new File(path);
//读取
try {
//需要使用InputStream对读入的文件转码
BufferedReader reader=new BufferedReader(new InputStreamReader(new FileInputStream(file),"GBK"));
String line=null;
//保存所有文件的stringbuilder,适合单线程（最快），在多线程不安全
StringBuilder builder=new StringBuilder();
//记录当前读了多大的文件
int size=0;
while ((line=reader.readLine())!=null) {
builder.append(line+"\r\n");
size+=line.getBytes().length;
if (size>10240) {
//大于10K增加进度条
dialog.incrementProgressBy(size);
size=0;
Thread.sleep(10);
}
}
reader.close();
//将数据通过handler设置到textview
Message msg=new Message();
msg.obj=builder.toString();
handler.sendMessage(msg);

//不传数据的话可以传个标示位handler.sendEmptyMessage(0);上面的不用写
} catch (Exception e) {
// TODO: handle exception
}
}
};
t.start();
}
}