Android ListActivity实现遍历文件列表，查看文档类文件

package com.shawn.zp.reader.activity;

import java.io.File;
import java.io.FileFilter;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;

import android.app.ListActivity;
import android.content.Context;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class AddBookActivity extends ListActivity{
    private TextView currentFolder;        //当前文件夹
    
    private FileListAdapter fileList;
    
    //文件过滤器，查找文件夹或文本文件
    private static final FileFilter BOOKS_FILTER = new FileFilter() {
        public boolean accept(File f) {
            return f.isDirectory() || f.getName().toLowerCase().matches("^.*?\\.(txt|text)$");
        }
    };

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_addbook_directory);
        currentFolder = (TextView)findViewById(R.id.addbook_current_folder);
        fill(new File("/"));
    }

    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK && !fileList.isRoot) {
            fill(fileList.getItem(0));
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        File file = fileList.getItem(position);
        if (file.isDirectory())
            fill(file);
    }
    //跳转目录
    private void fill(File folder) {
        boolean isRoot = folder.getParent() == null;
        currentFolder.setText(AddBookActivity.this.getResources().getString(R.string.addbook_current_folder) + folder.getAbsolutePath());
        List<File> files = new ArrayList<File>();
        if (!isRoot)
            files.add(folder.getParentFile());
        File[] filterFiles = folder.listFiles(BOOKS_FILTER);
        if(null != filterFiles && filterFiles.length>0) {
            for (File file : filterFiles) {
                files.add(file);
            }
        }
        fileList = new FileListAdapter(this, R.layout.layout_addbook_file, files, isRoot);
        setListAdapter(fileList);
    }
}

//文件列表适配器
class FileListAdapter extends ArrayAdapter<File>{
    private LayoutInflater mInflater;
    boolean isRoot;        //根目录
    
    public FileListAdapter(Context context, int Resource, List<File> objects, boolean isRoot) {
        super(context,Resource,objects);
        this.isRoot = isRoot;
        this.mInflater = LayoutInflater.from(context);
    }
 
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        convertView = mInflater.inflate(R.layout.layout_addbook_file, null);
        TextView title = (TextView)convertView.findViewById(R.id.addbook_title);
        TextView info = (TextView)convertView.findViewById(R.id.addbook_info);

        File file = getItem(position);
        if (position == 0 && !isRoot)
            title.setText(R.string.addbook_parent_folder);
        else {
            title.setText(file.getName());
            if (file.isDirectory())
                info.setText(R.string.addbook_directory);
            else {
                long fileSize = file.length();
                if(fileSize >= 1024*1024) {
                    float size = fileSize/(1024f*1024f);
                    info.setText(new DecimalFormat("#.00").format(size) + "MB");
                }else if(fileSize >= 1024) {
                    float size = fileSize/1024f;
                    info.setText(new DecimalFormat("#.00").format(size) + "KB");
                }else {
                    info.setText(fileSize + "B");
                }
            }
        }
        return convertView;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:paddingLeft="8dip"
    android:paddingRight="8dip">
    
    <TextView android:id="@+id/addbook_current_folder" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FFF000"
        android:textSize="25sp"
        android:background="#000FFF"
        />
    
    <ListView android:id="@android:id/list"
        android:layout_width="fill_parent" 
        android:layout_height="0dip"
        android:layout_weight="1"
        android:drawSelectorOnTop="false"/>
        
        
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    >
    <TextView android:id="@+id/addbook_title" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FFF000"
        android:textSize="25sp"
        android:textStyle="bold"
        />
    <TextView android:id="@+id/addbook_info" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#FFF000"
        android:textSize="15sp"
        />
</LinearLayout>