SD卡文件浏览

activity_mai.xml:

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >
    <!-- 显示当前路径的文本框 -->
    <TextView
        android:id="@+id/path"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_alignParentTop="true" />
    <!-- 列出当前路径下所有文件的ListView -->
    <ListView android:id="@+id/list"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:divider="#000"
        android:dividerHeight="1px"
        android:layout_below="@id/path"/>
    <!-- 返回上一级目录的按钮-->
    <Button android:id="@+id/parent"
        android:layout_width="38dp"
        android:layout_height="34dp"
        android:background="@drawable/home"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"/>
</RelativeLayout>

line.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ImageView 
        android:id="@+id/icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:paddingLeft="10dp"/>
    <TextView 
        android:id="@+id/file_name"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

MainActivity.java:

package com.example.sdfiledemo;

import java.io.File;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
  ListView listView;
  TextView textView;
  //记录当前的父文件夹
  File currentParent;
  //记录当前路径下的所有文件的数组
  File [] currentFiles;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //获取列出全部文件的ListView
    listView = (ListView) findViewById(R.id.list);
    textView = (TextView) findViewById(R.id.path);
    //获取系统的SD卡的目录
    File root = new File("/mnt/sdcard/");
    //如果Sd卡存在
    if(root.exists()){
      currentParent = root;
      currentFiles = root.listFiles();
      //使用当前目录下的全部文件，文件夹来填充ListView
      
    }
    //为ListView的列表项的单击事件绑定监听器
    listView.setOnItemClickListener(new OnItemClickListener() {

      @Override
      public void onItemClick(AdapterView<?> parent, View view, int postion,
          long id) {
        // TODO Auto-generated method stub
        //用户单击了文件，直接返回，不做任何处理
        if(currentFiles[postion].isFile())
          return ;
        //获取用户点击的文件夹下的所有文件
        File[] tmp = currentFiles[postion].listFiles();
        if(tmp == null || tmp.length==0){
          Toast.makeText(MainActivity.this, "当前路径下面没有文件~！",Toast.LENGTH_SHORT).show();
        } else {
          //获取用户单击的列表项对应的文件夹，设为当前的父文件夹
          currentParent = currentFiles[postion];
          //保存当期的父文件夹内的全部文件和文件夹
          currentFiles = tmp;
          infalateListView(currentFiles);
        }
      }
    });
    //获取上一级的目录按钮
    Button parent = (Button) findViewById(R.id.parent);
    parent.setOnClickListener(new  OnClickListener() {
      
      @Override
      public void onClick(View arg0) {
        // TODO Auto-generated method stub
        try {
          if(!currentParent.getCanonicalPath().equals("/mnt/sdcard/")){
            //获取上一级的目录
            currentParent = currentParent.getParentFile();
            //列出当前目录下所有文件
            currentFiles = currentParent.listFiles();
            //再次更新ListView
            infalateListView(currentFiles);
          }
        } catch (Exception e) {
          // TODO: handle exception
        }
      }
    });
  }

  private void infalateListView(File[] files){
    //创建一个List集合，List集合的元素是Map
    List<Map<String,Object>> listItems = new ArrayList<Map<String, Object>>();
    for(int i = 0; i < files.length; i++){
      Map<String, Object> listItem = new HashMap<String, Object>();
      //如果当前File是文件夹，使用folder图标，否则使用file图标
      if(files[i].isDirectory()){
        listItem.put("icon", R.drawable.folder);
      } else {
        listItem.put("icon", R.drawable.file);
      }
      listItem.put("fileName", files[i].getName());
      //添加List项
      listItems.add(listItem);
    }
    //创建一个SimpleAdapter
    SimpleAdapter simpleAdapter = new SimpleAdapter(this, listItems, 
        R.layout.line, 
        new String[] {"incon", "file_name"}, 
        new int[] {R.id.icon, R.id.file_name});
    //为ListView设置Adapter
    listView.setAdapter(simpleAdapter);
    try {
      textView.setText("当前路径为：" + currentParent.getCanonicalPath());
    } catch (Exception e) {
      // TODO: handle exception
    }
  }

}