<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"
? ? tools:context=".FileExplorerActivity" >
?? ?<TextView?
?? ? ? ?android:id="@+id/currentTv"
?? ? ? ?android:layout_alignParentTop="true"
?? ? ? ?android:clickable="true"
?? ? ? ?android:layout_width="match_parent"
? ? ? ? android:layout_height="wrap_content"/>
? ? <ListView?
? ? ? ? android:id="@+id/fileLv"
? ? ? ? android:layout_below="@id/currentTv"
? ? ? ? android:layout_alignParentBottom="true"
? ? ? ? android:layout_width="match_parent"
? ? ? ? android:layout_height="wrap_content">
? ? ? ??
? ? </ListView>
? ??
</RelativeLayout>

布局很簡單，就是放置了一個ListView控件，這里要注意的是，ListView標簽下不能再放入其他的子控件。內容是通過子布局和Adapter來顯示的。

2.ListView中的子布局file_list_item.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="horizontal" >
? ? <ImageView?
? ? ? ? android:id="@+id/icon"
? ? ? ? android:layout_width="wrap_content"
? ? ? ? android:layout_height="wrap_content"
? ? ? ? />
? ? <TextView
? ? ? ? android:id="@+id/filename"
? ? ? ? android:layout_width="wrap_content"
? ? ? ? android:layout_height="wrap_content"/>
?
</LinearLayout>

子布局也很簡單，就是在水平方向上左邊顯示一個圖標，用來顯示文件夾或文件圖標，右邊顯示文件名。

3.Activity代碼（功能點寫在注釋中）

public class FileExplorerActivity extends Activity {
?? ?//Adapter中ICON和Filename鍵值對常量
?? ?private static final String ICON = "icon";
?? ?private static final String FILENAME = "filename";
?? ?private TextView currentTv;//ListView上顯示當前路徑的TextView
?? ?private ListView fileLv;//文件列表顯示的ListView
?? ?SimpleAdapter adapter;//適配器
?? ?private List<HashMap<String, Object>> data;//填充的數(shù)據
?? ?private File root;//文件夾根節(jié)點
?? ?private File[] currentFiles; //根節(jié)點下的所有文件（包括文件夾）
?? ?private File currentPath;//記錄當前節(jié)點
?? ?@Override
?? ?protected void onCreate(Bundle savedInstanceState) {
?? ??? ?super.onCreate(savedInstanceState);
?? ??? ?setContentView(R.layout.activity_file_explorer);
?? ??? ?
?? ??? ?currentTv = (TextView)findViewById(R.id.currentTv);
?? ??? ?fileLv = (ListView)findViewById(R.id.fileLv);
?? ??? ?
?? ??? ?//得到根節(jié)點root -->/mnt/sdcard
?? ??? ?root = getFileSystemRoot();
?? ??? ?//得到第一屏的信息
?? ??? ?if(root != null){
?? ??? ??? ?//從/mnt/sdcard下得到文件列表
?? ??? ??? ?data = getFileListFromSdcard(root);
?? ??? ?}else{
?? ??? ??? ?//如果沒有掛載sdcard，則提示用戶
?? ??? ??? ?data = new ArrayList<HashMap<String, Object>>();
?? ??? ??? ?HashMap<String, Object> map = new HashMap<String, Object>();
?? ??? ??? ?map.put(ICON, R.drawable.none);
?? ??? ??? ?map.put(FILENAME, "逗我玩啊，插卡啊");
?? ??? ??? ?data.add(map);
?? ??? ?}
?? ??? ?//創(chuàng)建Adapater
?? ??? ?adapter = new SimpleAdapter(
?? ??? ??? ??? ??? ?this,?
?? ??? ??? ??? ??? ?data,?
?? ??? ??? ??? ??? ?R.layout.file_list_item,?
?? ??? ??? ??? ??? ?new String[]{ICON, FILENAME},?
?? ??? ??? ??? ??? ?new int[]{R.id.icon, R.id.filename});
?? ??? ?
?? ??? ?fileLv.setAdapter(adapter);
?? ??? ?//綁定事件
?? ??? ?fileLv.setOnItemClickListener(new OnItemClickListener() {
?? ??? ??? ?@Override
?? ??? ??? ?public void onItemClick(AdapterView<?> parent, View view,
?? ??? ??? ??? ??? ?int position, long id) {
?? ??? ??? ??? ?//點擊listview 項時，如果是目錄，則進入下一層次，如果是文件，不做處理
?? ??? ??? ??? ?File currentPosFile = currentFiles[position];
?? ??? ??? ??? ?if(currentPosFile.isDirectory()){
?? ??? ??? ??? ??? ?getFileListFromSdcard(currentPosFile);
?? ??? ??? ??? ?}else{
?? ??? ??? ??? ??? ?Toast.makeText(FileExplorerActivity.this, "您點擊的是文件夾", Toast.LENGTH_LONG).show();
?? ??? ??? ??? ?}
?? ??? ??? ?}
?? ??? ?});
?? ?}
?
?? ?/**
?? ? * 攔截back鍵返回
?? ? * @return
?? ? */
?? ?@Override
?? ?public boolean onKeyDown(int keyCode, KeyEvent event) {
?? ??? ?if(KeyEvent.KEYCODE_BACK == keyCode){
?? ??? ??? ?File parentFile = currentPath.getParentFile();
?? ??? ??? ?//不能超過最頂層
?? ??? ??? ?try {
?? ??? ??? ??? ?if(parentFile.getCanonicalPath().toString().equals("/mnt")){
?? ??? ??? ??? ??? ?Toast.makeText(this, "別按了，到家了", Toast.LENGTH_LONG).show();
?? ??? ??? ??? ??? ?return true;
?? ??? ??? ??? ?}else{
?? ??? ??? ??? ??? ?getFileListFromSdcard(parentFile);
?? ??? ??? ??? ?}
?? ??? ??? ?} catch (IOException e) {
?? ??? ??? ??? ?e.printStackTrace();
?? ??? ??? ?}
?? ??? ?}
?? ??? ?return super.onKeyDown(keyCode, event);
?? ?}
?? ?private File getFileSystemRoot() {
?? ??? ?//首先得到Sd卡是否加載了
?? ??? ?if(Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())){
?? ??? ??? ?//得到sd卡路徑 root --> /mnt/sdcard
?? ??? ??? ?root = Environment.getExternalStorageDirectory();
?? ??? ?}else{
?? ??? ??? ?Toast.makeText(this, "逗我玩啊，插卡啊", Toast.LENGTH_LONG).show();
?? ??? ?}
?? ??? ?return root;
?? ?}
?
?? ?/**
?? ? * 得到Sdcard中的文件列表
?? ? * @return
?? ? */
?? ?private List<HashMap<String, Object>> getFileListFromSdcard(File root) {
?? ??? ?try {
?? ??? ??? ?currentPath = root;
?? ??? ??? ?currentTv.setText(root.getCanonicalPath().toString());
?? ??? ?} catch (IOException e) {
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
?? ??? ?List<HashMap<String, Object>> list = new ArrayList<HashMap<String, Object>>();
?? ??? ?currentFiles = root.listFiles();//列出當前目錄下的所有文件和目錄
?? ??? ?for(File f : currentFiles){
?? ??? ??? ?HashMap<String, Object> map = new HashMap<String, Object>();
?? ??? ??? ?String fileName = f.getName();
?? ??? ??? ?int icon;
?? ??? ??? ?if(f.isDirectory()){
?? ??? ??? ??? ?icon = R.drawable.dir;
?? ??? ??? ??? ?map.put(ICON, icon);
?? ??? ??? ?}else if(f.isFile()){
?? ??? ??? ??? ?icon = R.drawable.file;
?? ??? ??? ??? ?map.put(ICON, icon);
?? ??? ??? ?}
?? ??? ??? ?map.put(FILENAME, fileName);
?? ??? ??? ?list.add(map);
?? ??? ?}
?? ??? ?//把原來的data list清空，然后把list放進去，再通知adapter
?? ??? ?if(data != null){
?? ??? ??? ?data.clear();
?? ??? ??? ?data.addAll(list);
?? ??? ??? ?adapter.notifyDataSetChanged();
?? ??? ?}
?? ??? ?return list;
?? ?}
}

運行效果：