学步园

做个应用，需要浏览SD卡上面的所有.mp3格式的文件。

具体如下：

public class SelectMusicActivity extends Activity {

	private Button btnGoBack;
	private ListView fileListView;// 遍历文件的列表
	private TextView parentPathTView;// 当前付路径的
	private File parentFile;// 父路径
	private ArrayList<File> currentFiles;// 当前的目录中所有的文件
	private File rootFile;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.selectmusic);
		fileListView = (ListView) findViewById(R.id.id_fileList);
		parentPathTView = (TextView) findViewById(R.id.id_filePath);
		btnGoBack=(Button)findViewById(R.id.id_goBack);
		rootFile = Environment.getExternalStorageDirectory().getAbsoluteFile();
		Log.i("test", rootFile.toString());
		if (rootFile.exists()) {
			Log.i("test", "1111");
			parentFile = rootFile;
			currentFiles = toList(rootFile.listFiles());
			Log.i("test", currentFiles.size()+"");
			// 选择文件夹和.mp3格式的文件名字
			inflateListView(currentFiles);
		}

		fileListView.setOnItemClickListener(new OnItemClickListener() {
			public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
				if (currentFiles.get(position).isFile()) {// 如果点击的是文件，直接选中
					Toast.makeText(SelectMusicActivity.this,
							"您选择了" + currentFiles.get(position).getName() + "作为铃声", 1000).show();
				} else {// 如果点击的是文件夹，进入下一集
					parentFile=currentFiles.get(position);
					currentFiles=toList(parentFile.listFiles());
					inflateListView(currentFiles);
				}
			}
		});
		
		btnGoBack.setOnClickListener(new View.OnClickListener() {
			public void onClick(View v) {
				try {
					if(!parentFile.getCanonicalPath().equals(rootFile.getCanonicalPath())){
						parentFile=parentFile.getParentFile();
						currentFiles=toList(parentFile.listFiles());
						inflateListView(currentFiles);
					}
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		});
	}

	private void inflateListView(ArrayList<File> files) {
		List<Map<String, Object>> fileList = new ArrayList<Map<String, Object>>();
		for (int i = 0; i < files.size(); i++) {
			Map<String, Object> fileMap = new HashMap<String, Object>();
			// 文件的图标
			if (files.get(i).isDirectory())
				fileMap.put("icon", R.drawable.icon_package);
			else {
				fileMap.put("icon", R.drawable.icon_music);
			}
			// 文件的名字
			fileMap.put("fileName", files.get(i).getName());
			fileList.add(fileMap);
		}
		SimpleAdapter fileAdapter = new SimpleAdapter(this, fileList, R.layout.selectmusic_item,
				new String[] { "icon", "fileName" },
				new int[] { R.id.id_fileIcon, R.id.id_fileName });
		fileListView.setAdapter(fileAdapter);
	}

	private ArrayList<File> toList(File[] files) {
		ArrayList<File> arrayFiles = new ArrayList<File>();
		for (int i = 0; i < files.length; i++) {
			// 如果是个文件夹，或者名字是.mp3结尾，那么就方法文件ArrayList中
			if (files[i].isDirectory() || files[i].toString().endsWith(".mp3"))
				arrayFiles.add(files[i]);
		}
		return arrayFiles;
	}
}

selectmusci_item.xml文件

<?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="fill_parent"
    android:orientation="horizontal" >
    <ImageView 
        android:id="@+id/id_fileIcon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <TextView 
        android:id="@+id/id_fileName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>

selectmusic.xml文件

<?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="fill_parent"
    android:orientation="vertical" >
    <!-- 显示当前目录的路径 -->
    <TextView 
        android:id="@+id/id_filePath"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <!-- 当前文件夹中文件的遍历 -->
    <ListView 
        android:id="@+id/id_fileList"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <!-- 返回按钮 -->
    <Button 
        android:text="返回上层目录"
        android:id="@+id/id_goBack"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>