安卓开发实例二：文件浏览器

概述：

需求：显示手机内所有文件、文件夹，显示文件内容，对文件拷贝、删除等。

实现：遍历文件，显示文件信息到ListView中；读取文件，显示到界面上；ListView添加菜单，处理文件操作。

扩展：自定义Activity标题栏，创建后台服务播放MP3文件。

代码：

<span style="font-family:Microsoft YaHei;font-size:12px;">public class MainActivity extends Activity {
	public static final int MENU_ID_BASE = 0;
	
	@Override
	public boolean onContextItemSelected(MenuItem item) {
		// TODO Auto-generated method stub
		switch( item.getItemId() ){
		case MENU_ID_BASE+1://删除
			Toast.makeText(this, "删除文件", Toast.LENGTH_LONG).show();
			break;
		case MENU_ID_BASE+2://复制
			Toast.makeText(this, "复制文件", Toast.LENGTH_LONG).show();
			break;
		case MENU_ID_BASE+3://重命名
			Toast.makeText(this, "重命名文件", Toast.LENGTH_LONG).show();
			break;
		}
		return super.onContextItemSelected(item);
	}

	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event) {
		// TODO Auto-generated method stub
		if ( keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN ){
			if ( !isRoot() ){
				goBack();
				return true;
			}
		}
		return super.onKeyDown(keyCode, event);
	}
	private ListView m_lv = null;
	private TouchCallback m_tcb = null;
	private ArrayList<File> m_files = new ArrayList<File>();
	private String m_strDir = "./";
	private TextView m_tvFile = null;
	private OnItemLongClickListenerEx mItemLclickCb = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		m_lv = (ListView)findViewById(R.id.lv1);
		m_tvFile = (TextView)findViewById(R.id.tv_file);
		m_tcb = new TouchCallback();
		mItemLclickCb = new OnItemLongClickListenerEx();
	    m_tcb.setMainActivity(this);
	    m_lv.setOnItemClickListener(m_tcb);
	    mItemLclickCb.SetActivity(this);
	    mItemLclickCb.SetListView(m_lv);
	    m_lv.setOnItemLongClickListener(mItemLclickCb);
	    //m_lv.setOnClickListener(m_tcb);
		//生成动态数组，加入数据  
		File fRoot = new File(m_strDir);
        AddFiles(fRoot);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.x