因项目需要打开文件，因此做了一个打开文件的对话框，现在把这部分的代码共享出来了。
首先是一个回调接口，，该接口在文件选择完毕的通知调用者进行如果何种操作。文件接口声明，如下：
// filename: CallbackBundle.javapackage com.example.openfiledemo;import android.os.Bundle;// 简单的Bundle参数回调接口public interface CallbackBundle {abstract void callback(Bundle bundle);}然后的打开文件对话框的一下封装：
// filename: OpenFileDialog.javapackage com.example.openfiledemo;import java.io.File;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.app.Activity;import android.app.AlertDialog;import android.app.Dialog;import android.content.Context;import android.os.Bundle;import android.view.View;import android.widget.AdapterView;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.Toast;import android.widget.AdapterView.OnItemClickListener;public class OpenFileDialog {public static String tag = "OpenFileDialog";static final public String sRoot = "/"; static final public String sParent = "..";static final public String sFolder = ".";static final public String sEmpty = "";static final private String sOnErrorMsg = "No rights to access!";// 参数说明// context:上下文// dialogid:对话框ID// title:对话框标题// callback:一个传递Bundle参数的回调接口// suffix:需要选择的文件后缀，比如需要选择wav、mp3文件的时候设置为".wav;.mp3;"，注意最后需要一个分号(;)// images:用来根据后缀显示的图标资源ID。//根目录图标的索引为sRoot;//父目录的索引为sParent;//文件夹的索引为sFolder;//默认图标的索引为sEmpty;//其他的直接根据后缀进行索引，比如.wav文件图标的索引为"wav"public static Dialog createDialog(int id, Context context, String title, CallbackBundle callback, String suffix, Map<String, Integer> images){AlertDialog.Builder builder = new AlertDialog.Builder(context);builder.setView(new FileSelectView(context, id, callback, suffix, images));Dialog dialog = builder.create();//dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);dialog.setTitle(title);return dialog;}static class FileSelectView extends ListView implements OnItemClickListener{private CallbackBundle callback = null;private String path = sRoot;private List<Map<String, Object>> list = null;private int dialogid = 0;private String suffix = null;private Map<String, Integer> imagemap = null;public FileSelectView(Context context, int dialogid, CallbackBundle callback, String suffix, Map<String, Integer> images) {super(context);this.imagemap = images;this.suffix = suffix==null?"":suffix.toLowerCase();this.callback = callback;this.dialogid = dialogid;this.setOnItemClickListener(this);refreshFileList();}private String getSuffix(String filename){int dix = filename.lastIndexOf(‘.’);if(dix<0){return "";}else{return filename.substring(dix+1);}}private int getImageId(String s){if(imagemap == null){return 0;}else if(imagemap.containsKey(s)){return imagemap.get(s);}else if(imagemap.containsKey(sEmpty)){return imagemap.get(sEmpty);}else {return 0;}}private int refreshFileList(){// 刷新文件列表File[] files = null;try{files = new File(path).listFiles();}catch(Exception e){files = null;}if(files==null){// 访问出错Toast.makeText(getContext(), sOnErrorMsg,Toast.LENGTH_SHORT).show();return -1;}if(list != null){list.clear();}else{list = new ArrayList<Map<String, Object>>(files.length);}// 用来先保存文件夹和文件夹的两个列表ArrayList<Map<String, Object>> lfolders = new ArrayList<Map<String, Object>>();ArrayList<Map<String, Object>> lfiles = new ArrayList<Map<String, Object>>();if(!this.path.equals(sRoot)){// 添加根目录 和 上一层目录Map<String, Object> map = new HashMap<String, Object>();map.put("name", sRoot);map.put("path", sRoot);map.put("img", getImageId(sRoot));list.add(map);map = new HashMap<String, Object>();map.put("name", sParent);map.put("path", path);map.put("img", getImageId(sParent));list.add(map);}for(File file: files){if(file.isDirectory() && file.listFiles()!=null){// 添加文件夹Map<String, Object> map = new HashMap<String, Object>();map.put("name", file.getName());map.put("path", file.getPath());map.put("img", getImageId(sFolder));lfolders.add(map);}else if(file.isFile()){// 添加文件String sf = getSuffix(file.getName()).toLowerCase();if(suffix == null || suffix.length()==0 || (sf.length()>0 && suffix.indexOf("."+sf+";")>=0)){Map<String, Object> map = new HashMap<String, Object>();map.put("name", file.getName());map.put("path", file.getPath());map.put("img", getImageId(sf));lfiles.add(map);}}}list.addAll(lfolders); // 先添加文件夹，确保文件夹显示在上面list.addAll(lfiles);//再添加文件SimpleAdapter adapter = new SimpleAdapter(getContext(), list, R.layout.filedialogitem, new String[]{"img", "name", "path"}, new int[]{R.id.filedialogitem_img, R.id.filedialogitem_name, R.id.filedialogitem_path});this.setAdapter(adapter);return files.length;}@Overridepublic void onItemClick(AdapterView<?> parent, View v, int position, long id) {// 条目选择String pt = (String) list.get(position).get("path");String fn = (String) list.get(position).get("name");if(fn.equals(sRoot) || fn.equals(sParent)){// 如果是更目录或者上一层File fl = new File(pt);String ppt = fl.getParent();if(ppt != null){// 返回上一层path = ppt;}else{// 返回更目录path = sRoot;}}else{File fl = new File(pt);if(fl.isFile()){// 如果是文件((Activity)getContext()).dismissDialog(this.dialogid); // 让文件夹对话框消失// 设置回调的返回值Bundle bundle = new Bundle();bundle.putString("path", pt);bundle.putString("name", fn);// 调用事先设置的回调函数this.callback.callback(bundle);return;}else if(fl.isDirectory()){// 如果是文件夹// 那么进入选中的文件夹path = pt;}}this.refreshFileList();}}}
下面是文件条目的一个布局（文件名：filedialogitem.xml）：
不畏不惧，不言不弃，冲破风雨的阻隔，黎明就在前方！
