显示出sdcard的图片文件

package cn.fly.fileResourceManage;

import java.io.File;
import java.io.FileFilter;
import java.util.ArrayList;
import java.util.List;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.DialogInterface;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class ActivityMain extends ListActivity {
private TextView lv =null;
private List<String> item =null;

private List<File> paths =null;
private File path = null;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        lv = (TextView)this.findViewById(R.id.tv);
        boolean sdCardsExist = Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
        if(sdCardsExist){
            path=Environment.getExternalStorageDirectory();
            file(path);
        }else{
            Toast.makeText(this, "SdCard not exist", 1).show();
        }
    }
    private void file(File filePath){
        lv.setText(filePath.getPath());
        item = new ArrayList<String>();
        paths = new ArrayList<File>();

        File[] files = filePath.listFiles(new filePase());
        if(!filePath.equals(path)){
            /*第一设置为回到根目录*/
            item.add("Back to "+path.getPath());
            paths.add(path);
            /*第二设置为回到上层*/
            item.add("Back to ../");
            paths.add(filePath.getParentFile());
        }
        for(int i= 0 ;i<files.length ;i++){
            File file = files[i];
            if(file.canRead()){
                item.add(file.getName());
                paths.add(file.getAbsoluteFile());
            }
        }
        ArrayAdapter< String> adapter = new ArrayAdapter<String>(this,R.layout.item,R.id.item_tv,item);
        setListAdapter(adapter);
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        if(paths.get(position).isDirectory()){
            file(paths.get(position));
        }else{
            new AlertDialog.Builder(this).setIcon(R.drawable.icon).setTitle("["+paths.get(position).getName()+"] is file")
            .setPositiveButton("OK", new DialogInterface.OnClickListener (){
                @Override
                public void onClick(DialogInterface dialog, int which) {
                }

            }).show();
        }
    }

    class filePase implements FileFilter{
        @Override
        public boolean accept(File pathname) {
            String path = pathname.getName();
            if(path.endsWith("jpg") || path.endsWith("jpeg")|| path.endsWith("png")|| path.endsWith("gif")|| path.endsWith("bmp"))
                return true;
            if(pathname.isDirectory())
                return true;
            return false;
        }

    }
}