ListView上的Item长按弹出菜单或者对话框是常见的功能之一：

其实现如下：

extends ListActivity{

在方法：

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); setContentView(R.layout.localfilebrowser); registerForContextMenu(this.getListView());

增加方法：

@Override public void onCreateContextMenu(ContextMenu menu, View view, ContextMenuInfo menuInfo) { AdapterView.AdapterContextMenuInfo info; try { info = (AdapterView.AdapterContextMenuInfo) menuInfo; } catch (ClassCastException e) { Log.e("test", "bad menuInfo", e); return; } currentPath = new File(paths.get(info.position)); showDialog(UPDATE_FILEPATH); }

本文使用了弹出式窗口，如果是菜单的话，需要增加如下代码

@Override public boolean onContextItemSelected(MenuItem item) { super.onContextItemSelected(item); AdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo) item .getMenuInfo(); // Remember current selection IconifiedTextListAdapter adapter = (IconifiedTextListAdapter) getListAdapter(); if (adapter == null) { return false; } return true; }

showDialog(UPDATE_FILEPATH);对应于如下代码

@Override protected Dialog onCreateDialog(int id) { switch (id) { case UPDATE_FILEPATH: LayoutInflater inflater = LayoutInflater.from(this); View view = inflater.inflate(R.layout.dialog_change_filepath, null); final TextView oldet = (TextView) view.findViewById(R.id.oldfilepath); final TextView newet = (TextView) view.findViewById(R.id.newfilepath); prefs = PreferenceManager.getDefaultSharedPreferences(this); oldet.setText(oldet.getText()+prefs.getString("CLB_DOWNLOAD_PATH", "")); if(currentPath!=null) newet.setText(newet.getText()+currentPath.getAbsolutePath()); return new AlertDialog.Builder(this).setIcon( android.R.drawable.ic_dialog_alert).setTitle( R.string.dialog_filepath).setView(view) .setPositiveButton(android.R.string.ok, new OnClickListener() { public void onClick(DialogInterface dialog, int which) { Editor editor = prefs.edit(); editor.putString("CLB_DOWNLOAD_PATH", currentPath.getAbsolutePath()); editor.commit(); ListOSDir.this.finish(); } }).setNegativeButton(android.R.string.cancel, new OnClickListener() { public void onClick(DialogInterface dialog, int which) { // Cancel should not do anything. removeDialog(UPDATE_FILEPATH); } }).create(); } return null; }

其中：removeDialog(UPDATE_FILEPATH); 是解决

因为create 一个dialog的开销很大，所以android会先查找有没有dialog实例存在，如果有，不create，prepared之后就show，弹出窗口一直都相同的问题

整个程序是选择一个目录来设置下载需要存储的路径的，代码如下：

package cn.cnic.cerc.moblie.clbclient.filemanager; import java.io.File; import java.util.ArrayList; import java.util.List; import android.app.AlertDialog; import android.app.Dialog; import android.app.ListActivity; import android.content.DialogInterface; import android.content.SharedPreferences; import android.content.DialogInterface.OnClickListener; import android.content.SharedPreferences.Editor; import android.os.Bundle; import android.os.Environment; import android.preference.PreferenceManager; import android.util.Log; import android.view.ContextMenu; import android.view.LayoutInflater; import android.view.MenuItem; import android.view.View; import android.view.Window; import android.view.ContextMenu.ContextMenuInfo; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.TextView; import android.widget.AdapterView.AdapterContextMenuInfo; import cn.cnic.cerc.moblie.clbclient.R; public class ListOSDir extends ListActivity { private static final int UPDATE_FILEPATH = 0; /** Called when the activity is first created. */ private List<String> items = null;// 存放名称 private List<String> paths = null;// 存放路径 private String rootPath = "/"; private TextView tv; private SharedPreferences prefs; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS); setContentView(R.layout.localfilebrowser); registerForContextMenu(this.getListView()); tv = (TextView) this.findViewById(R.id.TextView); this.getFileDir(rootPath);// 获取rootPath目录下的文件. prefs = PreferenceManager.getDefaultSharedPreferences(this); if(prefs.getString("CLB_DOWNLOAD_PATH", "").equals("")) { File sdcardDir = Environment.getExternalStorageDirectory(); String path = sdcardDir.getParent() + sdcardDir.getName(); String fileDirectory = path + java.io.File.separator + "clb"; Editor editor = prefs.edit(); editor.putString("CLB_DOWNLOAD_PATH", fileDirectory); editor.commit(); } } public void getFileDir(String filePath) { try { this.tv.setText("当前路径:" + filePath);// 设置当前所在路径 items = new ArrayList<String>(); paths = new ArrayList<String>(); File f = new File(filePath); File[] files = f.listFiles();// 列出所有文件 // 如果不是根目录,则列出返回根目录和上一目录选项 if (!filePath.equals(rootPath)) { items.add("返回根目录"); paths.add(rootPath); items.add("返回上一层目录"); paths.add(f.getParent()); } // 将所有文件存入list中 if (files != null) { int count = files.length;// 文件个数 for (int i = 0; i < count; i++) { File file = files[i]; if (file.isDirectory()) { items.add(file.getName()); paths.add(file.getPath()); } } } ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items); this.setListAdapter(adapter); } catch (Exception ex) { ex.printStackTrace(); } } @Override protected void onListItemClick(ListView l, View v, int position, long id) { super.onListItemClick(l, v, position, id); String path = paths.get(position); File file = new File(path); // 如果是文件夹就继续分解 if (file.isDirectory()) { this.getFileDir(path); } else { new AlertDialog.Builder(this).setTitle("提示").setMessage( file.getName() + " 是一个文件！").setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { } }).show(); } } private File currentPath; @Override public void onCreateContextMenu(ContextMenu menu, View view, ContextMenuInfo menuInfo) { AdapterView.AdapterContextMenuInfo info; try { info = (AdapterView.AdapterContextMenuInfo) menuInfo; } catch (ClassCastException e) { Log.e("test", "bad menuInfo", e); return; } currentPath = new File(paths.get(info.position)); showDialog(UPDATE_FILEPATH); } @Override public boolean onContextItemSelected(MenuItem item) { super.onContextItemSelected(item); AdapterContextMenuInfo menuInfo = (AdapterContextMenuInfo) item .getMenuInfo(); // Remember current selection IconifiedTextListAdapter adapter = (IconifiedTextListAdapter) getListAdapter(); if (adapter == null) { return false; } return true; } @Override protected Dialog onCreateDialog(int id) { switch (id) { case UPDATE_FILEPATH: LayoutInflater inflater = LayoutInflater.from(this); View view = inflater.inflate(R.layout.dialog_change_filepath, null); final TextView oldet = (TextView) view.findViewById(R.id.oldfilepath); final TextView newet = (TextView) view.findViewById(R.id.newfilepath); prefs = PreferenceManager.getDefaultSharedPreferences(this); oldet.setText(oldet.getText()+prefs.getString("CLB_DOWNLOAD_PATH", "")); if(currentPath!=null) newet.setText(newet.getText()+currentPath.getAbsolutePath()); return new AlertDialog.Builder(this).setIcon( android.R.drawable.ic_dialog_alert).setTitle( R.string.dialog_filepath).setView(view) .setPositiveButton(android.R.string.ok, new OnClickListener() { public void onClick(DialogInterface dialog, int which) { Editor editor = prefs.edit(); editor.putString("CLB_DOWNLOAD_PATH", currentPath.getAbsolutePath()); editor.commit(); ListOSDir.this.finish(); } }).setNegativeButton(android.R.string.cancel, new OnClickListener() { public void onClick(DialogInterface dialog, int which) { // Cancel should not do anything. removeDialog(UPDATE_FILEPATH); } }).create(); } return null; } }

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