ListView项目长按的菜单功能总结

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：

@Overridepublic 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：

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

 

showDialog(UPDATE_FILEPATH);对应于如下代码：

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