如何在Android中获取文件扩展名? [英] How to get the file extension in Android?

问题描述

我是新手.我有一个EditText和一个浏览按钮来浏览文件夹并仅选择文件.从浏览按钮中，单击文件后，它将在一个字符串中存储该文件的文件夹路径，在另一个字符串中存储无扩展名的文件名，这是我用来将这两个文件之一存储在EditText中的./p>

我想使用精确的文件扩展名(无论是一两个点)还是文件名，但是我也不知道如何获取文件扩展名.

所有答案将不胜感激. FileChooser.java

 包com.threefriends.filecrypto;/***由hp创建于2016年1月6日.*/导入java.io.File;导入java.sql.Date;导入java.util.ArrayList;导入java.util.Collections;导入java.util.List;导入java.text.DateFormat;导入android.os.Bundle;导入android.app.ListActivity;导入android.content.Intent;导入android.view.View;导入android.widget.ListView;公共类FileChooser扩展了ListActivity {私有文件currentDir;私有FileArrayAdapter适配器；@Override公共无效onCreate(捆绑保存的InstanceState){super.onCreate(savedInstanceState);currentDir = new File("/sdcard/");填充(currentDir);}私人空白填充(文件f){File [] dirs = f.listFiles();this.setTitle(当前目录:" + f.getName());List< Item> dir =新ArrayList< Item>();List< Item> fls =新ArrayList< Item>();尝试{for(文件ff:目录){日期lastModDate =新日期(ff.lastModified());DateFormat formater = DateFormat.getDateTimeInstance();字符串date_modify = formater.format(lastModDate);if(ff.isDirectory()){File [] fbuf = ff.listFiles();int buf = 0;if(fbuf！= null){buf = fbuf.length;}别的buf = 0;字符串num_item = String.valueOf(buf);if(buf == 0)num_item = num_item +项目";别的num_item = num_item +个项目";//已格式化的字符串= lastModDate.toString();dir.add(new Item(ff.getName()，num_item，date_modify，ff.getAbsolutePath()，"directory_icon"));}别的{fls.add(new Item(ff.getName()，ff.length()+"Byte"，date_modify，ff.getAbsolutePath()，"file_icon"));}}} catch(异常e){}Collections.sort(dir);Collections.sort(fls);dir.addAll(fls);if(！f.getName().equalsIgnoreCase("sdcard"))dir.add(0，new Item(".."，父目录"，"，f.getParent()，"directory_up")));adapter = new FileArrayAdapter(FileChooser.this，R.layout.file_view，dir);this.setListAdapter(adapter);}@Override受保护的void onListItemClick(ListView l，View v，int position，long id){//TODO自动生成的方法存根super.onListItemClick(l，v，position，id);项目o = adapter.getItem(position);if(o.getImage().equalsIgnoreCase("directory_icon")|| o.getImage().equalsIgnoreCase("directory_up")){currentDir =新文件(o.getPath());填充(currentDir);}别的{onFileClick(o);}}私人void onFileClick(Item o){//Toast.makeText(this，"Folder Clicked:" + currentDir，Toast.LENGTH_SHORT).show();Intent intent = new Intent();intent.putExtra("GetPath"，currentDir.toString());intent.putExtra("GetFileName"，o.getName());setResult(RESULT_OK，intent);结束();}} 

MainActivity.java

的一部分

 //定义用于文件edittext.EditText editText2;私有静态字符串TAG = MainFragment.class.getSimpleName();//用于文件浏览.私有静态最终int REQUEST_PATH = 1;字符串curFileName;字符串filePath;EditText edittext;@Override公共视图onCreateView(LayoutInflater充气器，ViewGroup容器，捆绑保存的InstanceState){视图view = inflater.inflate(R.layout.fragment_main，container，false);edittext =(EditText)view.findViewById(R.id.editText);//完成文件浏览，EditText，浏览按钮.按钮b1 =(按钮)view.findViewById(R.id.skipButton);b1.setOnClickListener(new View.OnClickListener(){@Override公共无效的onClick(View v){Intent intent1 = new Intent(v.getContext()，FileChooser.class);startActivityForResult(intent1，REQUEST_PATH);}});}public void onActivityResult(int requestCode，int resultCode，Intent data){//查看哪个儿童活动正在给我们回电.如果(requestCode == REQUEST_PATH){如果(resultCode == Activity.RESULT_OK){curFileName = data.getStringExtra("GetFileName");filePath = data.getStringExtra("GetPath");edittext.setText(filePath);}}} 

解决方案

很多方法.这是2个样本-

  String someFilepath ="image.fromyesterday.test.jpg";字符串扩展名= someFilepath.substring(someFilepath.lastIndexOf(.")); 

因此，在您的情况下，应该是这样的

 字符串扩展= ff.getAbsolutePath().substring(ff.getAbsolutePath().lastIndexOf(.")); 

如果您不想自己做的话-

使用FilenameUtils.getExtension "rel =" noreferrer> Apache Commons IO -

 字符串扩展名= FilenameUtils.getExtension("/path/to/file/mytext.txt"); 

或者您的情况-

 字符串扩展名= FilenameUtils.getExtension(ff.getAbsolutePath()); 

I am a newbie. I have an EditText and a Browse Button to explore Folders and select files only. From the Browse Button, when a file is clicked it stores the folder path in which that file is in one string and the file name without extension in other string, which I am using to store, either of these two, in the EditText.

I want to make the file name with the exactly file extension (whether one or two dots), but I don't have any idea how to get the file extension also.

All answers will be appreciated. FileChooser.java

    package com.threefriends.filecrypto;

/**
 * Created by hp on 01-06-2016.
 */

import java.io.File;
import java.sql.Date;
import java.util.ArrayList; 
import java.util.Collections;
import java.util.List;
import java.text.DateFormat;
import android.os.Bundle;
import android.app.ListActivity;
import android.content.Intent; 
import android.view.View;
import android.widget.ListView; 

public class FileChooser extends ListActivity {

    private File currentDir;
    private FileArrayAdapter adapter;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 
        currentDir=new File("/sdcard/");
        fill(currentDir); 
    }
    private void fill(File f)
    {
        File[]dirs=f.listFiles();
        this.setTitle("Current Dir: "+f.getName());
        List<Item>dir=new ArrayList<Item>();
        List<Item>fls=new ArrayList<Item>();
        try{
             for(File ff: dirs)
             { 
                Date lastModDate=new Date(ff.lastModified());
                DateFormat formater=DateFormat.getDateTimeInstance();
                String date_modify=formater.format(lastModDate);
                if(ff.isDirectory()){


                    File[] fbuf=ff.listFiles();
                    int buf=0;
                    if(fbuf != null){ 
                        buf=fbuf.length;
                    } 
                    else
                        buf=0;
                    String num_item=String.valueOf(buf);
                    if(buf == 0)
                        num_item=num_item+" item";
                    else
                        num_item = num_item+" items";

                    //String formated = lastModDate.toString();
                    dir.add(new Item(ff.getName(), num_item, date_modify, ff.getAbsolutePath(), "directory_icon"));
                }
                else
                {
                    fls.add(new Item(ff.getName(), ff.length()+" Byte", date_modify, ff.getAbsolutePath(), "file_icon"));
                }
             }
        }catch(Exception e)
        {

        }
        Collections.sort(dir);
        Collections.sort(fls);
        dir.addAll(fls);
        if(!f.getName().equalsIgnoreCase("sdcard"))
            dir.add(0, new Item("..", "Parent Directory", "", f.getParent(), "directory_up"));
        adapter=new FileArrayAdapter(FileChooser.this, R.layout.file_view, dir);
        this.setListAdapter(adapter);
    }
    @Override
    protected void onListItemClick(ListView l, View v, int position, long id){
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
        Item o = adapter.getItem(position);
        if(o.getImage().equalsIgnoreCase("directory_icon") || o.getImage().equalsIgnoreCase("directory_up")){
                currentDir=new File(o.getPath());
                fill(currentDir);
        }
        else
        {
            onFileClick(o);
        }
    }
    private void onFileClick(Item o)
    {
        //Toast.makeText(this, "Folder Clicked: "+ currentDir, Toast.LENGTH_SHORT).show();
        Intent intent = new Intent();
        intent.putExtra("GetPath", currentDir.toString());
        intent.putExtra("GetFileName", o.getName());
        setResult(RESULT_OK, intent);
        finish();
    }
}

Part of MainActivity.java

//Defined for file edittext.
    EditText editText2;
 private static String TAG = MainFragment.class.getSimpleName(); //For File Exploring.
    private static final int REQUEST_PATH = 1;
    String curFileName;
    String filePath;
    EditText edittext;
 @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View view = inflater.inflate(R.layout.fragment_main, container, false);

        edittext = (EditText) view.findViewById(R.id.editText);  //Done for File Exploring, EditText, Browse Button.
        Button b1 = (Button) view.findViewById(R.id.skipButton);
        b1.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Intent intent1 = new Intent(v.getContext(), FileChooser.class);
                startActivityForResult(intent1, REQUEST_PATH);
            }
        }
        );
}
 public void onActivityResult(int requestCode, int resultCode, Intent data) {
        // See which child activity is calling us back.
        if (requestCode == REQUEST_PATH)
        {
            if (resultCode == Activity.RESULT_OK)
            {
                curFileName = data.getStringExtra("GetFileName");
                filePath=data.getStringExtra("GetPath");
                edittext.setText(filePath);
            }
        }
    }

解决方案

lots of ways . here are 2 sample-

String someFilepath = "image.fromyesterday.test.jpg"; 
String extension = someFilepath.substring(someFilepath.lastIndexOf("."));

So in you case, it should be something like that

String extension = ff.getAbsolutePath().substring(ff.getAbsolutePath().lastIndexOf("."));

In case if you don't want to do it yourself-

use FilenameUtils.getExtension from Apache Commons IO-

String extension = FilenameUtils.getExtension("/path/to/file/mytext.txt");

or in your case -

String extension = FilenameUtils.getExtension(ff.getAbsolutePath());

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