非常简单的Android打开和保存对话框功能

前端技术 2023/09/02 Android

在Android上没有标准的打开和另存为对话框。在本代码中,我将详细描述一个非常简单的打开和保存对话框实现过程,对于Android初学者来说非常有用，对话框都是全屏活动的。

主要功能：

1、访问任何目录的SD卡
2、递归访问文件夹
3、单一文件选择
4、通过按硬件后退按钮升级
5、确认文件选择OK按钮 

activity_open_file.xml

<LinearLayout xmlns:android=\"<a href=\"http://schemas.android.com/apk/res/android\"\" rel=\"nofollow\" target=\"_blank\">http://schemas.android.com/apk/res/android\"</a>
  xmlns:tools=\"<a href=\"http://schemas.android.com/tools\"\" rel=\"nofollow\" target=\"_blank\">http://schemas.android.com/tools\"</a>
  android:layout_width=\"match_parent\"
  android:layout_height=\"match_parent\"
  android:orientation=\"vertical\" >

  <ListView
    android:id=\"@+id/LvList\"
    android:layout_width=\"fill_parent\"
    android:layout_height=\"fill_parent\"
    android:layout_weight=\"1\" >

  </ListView>
  <LinearLayout
    android:layout_width=\"match_parent\"
    android:layout_height=\"wrap_content\"
    android:orientation=\"horizontal\" >

    <Button
      android:id=\"@+id/BtnOK\"
      android:layout_width=\"fill_parent\"
      android:layout_height=\"wrap_content\"
      android:layout_weight=\"1\"
      android:text=\"OK\" />
    <Button
      android:id=\"@+id/BtnCancel\"
      android:layout_width=\"fill_parent\"
      android:layout_height=\"wrap_content\"
      android:layout_weight=\"1\"
      android:text=\"Cancel\" />

  </LinearLayout>
</LinearLayout>

OpenFileActivity.java

package com.example.androidfiledialogs;

import java.io.File;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.Toast;


public class OpenFileActivity extends Activity
  implements OnClickListener, OnItemClickListener {
  ListView LvList;
  ArrayList<String> listItems = new ArrayList<String>();
  ArrayAdapter<String> adapter;
  Button BtnOK;
  Button BtnCancel;
  String currentPath = null;
  String selectedFilePath = null; /* Full path, i.e. /mnt/sdcard/folder/file.txt */
  String selectedFileName = null; /* File Name Only, i.e file.txt */
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_open_file);
    try {

      /* Initializing Widgets */
      LvList = (ListView) findViewById(R.id.LvList);
      BtnOK = (Button) findViewById(R.id.BtnOK);
      BtnCancel = (Button) findViewById(R.id.BtnCancel);    

      /* Initializing Event Handlers */
      LvList.setOnItemClickListener(this);
      BtnOK.setOnClickListener(this);
      BtnCancel.setOnClickListener(this);

      //
    setCurrentPath(Environment.getExternalStorageDirectory().getAbsolutePath() + \"/\");
    } catch (Exception ex) {
      Toast.makeText(this,
          \"Error in OpenFileActivity.onCreate: \" + ex.getMessage(),
          Toast.LENGTH_SHORT).show();
    }

  }

  void setCurrentPath(String path) {
    ArrayList<String> folders = new ArrayList<String>();
    ArrayList<String> files = new ArrayList<String>();
    currentPath = path;
    File allEntries = new File(path).listFiles();
    for (int i = 0; i < allEntries.length; i++) {
      if (allEntries.isDirectory()) {
        folders.add(allEntries.getName());
      } else if (allEntries.isFile()) {
        files.add(allEntries.getName());
      }
    }

    Collections.sort(folders, new Comparator<String>() {
      @Override
      public int compare(String s1, String s2) {
        return s1.compareToIgnoreCase(s2);
      }
    });

     Collections.sort(files, new Comparator<String>() {
      @Override
      public int compare(String s1, String s2) {
        return s1.compareToIgnoreCase(s2);

      }

    });

    listItems.clear();
    for (int i = 0; i < folders.size(); i++) {
      listItems.add(folders.get(i) + \"/\");
    }

    for (int i = 0; i < files.size(); i++) {
      listItems.add(files.get(i));

    }

    

    adapter = new ArrayAdapter<String>(this,

        android.R.layout.simple_list_item_1,

        listItems);

    adapter.notifyDataSetChanged();

    

    LvList.setAdapter(adapter);

  }

  

  @Override

  public void onBackPressed()

  {

    if (!currentPath.equals(Environment.getExternalStorageDirectory().getAbsolutePath() + \"/\")) {

      setCurrentPath(new File(currentPath).getParent() + \"/\");

    } else {

      super.onBackPressed();

    }

  }

  

  @Override

  public void onClick(View v) {

    Intent intent;

    

    switch (v.getId()) {

    case R.id.BtnOK:

      

      intent = new Intent();

      intent.putExtra(\"fileName\", selectedFilePath);

      intent.putExtra(\"shortFileName\", selectedFileName);

      setResult(RESULT_OK, intent);

      

      this.finish();

      

      break;

    case R.id.BtnCancel:

      

      intent = new Intent();

      intent.putExtra(\"fileName\", \"\");

      intent.putExtra(\"shortFileName\", \"\");

      setResult(RESULT_CANCELED, intent);

      

      this.finish();

      

      break;

    }

  }


  @Override

  public void onItemClick(AdapterView<?> parent, View view, int position,

      long id) {

    String entryName = (String)parent.getItemAtPosition(position);

    if (entryName.endsWith(\"/\")) {

      setCurrentPath(currentPath + entryName);

    } else {

      selectedFilePath = currentPath + entryName;

      

      selectedFileName = entryName;

      

      this.setTitle(this.getResources().getString(R.string.title_activity_open_file)

          + \"<span>[</span>\" + entryName + \"]\");

    }

  }

}

activity_save_file.xml

<LinearLayout xmlns:android=\"<a href=\"http://schemas.android.com/apk/res/android\"\" rel=\"nofollow\" target=\"_blank\">http://schemas.android.com/apk/res/android\"</a>

  xmlns:tools=\"<a href=\"http://schemas.android.com/tools\"\" rel=\"nofollow\" target=\"_blank\">http://schemas.android.com/tools\"</a>

  android:layout_width=\"match_parent\"

  android:layout_height=\"match_parent\"

  android:orientation=\"vertical\" >


  <ListView

    android:id=\"@+id/SFA_LvList\"

    android:layout_width=\"fill_parent\"

    android:layout_height=\"fill_parent\"

    android:layout_weight=\"1\" >

  </ListView>


  <EditText

    android:id=\"@+id/SFA_TxtFileName\"

    android:layout_width=\"match_parent\"

    android:layout_height=\"wrap_content\"

    android:ems=\"10\"

    android:text=\"file.txt\" />

  

  <LinearLayout

    android:layout_width=\"match_parent\"

    android:layout_height=\"wrap_content\"

    android:orientation=\"horizontal\" >


    <Button

      android:id=\"@+id/SFA_BtnOK\"

      android:layout_width=\"fill_parent\"

      android:layout_height=\"wrap_content\"

      android:layout_weight=\"1\"

      android:text=\"OK\" />


    <Button

      android:id=\"@+id/SFA_BtnCancel\"

      android:layout_width=\"fill_parent\"

      android:layout_height=\"wrap_content\"

      android:layout_weight=\"1\"

      android:text=\"Cancel\" />

    

  </LinearLayout>

    

</LinearLayout>
</LinearLayout>

SaveFileActivity.java

package com.example.androidfiledialogs;

import java.io.File;
import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;


import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.os.Environment;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.AdapterView;

import android.widget.ArrayAdapter;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ListView;

import android.widget.Toast;

import android.widget.AdapterView.OnItemClickListener;


public class SaveFileActivity extends Activity

  implements OnClickListener, OnItemClickListener {


    ListView LvList;

    

    ArrayList<String> listItems = new ArrayList<String>();

    

    ArrayAdapter<String> adapter;

    

    EditText TxtFileName;

    

    Button BtnOK;

    Button BtnCancel;

    

    String currentPath = null;

    

  @Override

  protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_save_file);

    

    try {

      /* Initializing Widgets */

      LvList = (ListView) findViewById(R.id.SFA_LvList);

      TxtFileName = (EditText) findViewById(R.id.SFA_TxtFileName);

      BtnOK = (Button) findViewById(R.id.SFA_BtnOK);

      BtnCancel = (Button) findViewById(R.id.SFA_BtnCancel);

      

      /* Initializing Event Handlers */

      

      LvList.setOnItemClickListener(this);

      

      BtnOK.setOnClickListener(this);

      BtnCancel.setOnClickListener(this);

      

      //

      

      setCurrentPath(Environment.getExternalStorageDirectory().getAbsolutePath() + \"/\");

    } catch (Exception ex) {

      Toast.makeText(this,

          \"Error in SaveFileActivity.onCreate: \" + ex.getMessage(),

          Toast.LENGTH_SHORT).show();

    }

  }

  

  void setCurrentPath(String path) {

    ArrayList<String> folders = new ArrayList<String>();

    

    ArrayList<String> files = new ArrayList<String>();

    

    currentPath = path;

    

    File allEntries = new File(path).listFiles();

    

    for (int i = 0; i < allEntries.length; i++) {

      if (allEntries.isDirectory()) {

        folders.add(allEntries.getName());

      } else if (allEntries.isFile()) {

        files.add(allEntries.getName());

      }

    }

    

    Collections.sort(folders, new Comparator<String>() {

      @Override

      public int compare(String s1, String s2) {

        return s1.compareToIgnoreCase(s2);

      }

    });

    

    Collections.sort(files, new Comparator<String>() {

      @Override

      public int compare(String s1, String s2) {

        return s1.compareToIgnoreCase(s2);

      }

    });

    

    listItems.clear();

    

    for (int i = 0; i < folders.size(); i++) {

      listItems.add(folders.get(i) + \"/\");

    }

    

    for (int i = 0; i < files.size(); i++) {

      listItems.add(files.get(i));

    }

    

    adapter = new ArrayAdapter<String>(this,

        android.R.layout.simple_list_item_1,

        listItems);

    adapter.notifyDataSetChanged();

    

    LvList.setAdapter(adapter);

  }

  

  @Override

  public void onBackPressed()

  {

    if (!currentPath.equals(Environment.getExternalStorageDirectory().getAbsolutePath() + \"/\")) {

      setCurrentPath(new File(currentPath).getParent() + \"/\");

    } else {

      super.onBackPressed();

    }

  }

  

  @Override

  public void onClick(View v) {

    Intent intent;

    

    switch (v.getId()) {

    case R.id.SFA_BtnOK:

      

      intent = new Intent();

      intent.putExtra(\"fileName\", currentPath + TxtFileName.getText().toString());

      intent.putExtra(\"shortFileName\", TxtFileName.getText().toString());

      setResult(RESULT_OK, intent);

      

      this.finish();

      

      break;

    case R.id.SFA_BtnCancel:

      

      intent = new Intent();

      intent.putExtra(\"fileName\", \"\");

      intent.putExtra(\"shortFileName\", \"\");

      setResult(RESULT_CANCELED, intent);

      

      this.finish();

      

      break;

    }

  }


  @Override

  public void onItemClick(AdapterView<?> parent, View view, int position,

      long id) {

    String entryName = (String)parent.getItemAtPosition(position);

    if (entryName.endsWith(\"/\")) {

      setCurrentPath(currentPath + entryName);

    } else {

      this.setTitle(this.getResources().getString(R.string.title_activity_open_file)

          + \"<span>[</span>\" + entryName + \"]\");

      

      TxtFileName.setText(entryName);

    }

  }

}

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