การเปิดอ่านเท็กซ์ไฟล์จากในเครื่องด้วย Intent.ACTION_OPEN_DOCUMENT

ไฟล์ที่เกี่ยวข้อง

• activity_main.xml
• MainActivity.java

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@+id/textView"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="top" />

        <Button
            android:id="@+id/button"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Open Textfile" />
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.phaisarn.myapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class MainActivity extends AppCompatActivity {

    private static final int READ_REQUEST_CODE = 42;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        textView = findViewById(R.id.textView);

        findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                performFileSearch();
            }
        });
    }

    public void performFileSearch() {
        Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("text/*");

        startActivityForResult(intent, READ_REQUEST_CODE);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent resultData) {

        if (requestCode == READ_REQUEST_CODE && resultCode == Activity.RESULT_OK) {
            if (resultData != null) {
                Uri uri = resultData.getData();

                try {
                    String content = readFileContent(uri);
                    textView.setText(content);
                } catch (IOException e) {
                    Log.e("Error: ", e.getMessage());
                }
            }
        }
    }

    private String readFileContent(Uri uri) throws IOException {
        InputStream inputStream = getContentResolver().openInputStream(uri);
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));

        StringBuilder stringBuilder = new StringBuilder();
        String currentLine;
        while ((currentLine = reader.readLine()) != null) {
            stringBuilder.append(currentLine + "\n");
        }
        inputStream.close();

        return stringBuilder.toString();
    }
}

Link

• Storage Access Framework (SAF)