場景

在Android應用中需要將某些文字內容儲存到儲存器中的txt檔案中。

在顯示時還需要將txt檔案的內容讀取加載出來。形成一個簡單記事本的效果

注：

部落格：
https://blog.csdn.net/badao_liumang_qizhi
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實現

首先新建一個Activity並設計頁面佈局如上，xml佈局程式碼為

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical"
    tools:context=".StoreTextActivity">

    <TextView
        android:layout_width
 
="match_parent"
        android:layout_height="wrap_content"
        android:padding="10dp"
        android:gravity="center_horizontal"
        android:textSize="18sp"
        android:textColor="@android:color/black"
        android:text="記事本"
        />

    <View
        android:layout_width="match_parent
 
"
        android:layout_height="1dp"
        android:background="#FFC8C8C8"/>
    <EditText
        android:id="@+id/edit_text"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:gravity="start"
        android:hint="請輸入文字"
        android:inputType="textMultiLine"
        />

    <Button
        android:id="@+id/btn_save"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="saveFile"
        android:text="儲存"
        />
</LinearLayout>

然後在Activity,在儲存按鈕的點選事件執行的儲存到檔案的方法中，將editText的文字內容儲存到檔案

   /***
     * 儲存到檔案
     * @param str
     */
    public void saveFile(String str)
    {
        FileOutputStream fos = null;
        BufferedWriter writer = null;

        try {
            fos = openFileOutput("badao.txt", Context.MODE_PRIVATE);
            writer = new BufferedWriter(new OutputStreamWriter(fos));
            try {
                writer.write(str);
                Toast.makeText(this,"儲存成功",Toast.LENGTH_LONG).show();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            if(writer!=null)
            {
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fos!=null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

儲存成功後，檔案會在內部儲存下data/data/包名/files下找到

然後在onCreate方法中，首先執行從txt載入內容的方法

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_store_text);
        editText = findViewById(R.id.edit_text);
        String str = load();
        if(!(TextUtils.isEmpty(str)))
        {
            editText.setText(str);
            Toast.makeText(this,"載入成功",Toast.LENGTH_LONG).show();
        }
    }

在載入內容的方法load中

   /***
     * 從檔案中載入
     * @return
     */
    public String load()
    {
        FileInputStream fis = null;
        BufferedReader reader = null;
        StringBuilder content = new StringBuilder();
        try {
            fis = openFileInput("badao.txt");
            reader = new BufferedReader(new InputStreamReader(fis));
            String str;

            while ((str=reader.readLine())!=null) {
                content.append(str);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(reader!=null)
            {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fis!=null)
            {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return content.toString();
    }

activity的完整程式碼

package com.badao.androidstudy;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class StoreTextActivity extends AppCompatActivity {

    private EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_store_text);
        editText = findViewById(R.id.edit_text);
        String str = load();
        if(!(TextUtils.isEmpty(str)))
        {
            editText.setText(str);
            Toast.makeText(this,"載入成功",Toast.LENGTH_LONG).show();
        }
    }


    public void saveFile(View view)
    {
        saveFile(editText.getText().toString());
    }


    /***
     * 從檔案中載入
     * @return
     */
    public String load()
    {
        FileInputStream fis = null;
        BufferedReader reader = null;
        StringBuilder content = new StringBuilder();
        try {
            fis = openFileInput("badao.txt");
            reader = new BufferedReader(new InputStreamReader(fis));
            String str;

            while ((str=reader.readLine())!=null) {
                content.append(str);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(reader!=null)
            {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fis!=null)
            {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return content.toString();
    }

    /***
     * 儲存到檔案
     * @param str
     */
    public void saveFile(String str)
    {
        FileOutputStream fos = null;
        BufferedWriter writer = null;

        try {
            fos = openFileOutput("badao.txt", Context.MODE_PRIVATE);
            writer = new BufferedWriter(new OutputStreamWriter(fos));
            try {
                writer.write(str);
                Toast.makeText(this,"儲存成功",Toast.LENGTH_LONG).show();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }finally {
            if(writer!=null)
            {
                try {
                    writer.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fos!=null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

執行之後，輸入一些文字內容，點選儲存

然後退出app重新啟動後