Android中实现保存和读取文本文件到内部存储器(实现简易的记事本为例)

短命女 2023-10-05 14:53 12阅读 0赞

## 场景 ##

在Android应用中需要将某些文本内容保存到存储器中的txt文件中。

在显示时还需要将txt文件的内容读取加载出来。形成一个简单记事本的效果

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70][]

注：

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[https://blog.csdn.net/badao\_liumang\_qizhi][https_blog.csdn.net_badao_liumang_qizhi]  
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## 实现 ##

首先新建一个Activity并设计页面布局如上，xml布局代码为

<?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="记事本"
            />
    
        <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="请输入文本"
            android:inputType="textMultiLine"
            />
    
        <Button
            android:id="@+id/btn_save"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:onClick="saveFile"
            android:text="保存"
            />
    </LinearLayout>

然后在Activity,在保存按钮的点击事件执行的保存到文件的方法中，将editText的文本内容保存到文件

/***
         * 保存到文件
         * @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,"保存成功",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();
                    }
                }
            }
        }

保存成功后，文件会在内部存储下data/data/包名/files下找到

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1][]

然后在onCreate方法中，首先执行从txt加载内容的方法

@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,"加载成功",Toast.LENGTH_LONG).show();
            }
        }

在加载内容的方法load中

/***
         * 从文件中加载
         * @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的完整代码

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,"加载成功",Toast.LENGTH_LONG).show();
            }
        }
    
    
        public void saveFile(View view)
        {
            saveFile(editText.getText().toString());
        }
    
    
        /***
         * 从文件中加载
         * @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();
        }
    
        /***
         * 保存到文件
         * @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,"保存成功",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();
                    }
                }
            }
        }
    }

运行之后，输入一些文本内容，点击保存

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2][]

然后退出app重新启动后

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20201202211444421.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20201202211507462.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20201202211537631.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20201202211541186.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0JBREFPX0xJVU1BTkdfUUlaSEk=,size_16,color_FFFFFF,t_70