第十二篇-简易实现文件的增删查改功能

入口文件MainActivity.java

package com.example.aimee.aimee_dealfile;

import android.content.Intent;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends AppCompatActivity {

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

    public void CreateFile(View view) {
        Intent i=new Intent(this,InputFileName.class);
        startActivity(i);
    }

    public void OpenFile(View view) {
        Intent i=new Intent(this,openFileName.class);
        startActivity(i);
    }

    public void delfile(View view) {
        Intent i=new Intent(this,delFileName.class);
        startActivity(i);
    }
}

layout文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">

    <Button
        android:id="@+id/CreateFile"
        android:onClick="CreateFile"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="创建文件"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/OpenFile"
        android:onClick="OpenFile"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        android:layout_marginEnd="8dp"
        android:text="打开文件"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/CreateFile" />

    <Button
        android:id="@+id/button"
        android:onClick="delfile"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:text="删除文件"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/OpenFile" />

</android.support.constraint.ConstraintLayout>

创建文件InputFileName.java

package com.example.aimee.aimee_dealfile;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Build;
import android.os.Environment;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;

public class InputFileName extends AppCompatActivity {
    private EditText inputName;
    private final int REQUESTCODE=101;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.input_file_name);
        inputName=(EditText) findViewById(R.id.inputName);
    }

    public void startCreate(View view) throws IOException {
        switch (view.getId()){
            case R.id.ok:
                String path_directory=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"save";
                String file_name=inputName.getText().toString().trim();
                fileMethodSet fileMethodSet=new fileMethodSet();
                fileMethodSet.create_file(path_directory,file_name);
                Toast.makeText(this,file_name+"文件创建成功",Toast.LENGTH_LONG).show();
                inputName.setText("");
                Intent i=new Intent(this,MainActivity.class);
                startActivity(i);
                break;
            case R.id.cancel:
                inputName.setText("");
            default:
                break;
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults){
        super.onRequestPermissionsResult(requestCode,permissions,grantResults);
        if(requestCode==REQUESTCODE){
            if (permissions[0].equals(Manifest.permission.WRITE_EXTERNAL_STORAGE) && grantResults[0]== PackageManager.PERMISSION_GRANTED){
                Toast.makeText(this,"ok",Toast.LENGTH_LONG).show();

            }else {
                Toast.makeText(this,"无权限",Toast.LENGTH_LONG).show();
            }
        }
    }

}

layout文件input_file_name.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/inputName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请输入文件名"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/cancel"
        android:onClick="startCreate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="8dp"
        android:text="取消"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/ok"
        android:onClick="startCreate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="确认"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>

打开文件openFileName.java

package com.example.aimee.aimee_dealfile;

import android.content.Intent;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

public class openFileName extends AppCompatActivity {
    private EditText openName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.open_file_name);
        openName=(EditText) findViewById(R.id.openName);
    }

    public void startOpen(View view) throws IOException {
        switch (view.getId()){
            case R.id.ok:
                String path_directory=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"save";
                String file_name=openName.getText().toString().trim();
                openName.setText("");
                fileMethodSet fileMethodSet=new fileMethodSet();
                String new_line=fileMethodSet.read_file(path_directory,file_name);
                fileMethodSet.write_file(file_name,path_directory,"filename.txt");
                fileMethodSet.write_file(new_line,path_directory,"temp.txt");
                Intent i=new Intent(this,saveFile.class);
                startActivity(i);
                break;
            case R.id.cancel:
                openName.setText("");
            default:
                break;
        }
    }

}

layout文件open_file_name.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/openName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请输入文件名"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/cancel"
        android:onClick="startOpen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="8dp"
        android:text="取消"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/ok"
        android:onClick="startOpen"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="确认"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>

保存文件saveFile.java

package com.example.aimee.aimee_dealfile;

import android.content.Intent;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

public class saveFile extends AppCompatActivity {
    String file_name1;
    String filename1="temp.txt";
    String filename2="filename.txt";
    private EditText content;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.file_edit);
        content=(EditText) findViewById(R.id.opename);
        String path_directory=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"save";
        fileMethodSet fileMethodSet=new fileMethodSet();
        String new_line= null;
        try {
            new_line = fileMethodSet.read_file(path_directory,filename1);
            file_name1=fileMethodSet.read_file(path_directory,filename2).trim();
            File file1=new File(path_directory+"/"+filename2);
            fileMethodSet.del_file(path_directory,filename2);
            File file=new File(path_directory+"/"+filename1);
            fileMethodSet.del_file(path_directory,filename1);
        } catch (IOException e) {
            e.printStackTrace();
        }
        content.setText(new_line);
    }

    public void startSave(View view) throws IOException {
        String strcontent=content.getText().toString();
        String path_directory=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"save";
        fileMethodSet fileMethodSet=new fileMethodSet();
        fileMethodSet.write_file(strcontent,path_directory,"temp1.txt");
        File oldfile=new File(path_directory+"/"+"temp1.txt");
        File newfile=new File(path_directory+"/"+file_name1);
        oldfile.renameTo(newfile);
        Toast.makeText(this,"文件保存成功",Toast.LENGTH_LONG).show();
        Intent i=new Intent(this,MainActivity.class);
        startActivity(i);
    }

    public void cancelSave(View view) {
        Intent i=new Intent(this,MainActivity.class);
        startActivity(i);
    }
}

layout文件file_edit.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/opename"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="test"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/cancel"
        android:onClick="cancelSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="8dp"
        android:text="取消"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/save"
        android:onClick="startSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="保存"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>

删除文件delFileName.java

package com.example.aimee.aimee_dealfile;

import android.content.Intent;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import java.io.File;

public class delFileName extends AppCompatActivity {
    private EditText delName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.del_file_name);
        delName=(EditText) findViewById(R.id.delName);
    }

    public void cancelCreate(View view) {
        Intent i=new Intent(this,MainActivity.class);
        startActivity(i);
    }

    public void startCreate(View view) {
        String path=Environment.getExternalStorageDirectory().getAbsolutePath()+"/"+"save";
        String filename=delName.getText().toString().trim();
        String final_path=path+"/"+filename;
        File file=new File(final_path);
        if(file.exists()){
            file.delete();
            Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();
            Intent i=new Intent(this,MainActivity.class);
            startActivity(i);
        }
    }
}

layout文件del_file_name.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="@+id/linearLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/delName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="请输入文件名"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/cancel"
        android:onClick="cancelCreate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="8dp"
        android:text="取消"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/ok"
        android:onClick="startCreate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        android:text="确认"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</android.support.constraint.ConstraintLayout>

权限修改文件AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.aimee.aimee_dealfile">

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

                <!-- <action android:name="android.intent.action.VIEW" /> -->


                <!-- <category android:name="android.intent.category.DEFAULT" /> -->


                <!-- <data android:scheme="file" /> -->
                <!-- <data android:scheme="content" /> -->
                <!-- <data android:mimeType="text/plain" /> -->
            </intent-filter>
        </activity>
        <activity android:name=".InputFileName" />
        <activity android:name=".openFileName" />
        <activity android:name=".saveFile" />
        <activity android:name=".delFileName" />
        <activity android:name=".fileMethodSet"></activity>
    </application>

</manifest>

方法类文件fileMethodSet.java

package com.example.aimee.aimee_dealfile;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

public class fileMethodSet{


    public String read_file(String path_directory,String file_name) throws IOException {
        String path=path_directory+"/"+file_name;
        File file=new File(path);
        if(!file.exists()){
            String new_line="文件不存在";
            return new_line;
        }
        else {
            RandomAccessFile raf = new RandomAccessFile(file, "rwd");
            int j = 0;
            while (raf.readLine() != null) {
                j = j + 1;
            }
            raf.seek(0);
            String new_line = "";
            String tep = "";
            for (int i = 0; i < j; i++) {
                String line = new String(raf.readLine().getBytes("ISO-8859-1"), "utf8");
                tep = line + "
";
                new_line = new_line + tep;
            }
            raf.close();
            return new_line.toString();
        }
    }

    public void write_file(String strcontent,String path_directory,String file_name) throws IOException {
        String strFilePath=path_directory+"/"+file_name;
        String strContent=strcontent;
        File file=new File(strFilePath);
        if(!file.exists()){
            file.createNewFile();
        }
        RandomAccessFile raf=new RandomAccessFile(file,"rwd");
        raf.seek(file.length());
        raf.write(strContent.getBytes());
        raf.close();
    }


    public void del_file(String path_directory,String file_name){
        String path=path_directory+"/"+file_name;
        File file=new File(path);
        file.delete();
    }

    public void create_file(String path_directory,String file_name) throws IOException {
        File file = new File(path_directory);
        if (!file.exists()) {
            file.mkdirs();
        }
        String path = path_directory + "/" + file_name;
        File f = new File(path);
        if (!f.exists()) {
            f.createNewFile();
        }
    }
}

一个简易的增删查改文件处理器就完成了。