第十一十二周作业

图片一 用内部存储实现文件写入和读取功能

 

package com.example.innerfilesave;
 
import androidx.appcompat.app.AppCompatActivity;
 
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
 
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
 
public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.b1);
        findViewById(R.id.b2);
        EditText editText1=findViewById(R.id.et_in);
        EditText editText2=findViewById(R.id.et_out);
    }
    public void click1(View view){
        EditText editText1=findViewById(R.id.et_in);
        EditText editText2=findViewById(R.id.et_out);
        String filename="data.txt";
        String context=editText1.getText().toString();
        FileOutputStream fos=null;
        try {
            fos=openFileOutput(filename,MODE_PRIVATE);
            fos.write(context.getBytes());
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (fos!=null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        Toast.makeText(this,"保存成功",Toast.LENGTH_SHORT).show();
 
    }
    public void click2(View view){
        EditText editText2=findViewById(R.id.et_out);
        String context="";
        FileInputStream fis=null;
        try {
            fis=openFileInput("data.txt");
            byte[]buffer=new byte[fis.available()];
            fis.read(buffer);
            context=new String(buffer);
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (fis!=null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        editText2.setText(context);
    }
}

 

<?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"
    tools:context=".MainActivity"
    android:orientation="vertical">
 
   <EditText
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:hint="输入你想要写入的内容"
       android:layout_margin="10dp"
       android:id="@+id/et_in"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="写入"
        android:layout_margin="10dp"
        android:id="@+id/b1"
        android:onClick="click1"/>
    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="显示读取的内容"
        android:layout_margin="10dp"
        android:id="@+id/et_out"/>
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="读取"
        android:layout_margin="10dp"
        android:id="@+id/b2"
        android:onClick="click2"/>
 
 
 
</LinearLayout>

 

 

　　

图片二 使用sharedpreference实现记住密码功能

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">
  
<!--    <TextView-->
<!--        android:layout_width="wrap_content"-->
<!--        android:layout_height="wrap_content"-->
<!--        android:text="Hello World!"-->
<!--        app:layout_constraintBottom_toBottomOf="parent"-->
<!--        app:layout_constraintLeft_toLeftOf="parent"-->
<!--        app:layout_constraintRight_toRightOf="parent"-->
<!--        app:layout_constraintTop_toTopOf="parent" />-->
    <TextView
        android:id="@+id/tv1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="账号"
        android:textSize="25dp"
        android:layout_margin="10dp"/>
    <EditText
        android:id="@+id/et1"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:hint="请输入用户名"
        android:layout_toRightOf="@id/tv1"/>
    <TextView
        android:id="@+id/tv2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="密码"
        android:textSize="25dp"
        android:layout_margin="10dp"
        android:layout_below="@id/tv1"/>
    <EditText
        android:id="@+id/et2"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:hint="请输入密码"
        android:layout_toRightOf="@id/tv2"
        android:layout_below="@id/et1"
        android:layout_marginTop="10dp"/>
    <CheckBox
        android:id="@+id/cb1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv2"
        android:onClick="cbclick"/>
    <TextView
        android:id="@+id/tv3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="记住密码"
        android:layout_toRightOf="@id/cb1"
        android:layout_below="@id/tv2"
        android:textSize="20dp"/>
    <CheckBox
        android:id="@+id/cb2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv2"
        android:layout_toRightOf="@id/tv3"/>
    <TextView
        android:id="@+id/tv4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="自动登录"
        android:layout_toRightOf="@id/cb2"
        android:layout_below="@id/tv2"
        android:textSize="20dp" />
    <Button
        android:id="@+id/bt1"
        android:layout_width="100dp"
        android:layout_height="50dp"
        android:text="登录"
        android:layout_toRightOf="@id/tv4"
        android:layout_below="@id/et2"
        android:onClick="btclick"/>

  
import androidx.appcompat.app.AppCompatActivity;
import android.view.View;
import android.widget.EditText;
import android.content.SharedPreferences;
import android.os.Bundle;
  
public class MainAct

　　

</RelativeLayout>　　
 
package com.example.work5_2;ivity extends AppCompatActivity {
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    public void btclick(View view){
        String et1=((EditText)(findViewById(R.id.et1))).getText().toString();
        String et2=((EditText)(findViewById(R.id.et2))).getText().toString();
        SharedPreferences sp=getSharedPreferences("cdate",MODE_PRIVATE);
        SharedPreferences.Editor editor=sp.edit();
        editor.putString("zh", et1);
        editor.putString("mm", et2);
        editor.commit();
    }
    public void cbclick(View view){
        SharedPreferences sp=getSharedPreferences("cdate", MODE_PRIVATE);
        String zh=sp.getString("zh", "");
        String mm=sp.getString("mm", "");
        EditText et1=(EditText)findViewById(R.id.et1);
        EditText et2=(EditText)findViewById(R.id.et2);
        et1.setText(zh);
        et2.setText(mm);
    }
}