java - 如何修复共享首选项以保存我的数据并跳过 Activity ？

Question

我想使用“共享首选项”来保存我的用户名和密码，它已保存，但在我第二次打开应用程序时不起作用。

 import android.content.Intent;
 import android.content.SharedPreferences;
 import android.graphics.Typeface;
 import android.icu.text.IDNA;
 import android.support.v4.media.RatingCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.view.animation.Animation;
 import android.view.animation.AnimationUtils;
 import android.widget.Button;
 import android.widget.EditText;
 import android.widget.ImageView;
 import android.widget.TextView;
 import android.widget.Toast;

public class Login_page extends AppCompatActivity {

TextView tv_user, tv_pass;
EditText tx_user, tx_pass;
Button btn_login;
ImageView img_ghorme;

SharedPreferences save;

public void findall()
{
    tv_user = (TextView)findViewById(R.id.tv_user);
    tv_pass = (TextView)findViewById(R.id.tv_pass);
    tx_user = (EditText)findViewById(R.id.tx_user);
    tx_pass = (EditText)findViewById(R.id.tx_pass);
    btn_login = (Button)findViewById(R.id.btn_login);
    img_ghorme = (ImageView)findViewById(R.id.img_ghorme);
}



public String save_user = "";
public String save_pass = "";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login_page2);

    findall();



    if(save_user.equals("admin") && save_pass.equals("admin"))
    {

        Intent skip = new Intent(Login_page.this, food_page.class);
        startActivity(skip);
    }


    btn_login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String user = tx_user.getText()+"";
            String pass = tx_pass.getText()+"";

            save_user = save.getString("username", "");
            save_pass = save.getString("password", "");

            SharedPreferences.Editor e = save.edit();
            e.putString("username", user);
            e.putString("password", pass);
            e.apply();



            if(user.equals("admin") && pass.equals("admin"))
            {

                Intent food = new Intent(Login_page.this, food_page.class);
                startActivity(food);

            }

            if (!user.equals("admin") || !pass.equals("admin"))
            {

                e.putString("username", "");
                e.putString("password", "");
                e.apply();

                tx_user.setText("");
                tx_pass.setText("");
            }
        }
    });



    save = getSharedPreferences("user", MODE_PRIVATE);
    save = getSharedPreferences("pass", MODE_PRIVATE);

    Typeface font_shabnam = Typeface.createFromAsset(getAssets(),"fonts/Shabnam.ttf");
    Typeface font_shabnam_light = Typeface.createFromAsset(getAssets(),"fonts/Shabnam_Light.ttf");
    Typeface font_shabnam_bold = Typeface.createFromAsset(getAssets(),"fonts/Shabnam.ttf");

    tv_user.setTypeface(font_shabnam_bold);
    tv_pass.setTypeface(font_shabnam_bold);
    tx_user.setTypeface(font_shabnam_light);
    tx_pass.setTypeface(font_shabnam_light);
    btn_login.setTypeface(font_shabnam_bold);


    Animation ani_rtl = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_ltr);
    Animation ani_ltr = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_rtl);
    Animation ani_fade = AnimationUtils.loadAnimation(Login_page.this, R.anim.fade);
    Animation ani_dtu = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_dtu);

    tv_user.setVisibility(View.VISIBLE);
    tv_user.startAnimation(ani_rtl);

    tv_pass.setVisibility(View.VISIBLE);
    tv_pass.startAnimation(ani_rtl);

    tx_user.setVisibility(View.VISIBLE);
    tx_user.startAnimation(ani_ltr);

    tx_pass.setVisibility(View.VISIBLE);
    tx_pass.startAnimation(ani_ltr);

    btn_login.setVisibility(View.VISIBLE);
    btn_login.startAnimation(ani_fade);

    img_ghorme.startAnimation(ani_dtu);

}

@Override
protected void onPause() {
    super.onPause();
    finish();
    }
}

<小时/>

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="com.home.seesion10.Login_page"
android:layoutDirection="rtl"
android:textDirection="rtl"
android:background="@color/textShiri">

<ImageView
    android:id="@+id/img_ghorme"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:srcCompat="@drawable/cirlcleghormesabzi"
    android:layout_marginTop="1500dp"
    app:layout_constraintTop_toTopOf="parent"
    android:layout_marginLeft="100dp"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintVertical_bias="0.902"
    android:layout_marginStart="100dp" />

<TextView
    android:id="@+id/tv_user"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="15dp"
    android:layout_marginTop="20dp"
    android:text="نام کاربری"
    android:textSize="15sp"
    android:visibility="invisible"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<EditText
    android:id="@+id/tx_user"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="80dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="10dp"
    android:background="@drawable/tx_bg"
    android:drawableLeft="@drawable/ic_user"
    android:ems="10"
    android:hint="نام کاربری"
    android:inputType="textPersonName"
    android:padding="10dp"
    android:text=""
    android:textColor="@color/textShiri"
    android:textColorHint="@color/textShiri"
    android:visibility="invisible"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/tv_user" />

<TextView
    android:id="@+id/tv_pass"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="15dp"
    android:layout_marginTop="20dp"
    android:text="رمز عبور"
    android:textSize="15sp"
    android:visibility="invisible"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/tx_user" />

<EditText
    android:id="@+id/tx_pass"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginLeft="80dp"
    android:layout_marginRight="30dp"
    android:layout_marginTop="10dp"
    android:background="@drawable/tx_bg"
    android:drawableLeft="@drawable/ic_pass"
    android:ems="15"
    android:hint="........."
    android:inputType="textPassword"
    android:padding="10dp"
    android:text=""
    android:textColor="@color/textShiri"
    android:textColorHint="@color/textShiri"
    android:visibility="invisible"
    app:layout_constraintHorizontal_bias="1.0"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/tv_pass" />

<Button
    android:id="@+id/btn_login"
    android:layout_width="122dp"
    android:layout_height="50dp"
    android:layout_marginBottom="0dp"
    android:layout_marginLeft="8dp"
    android:layout_marginRight="8dp"
    android:layout_marginTop="20dp"
    android:background="@drawable/btn_bg"
    android:text="ورود"
    android:textColor="@color/textShiri"
    android:visibility="invisible"
    app:layout_constraintBottom_toTopOf="@+id/img_ghorme"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintRight_toRightOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/tx_pass" />



 </android.support.constraint.ConstraintLayout>

我预计当我为用户名和密码写入 admin admin 时，它会保存它，并且第二次打开应用程序时它会跳过该登录页面，但它不起作用并再次显示登录页面

Answer 1

在使用sharedPreference并为每个 key 对定义两个sharedPreference之前，您没有初始化它。如下更改您的代码。

public class Login_page extends AppCompatActivity {

TextView tv_user, tv_pass;
EditText tx_user, tx_pass;
Button btn_login;
ImageView img_ghorme;

SharedPreferences save;

public void findall()
{
    tv_user = findViewById(R.id.tv_user);
    tv_pass = findViewById(R.id.tv_pass);
    tx_user = findViewById(R.id.tx_user);
    tx_pass = findViewById(R.id.tx_pass);
    btn_login = findViewById(R.id.btn_login);
    img_ghorme = findViewById(R.id.img_ghorme);
}



public String save_user = "";
public String save_pass = "";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main2);

    findall();

    save = getSharedPreferences("userInfo", MODE_PRIVATE);
    save_user = save.getString("username", "");
    save_pass = save.getString("password", "");


    if(save_user.equals("admin") && save_pass.equals("admin"))
    {

        Intent skip = new Intent(Login_page.this, food_page.class);
        startActivity(skip);
    }


    btn_login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
            String user = tx_user.getText().toString();
            String pass = tx_pass.getText().toString();


            SharedPreferences.Editor e = save.edit();
            e.putString("username", user);
            e.putString("password", pass);
            e.apply();



            if(user.equals("admin") && pass.equals("admin"))
            {

                Intent food = new Intent(Login_page.this, food_page.class);
                startActivity(food);

            }

            if (!user.equals("admin") || !pass.equals("admin"))
            {

                e.putString("username", "");
                e.putString("password", "");
                e.apply();

                tx_user.setText("");
                tx_pass.setText("");
            }
        }
    });


    Typeface font_shabnam = Typeface.createFromAsset(getAssets(),"fonts/Shabnam.ttf");
    Typeface font_shabnam_light = Typeface.createFromAsset(getAssets(),"fonts/Shabnam_Light.ttf");
    Typeface font_shabnam_bold = Typeface.createFromAsset(getAssets(),"fonts/Shabnam.ttf");

    tv_user.setTypeface(font_shabnam_bold);
    tv_pass.setTypeface(font_shabnam_bold);
    tx_user.setTypeface(font_shabnam_light);
    tx_pass.setTypeface(font_shabnam_light);
    btn_login.setTypeface(font_shabnam_bold);


    Animation ani_rtl = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_ltr);
    Animation ani_ltr = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_rtl);
    Animation ani_fade = AnimationUtils.loadAnimation(Login_page.this, R.anim.fade);
    Animation ani_dtu = AnimationUtils.loadAnimation(Login_page.this, R.anim.animation_dtu);

    tv_user.setVisibility(View.VISIBLE);
    tv_user.startAnimation(ani_rtl);

    tv_pass.setVisibility(View.VISIBLE);
    tv_pass.startAnimation(ani_rtl);

    tx_user.setVisibility(View.VISIBLE);
    tx_user.startAnimation(ani_ltr);

    tx_pass.setVisibility(View.VISIBLE);
    tx_pass.startAnimation(ani_ltr);

    btn_login.setVisibility(View.VISIBLE);
    btn_login.startAnimation(ani_fade);

    img_ghorme.startAnimation(ani_dtu);

}

@Override
protected void onPause() {
    super.onPause();
    finish();
}

}