Kotlin开发：如何将SharedPreferences存储的密码从设置Fragment传递到锁屏Fragment

你已经通过SharedPreferences完成了密码持久化存储，无需额外做跨页面参数传递，直接在锁屏页读取相同SP文件的密码即可完成校验，以下是完整实现说明与代码修正：

现有代码问题修正 #

你当前clear()方法存在逻辑错误：存储passwordStatus时是和密码同存在名为Password的SP文件中，但清除时你单独创建了名为passwordStatus的SP文件操作，会导致清除密码功能不生效，修改后的代码如下：

private fun clear() {
    val passKey = "Password"
    val sharedPreference =
        requireActivity().getSharedPreferences(passKey, Context.MODE_PRIVATE)
    sharedPreference.edit().clear().apply()
}

锁屏页读取密码实现 #

直接在LockScreenFragment中读取同一SP文件的存储内容即可，修改后的LockScreenFragment代码如下：

class LockScreenFragment : Fragment() {
    // 定义SP文件名常量，和设置页保持一致
    private val PASS_KEY = "Password"

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_lock_screen, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // 读取SP中存储的密码和密码状态
        val sharedPref = requireActivity().getSharedPreferences(PASS_KEY, Context.MODE_PRIVATE)
        val savedPassword = sharedPref.getString("password", "")
        val isPasswordSet = sharedPref.getBoolean("passwordStatus", false)
        
        // 此处添加密码校验逻辑：获取用户在锁屏页输入的密码和savedPassword比对即可
        // 示例逻辑参考：
        // val inputPassword = view.findViewById<EditText>(R.id.lock_password_input).text.toString()
        // if (inputPassword == savedPassword) {
        //     // 校验通过，跳转至主页面
        // } else {
        //     // 提示密码错误
        // }
    }
}

附：原代码中文翻译（含提示文本） #

密码存储核心代码 #

private fun createPassword() {
    val passKey = "Password"
    val sharedPreference =
        requireActivity().getSharedPreferences(passKey, Context.MODE_PRIVATE)
    val editor = sharedPreference.edit()
    editor.putString("password", mSetPasswordBinding.password.text.toString())
    editor.putBoolean("passwordStatus", true)
    editor.apply()
}

CreatePasswordFragment完整代码 #

class CreatePasswordFragment : DialogFragment() {
    lateinit var mSetPasswordBinding: FragmentCreatePasswordBinding

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // 加载当前Fragment的布局
        mSetPasswordBinding =
            DataBindingUtil.inflate(
                layoutInflater,
                R.layout.fragment_create_password,
                container,
                false
            )
        mSetPasswordBinding.submit.setOnClickListener {
            checkPassword()
        }
        mSetPasswordBinding.clear.setOnClickListener {
            clear()
        }
        val passKey = "Password"
        val sharedPreference =
            requireActivity().getSharedPreferences(passKey, Context.MODE_PRIVATE)
        sharedPreference.getString("password", "defaultName")
        mSetPasswordBinding.submit.text = sharedPreference.getString("password", "")

        if (sharedPreference.getBoolean("passwordStatus", false)) {
            mSetPasswordBinding.passwordStatus.text = "修改密码"
        }
        return mSetPasswordBinding.root
    }

    private fun checkPassword(): Boolean {
        val getEditTextValue = mSetPasswordBinding.password.text.toString()
        val getRepeatEditTextValue = mSetPasswordBinding.repeat.text.toString()

        if (getEditTextValue != getRepeatEditTextValue) {
            mSetPasswordBinding.repeatL.error = "两次输入的密码不一致"
        } else {
            mSetPasswordBinding.repeatL.error = null
            createPassword()
            Toast.makeText(activity, "密码设置成功", Toast.LENGTH_SHORT).show()
            findNavController().popBackStack()
            return true
        }
        return true
    }

    private fun createPassword() {
        val passKey = "Password"
        val sharedPreference =
            requireActivity().getSharedPreferences(passKey, Context.MODE_PRIVATE)
        val editor = sharedPreference.edit()
        editor.putString("password", mSetPasswordBinding.password.text.toString())
        editor.putBoolean("passwordStatus", true)
        editor.apply()
    }

    private fun clear() {
        val passKey = "Password"
        val sharedPreference =
            requireActivity().getSharedPreferences(passKey, Context.MODE_PRIVATE)
        sharedPreference.edit().clear().apply()
    }
}

密码设置页布局代码（中文提示版本） #

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

<LinearLayout xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/for_pop_up_square"
    android:orientation="vertical"
    android:id="@+id/t1"
    tools:context=".ui.createPassword.CreatePasswordFragment">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="50dp"
            android:id="@+id/passwordStatus"
            android:layout_marginLeft="2dp"
            android:layout_marginTop="5dp"
            android:layout_marginRight="2dp"
            android:gravity="center"
            android:text="登录密码"
            android:textColor="@color/black"
            android:textSize="20sp" />
    </FrameLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20sp"
        android:layout_marginTop="20sp"
        android:layout_marginRight="20sp"
        android:orientation="vertical">

        <com.google.android.material.textfield.TextInputLayout
            android:id="@+id/cardNumberLt"
            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="登录密码">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/password"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:inputType="textPassword" />
        </com.google.android.material.textfield.TextInputLayout>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20sp"
        android:layout_marginTop="20sp"
        android:layout_marginRight="20sp"
        android:orientation="vertical">

        <com.google.android.material.textfield.TextInputLayout
            android:id="@+id/repeatL"
            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="确认密码">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/repeat"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:inputType="textPassword" />
        </com.google.android.material.textfield.TextInputLayout>
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="20sp"
        android:layout_marginTop="20sp"
        android:layout_marginRight="20sp"
        android:layout_marginBottom="30sp"
        android:orientation="vertical">

        <com.google.android.material.textfield.TextInputLayout
            android:id="@+id/rememberl"
            style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="密码提示">
            <com.google.android.material.textfield.TextInputEditText
                android:id="@+id/remember"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:inputType="textPassword" />
        </com.google.android.material.textfield.TextInputLayout>
    </LinearLayout>

    <Button
        android:id="@+id/submit"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:text="确认"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/clear"
        android:layout_marginLeft="30dp"
        android:layout_marginRight="30dp"
        android:text="清除密码"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

内容的提问来源于stack exchange，提问作者AmirHossein