我想在本机应用程序上锁屏并在屏幕加载前检查密码

Question

我将应用程序密码存储在应用程序的本地存储中，我只想在 App.js

屏幕呈现之前检查密码

var passwords = null;

function get_passwords() {
        // fetch the user defined settings
        var db = openDatabase({ name: 'trans_DB.db', createFromLocation: '~www/test_Db.db' });
        //to read currency
        db.transaction((tx) => {
            tx.executeSql(
                'SELECT * FROM password_table', [],
                (tx, results) => {
                    var len = results.rows.length;
                    if (len > 0) {
                            passwords = results.rows.item(0).passwords
                    }
                }
            );
        });
    }


function App(){
 get_passwords();
 if(passwords == null){
   return lockScreen(); //contains lockscreen 
 }
else{
    return mainScreen(); //if user didn't set the security to app then render main screen
  }
}

我试过了，但问题是数据库 returns 在从数据库获取值之前，值延迟和屏幕首先加载

Answer 1

您可以在从数据库检索后的状态下设置密码

import React, { useState, useEffect } from 'react';

        function App(){
              const [passwords, setPasswords] = useState("");
               
           // set password 
               useEffect(() => {
                 get_passwords()
               },[]);
             
              const get_passwords = () => {
              // fetch the user defined settings
              var db = openDatabase({
                name: "trans_DB.db",
                createFromLocation: "~www/test_Db.db",
              });
              //to read currency
              db.transaction(tx => {
                tx.executeSql("SELECT * FROM password_table", [], (tx, results) => {
                  var len = results.rows.length;
                  if (len > 0) {
                    passwords = results.rows.item(0).passwords;
                    setPasswords(passwords)
                  }
                });
              });
            };
            
                 if(passwords == ""){
                   return lockScreen(); //contains lockscreen 
                 }
                else{
                    return mainScreen(); //if user didn't set the security to app then render main screen
                  }
                }

我想在本机应用程序上锁屏并在屏幕加载前检查密码

I want lockscreen on react native application and check passwords before screen load

sqlite

react-native

react-native-android