Android Studio中SQLite+Kotlin登录注册验证失败问题求助

问题根源分析 #

以下代码中的几个错误导致登录时提示“无效的用户名和密码”：

• 注册参数顺序颠倒：RegisterActivity调用db.register时，密码和邮箱参数传递顺序错误，导致数据库中密码字段存储的是邮箱值，登录时无法匹配。
• 登录控件ID错误：LoginActivity使用了注册页面的控件ID获取输入，实际读取的不是登录页面的用户名和密码内容。
• 游标管理不规范：数据库查询游标未使用安全的资源管理方式，存在内存泄漏风险。

修复后的代码实现 #

1. 修正RegisterActivity参数传递 #

package com.example.app

import android.content.Intent
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class RegisterActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_register)

        val regUserName = findViewById<EditText>(R.id.regUuserNameSection)
        val regEmail = findViewById<EditText>(R.id.regemailSection)
        val regPassword = findViewById<EditText>(R.id.regpasswordSection)
        val confirm = findViewById<EditText>(R.id.regConformPasswordSection)
        val regButton = findViewById<Button>(R.id.regButton)
        val loginText = findViewById<TextView>(R.id.registration)

        loginText.setOnClickListener {
            startActivity(Intent(this, LoginActivity::class.java))
        }

        regButton.setOnClickListener {
            val username = regUserName.text.toString().trim()
            val email = regEmail.text.toString().trim()
            val password = regPassword.text.toString().trim()
            val conform = confirm.text.toString().trim()
            val db = Data(applicationContext, "healthcare", null, 1)

            if (username.isEmpty() || email.isEmpty() || password.isEmpty() || conform.isEmpty()) {
                Toast.makeText(this, "请填写所有信息", Toast.LENGTH_SHORT).show()
            } else {
                if (password == conform) {
                    if (isValid(password)) {
                        db.register(username, password, email) // 修正参数顺序
                        Toast.makeText(this, "注册成功", Toast.LENGTH_SHORT).show()
                        startActivity(Intent(this, LoginActivity::class.java))
                    } else {
                        Toast.makeText(this, "密码需包含至少8个字符、一个大写字母、一个数字和一个特殊符号", Toast.LENGTH_LONG).show()
                    }
                } else {
                    Toast.makeText(this, "两次输入的密码不一致", Toast.LENGTH_SHORT).show()
                }
            }
        }
    }

    private fun isValid(password: String): Boolean {
        val passwordRegex = Regex("^(?=.*[A-Z])(?=.*[!@#\$&*])(?=.*[0-9])(?=.{9,17}).*$")
        return password.matches(passwordRegex)
    }
}

2. 修正LoginActivity控件ID #

（注意：请根据实际登录布局文件调整控件ID）

package com.example.app

import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class LoginActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_login)

        // 使用登录页面正确的控件ID
        val edUserName: EditText = findViewById(R.id.loginUsername)
        val edPassword: EditText = findViewById(R.id.loginPassword)
        val loginButton: Button = findViewById(R.id.loginButton)
        val newRegister: TextView = findViewById(R.id.toRegister)
        val db = Data(applicationContext, "healthcare", null, 1)

        loginButton.setOnClickListener {
            val username = edUserName.text.toString().trim()
            val password = edPassword.text.toString().trim()

            if (username.isEmpty() || password.isEmpty()) {
                Toast.makeText(this, "请填写用户名和密码", Toast.LENGTH_SHORT).show()
            } else {
                if (db.login(username, password) == 1) {
                    Toast.makeText(this, "登录成功", Toast.LENGTH_SHORT).show()
                    val sharedPref = getSharedPreferences("share_prefs", Context.MODE_PRIVATE)
                    sharedPref.edit().putString("username", username).apply()
                    startActivity(Intent(this, HomeActivity::class.java))
                } else {
                    Toast.makeText(this, "无效的用户名或密码", Toast.LENGTH_SHORT).show()
                }
            }
        }

        newRegister.setOnClickListener {
            startActivity(Intent(this, RegisterActivity::class.java))
        }
    }
}

3. 修正Data类的数据库操作 #

package com.example.app

import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper

class Data(
    context: Context?,
    name: String?,
    factory: SQLiteDatabase.CursorFactory?,
    version: Int
) : SQLiteOpenHelper(context, name, factory, version) {

    override fun onCreate(db: SQLiteDatabase) {
        val query = "CREATE TABLE $TABLE_NAME ($USERNAME_COL TEXT, $PASSWORD_COL TEXT, $EMAIL_COL TEXT)"
        db.execSQL(query)
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        db?.execSQL("DROP TABLE IF EXISTS $TABLE_NAME")
        onCreate(db!!)
    }

    fun register(username: String, password: String, email: String) {
        val cv = ContentValues().apply {
            put(USERNAME_COL, username)
            put(PASSWORD_COL, password)
            put(EMAIL_COL, email)
        }

        writableDatabase.use { db ->
            db.insert(TABLE_NAME, null, cv)
        }
    }

    fun login(username: String, password: String): Int {
        var result = 0
        val selectionArgs = arrayOf(username, password)
        readableDatabase.use { db ->
            db.rawQuery("SELECT * FROM $TABLE_NAME WHERE $USERNAME_COL =? AND $PASSWORD_COL =?", selectionArgs).use { cursor ->
                if (cursor.moveToFirst()) {
                    result = 1
                }
            }
        }
        return result
    }

    companion object {
        const val TABLE_NAME = "users"
        const val USERNAME_COL = "username"
        const val PASSWORD_COL = "password"
        const val EMAIL_COL = "email"
    }
}

额外注意事项 #

• 确保登录布局文件的控件ID与LoginActivity中使用的ID完全一致
• 生产环境中建议对密码进行加密存储（如SHA-256）
• 可添加用户名唯一性校验，避免重复注册

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