java - 连接到 MySql 数据库时，Andriod studios 应用程序崩溃

Question

目前，我在 android studios 中的应用程序在尝试连接到 MySql 数据库时崩溃。使用调试模式，它显示崩溃发生在我的 MainActivity.java 的第 46 行。

Connection connection = DriverManager.getConnection("jdbc:mysql://192.168.0.124:3306/android","andro","andro");

奇怪的是，当使用错误的密码连接时，它会吐出这个错误代码

java.sql.SQLException: Access denied for user 'andro'@'LAPTOP-NFKLKR3L' (using password: YES)

如果有帮助，这是完整的代码和 logcat

MainActivity.java

package de.vogella.mysql.androidmysql;

import androidx.appcompat.app.AppCompatActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class MainActivity extends AppCompatActivity {

    TextView text, errorText;
    Button show;

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

        text = (TextView) findViewById(R.id.textView);
        errorText = (TextView) findViewById(R.id.textView2);
        show = (Button) findViewById(R.id.button);

        show.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                new Task().execute();
            }
        });
    }

    class Task extends AsyncTask <Void, Void, Void>{
        String records="", error="";

        @Override
        protected Void doInBackground(Void... voids) {
            try{
                Class.forName("com.mysql.cj.jdbc.Driver");
                //Connection connection = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/android","root","test123");
                Connection connection = DriverManager.getConnection("jdbc:mysql://192.168.0.124:3306/android","andro","andro");
                Statement statement = connection.createStatement();
                //ResultSet resultSet = statement.executeQuery("Select * FROM new_table");
                ResultSet resultSet = statement.executeQuery("Select * FROM test");

                while (resultSet.next()){
                    records +=   resultSet.getString(1) + " " + resultSet.getString(2) + "\n";
                }
            }
            catch (Exception e){
                error = e.toString();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            text.setText(records);
            if (error != "")
                errorText.setText(error);
            super.onPostExecute(aVoid);
        }
    }
}'''

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="67dp"
        android:text="TextView"
        android:textSize="24sp"
        app:layout_constraintBottom_toTopOf="@+id/button"
        app:layout_constraintStart_toStartOf="@+id/button" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="4dp"
        android:layout_marginBottom="56dp"
        android:text="Show Records"
        android:textSize="24sp"
        app:layout_constraintBottom_toTopOf="@+id/textView2"
        app:layout_constraintStart_toStartOf="@+id/textView2" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="28dp"
        android:layout_marginBottom="264dp"
        android:text="No Error"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

日志猫

2021-05-03 22:11:19.111 5369-5428/de.vogella.mysql.androidmysql E/AndroidRuntime: FATAL EXCEPTION: AsyncTask #1
    Process: de.vogella.mysql.androidmysql, PID: 5369
    java.lang.RuntimeException: An error occurred while executing doInBackground()
        at android.os.AsyncTask$4.done(AsyncTask.java:415)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:383)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:252)
        at java.util.concurrent.FutureTask.run(FutureTask.java:271)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at java.lang.Thread.run(Thread.java:923)
     Caused by: java.lang.NoClassDefFoundError: Failed resolution of: Ljava/sql/SQLType;
        at com.mysql.cj.jdbc.DatabaseMetaData.getInstance(DatabaseMetaData.java:765)
        at com.mysql.cj.jdbc.ConnectionImpl.getMetaData(ConnectionImpl.java:1175)
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:444)
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
        at java.sql.DriverManager.getConnection(DriverManager.java:580)
        at java.sql.DriverManager.getConnection(DriverManager.java:218)
        at de.vogella.mysql.androidmysql.MainActivity$Task.doInBackground(MainActivity.java:46)
        at de.vogella.mysql.androidmysql.MainActivity$Task.doInBackground(MainActivity.java:38)
        at android.os.AsyncTask$3.call(AsyncTask.java:394)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
        at java.lang.Thread.run(Thread.java:923) 
     Caused by: java.lang.ClassNotFoundException: Didn't find class "java.sql.SQLType" on path: DexPathList[[zip file "/data/app/~~THuka99suUWYu1b7kAZCNQ==/de.vogella.mysql.androidmysql-b1gObJE34c5dALSARnq7UQ==/base.apk"],nativeLibraryDirectories=[/data/app/~~THuka99suUWYu1b7kAZCNQ==/de.vogella.mysql.androidmysql-b1gObJE34c5dALSARnq7UQ==/lib/x86, /system/lib, /system_ext/lib]]
        at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:207)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
        at com.mysql.cj.jdbc.DatabaseMetaData.getInstance(DatabaseMetaData.java:765) 
        at com.mysql.cj.jdbc.ConnectionImpl.getMetaData(ConnectionImpl.java:1175) 
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:444) 
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) 
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) 
        at java.sql.DriverManager.getConnection(DriverManager.java:580) 
        at java.sql.DriverManager.getConnection(DriverManager.java:218) 
        at de.vogella.mysql.androidmysql.MainActivity$Task.doInBackground(MainActivity.java:46) 
        at de.vogella.mysql.androidmysql.MainActivity$Task.doInBackground(MainActivity.java:38) 
        at android.os.AsyncTask$3.call(AsyncTask.java:394) 
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) 
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641) 
        at java.lang.Thread.run(Thread.java:923) 
2021-05-03 22:11:19.239 5369-5428/de.vogella.mysql.androidmysql I/Process: Sending signal. PID: 5369 SIG: 9

标签： javaandroidmysql