ANDROID：java.lang.NoClassDefFoundError：解析失败：Lcom/mysql/cj/MysqlType

【问题标题】：ANDROID: java.lang.NoClassDefFoundError: Failed resolution of: Lcom/mysql/cj/MysqlTypeANDROID：java.lang.NoClassDefFoundError：解析失败：Lcom/mysql/cj/MysqlType
【发布时间】：2021-10-01 02:54:05
【问题描述】：

我正在尝试将我的项目与 mysql 数据库连接，但在驱动程序中出现此错误：

E/AndroidRuntime: FATAL EXCEPTION: main
        Process: com.example.catalyst, PID: 12531
        java.lang.NoClassDefFoundError: Failed resolution of: Lcom/mysql/cj/MysqlType;
            at com.mysql.cj.protocol.a.NativeProtocol.findMysqlType(NativeProtocol.java:1466)
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.unpackField(ColumnDefinitionReader.java:134)
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:77)
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:40)
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1588)
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:68)
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:48)
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1601)
            at com.mysql.cj.protocol.a.NativeProtocol.readAllResults(NativeProtocol.java:1655)
            at com.mysql.cj.NativeSession.loadServerVariables(NativeSession.java:765)
            at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1303)
            at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:964)
            at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823)
            at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:453)
            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:569)
            at java.sql.DriverManager.getConnection(DriverManager.java:219)
            at modelo.Conexion.conectar(Conexion.java:24)
            at modelo.EnviarIngresos.ejecutarServicio(EnviarIngresos.java:27)
            at GUIs.QRscanner.enviarIngreso(QRscanner.java:75)
            at GUIs.QRscanner.onClick(QRscanner.java:42)
            at android.view.View.performClick(View.java:6297)
            at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119)
            at android.view.View$PerformClick.run(View.java:24797)
            at android.os.Handler.handleCallback(Handler.java:790)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:164)
            at android.app.ActivityThread.main(ActivityThread.java:6626)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)
         Caused by: java.lang.ClassNotFoundException: com.mysql.cj.MysqlType
            at java.lang.VMClassLoader.findLoadedClass(Native Method)
            at java.lang.ClassLoader.findLoadedClass(ClassLoader.java:738)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:363)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
            at com.mysql.cj.protocol.a.NativeProtocol.findMysqlType(NativeProtocol.java:1466) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.unpackField(ColumnDefinitionReader.java:134) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:77) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:40) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1588) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:68) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:48) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1601) 
            at com.mysql.cj.protocol.a.NativeProtocol.readAllResults(NativeProtocol.java:1655) 
            at com.mysql.cj.NativeSession.loadServerVariables(NativeSession.java:765) 
            at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1303) 
            at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:964) 
            at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823) 
            at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:453) 
            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:569) 
            at java.sql.DriverManager.getConnection(DriverManager.java:219) 
            at modelo.Conexion.conectar(Conexion.java:24) 
            at modelo.EnviarIngresos.ejecutarServicio(EnviarIngresos.java:27) 
            at GUIs.QRscanner.enviarIngreso(QRscanner.java:75) 
            at GUIs.QRscanner.onClick(QRscanner.java:42) 
            at android.view.View.performClick(View.java:6297) 
            at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119) 
            at android.view.View$PerformClick.run(View.java:24797) 
            at android.os.Handler.handleCallback(Handler.java:790) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6626) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 
         Caused by: java.lang.NoClassDefFoundError: Failed resolution of: Ljava/sql/SQLType;
            at com.mysql.cj.protocol.a.NativeProtocol.findMysqlType(NativeProtocol.java:1466) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.unpackField(ColumnDefinitionReader.java:134) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:77) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:40) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1588) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:68) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:48) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1601) 
            at com.mysql.cj.protocol.a.NativeProtocol.readAllResults(NativeProtocol.java:1655) 
            at com.mysql.cj.NativeSession.loadServerVariables(NativeSession.java:765) 
            at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1303) 
            at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:964) 
            at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823) 
            at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:453) 
            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:569) 
            at java.sql.DriverManager.getConnection(DriverManager.java:219) 
            at modelo.Conexion.conectar(Conexion.java:24) 
            at modelo.EnviarIngresos.ejecutarServicio(EnviarIngresos.java:27) 
            at GUIs.QRscanner.enviarIngreso(QRscanner.java:75) 
            at GUIs.QRscanner.onClick(QRscanner.java:42) 
            at android.view.View.performClick(View.java:6297) 
            at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119) 
            at android.view.View$PerformClick.run(View.java:24797) 
            at android.os.Handler.handleCallback(Handler.java:790) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6626) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811) 
         Caused by: java.lang.ClassNotFoundException: Didn't find class "java.sql.SQLType" on path: DexPathList[[zip file "/data/app/com.example.catalyst-r_unhHUpn3kJ_xqUGFYc4w==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.catalyst-fumFeudS3H2K2UqSBclr7A==/lib/arm, /system/lib, /system/vendor/lib]]
            at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:125)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
            at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
            at com.mysql.cj.protocol.a.NativeProtocol.findMysqlType(NativeProtocol.java:1466) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.unpackField(ColumnDefinitionReader.java:134) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:77) 
            at com.mysql.cj.protocol.a.ColumnDefinitionReader.read(ColumnDefinitionReader.java:40) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1588) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:68) 
            at com.mysql.cj.protocol.a.TextResultsetReader.read(TextResultsetReader.java:48) 
            at com.mysql.cj.protocol.a.NativeProtocol.read(NativeProtocol.java:1601) 
            at com.mysql.cj.protocol.a.NativeProtocol.readAllResults(NativeProtocol.java:1655) 
            at com.mysql.cj.NativeSession.loadServerVariables(NativeSession.java:765) 
            at com.mysql.cj.jdbc.ConnectionImpl.initializePropsFromServer(ConnectionImpl.java:1303) 
            at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:964) 
            at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:823) 
            at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:453) 
            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:569) 
            at java.sql.DriverManager.getConnection(DriverManager.java:219) 
            at modelo.Conexion.conectar(Conexion.java:24) 
            at modelo.EnviarIngresos.ejecutarServicio(EnviarIngresos.java:27) 
            at GUIs.QRscanner.enviarIngreso(QRscanner.java:75) 
            at GUIs.QRscanner.onClick(QRscanner.java:42) 
            at android.view.View.performClick(View.java:6297) 
            at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:1119) 
            at android.view.View$PerformClick.run(View.java:24797) 
            at android.os.Handler.handleCallback(Handler.java:790) 
            at android.os.Handler.dispatchMessage(Handler.java:99) 
            at android.os.Looper.loop(Looper.java:164) 
            at android.app.ActivityThread.main(ActivityThread.java:6626) 
            at java.lang.reflect.Method.invoke(Native Method) 
            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

 这些是我的依赖项（gradle）：

dependencies {
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'com.google.android.gms:play-services-maps:17.0.1'

    implementation files('libs\\UMLDesignTool.jar')
    implementation files('libs/mysql-connector-java-8.0.25.jar')
    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.0'
    testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.4.0'
    testImplementation 'org.junit.platform:junit-platform-launcher:1.0.0'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
    implementation 'com.journeyapps:zxing-android-embedded:3.4.0'
    androidTestImplementation 'org.junit.jupiter:junit-jupiter'
    androidTestImplementation 'org.testng:testng:6.9.6'
    implementation 'com.android.volley:volley:1.2.0'

}

这是我进行连接的项目类：

import android.os.StrictMode;

import java.sql.Connection;
import java.sql.DriverManager;

public class Conexion {
    private static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
    private static final String DB_URL = "jdbc:mysql://localhost:3306/databasename";
    private static final String USER = "root";
    private static final String PASS = "";


    public Connection conectar(){

        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

        Connection conexion = null;

        try {
            Class.forName(JDBC_DRIVER).newInstance();
            conexion= DriverManager.getConnection(DB_URL, USER, PASS);
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        return conexion;
    }
    
}

错误说我没有驱动，但我有，我不知道该怎么办，我找不到任何与我有相同错误的帖子。

【问题讨论】：

    标签： java android mysql mysql-connector


    【解决方案1】：

    您不能在 Android 上使用最新版本的 MySQL Connector/J，因为它使用了 Android 上不可用的类型和功能。这里的具体原因是com.mysql.cj.MysqlType类型实现了java.sql.SQLType（Java 8 / JDBC 4.2引入），根据错误判断该类型在Android中是不存在的。过去，我也看到过与在正则表达式中使用命名组相关的错误，这些错误在 Android 上（或曾经）也不支持。

    一般来说，您不应该在 Android 上使用 JDBC，最好使用 REST API 在您的 Android 应用程序和数据库之间进行调解。但是，如果您真的想在 Android 中使用 MySQL，则必须使用 MySQL Connector/J 5.1.x 而不是 8.0.x。

    【讨论】：

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