Android Studio-java.lang.NoClassDefFoundError
我将Android Studio-java.lang.NoClassDefFoundError,java,android,build,gradle,runtime-error,Java,Android,Build,Gradle,Runtime Error,我将.jar文件添加到项目目录中的lib文件夹中: 接下来,我右键单击每个.jar文件并选择“AddasLibrary” 然后,我将依赖项添加到build.gradle文件: apply plugin: 'com.android.application' android { compileSdkVersion 21 buildToolsVersion "21.1.2" defaultConfig { appli
.jar
文件添加到项目目录中的lib
文件夹中:
接下来,我右键单击每个.jar文件并选择“AddasLibrary”
然后,我将依赖项添加到build.gradle文件:
apply plugin: 'com.android.application'
android {
compileSdkVersion 21
buildToolsVersion "21.1.2"
defaultConfig {
applicationId "com.ryzomarmory.crm.ryzomarmory"
minSdkVersion 16
targetSdkVersion 21
versionCode 1
versionName "1.0"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'lib', include: ['*.jar'])
compile 'com.android.support:appcompat-v7:21.0.3'
compile files('commons-dbcp-1.4.jar')
compile files('commons-pool-1.6.jar')
compile files('mysql-connector-java-5.1.30-bin.jar')
}
当我尝试运行android应用程序时,它会显示java.lang.NoClassDefFoundError
。以下是完整日志:
02-26 11:13:54.671 20960-20960/com.ryzomarmory.crm.ryzomarmory E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.ryzomarmory.crm.ryzomarmory, PID: 20960
java.lang.NoClassDefFoundError: com.mysql.jdbc.jdbc2.optional.MysqlDataSource
at com.ryzomarmory.crm.ryzomarmory.DataSourceFactory.getMySQLDataSource(DataSourceFactory.java:19)
at com.ryzomarmory.crm.ryzomarmory.LoginService.<init>(LoginService.java:13)
at com.ryzomarmory.crm.ryzomarmory.LoginActivity.<init>(LoginActivity.java:18)
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.Class.newInstance(Class.java:1572)
at android.app.Instrumentation.newActivity(Instrumentation.java:1065)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2199)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
转到项目的“libs”文件夹,选择并右键单击yourlibrary.jar,选择“addaslibrary…”。选择OK。清除项目并再次运行
希望这能有所帮助。不建议让您的android应用程序通过JDBC直接连接到DB,原因请参见Mark Murphy。这在技术上是可能的,但您必须进行黑客攻击,这是不值得的,您应该通过与web服务接口,将精力投入到正确的操作中 理想情况下,您希望将数据库调用封装在web服务中,将其放在某个应用程序服务器上,并让您的应用程序通过REST进行交互以获取和更新数据
引入REST层的一个好处是,除了移动应用程序或iOS等之外,您还可以拥有一个web前端。我忘了提到我以前做过这件事,并且不再有再次做这件事的选项。
import javax.sql.DataSource;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;
// establishes a persistent database connection
public class DataSourceFactory {
public static DataSource getMySQLDataSource() {
MysqlDataSource mysqlDS = null;
final Configuration conf = new Configuration();
final String dbHostName = conf.getDbHostname();
final String dbDatabaseName = conf.getDbDatabaseName();
final String dbUsername = conf.getDbUsername();
final String dbPassword = conf.getDbPassword();
try {
mysqlDS = new MysqlDataSource();
mysqlDS.setURL(dbHostName + dbDatabaseName);
mysqlDS.setUser(dbUsername);
mysqlDS.setPassword(dbPassword);
} catch (Exception e) {
throw new IllegalStateException(e);
}
return mysqlDS;
}
}