Android Studio：NoClassDefFoundError [英] Android Studio: NoClassDefFoundError

问题描述

我正在尝试构建一个使用javamail和gmail的smtp服务发送电子邮件的应用程序，但是当我运行它时，它会在我调用Session.getInstance时崩溃。调试后，它显示它是关于com.sun.mail.util.MailLogger的NoClassDefFoundError。我阅读了其他地方，我必须按顺序添加一个较旧的邮件包获取它，但我仍然收到错误。

以下是我在Android Studio中的内容：

  //获取系统属性
属性properties = System.getProperties（）; 
 
 //安装邮件服务器
 properties.put（mail.smtp.host，host）; 
 properties.put（mail.smtp.auth，true）; 
 properties.put（mail.smtp.starttls.enable，true）; 
 properties.put（mail.transport.protocol，smtp）; 
 properties.put（mail.smtp.port，587）; 
 
 authenticator = getAuthenticator（）; 
 / * getAuthenticator的样子：
返回新的javax.mail.Authenticator（）{
 protected PasswordAuthentication getPasswordAuthentication（）{
返回新的PasswordAuthentication（[e-mail] ，密码）; 
} 
}; 
 * / 
 
 //获取默认的Session对象，使用身份验证
尝试{
 session = Session.getInstance（properties，authenticator）; 
} catch（Error e）{
 //用于调试的不必要的代码
 int hold = 0; 
} 
 
 //创建一个默认的MimeMessage对象。 
 MimeMessage message = new MimeMessage（session）; 
 
尝试{
 // Set From：标题的标题字段。 
 message.setFrom（new InternetAddress（from））; 
 
 //设置为：标题的标题字段。 
 message.addRecipient（Message.RecipientType.TO，new InternetAddress（to））; 
 
 //设定主题：标题栏
 message.setSubject（subject）; 
 
 //现在设置实际的消息
 message.setText（content）; 
 
 //发送消息
 Transport.send（message）; 
 catch（AddressException e）{
 throw new Error（bad address）; 
 catch（MessagingException e）{
 throw new Error（bad message data）; 
} 
  

我的构建看起来像这样：

  apply plugin：'com.android.application'
 android {
 compileSdkVersion 22 
 buildToolsVersion22.0.1
 
 defaultConfig {
 applicationIdcom.bsitpa.myfirstapp
 minSdkVersion 15 
 targetSdkVersion 22 
 versionCode 1 
 versionName1.0
} 
 buildTypes {
 release {
 minifyEnabled false 
 proguardFiles getDefaultProguardFile（'proguard-android.txt'），'proguard-rules.pro'
} 
 } 
 packagingOptions {
 exclude'META-INF / LICENSE.txt'
} 
} 
 
依赖关系{
编译fileTree（包括： ['* .jar']，dir：'libs'）
编译'com.android.support:appcompat-v7:22.2.1'
编译'javax.mail：javax.mail-api： 1.5.3'
 //编译'javax.mail：mail：1.5.0-b01'
编译文件（'mail-1.5.0-b01.jar'）
} 
  

调试错误：
java.lang.NoClassDefFoundError：Lcom / sun / mail / util / MailLogger的解析失败

只要你知道，我完全是AndroidStudio和Gradle的新手。

感谢一下，
Ryan 不知道你是否已经解决了这个问题，但是我发现你需要使用一个Android专用的Java邮件库。

  compile'c​​om.sun.mail：android-mail：1.5.5'
 compile'c​​om.sun。 mail：android-activation：1.5.5'
  

我遇到了你的错误和其他类似的错误最新的Java邮件库，但切换到这些固定的所有。

https://java.net/projects/javamail/pages/Android

I'm trying to build an app that sends an email using javamail and gmail's smtp service, but when I run it it crashes when I call Session.getInstance. After debugging it appears that it's a NoClassDefFoundError regarding com.sun.mail.util.MailLogger. I read elsewhere that I had to add an older mail package in order to get it, but I'm still getting errors.

Here's what I have in Android Studio:

 // Get system properties
    Properties properties = System.getProperties();

    // Setup mail server
    properties.put("mail.smtp.host", host);
    properties.put("mail.smtp.auth", "true");
    properties.put("mail.smtp.starttls.enable", "true");
    properties.put("mail.transport.protocol","smtp");
    properties.put("mail.smtp.port", "587");

    authenticator = getAuthenticator();
    /* What getAuthenticator looks like:
    return new javax.mail.Authenticator() {
        protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication("[e-mail] ", "password");
        }
    };
    */

    // Get the default Session object, with authentication
    try {
        session = Session.getInstance(properties, authenticator);
    } catch (Error e) {
        // Unnecessary code for debugging
        int hold = 0;
    }

    // Create a default MimeMessage object.
    MimeMessage message = new MimeMessage(session);

    try {
        // Set From: header field of the header.
        message.setFrom(new InternetAddress(from));

        // Set To: header field of the header.
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

        // Set Subject: header field
        message.setSubject(subject);

        // Now set the actual message
        message.setText(content);

        // Send message
        Transport.send(message);
    } catch (AddressException e) {
        throw new Error("bad address");
    } catch (MessagingException e){
        throw new Error("bad message data");
    }

And my build looks like this:

apply plugin: 'com.android.application'
android {
     compileSdkVersion 22
     buildToolsVersion "22.0.1"

     defaultConfig {
         applicationId "com.bsitpa.myfirstapp"
         minSdkVersion 15
         targetSdkVersion 22
         versionCode 1
         versionName "1.0"
     }
     buildTypes {
         release {
             minifyEnabled false
             proguardFiles getDefaultProguardFile('proguard-android.txt'),    'proguard-rules.pro'
         }
     }
     packagingOptions {
        exclude 'META-INF/LICENSE.txt'
     }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    compile 'com.android.support:appcompat-v7:22.2.1'
    compile 'javax.mail:javax.mail-api:1.5.3'
    //compile 'javax.mail:mail:1.5.0-b01'
    compile files('mail-1.5.0-b01.jar')
}

The debugging error: "java.lang.NoClassDefFoundError: Failed resolution of Lcom/sun/mail/util/MailLogger"

And just so you know, I am completely new to AndroidStudio and Gradle.

Thanks a ton, Ryan

解决方案

Not sure if you solved this already, but I found you need to use an Android specific Java Mail library.

compile 'com.sun.mail:android-mail:1.5.5'
compile 'com.sun.mail:android-activation:1.5.5'

I was running into your error and other similar ones using the latest Java Mail libraries but switching to these fixed all of them.

https://java.net/projects/javamail/pages/Android

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