NoClassDefFoundError 在 Android 上使用 Jackson 2.2.x 和 Gradle [英] NoClassDefFoundError using Jackson 2.2.x on Android with Gradle

问题描述

对于我的 Android 项目，我使用 Jackson 2.2.x 设置 Gradle，如下所示:

For my Android project I set up Gradle with Jackson 2.2.x as follows:

// build.gradle
buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.6.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 18
    buildToolsVersion "18.1.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 18
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:18.0.0'
    compile 'com.android.support:support-v4:18.0.0'
    compile 'com.google.android.gms:play-services:3.1.36'
    compile 'com.fasterxml.jackson.core:jackson-databind:2.2.+'
    compile 'com.fasterxml.jackson.core:jackson-core:2.2.+'
    compile 'com.fasterxml.jackson.core:jackson-annotations:2.2.+'
}

我只是在这里使用 ObjectMapper:

import com.fasterxml.jackson.databind.ObjectMapper;

// ...

ObjectMapper objectMapper = new ObjectMapper();
try {
    Content content = objectMapper.readValue(inputStream, Content.class);
} catch (IOException e) {
    e.printStackTrace();
}

当我运行 gradle installDebug 并启动应用程序的相关部分时，它崩溃了:

When I run gradle installDebug and launch the relevant part of the application it crashes:

java.lang.NoClassDefFoundError: com.fasterxml.jackson.databind.ObjectMapper

java.lang.NoClassDefFoundError: com.fasterxml.jackson.databind.ObjectMapper

<小时>

想法:

• 我注意到在错误消息中提到了 com.fasterxml.jackson... 而 com.fasterxml.jackson.core 是在 build 中定义的.gradle.是否存在导致问题的不匹配?
• 我暂时将 dependencies 块移动到 android 块中，因为我找到其他以这种方式构建的build.gradle 配置.不过好像没什么区别.

---

Thoughts:

• I noticed that in the error message com.fasterxml.jackson... is mentioned while com.fasterxml.jackson.core is defined in build.gradle. Is there a mismatch causing the problem?
• I temporarily moved the dependencies block into the android block since I found other build.gradle configurations structured this way. However it seems to make no difference.

推荐答案

Gradle 和 Android 并不总是与依赖项很好地放置在一起(目前).运行

Gradle and Android don't always place nicely with dependencies(yet). Running

 gradle clean

似乎为我解决了大部分问题.

seems to fix most problems for me.

注意:如果这不起作用，您可以运行

Note: If that didn't work, you can run

dexdump classes.dex | grep 'Class descriptor'

在 APK 中的 classes.dex 文件上.这将检查该类是否包含在 classes.dex 文件中.(有时，如果您想仔细检查发生了什么，这很有用).

on the classes.dex file in the APK. That will check to see if the class is included in the classes.dex file. (Sometimes it's useful if you want to double check whats going on).

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