未能将简单的POJO写入Firebase（Android） [英] Failure to write a simple POJO to Firebase (Android)

问题描述

我试图用一些简单的POJO来使用Firebase Android，但即使使用下面的示例代码，我也会遇到一些异常：

  final Firebase fb = getFirebaseAccess（）; 
 final订阅订阅=新订阅（url，System.currentTimeMillis（））; 
 Firebase subscriptionRef = fb.child（subscriptions）。push（）; 
 subscriptionRef.setValue（subscription）; //抛出的异常
  

// Subscription.java

  public class Subscription {
 
 private String url; 
私人长期订阅; 
 $ b $ public订阅（）{
} 
 
公共订阅（字符串url，long subscribedAt）{
 this.url = url; 
 this.subscribedAt = subscribedAt; 
} 
 
 public String getUrl（）{
 return this.url; 
} 
 
 public void setUrl（String url）{
 this.url = url; 
} 
 
 public long getSubscribedAt（）{
 return this.subscribedAt; 
} 
 
 public void setSubscribedAt（long subscribedAt）{
 this.subscribedAt = subscribedAt; 
 
 
 $ / code $ / pre 
 $ b $ p 
引发以下异常：
 
 
无法解析到快照
 com.fasterxml.jackson.databind.JsonMappingException：找不到类com.mypackage的序列化程序。创建BeanSerializer（避免异常，禁用SerializationFeature.FAIL_ON_EMPTY_BEANS））
没有发现类com.myPackage.Subscription的序列化程序，也没有发现创建BeanSerializer的属性（以避免异常，禁用SerializationFeature.FAIL_ON_EMPTY_BEANS））
 
 
我不明白什么是失败的，因为我保留了公共的默认构造函数，并且每个变量都有它自己的公共getter ... 
 
 
 
任何想法？
 
 
 
顺便说一句，如果我用一个字符串字段或属性映射替换POJO它的工作正常
 
 
 
编辑：
我正在使用Proguard启用缩小。 
我有以下指示： 
 
 
 ＃Firebase 2.0 
＃keep POJOs 
 -keepnames class com.myPackage。** {*; } 
 -keep class com.firebase。** {*; } 
 -keep class org.apache。** {*; } 
 -keepnames class com.fasterxml.jackson。** {*; } 
 -keepnames class javax.servlet。** {*; } 
 -keepnames class org.ietf.jgss。** {*; } 
 -dontwarn org.w3c.dom。** 
 -dontwarn org.joda.time。** 
 -dontwarn org.shaded.apache。** 
 -dontwarn org .ietf.jgss。** 
  
 
 
解决方案
 
文件正在通过Proguard删除，请尝试以下Proguard配置：
 
 pre $ ＃对于Jackson 2.x的Proguard配置（更快的xml包codehaus包）
 
 -keep class com.fasterxml.jackson.databind.ObjectMapper {
 public< methods> ;; 
保护<方法>; 
 
 -keep class com.fasterxml.jackson.databind.ObjectWriter {
 public ** writeValueAsString（**）; 
} 
 
＃Firebase的基本ProGuard规则Android SDK 2.0.0+ 
 
 --keep class com.firebase。** {*; } 
 -keep class org.apache。** {*; } 
 -keepnames class com.fasterxml.jackson。** {*; } 
 -keepnames class javax.servlet。** {*; } 
 -keepnames class org.ietf.jgss。** {*; } 
 -dontwarn org.apache。** 
 -dontwarn org.w3c.dom。** 
 
＃Facebook 
 
 -keep class com。 Facebook。** {*;} 
 -keepattributes签名
 
＃Firebase UI 
 
 -twtwarn com.firebase.ui.auth.twitter。** 
  




I'm trying to use Firebase Android with some simple POJO but I'm getting some exceptions even with the following sample code

final Firebase fb = getFirebaseAccess();
final Subscription subscription = new Subscription(url, System.currentTimeMillis());
Firebase subscriptionRef = fb.child("subscriptions").push();
subscriptionRef.setValue(subscription); // exception thrown here

// Subscription.java

 public class Subscription {

        private String url;
        private long subscribedAt;

        public Subscription() {
        }

        public Subscription(String url, long subscribedAt) {
            this.url = url;
            this.subscribedAt = subscribedAt;
        }

        public String getUrl() {
            return this.url;
        }

        public void setUrl(String url) {
            this.url = url;
        }

        public long getSubscribedAt() {
            return this.subscribedAt;
        }

        public void setSubscribedAt(long subscribedAt) {
            this.subscribedAt = subscribedAt;
        }
    }

The following exception is thrown:

Failed to parse to snapshot com.fasterxml.jackson.databind.JsonMappingException: No serializer found for class com.mypackage.Subscription and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) No serializer found for class com.myPackage.Subscription and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )

I don't understand what's failing because I kept the public default constructor and every variable has its own public getter...

Any idea ?

BTW if I replace the POJO with a String field or a map of attributes it works fine

Edit: I'm using Proguard with minify enabled. I have the following instructions:

# Firebase 2.0
# keep POJOs
-keepnames class com.myPackage.** { *; }
-keep class com.firebase.** { *; }
-keep class org.apache.** { *; }
-keepnames class com.fasterxml.jackson.** { *; }
-keepnames class javax.servlet.** { *; }
-keepnames class org.ietf.jgss.** { *; }
-dontwarn org.w3c.dom.**
-dontwarn org.joda.time.**
-dontwarn org.shaded.apache.**
-dontwarn org.ietf.jgss.**

解决方案

Looks like Jackson related files are being deleted via Proguard, try with the following Proguard Configuration:

    # Proguard configuration for Jackson 2.x (fasterxml package instead of codehaus package)

        -keep class com.fasterxml.jackson.databind.ObjectMapper {
            public <methods>;
            protected <methods>;
        }
        -keep class com.fasterxml.jackson.databind.ObjectWriter {
            public ** writeValueAsString(**);
        }

        # Basic ProGuard rules for Firebase Android SDK 2.0.0+

        -keep class com.firebase.** { *; }
        -keep class org.apache.** { *; }
        -keepnames class com.fasterxml.jackson.** { *; }
        -keepnames class javax.servlet.** { *; }
        -keepnames class org.ietf.jgss.** { *; }
        -dontwarn org.apache.**
        -dontwarn org.w3c.dom.**

# Facebook

-keep class com.facebook.** {*;}
-keepattributes Signature

# Firebase UI

-dontwarn com.firebase.ui.auth.twitter.**

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