Java Apache Avro:UnsolvedUnionException在使用union数据类型时发生异常
我使用的是对象序列化 对于Java Apache Avro:UnsolvedUnionException在使用union数据类型时发生异常,java,apache,avro,Java,Apache,Avro,我使用的是对象序列化 对于学校对象,我有一个Avro模式: {"namespace": "com.my.model", "type": "record", "name": "School", "fields": [ {"name": "sid", "type": "int"}, {"name": "size", "type": "long"}, {"name": "other", "type": ["null", "Teacher", "Student"]
学校
对象,我有一个Avro模式:
{"namespace": "com.my.model",
"type": "record",
"name": "School",
"fields": [
{"name": "sid", "type": "int"},
{"name": "size", "type": "long"},
{"name": "other", "type": ["null", "Teacher", "Student"]}
]
}
如上所述,“other”
字段包含一个联合数据类型,它可以是null
或教师
实例或学生
实例
教师对象模式:
{"namespace": "com.my.model",
"type": "record",
"name": "Teacher",
"fields": [
{"name": "isMale", "type": "boolean"}
]
}
{"namespace": "com.my.model",
"type": "record",
"name": "Student",
"fields": [
{"name": "age", "type": "int"}
]
}
学生对象模式:
{"namespace": "com.my.model",
"type": "record",
"name": "Teacher",
"fields": [
{"name": "isMale", "type": "boolean"}
]
}
{"namespace": "com.my.model",
"type": "record",
"name": "Student",
"fields": [
{"name": "age", "type": "int"}
]
}
我用Avro工具编译了上面的模式&Avro自动为我生成了所有Java类
然后,在我的java程序中,我以以下方式创建School
实例:
School school = new School();
school.setSid(3);
school.setSize(2000);
//create a student object
Student student = new Student();
student.setAge(18);
//set student into school instance
school.setOther(student);
如上所示,学校实例的other
字段包含一个学生对象。然而,当我编译代码时,我得到了unsolvedUnionException。它抱怨School
模式的other
字段的联合数据类型。似乎它无法解析我在Java代码中设置为学校的学生
。为什么会出现这种例外?Stacktrace是:
org.apache.avro.UnresolvedUnionException: Not in union ["null",{"type":"record","name":"Student","namespace":"com.my.model","fields":[{"name":"age","type":"long"}]},{"type":"record","name":"Teacher","namespace":"com.model","fields":[{"name":"isMale","type":"boolean"}]}]: false
at org.apache.avro.generic.GenericData.resolveUnion(GenericData.java:561)
at org.apache.avro.generic.GenericDatumWriter.resolveUnion(GenericDatumWriter.java:144)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:71)
at org.apache.avro.generic.GenericDatumWriter.writeRecord(GenericDatumWriter.java:106)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:66)
at org.apache.avro.generic.GenericDatumWriter.writeArray(GenericDatumWriter.java:131)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:68)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:73)
at org.apache.avro.generic.GenericDatumWriter.writeRecord(GenericDatumWriter.java:106)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:66)
at org.apache.avro.generic.GenericDatumWriter.write(GenericDatumWriter.java:58)
我可能弄错了,但我认为联合类型应该只包含一个非默认值:
{
"name": "other",
"type": [
"null",
"Teacher",
"Student"
]
}
应该是:
{
"name": "other",
"type": [
"null",
{
"name": "Visitors",
"symbols": [
"Student",
"Teacher"
],
"type": "enum"
}
]
}