I have a third party library class (from Apache Axis) that I want to serialize by Jackson JSON:
public class NonNegativeInteger extends BigInteger { public NonNegativeInteger(byte[] val) { super(val); checkValidity(); } // ctor public NonNegativeInteger(int signum, byte[] magnitude) { super(signum, magnitude); checkValidity(); } // ctor public NonNegativeInteger(int bitLength, int certainty, Random rnd) { super(bitLength, certainty, rnd); checkValidity(); } // ctor public NonNegativeInteger(int numBits, Random rnd) { super(numBits, rnd); checkValidity(); } // ctor public NonNegativeInteger(String val) { super(val); checkValidity(); } public NonNegativeInteger(String val, int radix) { super(val, radix); checkValidity(); } // ctor /** * validate the value against the xsd definition */ private BigInteger zero = new BigInteger("0"); private void checkValidity() { if (compareTo(zero) < 0) { throw new NumberFormatException( Messages.getMessage("badNonNegInt00") + ": " + this); } } // checkValidity /** * Work-around for http://developer.java.sun.com/developer/bugParade/bugs/4378370.html * @return BigIntegerRep * @throws ObjectStreamException */ public Object writeReplace() throws ObjectStreamException { return new BigIntegerRep(toByteArray()); } protected static class BigIntegerRep implements java.io.Serializable { private byte[] array; protected BigIntegerRep(byte[] array) { this.array = array; } protected Object readResolve() throws java.io.ObjectStreamException { return new NonNegativeInteger(array); } } } I have my entity class containing a NonNegativeInteger field that I want to serialize by JSON:
public class TestEntity { private NonNegativeInteger number; public NonNegativeInteger getNumber() { return number; } public void setNumber(NonNegativeInteger number) { this.number = number; } } When I serialize the above object by Jackson JSON, I got the following error:
Can not instantiate value of type [simple type, class org.apache.axis.types.NonNegativeInteger] from Integral number; no single-int-arg constructor/factory method Then I looked at the POST request entity, it is actually {"number" : 10} as serialized by Jackson. But since NonNegativeInteger doesn't have a constructor taking a single-int, Jackson can't instantiate a NonNegativeInteger object. So I followed someone's suggestions to add a Mixin class for NonNegativeInteger so that it will have a constructor with int as arg:
public abstract class NonNegativeIntegerMixin extends NonNegativeInteger { @JsonCreator public NonNegativeIntegerMixin(int val) { super(String.valueOf(val)); } } Then I registered it in my JSON configuration class:
objectMapper.addMixInAnnotations(NonNegativeInteger.class, NonNegativeIntegerMixin.class); But it doesn't help, it still reported the same error. I tried manually writing the JSON request body to be {"number": "10"} then it worked well. But my client side used Jackson to serialize NonNegativeInteger. Jackson automatically converts to {"number": 10} without quotes. How can I fix this error?
Edit:
The NonNegativeInteger class doesn't have any class field (except a constant zero field). The number key is from my TestEntity class. So I even if I add @JsonProperty annotation in my NonNegativeIntegerMixin mixin class, Jackson JSON will not instantiate a NonNegativeInteger with an int type arg. Therefore, I still got the same error.