Ankur
ef05f9024e
37 runnable examples covering the eight feature posts on ankurm.com, verified against Jackson 3.2.1 on Temurin 21.0.5. Every output committed under docs/ was produced by run-all.sh. Also documents 11 places where the published snippets do not compile or do not behave as printed against a real Jackson 3 build - most notably that writeValueAsString(List<Base>) silently drops the polymorphic type discriminator, so the post's serialised output cannot be read back.
44 lines
1.7 KiB
Java
44 lines
1.7 KiB
Java
package com.ankurm.jackson3.part4custom;
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import tools.jackson.core.JsonGenerator;
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import tools.jackson.databind.SerializationContext;
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import tools.jackson.databind.ValueSerializer;
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import tools.jackson.databind.json.JsonMapper;
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import tools.jackson.databind.module.SimpleModule;
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/**
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* BEYOND THE POST — the rename that breaks every custom handler on upgrade.
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*
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* Jackson 2's JsonSerializer<T>/JsonDeserializer<T> are gone. The Jackson 3 names
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* are ValueSerializer<T>/ValueDeserializer<T>. Extending ValueSerializer directly
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* (rather than StdSerializer) is the leanest form and shows the rename plainly.
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*/
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public class E05ValueSerializerDirect {
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public record UserId(String value) { }
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/** Renders the wrapper as a bare JSON string rather than {"value":"..."}. */
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static class UserIdSerializer extends ValueSerializer<UserId> {
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@Override
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public void serialize(UserId id, JsonGenerator gen, SerializationContext ctxt) {
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gen.writeString(id.value());
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}
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}
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public record Ticket(UserId assignee, String title) { }
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public static void main(String[] args) {
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SimpleModule module = new SimpleModule("UserIdModule");
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module.addSerializer(UserId.class, new UserIdSerializer());
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JsonMapper mapper = JsonMapper.builder().addModule(module).build();
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System.out.println("custom : "
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+ mapper.writeValueAsString(new Ticket(new UserId("u-42"), "Fix build")));
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System.out.println("default : "
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+ JsonMapper.builder().build()
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.writeValueAsString(new Ticket(new UserId("u-42"), "Fix build")));
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System.out.println("base class: "
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+ UserIdSerializer.class.getSuperclass().getName());
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}
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}
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