1、使用Maven引用mbknor-jackson-jsonschema_2.12

<dependency>
    <groupId>com.kjetland</groupId>
    <artifactId>mbknor-jackson-jsonschema_2.12</artifactId>
    <version>1.0.28</version>
</dependency>

2、生成JsonSchema("additionalProperties" : false)

1）需要import的包

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.kjetland.jackson.jsonSchema.JsonSchemaConfig;
import com.kjetland.jackson.jsonSchema.JsonSchemaGenerator;

2）生成JsonSchema代码

ObjectMapper objectMapper = new ObjectMapper();
JsonSchemaConfig config = JsonSchemaConfig.nullableJsonSchemaDraft4();
JsonSchemaGenerator schemaGenerator = new JsonSchemaGenerator(objectMapper, config);
JsonNode jsonNode = schemaGenerator.generateJsonSchema(Test.class);
String jsonSchemaText = jsonNode.toString();

3）生成的jsonSchemaText

Test.java:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
public class Test {
    @JsonProperty(required = true)
    private final String name;
    private final TestChild child;
    @JsonCreator
    public Test (
            @JsonProperty("name") String name,
            @JsonProperty("child") TestChild child) {
        this.name = name;
        this.child = child;
    }
    public String getName () {
        return name;
    }
    public TestChild getChild () {
        return child;
    }
}

TestChild.java:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
public class TestChild {
    @JsonProperty(required = true)
    private final String childName;
    @JsonCreator
    public TestChild (@JsonProperty("childName") String childName) {
        this.childName = childName;
    }
    public String getChildName () {
        return childName;
    }
}

jsonSchemaText：

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Test",
  "type": "object",
  "additionalProperties": false,
  "properties": {
    "name": {
      "type": "string"
    },
    "child": {
      "oneOf": [
        {
          "type": "null",
          "title": "Not included"
        },
        {
          "$ref": "#/definitions/TestChild"
        }
      ]
    }
  },
  "required": [
    "name"
  ],
  "definitions": {
    "TestChild": {
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "childName": {
          "type": "string"
        }
      },
      "required": [
        "childName"
      ]
    }
  }
}