Jackson3におけるtoml・jsonの読み書き

はじめに

Jacksonとは、JSON(や、その他のテキスト形式)を読み書きできる。

pom

ポイント

• groupId変更に注意(tools.jackson)
• jackson-bomが利用可能

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>org.example</groupId>
  <artifactId>jackson-toml</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>jackson-toml</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.junit</groupId>
        <artifactId>junit-bom</artifactId>
        <version>5.14.0</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
      <dependency>
        <groupId>tools.jackson</groupId>
        <artifactId>jackson-bom</artifactId>
        <version>3.0.0</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.platform</groupId>
      <artifactId>junit-platform-launcher</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter-engine</artifactId>
      <scope>test</scope>
    </dependency>
    <!--  Jackson  -->
    <dependency>
      <groupId>tools.jackson.core</groupId>
      <artifactId>jackson-core</artifactId>
    </dependency>
    <dependency>
      <groupId>tools.jackson.core</groupId>
      <artifactId>jackson-databind</artifactId>
    </dependency>
    <dependency>
      <groupId>tools.jackson.dataformat</groupId>
      <artifactId>jackson-dataformat-toml</artifactId>
    </dependency>
  </dependencies>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>3.5.4</version>
      </plugin>
      <plugin>
        <artifactId>maven-failsafe-plugin</artifactId>
        <version>3.5.4</version>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>21</source>
          <target>21</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

実装&テスト

今回は簡単にするため、JUnitで動作確認を行う

package org.example;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.parallel.ExecutionMode.SAME_THREAD;

import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.parallel.Execution;
import org.junit.jupiter.params.ParameterizedClass;
import org.junit.jupiter.params.provider.MethodSource;
import tools.jackson.core.json.JsonWriteFeature;
import tools.jackson.databind.SerializationFeature;
import tools.jackson.databind.json.JsonMapper;
import tools.jackson.dataformat.toml.TomlMapper;
import tools.jackson.dataformat.toml.TomlReadFeature;

import java.util.stream.Stream;

@Execution(SAME_THREAD)
@ParameterizedClass
@MethodSource("data")
record AppTest(String tomlString, String jsonString) {
    static Stream<String[]> data() {
        String[] s1 = new String[]{"""
foo = 'bar'
[nested]
baz = 4
""", """
{
  "foo" : "bar",
  "nested" : {
    "baz" : 4
  }
}"""};
        return Stream.of(s1, s1).limit(1);
    }

    @Test
    void tomlMapperTest() {
        TestRecord expected = new TestRecord("bar", new TestRecord.Nested(4));
        TestRecord toml = readToml(tomlString);
        assertEquals(expected, toml);
        assertEquals(jsonString, writeJson(toml));
    }

    private TestRecord readToml(String input){
        TomlMapper mapper = TomlMapper.builder()
                .enable(TomlReadFeature.PARSE_JAVA_TIME)
                .build();
        return mapper.readValue(input, TestRecord.class);
    };

    private String writeJson(TestRecord input){
        JsonMapper mapper = JsonMapper.builder()
                .enable(JsonWriteFeature.QUOTE_PROPERTY_NAMES)
                .enable(SerializationFeature.INDENT_OUTPUT)
                .build();
        return mapper.writeValueAsString(input).replace("\r\n", "\n");
    };

    public record TestRecord(String foo, Nested nested){
        public record Nested(int baz){};
    };
}

結果出力