java - 使用 Jackson 和 Lombok 反序列化 ImmutableList
问题描述
我正在尝试使以下示例正常工作:
@Value
@JsonDeserialize(builder = SomeClass.Builder.class)
@Builder(builderClassName = "Builder")
public static class SomeClass {
@Wither
ImmutableList<String> words;
@JsonPOJOBuilder(withPrefix = "")
public static class Builder {
}
}
@Test
@SneakyThrows
public void serializeTest() {
ObjectMapper objectMapper = new ObjectMapper();
SomeClass someClass = SomeClass.builder()
.words(ImmutableList.of("word1", "word2", "word3"))
.build();
String jsonString = objectMapper.writeValueAsString(someClass);
log.info("serialized: {}", jsonString);
SomeClass newSomeClass = objectMapper.readValue(jsonString, SomeClass.class);
log.info("done");
newSomeClass.words.forEach(w -> log.info("word {}", w));
}
但是它失败了
Caused by: java.lang.IllegalArgumentException: Cannot find a deserializer for non-concrete Collection type [collection type; class com.google.common.collect.ImmutableList, contains [simple type, class java.lang.String]]
at com.fasterxml.jackson.databind.deser.BasicDeserializerFactory.createCollectionDeserializer(BasicDeserializerFactory.java:1205)
at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer2(DeserializerCache.java:399)
at com.fasterxml.jackson.databind.deser.DeserializerCache._createDeserializer(DeserializerCache.java:349)
at com.fasterxml.jackson.databind.deser.DeserializerCache._createAndCache2(DeserializerCache.java:264)
从这个答案,我尝试了类似的东西:
@Value
@JsonDeserialize(builder = SomeClass.Builder.class)
@Builder(builderClassName = "Builder")
public static class SomeClass {
@Wither
@JsonDeserialize(using = ImmutableListDeserializer.class)
ImmutableList<String> words;
@JsonPOJOBuilder(withPrefix = "")
public static class Builder {
}
}
@Test
@SneakyThrows
public void serializeTest() {
ObjectMapper objectMapper = new ObjectMapper();
SomeClass someClass = SomeClass.builder()
.words(ImmutableList.of("word1", "word2", "word3"))
.build();
String jsonString = objectMapper.writeValueAsString(someClass);
log.info("serialized: {}", jsonString);
SomeClass newSomeClass = objectMapper.readValue(jsonString, SomeClass.class);
log.info("done");
newSomeClass.words.forEach(w -> log.info("word {}", w));
}
但这失败了:
Caused by: java.lang.IllegalArgumentException: Cannot find a deserializer for non-concrete Collection type [collection type; class com.google.common.collect.ImmutableList, contains [simple type, class java.lang.String]]
由于我正在处理的项目的限制,我无法修改对象映射器。所以我不能简单地做:
objectMapper.registerModule(new GuavaModule());
这会奏效的。
有没有其他直接的方法可以让一个简单的 ImmutableList 反序列化工作?
编辑:我设法得到以下不同的错误:
@Value
@JsonDeserialize(builder = SomeClass.Builder.class)
@Builder(builderClassName = "Builder")
public static class SomeClass {
@Wither
ImmutableList<String> strings;
@JsonPOJOBuilder(withPrefix = "")
public static class Builder {
@JsonDeserialize(using = ImmutableListDeserializer.class)
public Builder strings(ImmutableList<String> strings) {
this.strings = strings;
return this;
}
}
}
@Test
@SneakyThrows
public void serializeTest() {
ObjectMapper objectMapper = new ObjectMapper();
SomeClass someClass = SomeClass.builder()
.strings(ImmutableList.of("word1", "word2", "word3"))
.build();
String jsonString = objectMapper.writeValueAsString(someClass);
log.info("serialized: {}", jsonString);
SomeClass newSomeClass = objectMapper.readValue(jsonString, SomeClass.class);
log.info("done");
newSomeClass.strings.forEach(w -> log.info("word {}", w));
}
抛出:
Caused by: java.lang.IllegalArgumentException: Class com.fasterxml.jackson.datatype.guava.deser.ImmutableListDeserializer has no default (no arg) constructor
如果我可以为 ImmutableListDeserializer 或类似的东西构建一个无参数构造函数,也许这更容易解决
解决方案
- 让 IDE 生成构造函数
- 添加
@JsonCreator
到构造函数 - 添加
ParameterNamesModule
- 添加
GuavaModule
到映射器。 -parameters
使用标志编译
import org.junit.jupiter.api.Test;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.guava.GuavaModule;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
import com.google.common.collect.ImmutableList;
import lombok.AccessLevel;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Singular;
import lombok.Value;
import lombok.With;
import lombok.extern.log4j.Log4j2;
@SuppressWarnings("javadoc")
@Log4j2
public class Q61900327 {
/**
* We add the ParameterNamesModule so Jackson can use the constructor arguments to
* properly map the fields.
*/
static final ObjectMapper OBJECT_MAPPER = new ObjectMapper().registerModule(new GuavaModule())
.registerModule(new ParameterNamesModule())
.registerModule(new Jdk8Module());
/**
* This solution works at the cost of having the IDE generate the constructor.
*/
static class ExplicitConstructorSolution {
@Value
@Builder(toBuilder = true)
public static class SomeClass {
@With
@Singular
private ImmutableList<String> words;
@JsonCreator
public SomeClass(ImmutableList<String> words) {
super();
this.words = words;
}
}
@Test
void serializeTest() throws JsonProcessingException {
var someClass = SomeClass.builder()
.word("word1")
.word("word2")
.word("word3")
.build();
try {
var jsonString = OBJECT_MAPPER.writeValueAsString(someClass);
log.info("serialized: {}", jsonString);
var newSomeClass = OBJECT_MAPPER.readValue(jsonString, SomeClass.class);
newSomeClass.words.forEach(w -> log.info("word {}", w));
}
catch (JsonProcessingException e) {
log.error("someClass could not roundtrip.", e);
throw e;
}
}
}
/**
* Note this solution looks great but unfortunately will cause javadoc to fail with:
* <p>
* {@code
* error: cannot find symbol [ERROR] @AllArgsConstructor(access = AccessLevel.PUBLIC, onConstructor_ =
* { @JsonCreator })}
* <p>
* @see <a href="https://github.com/rzwitserloot/lombok/issues/2137">lombok #2137</a>
*
*/
static class OnConstructorSolution {
@Value
@AllArgsConstructor(access = AccessLevel.PUBLIC, onConstructor_ = { @JsonCreator })
@Builder(toBuilder = true)
public static class SomeClass {
@With
@Singular
private ImmutableList<String> words;
}
@Test
void serializeTest() throws JsonProcessingException {
var someClass = SomeClass.builder()
.word("word1")
.word("word2")
.word("word3")
.build();
try {
var jsonString = OBJECT_MAPPER.writeValueAsString(someClass);
log.info("serialized: {}", jsonString);
var newSomeClass = OBJECT_MAPPER.readValue(jsonString, SomeClass.class);
newSomeClass.words.forEach(w -> log.info("word {}", w));
}
catch (JsonProcessingException e) {
log.error("someClass could not roundtrip.", e);
throw e;
}
}
}
}
起居室:
<?xml version="1.0" encoding="UTF-8" ?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>io.jeffmaxwell.stackoverflow</groupId>
<artifactId>stackoverflow</artifactId>
<version>0.0.1-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
<maven.compiler.source>14</maven.compiler.source>
<maven.compiler.target>14</maven.compiler.target>
<maven.compiler.release>14</maven.compiler.release>
<maven.compiler.parameters>true</maven.compiler.parameters>
<maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
<maven.compiler.showWarnings>true</maven.compiler.showWarnings>
<maven.compiler.verbose>true</maven.compiler.verbose>
<maven-dependency-plugin.version>3.1.2</maven-dependency-plugin.version>
<guava.version>29.0-jre</guava.version>
<junit.version>5.6.2</junit.version>
<log4j2.version>2.13.3</log4j2.version>
<jackson.version>2.11.0</jackson.version>
<lombok.version>1.18.12</lombok.version>
</properties>
<build>
<pluginManagement>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>${maven-compiler-plugin.version}</version>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>${maven-dependency-plugin.version}</version>
<configuration>
<outputXML>true</outputXML>
<verbose>true</verbose>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>${guava.version}</version>
</dependency>
<dependency>
<groupId>org.junit</groupId>
<artifactId>junit-bom</artifactId>
<version>${junit.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson</groupId>
<artifactId>jackson-bom</artifactId>
<version>${jackson.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-bom</artifactId>
<version>${log4j2.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-guava</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jdk8</artifactId>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.module</groupId>
<artifactId>jackson-module-parameter-names</artifactId>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-1.2-api</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-jcl</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>
</project>