json - 使用 Hibernate-GORM 时，如何将域类转换为 JSON 字符串？

Question

为了在 Micronaut 1.1.1 中使用 Hibernate-GORM，我使用以下命令创建一个 micronaut 应用程序：

mn create-app foo -l=groovy -f=hibernate-gorm

而且，为了增加接近 JSON 的能力，我在 build.gradle 中添加了以下行，以便使用 JsonSlurper 接近 JSON：

compile 'org.codehaus.groovy:groovy-all:2.5.6'

所以我的 build.grade 如下所示：

plugins {
    id "io.spring.dependency-management" version "1.0.6.RELEASE"
    id "groovy"
    id "com.github.johnrengelman.shadow" version "4.0.2"
    id "application"
}

version "0.1"
group "memberservice"

repositories {
    mavenCentral()
    maven { url "https://jcenter.bintray.com" }
}

dependencyManagement {
    imports {
        mavenBom 'io.micronaut:micronaut-bom:1.1.1'
    }
}

configurations {
    // for dependencies that are needed for development only
    developmentOnly 
}

dependencies {
    compile 'org.codehaus.groovy:groovy-all:2.5.6'
    compile "io.micronaut:micronaut-runtime-groovy"
    compile "io.micronaut:micronaut-validation"
    compile "io.micronaut:micronaut-http-client"
    compile "io.micronaut.configuration:micronaut-hibernate-validator"
    compile "io.micronaut.configuration:micronaut-hibernate-gorm"
    compile "io.micronaut:micronaut-http-server-netty"
    compileOnly "io.micronaut:micronaut-inject-groovy"
    runtime "ch.qos.logback:logback-classic:1.2.3"
    runtime "com.h2database:h2"
    runtime "org.apache.tomcat:tomcat-jdbc"
    testCompile("org.spockframework:spock-core") {
        exclude group: "org.codehaus.groovy", module: "groovy-all"
    }
    testCompile "io.micronaut:micronaut-inject-groovy"
    testCompile "io.micronaut.test:micronaut-test-spock"
}

test.classpath += configurations.developmentOnly

mainClassName = "memberservice.Application"
tasks.withType(GroovyCompile) {
    groovyOptions.forkOptions.jvmArgs.add('-Dgroovy.parameters=true')
}

shadowJar {
    mergeServiceFiles()
}

run.classpath += configurations.developmentOnly
run.jvmArgs('-noverify', '-XX:TieredStopAtLevel=1', '-Dcom.sun.management.jmxremote')

现在我有一个域类如下：

import grails.gorm.annotation.Entity

@Entity
class Member {
    String memberId
    String email

    static constraints = {
        memberId    maxSize: 20, nullable: false, unique: true
        email       maxSize: 60, nullable: false
    }
}

我有一个控制器如下：

import groovy.json.JsonBuilder
import groovy.util.logging.Slf4j
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import memberservice.domain.Member

@Slf4j
@Controller('/member')
class MemberController {


    @Get('/testFetchMember')
    def testFetchMember() {
        Member member
        Member.withTransaction {
            member = Member.findByMemberId('A0001')
        }
        log.info("member.email is ${member.email}")
        def jsonObject = new JsonBuilder(member)
        log.info("check point 1001: finish JsonBuilder")
        String jsonString = jsonObject.toPrettyString()
        log.info("jsonString=" + jsonString)
        return jsonString
    }

    @Get('/buildSampleData')
    def buildSampleData() {
        Member member = new Member()
        member.with {
            memberId = 'A0001'
            email = '[e-mail]'
        }
        Member.withTransaction {
            member.save()
//            new Member(memberId: 'A0002', '[e-mail]').save()
//            new Member(memberId: 'A0003', '[e-mail]').save()
        }
        return "Sample data built done"
    }
}

以下是输出日志：

09:23:30.610 [pool-2-thread-1] INFO  m.controller.MemberController - member.email is [e-mail]
09:23:30.619 [pool-2-thread-1] INFO  m.controller.MemberController - check point 1001: finish JsonBuilder
09:23:31.069 [pool-2-thread-1] ERROR i.m.h.s.netty.RoutingInBoundHandler - Unexpected error occurred: null
java.lang.StackOverflowError: null
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaBeanProperty.getProperty(MetaBeanProperty.java:59)
at groovy.lang.PropertyValue.getValue(PropertyValue.java:42)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.getProperties(DefaultGroovyMethods.java:557)
at groovy.json.DefaultJsonGenerator.getObjectProperties(DefaultJsonGenerator.java:242)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:236)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)
    .....
    .....
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:221)
at groovy.json.DefaultJsonGenerator.writeMapEntry(DefaultJsonGenerator.java:387)
at groovy.json.DefaultJsonGenerator.writeMap(DefaultJsonGenerator.java:375)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:237)
at groovy.json.DefaultJsonGenerator.writeObject(DefaultJsonGenerator.java:164)
at groovy.json.DefaultJsonGenerator.writeIterator(DefaultJsonGenerator.java:402)
at groovy.json.DefaultJsonGenerator.writeArray(DefaultJsonGenerator.java:285)

似乎 JsonSlurper 和 JsonBuilder 都无法处理从 GORM 构建的域类。

那么，有没有什么优雅的方法可以在 Micronaut 中将域类转换为 JSON 字符串？请不要让我使用Jackson库，因为Jackson的方法非常紧迫。

我知道在 Grails 中，转换器 JSON 可以毫无问题地将域类转换为 JSON 字符串。那么，是否可以像 Grails 一样将 JSON 转换器的功能添加到 Micronaut 中？

标签： jsonhibernategrails-ormmicronaut

Answer 1

而不是这个...

@Controller('/member')
class MemberController {


    @Get('/testFetchMember')
    def testFetchMember() {
        Member member
        Member.withTransaction {
            member = Member.findByMemberId('A0001')
        }
        log.info("member.email is ${member.email}")
        def jsonObject = new JsonBuilder(member)
        log.info("check point 1001: finish JsonBuilder")
        String jsonString = jsonObject.toPrettyString()
        log.info("jsonString=" + jsonString)
        return jsonString
    }
}

你可以这样做...

@Controller('/member')
class MemberController {


    @Get('/testFetchMember')
    Member testFetchMember() {
        Member member
        Member.withTransaction {
            member = Member.findByMemberId('A0001')
        }
        log.info("member.email is ${member.email}")
        member
    }
}

如果您的控制器操作返回 POJO/POGO/等，它将使用 Jackson 序列化为 JSON。

仅供参考...我不会.withTransaction在控制器操作中做这些事情，但这与提出的问题无关。