EclipseLink JPA报错：找不到java.util.Setjava.time.DayOfWeek类求助

实体类字段定义 #

@Column(name="DAYS_BITMAP", length=7)
@Convert(converter=DaysOfWeekSetToStringConverter.class)
private Set<DayOfWeek> daysRunning;

转换器实现 #

import java.time.DayOfWeek;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;

@Converter(autoApply = false)
public class DaysOfWeekSetToStringConverter implements AttributeConverter<Set<DayOfWeek>, String>
{

    @Override
    public String convertToDatabaseColumn(Set<DayOfWeek> attribute) {
        char[] result = "0000000".toCharArray();
        for (DayOfWeek dow : attribute)
        {
            result[dow.getValue()-1] = '1';
        }
        return new String(result);
    }

    @Override
    public Set<DayOfWeek> convertToEntityAttribute(String dbData) {
        Set<DayOfWeek> results = new HashSet<>();
        char[] daysOfWeekMonToSun = dbData.toCharArray();
        for (int i=0;i<7;i++) // 7 days in a week
        {
            if (daysOfWeekMonToSun[i] == '1')
            {
                results.add(DayOfWeek.of(i+1)); // days of week are indexed 1 = Monday, 7 = Sunday
            }
        }
        return results;
    }
}

错误日志 #

[EL Fine]: server: Configured server platform: org.eclipse.persistence.platform.server.NoServerPlatform
[EL Fine]: metadata: java.lang.ClassNotFoundException: java.util.Setjava.time.DayOfWeek
    at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.objects.MetadataAsmFactory.getVirtualMetadataClass(MetadataAsmFactory.java:542)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.objects.MetadataAsmFactory.buildClassMetadata(MetadataAsmFactory.java:143)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.objects.MetadataAsmFactory.getMetadataClass(MetadataAsmFactory.java:177)
    at org.eclipse.persistence.internal.jpa.metadata.ORMetadata.getMetadataClass(ORMetadata.java:408)
    at org.eclipse.persistence.internal.jpa.metadata.ORMetadata.getMetadataClass(ORMetadata.java:400)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.classes.ConverterAccessor.initClassificationClasses(ConverterAccessor.java:179)
    at org.eclipse.persistence.internal.jpa.metadata.accessors.classes.ConverterAccessor.<init>(ConverterAccessor.java:85)
    at org.eclipse.persistence.internal.jpa.metadata.MetadataProcessor.initPersistenceUnitClasses(MetadataProcessor.java:378)
    at org.eclipse.persistence.internal.jpa.metadata.MetadataProcessor.processEntityMappings(MetadataProcessor.java:563)
    at org.eclipse.persistence.internal.jpa.deployment.PersistenceUnitProcessor.processORMetadata(PersistenceUnitProcessor.java:625)
    at org.eclipse.persistence.internal.jpa.EntityManagerSetupImpl.predeploy(EntityManagerSetupImpl.java:2001)
    at org.eclipse.persistence.internal.jpa.deployment.JPAInitializer.callPredeploy(JPAInitializer.java:104)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactoryImpl(PersistenceProvider.java:107)
    at org.eclipse.persistence.jpa.PersistenceProvider.createEntityManagerFactory(PersistenceProvider.java:191)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
    at org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.buildEntityManagerFactory(Main.java:94)
    at org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.execute(Main.java:80)
    at org.eclipse.jpt.jpa.eclipselink.core.ddlgen.Main.main(Main.java:68)

解决方案 #

这个错误是因为旧版本EclipseLink解析泛型类型Set<DayOfWeek>时出现BUG，把两个类名直接拼接成了不存在的java.util.Setjava.time.DayOfWeek，可以通过以下方式解决：

方法1：升级EclipseLink版本 #

使用EclipseLink 2.7.0及以上版本，该版本开始完善支持Java 8的泛型和java.time包API。如果用Maven，修改依赖：

<dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>eclipselink</artifactId>
    <version>2.7.10</version> <!-- 或更高稳定版本 -->
</dependency>

方法2：用自定义包装类替代泛型集合 #

如果暂时无法升级，创建一个继承自HashSet<DayOfWeek>的具体类，避免泛型解析问题：

import java.time.DayOfWeek;
import java.util.HashSet;

public class DaysOfWeekSet extends HashSet<DayOfWeek> {
    // 无需额外代码，继承即可
}

修改实体类字段：

@Column(name="DAYS_BITMAP", length=7)
@Convert(converter=DaysOfWeekSetToStringConverter.class)
private DaysOfWeekSet daysRunning;

修改转换器的泛型参数：

public class DaysOfWeekSetToStringConverter implements AttributeConverter<DaysOfWeekSet, String> {

    @Override
    public String convertToDatabaseColumn(DaysOfWeekSet attribute) {
        char[] result = "0000000".toCharArray();
        for (DayOfWeek dow : attribute) {
            result[dow.getValue()-1] = '1';
        }
        return new String(result);
    }

    @Override
    public DaysOfWeekSet convertToEntityAttribute(String dbData) {
        DaysOfWeekSet results = new DaysOfWeekSet();
        char[] daysOfWeekMonToSun = dbData.toCharArray();
        for (int i=0;i<7;i++) {
            if (daysOfWeekMonToSun[i] == '1') {
                results.add(DayOfWeek.of(i+1));
            }
        }
        return results;
    }
}

方法3：确认基础配置 #

• 确保项目使用Java 8及以上版本编译运行，java.time.DayOfWeek是Java 8新增类；
• 在persistence.xml中显式声明实体类和转换器，确保被扫描到：

<persistence-unit name="yourPersistenceUnit">
    <!-- 其他配置 -->
    <class>com.yourpackage.YourEntityClass</class>
    <class>com.yourpackage.DaysOfWeekSetToStringConverter</class>
</persistence-unit>

内容的提问来源于stack exchange，提问作者simonalexander2005