从另一个包添加实体时出现“QuerySyntaxException：用户未映射”答案

【问题标题】："QuerySyntaxException: User is not mapped" when adding an entity from another package从另一个包添加实体时出现“QuerySyntaxException：用户未映射”
【发布时间】：2019-09-07 03:16:00
【问题描述】：

我制作了一个 Hibernate 配置 maven 项目（使用 maven-shade-plugin 构建），以允许我的代码库使用一个统一的“数据库类”。但是，当从正在运行的项目外部调用时，该类似乎没有映射（在运行时引发 org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped 异常）。

在项目中运行时，一切正常。但是，当从项目外部运行时，Hibernate 无法映射实体。

CommonDB.java（maven 包 meta1203-data 的一部分）

package com.meta1203.microservices;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class CommonDB <C extends BaseEntity> {
    private Configuration cfg;
    private SessionFactory sf;
    private Session session;
    private Class<C> c;

    public CommonDB(Class<C> anoClass) {
        String jdbcUrl = String.format(
                "jdbc:mysql://%s/%s",
                System.getenv("DB_URL"),
                System.getenv("DB_NAME"));

        cfg = new Configuration()
                .setProperty("hibernate.connection.url", jdbcUrl)
                .setProperty("hibernate.connection.username", System.getenv("DB_USERNAME"))
                .setProperty("hibernate.connection.password", System.getenv("DB_PASSWORD"))

                .setProperty("hibernate.connection.driver_class", "com.mysql.jdbc.Driver")
                .setProperty("hibernate.connection.pool_size", "1")
                .setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5Dialect")
                .setProperty("hibernate.hbm2ddl.auto", "update")
                .setProperty("hibernate.show_sql", "true")
                .addAnnotatedClass(anoClass.getClass());

        c = anoClass;
    }

    public void open() {
        sf = cfg.buildSessionFactory();
        session = sf.openSession();
    }

    public void close() {
        session.close();
        sf.close();
    }

    public C findOneBy(String field, String o) {
        String query = "select u from " + c.getSimpleName() + " u where u." + field + " = :id";

        return session.createQuery(query, c).setParameter("id", o).getSingleResult();
    }
 // other CRUD functions
}

TestDB.java（maven 包 meta1203-userservice 的一部分）

package com.meta1203.microservices.user;

import com.meta1203.microservices.CommonDB;
import com.meta1203.microservices.user.model.User;

public class TestDB {
    public static void main(String[] args) {
        TestDB tdb = new TestDB();
        CommonDB<User> db = new CommonDB<User>(User.class);
        db.open();

        User hunter = db.findOneBy("username", "hunter");
        System.out.println(hunter.getUsername());
        System.out.println(db.countBy("username", "hunter"));

        db.close();
    }
}

User.java（maven 包 meta1203-userservice 的一部分）

package com.meta1203.microservices.user.model;

import java.util.Set;

import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.Table;

import com.meta1203.microservices.BaseEntity;

@Entity
@Table(name = "users")
public class User extends BaseEntity {
    private String username;

    private String textNotificationList;
    private String emailNotificationList;

    @ElementCollection
    private Set<Long> ignoredAlerts;
    @ElementCollection
    private Set<Long> clients;

    // to be parsed with DateTimeFormatter.ISO_OFFSET_DATE_TIME
    private String lastItineraryUpdate;

     // getters and setters
}

父母的 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>com.meta1203</groupId>
    <artifactId>meta1203-services</artifactId>
    <packaging>pom</packaging>
    <version>0.0.1</version>

    <properties>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.2.0</version>
        </dependency>
        <dependency>
            <groupId>com.meta1203</groupId>
            <artifactId>meta1203-data</artifactId>
            <version>0.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.3.11.Final</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.36</version>
        </dependency>
    </dependencies>
    <modules>
        <module>meta1203-userservice</module>
    </modules>
</project>

Sep 07, 2019 2:36:13 AM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {[WORKING]}
Sep 07, 2019 2:36:13 AM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
Sep 07, 2019 2:36:13 AM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {5.0.4.Final}
Sep 07, 2019 2:36:14 AM org.hibernate.dialect.Dialect <init>
INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
Sep 07, 2019 2:36:14 AM org.hibernate.resource.transaction.backend.jdbc.internal.DdlTransactionIsolatorNonJtaImpl getIsolatedConnection
INFO: HHH10001501: Connection obtained from JdbcConnectionAccess [org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess@329dbdbf] for (non-JTA) DDL execution was not in auto-commit mode; the Connection 'local transaction' will be committed and the Connection will be set into auto-commit mode.
Sep 07, 2019 2:36:14 AM org.hibernate.hql.internal.QueryTranslatorFactoryInitiator initiateService
INFO: HHH000397: Using ASTQueryTranslatorFactory
Exception in thread "main" java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped [select u from User u where u.username = :id]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:138)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:729)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:745)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:104)
    at com.meta1203.microservices.CommonDB.findOneBy(CommonDB.java:72)
    at com.meta1203.microservices.user.TestDB.main(TestDB.java:12)
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped [select u from User u where u.username = :id]
    at org.hibernate.hql.internal.ast.QuerySyntaxException.generateQueryException(QuerySyntaxException.java:79)
    at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:103)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:219)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:143)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:119)
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:153)
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:611)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:720)
    ... 4 more
Caused by: org.hibernate.hql.internal.ast.QuerySyntaxException: User is not mapped
    at org.hibernate.hql.internal.ast.util.SessionFactoryHelper.requireClassPersister(SessionFactoryHelper.java:169)
    at org.hibernate.hql.internal.ast.tree.FromElementFactory.addFromElement(FromElementFactory.java:91)
    at org.hibernate.hql.internal.ast.tree.FromClause.addFromElement(FromClause.java:79)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.createFromElement(HqlSqlWalker.java:331)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElement(HqlSqlBaseWalker.java:3695)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromElementList(HqlSqlBaseWalker.java:3584)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.fromClause(HqlSqlBaseWalker.java:720)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:576)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:313)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:261)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:271)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:191)
    ... 10 more

【问题讨论】：

标签： java hibernate hibernate-mapping

【解决方案1】：

@Entity
@Table(name = "users")
public class User extends BaseEntity {

您的实体称为用户，但它映射到称为用户的表。

要么将实体更改为用户，要么将表更改为用户。

应该可以的。

【讨论】：

不起作用，执行时仍然得到Exception in thread "main" java.lang.IllegalArgumentException: org.hibernate.hql.internal.ast.QuerySyntaxException: Users is not mapped [select u from Users u where u.username = :id]。

【解决方案2】：

试试：

Configuration configuration = new Configuration().configure();
        for (Class cls : getEntityClassesFromPackage("com.example.hib.entities")) {
            configuration.addAnnotatedClass(cls);
        }

【讨论】：

【解决方案3】：

Whelp，我知道发生了什么事。我的银河大脑决定对 Class 对象执行addAnnotatedClass(anoClass.getClass())，所以我试图将 java.lang.Class 声明为 Hibernate Entity...哦，好吧，我只是个白痴。将其更改为 addAnnotatedClass(anoClass) 就可以了。

【讨论】：