在 java spring 应用程序 eclipselink 中更改 ORM

Question

我想在我的 spring 应用程序中使用 EclipseLink ORM，但我不知道如何将默认 Hibernate 更改为 EclipseLink。我将依赖项添加到我的 pom.xml 文件中。

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.microsoft.sqlserver</groupId>
            <artifactId>mssql-jdbc</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa</artifactId>
            <version>2.7.4</version>
        </dependency>
        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

接下来我用 EclipseLinkJpaConfiguration 创建了配置文件

package com.example.configuration;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.persistence.config.PersistenceUnitProperties;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.autoconfigure.transaction.TransactionManagerCustomizers;
import org.springframework.context.annotation.Configuration;
import org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver;
import org.springframework.orm.jpa.vendor.AbstractJpaVendorAdapter;
import org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter;
import org.springframework.transaction.jta.JtaTransactionManager;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;


@Configuration 
public class EclipseLinkJpaConfiguration extends JpaBaseConfiguration { 

    protected EclipseLinkJpaConfiguration(DataSource dataSource, JpaProperties properties, 
            ObjectProvider<JtaTransactionManager> jtaTransactionManager, 
            ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers) {
        super(dataSource, properties, jtaTransactionManager);
    }
    
    @Override 
    protected AbstractJpaVendorAdapter createJpaVendorAdapter() { 
        return new EclipseLinkJpaVendorAdapter(); 
    }
    
    @Override
    protected Map<String, Object> getVendorProperties() {
        HashMap<String, Object> map = new HashMap<>();
        map.put(PersistenceUnitProperties.WEAVING, true);
        map.put(PersistenceUnitProperties.DDL_GENERATION, "drop-and-create-tables");
        return map;
    }
    
    private String detectWeavingMode() {
        return InstrumentationLoadTimeWeaver.isInstrumentationAvailable() ? "true" : "static";
    }
}

最后我创建了 EclipseLinkFactory

package com.example.demo;

import java.lang.module.Configuration;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

public class EclipseLinkFactory{
    private EntityManagerFactory efact;
    private EntityManager eman;
    
    public EntityManager getSessionFactory() {
        efact = Persistence.createEntityManagerFactory("cars-pu");
        eman = efact.createEntityManager();
        
        return eman; 
    }

    public EntityManager getEntityManager() {
        return this.eman;
    }
    
    public EntityManagerFactory getEntityManagerFactory() {
        return this.efact;
    }
    
    public EntityTransaction getTransaction() {
        return this.eman.getTransaction();
    }
}

但是当我运行服务器时，我得到了这个错误

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project demo: Compilation failure: Compilation failure:
[ERROR] /D:/test/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[13,42] package org.springframework.orm.jpa.vendor does not exist
[ERROR] /D:/test/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[14,42] package org.springframework.orm.jpa.vendor does not exist
[ERROR] /D:/test/compare_frameworks_orm/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[15,43] package org.springframework.transaction.jta does not exist
[ERROR] /D:/test/compare_frameworks_orm/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[26,40] cannot find symbol
[ERROR]   symbol:   class JtaTransactionManager
[ERROR]   location: class com.example.configuration.EclipseLinkJpaConfiguration
[ERROR] /D:/test/compare_frameworks_orm/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[32,15] cannot find symbol
[ERROR]   symbol:   class AbstractJpaVendorAdapter
[ERROR]   location: class com.example.configuration.EclipseLinkJpaConfiguration
[ERROR] /D:/test/compare_frameworks_orm/java-eclipselink/src/main/java/com/example/configuration/EclipseLinkJpaConfiguration.java:[33,20] cannot find symbol
[ERROR]   symbol:   class EclipseLinkJpaVendorAdapter
[ERROR]   location: class com.example.configuration.EclipseLinkJpaConfiguration
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

我做错了什么？

第二种方法 我还找到了 persistence.xml 文件的方法，它可能更容易，但我不知道如何正确地做到这一点。我只需要在 src 中创建 META-INF 文件并在其中创建文件 persistence.xml?接下来在pom.xml 中添加依赖项org.eclipse.persistence.jpa 和mysql-connector-java，所以当我运行服务器maven 时应该下载所有包。最后我应该在persistence.xml 中添加模型并使用EntityManager eman 来获取具有关系等的实体？

为了生成项目结构，我使用了 Spring Initializr。 我有问题，因为我发现了太多信息，我不知道如何处理它。请帮帮我。

Answer 1

如果你想从休眠状态迁移，你必须完成这些任务。

1: Convert the Hibernate Entity Annotation

2: Convert the Hibernate Custom Sequence Generator Annotation

3: Convert Hibernate Mapping Annotations

4: Modify the persistence.xml File

5: Convert Hibernate API to EclipseLink API

Read More

我认为你还必须添加 Spring Transaction 依赖项

Spring Transaction