如何在构建时使用Maven适当地增强类？OpenJPA

Question

我正在尝试增强（实体）类，因此不会出现以下异常：

Exception in thread "main" <openjpa-3.1.2-r66d2a72 nonfatal user error> org.apache.op
enjpa.persistence.ArgumentException: Attempt to cast instance "entities.EntityPerson@
6dba847b" to PersistenceCapable failed.  Ensure that it has been enhanced.
FailedObject: entities.EntityPerson@6dba847b
    at org.apache.openjpa.kernel.BrokerImpl.assertPersistenceCapable(BrokerImpl.java:486
3)
    at org.apache.openjpa.kernel.BrokerImpl.persistInternal(BrokerImpl.java:2762)
    at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2707)
    at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2690)
    at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2592)
    at org.apache.openjpa.kernel.DelegatingBroker.persist(DelegatingBroker.java:1197)
    at org.apache.openjpa.persistence.EntityManagerImpl.persist(EntityManagerImpl.java:8
37)
    at openjpa.Test/main.Main.main(Main.java:23)

说我正在努力坚持的实例并没有得到加强。

我遵循了这一点：https://openjpa.apache.org/enhancement-with-maven.html官方openjpa页面，并将openjpa maven插件添加到我的pom部分。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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>registry</groupId>
    <artifactId>datalayer</artifactId>
    <version>0.0.1</version>
    <packaging>jar</packaging>

    <properties>
        <maven.compiler.target>11</maven.compiler.target>
        <maven.compiler.source>11</maven.compiler.source>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.sourceEncoding>UTF-8</project.reporting.sourceEncoding>
    </properties>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.1</version>
                </plugin>
                <plugin>
                    <groupId>org.apache.openjpa</groupId>
                    <artifactId>openjpa-maven-plugin</artifactId>
                    <version>3.1.2</version>
                    <configuration>
                        <includes>datalayer/dto/*.class</includes>
                        <addDefaultConstructor>true</addDefaultConstructor>
                        <enforcePropertyRestrictions>true</enforcePropertyRestrictions>
                    </configuration>
                    <executions>
                        <execution>
                            <id>enhancer</id>
                            <phase>process-classes</phase>
                            <goals>
                                <goal>enhance</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.apache.openjpa</groupId>
            <artifactId>openjpa</artifactId>
            <version>3.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
            <version>10.15.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derbytools</artifactId>
            <version>10.15.2.0</version>
        </dependency>
    </dependencies>
</project>

，但我还是有例外。我正在使用Eclipse和内置命令runas-

使用和不使用openjpa-maven-plugin运行mvn安装不会改变任何东西（用相同的. class文件生成相同的. jar，相同的maven输出到控制台）

正如答案所说，在使用Maven构建时，我需要运行openjpa:enhancegoal。事实上，我没有使用openjpamaven插件，所以我解决了这个问题。Maven输出：

[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
[INFO] 
[INFO] -------------------------< registry:datalayer >-------------------------
[INFO] Building datalayer 0.0.1
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ datalayer ---
[INFO] Deleting C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Openjpa.Test\target
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ datalayer ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ datalayer ---
[WARNING] Can't extract module name from geronimo-jms_1.1_spec-1.1.1.jar: geronimo.jm
s.1.1.spec: Invalid module name: '1' is not a Java identifier
[WARNING] Can't extract module name from geronimo-jta_1.1_spec-1.1.1.jar: geronimo.jt
a.1.1.spec: Invalid module name: '1' is not a Java identifier
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 3 source files to C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Op
enjpa.Test\target\classes
[INFO] 
[INFO] --- openjpa-maven-plugin:3.1.2:enhance (default-cli) @ datalayer ---
130  DataLayer  INFO   [main] openjpa.Tool - Enhancer running on type "class entities
.EntityPerson".
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ datalayer ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ datalayer ---
[WARNING] Can't extract module name from geronimo-jms_1.1_spec-1.1.1.jar: geronimo.jm
s.1.1.spec: Invalid module name: '1' is not a Java identifier
[WARNING] Can't extract module name from geronimo-jta_1.1_spec-1.1.1.jar: geronimo.jt
a.1.1.spec: Invalid module name: '1' is not a Java identifier
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 3 source files to C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Op
enjpa.Test\target\classes
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ datalay
er ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 0 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ datalayer 
---
[WARNING] Can't extract module name from geronimo-jta_1.1_spec-1.1.1.jar: geronimo.jt
a.1.1.spec: Invalid module name: '1' is not a Java identifier
[WARNING] Can't extract module name from geronimo-jms_1.1_spec-1.1.1.jar: geronimo.jm
s.1.1.spec: Invalid module name: '1' is not a Java identifier
[INFO] Changes detected - recompiling the module!
[INFO] 
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ datalayer ---
[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ datalayer ---
[INFO] Building jar: C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Openjpa.Test\tar
get\datalayer-0.0.1.jar
[INFO] 
[INFO] --- maven-install-plugin:2.4:install (default-install) @ datalayer ---
[INFO] Installing C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Openjpa.Test\target
\datalayer-0.0.1.jar to C:\Users\wortigson\.m2\repository\registry\datalayer\0.0.1\da
talayer-0.0.1.jar
[INFO] Installing C:\Users\wortigson\Desktop\ISMatrikaBcWorkspace\Openjpa.Test\pom.xm
l to C:\Users\wortigson\.m2\repository\registry\datalayer\0.0.1\datalayer-0.0.1.pom
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS

您可以看到我在EntityPerson类上运行了增强器，这是我测试这个的简单JPA实体。不过我还是有例外。我注意到maven编译器插件：3.8.1:compile运行了两次。openjpa maven插件：3.1.2:enhance前后的openjpa maven插件-这可能是问题吗？

我认为这不是我的情况：如何使用openJPA在构建时从单独的jar增强类？

发现有解决方法尝试将实例强制转换为PersistenceCapable失败。正如公认的答案所说，通过在配置中设置一些属性来确保它得到了增强，但我不想这样做，因为第一条评论说不建议这样做，并指向官方的openjpa页面，在那里我找到了如何在maven构建期间增强类的示例，但正如我所写的，它不起作用。

测试主要方法：

public static void main(String[] args)
    {
        HashMap<String, String> jpaProps = new HashMap<String, String>();
        jpaProps.put("javax.persistence.jdbc.url", "jdbc:derby:testDB;create=true");
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("DataLayer", jpaProps);
        EntityManager manager = factory.createEntityManager();
        EntityPerson person = new EntityPerson();
        person.setAge(25);
        person.setName("Andrej Hruska");
        manager.persist(person); // +
    }

EntityPerson类：

package entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class EntityPerson
{
    @Id
    @GeneratedValue
    private long id;
    
    @Column(nullable = false)
    private String name;
    
    private int age;

    public long getId()
    {
        return id;
    }

    public void setId(long id)
    {
        this.id = id;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getAge()
    {
        return age;
    }

    public void setAge(int age)
    {
        this.age = age;
    }
}

坚持不懈xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.2"
    xmlns="http://xmlns.jcp.org/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence https://www.oracle.com/webfolder/technetwork/jsc/xml/ns/persistence/persistence_2_2.xsd">
    <persistence-unit name="DataLayer"
        transaction-type="RESOURCE_LOCAL">
        <non-jta-data-source>DataSource</non-jta-data-source>
        <properties>
            <property
                name="javax.persistence.schema-generation.database.action"
                value="create" />
            <property name="javax.persistence.jdbc.driver"
                value="org.apache.derby.jdbc.EmbeddedDriver" />
            <property name="javax.persistence.jdbc.url"
                value="jdbc:derby:db;create=true" />
        </properties>
    </persistence-unit>
</persistence>

项目结构：

繁殖步骤：

1. Crete Maven项目在Eclipse
2. 复制我的pom.xml（或添加依赖到derby，openjpa和设置你的openjpa-maven-plugin，名称和路径）
3. 复制我的persistence.xml（或者用一些持久性单元创建自己的）
4. 复制我的EntityPerson类（或者创建简单的JPA实体来测试它）
5. 运行mvn清洁编译openjpa：增强安装（重要部分是openjpa：增强）
6. 尝试持久化实体，就像我在主方法中所做的那样




Answer 1

一些误解。

我尝试过只使用openjpa maven插件而不使用maven编译器插件，但没有任何帮助。

Maven的pom.xml被认为是“项目对象模型”，这意味着，对于你的“项目”来说，它是“建模”构建过程的“对象”。此对象从嵌入在Maven内部的父pom.xml中进行子类化，该pom.xml定义了默认构建；因此，如果您删除了“maven-编译器-插件”，您将获得默认的“maven-编译器-插件”配置。很可能配置很旧，与Maven一起发货，你可能最好包括一个“覆盖”来更新它。

Eclpise和Maven一起工作；但是，除非你知道它们是如何协同工作的，否则你会遇到很多问题。

Eclipse读取pom。xml文件并生成一个Eclipse配置，该配置应执行与pom相同的步骤。html" target="_blank">xml文件，以相同的方式。当您使用Eclipse编译时，它不会运行mvn compile，它基于Eclipse配置构建，该配置可能比最近编辑的pom更旧。xml。因此，您应该在每次编辑pom之后重新阅读项目配置。使用ecplise时使用xml。

如果您想查看与Eclipse类似的不同IDE；但是，调用mvncile而不是调用自己的interperted版本“应该是相同的，但通常不是”，看看NetBeans。https://netbeans.apache.org/download/nb122/index.html与Ecplipse不同，它不包含自己的Maven插件（或自己的嵌入式编译器）的“命令镜像”，它使用mvn命令和javac编译器，并通过配置启动它们以生成大量输出消息，然后读取这些消息以更新其“IDE端”的内容。

我指出这一点的原因是，您可能正在按照说明进行操作，如果是，您可能会从命令行在mvn包上看到正确的输出，但在Eclipse中看不到（因为需要从源pom.xml刷新Eclipse项目）

Answer 2

您需要告诉maven运行增强目标。

mvn clean compile openjpa:enhance

您应该看到这个输出：

[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ jpa-example ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 2 source files to /home/gordon/docs/programming/openjpa/jpa-example/target/classes
[INFO] 
[INFO] --- openjpa-maven-plugin:3.1.2:enhance (default-cli) @ jpa-example ---
[INFO] 

马文有等级制度。顶部是由作为插件目标实现的阶段组成的生命周期。包装决定了一个阶段的目标。

增强目标不是构建或编译的默认目标之一。

在eclipse中，如果更改pom。xml您需要右键单击并选择Maven-

Answer 3

将插件定义移动到from

<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>registry</groupId>
    <artifactId>datalayer</artifactId>
    <version>0.0.1</version>
    <packaging>jar</packaging>

    <properties>
        <maven.compiler.target>11</maven.compiler.target>
        <maven.compiler.source>11</maven.compiler.source>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.sourceEncoding>UTF-8</project.reporting.sourceEncoding>
    </properties>

    <build>
        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.1</version>
                </plugin>
            </plugins>
        </pluginManagement>
        <plugins>
                <plugin>
                    <groupId>org.apache.openjpa</groupId>
                    <artifactId>openjpa-maven-plugin</artifactId>
                    <version>3.1.2</version>
                    <configuration>
                        <includes>datalayer/dto/*.class</includes>
                        <addDefaultConstructor>true</addDefaultConstructor>
                        <enforcePropertyRestrictions>true</enforcePropertyRestrictions>
                    </configuration>
                    <executions>
                        <execution>
                            <id>enhancer</id>
                            <phase>process-classes</phase>
                            <goals>
                                <goal>enhance</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>
       </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.apache.openjpa</groupId>
            <artifactId>openjpa</artifactId>
            <version>3.1.2</version>
        </dependency>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derby</artifactId>
            <version>10.15.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derbytools</artifactId>
            <version>10.15.2.0</version>
        </dependency>
    </dependencies>
</project>

插件管理仅用于配置——插件不会自动运行。