调用getNextException以查看原因：如何使Hibernate / JPA显示数据库服务器消息中的异常

Question

我正在使用Postgresql，Hibernate和JPA。每当数据库中出现异常时，我都会得到类似这样的信息，因为它没有显示出数据库服务器上真正出了什么问题，所以它不是很有帮助。

Caused by: java.sql.BatchUpdateException: Batch entry 0 update foo set ALERT_FLAG='3' was aborted.  Call getNextException to see the cause.
    at org.postgresql.jdbc2.AbstractJdbc2Statement$BatchResultHandler.handleError(AbstractJdbc2Statement.java:2621)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1837)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:407)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeBatch(AbstractJdbc2Statement.java:2754)
    at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeBatch(NewProxyPreparedStatement.java:1723)
    at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:70)
    at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:268)
    ... 82 more

我希望数据库中的异常消息出现在应用程序的日志中。

我遇到过这篇文章，该文章使用Aspect填充异常链，否则在SQLExceptions情况下无法正确填充异常链。

有没有一种方法可以解决此问题，而无需使用Aspects或任何自定义代码。理想的解决方案将仅涉及配置文件更改。

Answer 1

无需编写任何自定义代码即可实现此目的-
默认情况下，Hibernate将记录异常原因。如果看不到此内容，则必须正确设置Hibernate日志记录。这是slf4j +
log4j的示例，并使用Maven进行依赖项管理。

src / main / java / pgextest / PGExceptionTest.java

public class PGExceptionTest {

    public static void main(String[] args) throws Exception {

        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory(
                "pgextest");
        EntityManager entityManager = entityManagerFactory.createEntityManager();
        entityManager.getTransaction().begin();
        // here I attempt to persist an object with an ID that is already in use
        entityManager.persist(new PGExceptionTestBean(1));
        entityManager.getTransaction().commit();
        entityManager.close();
    }
}

src / main / resources / log4j.properties

log4j.rootLogger=ERROR, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

src / main / resources / META-INF / persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
        version="2.0">
    <persistence-unit name="pgextest">
        <properties>
            <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/>
            <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost/pgextest"/>
            <property name="javax.persistence.jdbc.user" value="postgres"/>
            <property name="javax.persistence.jdbc.password" value="postgres"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
            <property name="hibernate.jdbc.batch_size" value="5"/>
        </properties>
    </persistence-unit>
</persistence>

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>pgextest</groupId>
    <artifactId>pgextest</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>3.6.9.Final</version>
        </dependency>

        <dependency>
            <groupId>postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <version>9.1-901.jdbc4</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.1</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.15</version>
            <scope>runtime</scope>
        </dependency>
    </dependencies>
</project>

然后执行main方法将记录以下内容：

ERROR [main] - Batch entry 0 insert into PGExceptionTestBean (label, id) values (NULL, '1') was aborted.  Call getNextException to see the cause.
ERROR [main] - ERROR: duplicate key value violates unique constraint "pgexceptiontestbean_pkey"

这也许值得一提的是，您可以禁用JDBC批处理，通过属性设置包装原始异常hibernate.jdbc.batch_size到0（不用说了你可能不希望这样做生产。）