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

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, stdoutlog4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.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

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