我正在使用 Spring Framework 事务注释进行事务管理，并且我有一个 abstract class 注释 @Transactional，如下所示:
package org.tts.maqraa.service;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import javax.persistence.EntityManager;
import javax.persistence.EntityNotFoundException;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
import javax.persistence.Query;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Parts of this code have been copied from JARVANA site.
*
* @author Younis alomoush
*
*/
@Transactional(propagation=Propagation.REQUIRED)
public abstract class AbstractMaqraaService implements MaqraaService {
private Logger logger = LoggerFactory.getLogger(this.getClass());
private int defaultMaxResults = DEFAULT_MAX_RESULTS;
@PersistenceContext(type=PersistenceContextType.TRANSACTION)
private EntityManager em;
/**
* The {@link EntityManager} which is used by all query manipulation and
* execution in this DAO.
*
* @return the {@link EntityManager}
*/
public EntityManager getEntityManager(){
return em;
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#getTypes()
*/
public abstract Set<Class<?>> getTypes();
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#store(java.lang.Object)
*/
@Transactional(propagation = Propagation.REQUIRED)
public <T extends Object> T store(T toStore) {
return getEntityManager().merge(toStore);
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#remove(java.lang.Object)
*/
@Transactional(propagation = Propagation.REQUIRED)
public void remove(Object toRemove) {
toRemove = getEntityManager().merge(toRemove);
getEntityManager().remove(toRemove);
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#flush()
*/
@Transactional(propagation = Propagation.REQUIRED)
public void flush() {
getEntityManager().flush();
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#refresh(java.lang.Object)
*/
@Transactional(propagation = Propagation.SUPPORTS)
public void refresh(Object o) {
try {
if (o != null) {
if (o instanceof java.util.Collection) {
for (Iterator<?> i = ((Collection<?>) o).iterator(); i
.hasNext();) {
try {
refresh(i.next());
} catch (EntityNotFoundException x) {
// This entity has been deleted - remove it from the
// collection
i.remove();
}
}
} else {
if (getTypes().contains(o.getClass())) {
getEntityManager().refresh(o);
}
}
}
} catch (EntityNotFoundException x) {
// This entity has been deleted
}
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#setDefaultMaxResults(int)
*/
@Transactional(propagation = Propagation.SUPPORTS)
public void setDefaultMaxResults(int defaultMaxResults) {
this.defaultMaxResults = defaultMaxResults;
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#getDefaultMaxResults()
*/
public int getDefaultMaxResults() {
return defaultMaxResults;
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByNameSingleResult(java
* .lang.String)
*/
@SuppressWarnings("unchecked")
public <T extends Object> T executeQueryByNameSingleResult(String queryName) {
return (T) executeQueryByNameSingleResult(queryName, (Object[]) null);
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByNameSingleResult(java
* .lang.String, java.lang.Object[])
*/
@SuppressWarnings("unchecked")
public <T extends Object> T executeQueryByNameSingleResult(
String queryName, Object... parameters) {
Query query = createNamedQuery(queryName, DEFAULT_FIRST_RESULT_INDEX,
1, parameters);
return (T) query.getSingleResult();
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByName(java.lang.String)
*/
public <T extends Object> List<T> executeQueryByName(String queryName) {
return executeQueryByName(queryName, DEFAULT_FIRST_RESULT_INDEX,
getDefaultMaxResults());
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByName(java.lang.String,
* java.lang.Integer, java.lang.Integer)
*/
public <T extends Object> List<T> executeQueryByName(String queryName,
Integer firstResult, Integer maxResults) {
return executeQueryByName(queryName, firstResult, maxResults,
(Object[]) null);
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByName(java.lang.String,
* java.lang.Object[])
*/
public <T extends Object> List<T> executeQueryByName(String queryName,
Object... parameters) {
return executeQueryByName(queryName, DEFAULT_FIRST_RESULT_INDEX,
getDefaultMaxResults(), parameters);
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQueryByName(java.lang.String,
* java.lang.Integer, java.lang.Integer, java.lang.Object[])
*/
@SuppressWarnings("unchecked")
public <T extends Object> List<T> executeQueryByName(String queryName,
Integer firstResult, Integer maxResults, Object... parameters) {
Query query = createNamedQuery(queryName, firstResult, maxResults,
parameters);
return query.getResultList();
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#createNamedQuery(java.lang.String,
* java.lang.Integer, java.lang.Integer)
*/
public Query createNamedQuery(String queryName, Integer firstResult,
Integer maxResults) {
return createNamedQuery(queryName, firstResult, maxResults,
(Object[]) null);
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#createNamedQuery(java.lang.String,
* java.lang.Integer, java.lang.Integer, java.lang.Object[])
*/
public Query createNamedQuery(String queryName, Integer firstResult,
Integer maxResults, Object... parameters) {
Query query = getEntityManager().createNamedQuery(queryName);
if (parameters != null) {
for (int i = 0; i < parameters.length; i++) {
query.setParameter(i + 1, parameters[i]);
}
}
query.setFirstResult(firstResult == null || firstResult < 0 ? DEFAULT_FIRST_RESULT_INDEX
: firstResult);
if (maxResults != null && maxResults > 0)
query.setMaxResults(maxResults);
return query;
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#executeQuery(java.lang.String,
* java.lang.Integer, java.lang.Integer, java.lang.Object[])
*/
@SuppressWarnings("unchecked")
public <T extends Object> List<T> executeQuery(String queryString,
Integer firstResult, Integer maxResults, Object... parameters) {
Query query = createQuery(queryString, firstResult, maxResults,
parameters);
return query.getResultList();
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#executeQuery(java.lang.String,
* java.lang.Object[])
*/
@SuppressWarnings("unchecked")
public <T extends Object> List<T> executeQuery(String queryString,
Object... parameters) {
Query query = createQuery(queryString, DEFAULT_FIRST_RESULT_INDEX,
getDefaultMaxResults(), parameters);
return query.getResultList();
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQuerySingleResult(java.lang.
* String)
*/
@SuppressWarnings("unchecked")
public <T extends Object> T executeQuerySingleResult(String queryString) {
return (T) executeQuerySingleResult(queryString, (Object[]) null);
}
/*
* (non-Javadoc)
*
* @see
* org.skyway.spring.util.dao.JpaDao#executeQuerySingleResult(java.lang.
* String, java.lang.Object[])
*/
@SuppressWarnings("unchecked")
public <T extends Object> T executeQuerySingleResult(String queryString,
Object... parameters) {
Query query = createQuery(queryString, DEFAULT_FIRST_RESULT_INDEX, 1,
parameters);
return (T) query.getSingleResult();
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#createQuery(java.lang.String,
* java.lang.Integer, java.lang.Integer)
*/
public Query createQuery(String queryString, Integer firstResult,
Integer maxResults) {
return createQuery(queryString, firstResult, maxResults,
(Object[]) null);
}
/*
* (non-Javadoc)
*
* @see org.skyway.spring.util.dao.JpaDao#createQuery(java.lang.String,
* java.lang.Integer, java.lang.Integer, java.lang.Object[])
*/
public Query createQuery(String queryString, Integer firstResult,
Integer maxResults, Object... parameters) {
Query query = getEntityManager().createQuery(queryString);
if (parameters != null) {
for (int i = 0; i < parameters.length; i++) {
query.setParameter(i + 1, parameters[i]);
}
}
query.setFirstResult(firstResult == null || firstResult < 0 ? DEFAULT_FIRST_RESULT_INDEX
: firstResult);
if (maxResults != null && maxResults > 0)
query.setMaxResults(maxResults);
return query;
}
public final void log(LogLevel logLevel, String message,
Object... messageParam) {
switch (logLevel) {
case TRACE:
if (logger.isTraceEnabled()) {
logger.trace(message, messageParam);
}
break;
case DEBUG:
if (logger.isDebugEnabled()) {
logger.debug(message, messageParam);
}
break;
case INFO:
if (logger.isInfoEnabled()) {
logger.info(message, messageParam);
}
break;
case WARN:
if (logger.isWarnEnabled()) {
logger.warn(message, messageParam);
}
break;
case ERROR:
if (logger.isErrorEnabled()) {
logger.error(message, messageParam);
}
break;
default:
throw new IllegalArgumentException("Log Level is not defined: "
+ logLevel);
}
}
public final void log(LogLevel logLevel, String message, Throwable throwable) {
switch (logLevel) {
case TRACE:
if (logger.isTraceEnabled()) {
logger.trace(message, throwable);
}
break;
case DEBUG:
if (logger.isDebugEnabled()) {
logger.debug(message, throwable);
}
break;
case INFO:
if (logger.isInfoEnabled()) {
logger.info(message, throwable);
}
break;
case WARN:
if (logger.isWarnEnabled()) {
logger.warn(message, throwable);
}
break;
case ERROR:
if (logger.isErrorEnabled()) {
logger.error(message, throwable);
}
break;
default:
throw new IllegalArgumentException("Log Level is not defined: "
+ logLevel);
}
}
public enum LogLevel{
TRACE, DEBUG, INFO, WARN, ERROR;
}
}
另外，我还有一个具体的类
package org.tts.maqraa.service;
import java.lang.annotation.Annotation;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.tts.maqraa.data.Student;
public class StudentsService extends AbstractMaqraaService {
@Override
public Set<Class<?>> getTypes() {
Set<Class<?>> set = new HashSet<Class<?>>();
set.add(Student.class);
return set;
}
public Student registerStudent(Student student) {
Annotation [] annotation = StudentsService.class.getAnnotations();
System.out.println(annotation);
return this.store(student);
}
public Student editStudent(Student student){
return this.store(student);
}
public void deregisterStudent(Student student){
this.remove(student);
}
public List<Student> findAllStudents(){
return this.executeQueryByName("Student.findAll");
}
}
如果你注意到方法 register student 已经提供了代码来检查我真正找到 @Transactional 注释的注释。
这是一个矛盾，我有另一个链接谈到注释的继承，它说根本没有继承。
查看此链接:http://fusionsoft-online.com/articles-java-annotations.php
谁能帮我解决这个矛盾？
最佳答案
是的，如果注释有 @Inherited 是可能的添加到它。例如，@Transactional注释有 @Inherited.
来自文档:
Indicates that an annotation type is automatically inherited. If an Inherited meta-annotation is present on an annotation type declaration, and the user queries the annotation type on a class declaration, and the class declaration has no annotation for this type, then the class's superclass will automatically be queried for the annotation type. This process will be repeated until an annotation for this type is found, or the top of the class hierarchy (Object) is reached. If no superclass has an annotation for this type, then the query will indicate that the class in question has no such annotation.
Note that this meta-annotation type has no effect if the annotated type is used to annotate anything other than a class. Note also that this meta-annotation only causes annotations to be inherited from superclasses; annotations on implemented interfaces have no effect.
@Transactional的文档:
@Target(value={METHOD,TYPE}) @Retention(value=RUNTIME) @Inherited @Documented public @interface Transactional
题外话:尽管在 Java 中，您不能子类型化注解。
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