Java 类是否可以继承超类的注释
我使用Spring框架事务性注释进行事务管理,我有一个Java 类是否可以继承超类的注释,java,spring,class,inheritance,annotations,Java,Spring,Class,Inheritance,Annotations,我使用Spring框架事务性注释进行事务管理,我有一个抽象类注释@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.persisten
抽象类注释@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;
}
}
package org.tts.maqraa.service;
导入java.util.Collection;
导入java.util.Iterator;
导入java.util.List;
导入java.util.Set;
导入javax.persistence.EntityManager;
导入javax.persistence.EntityNotFoundException;
导入javax.persistence.PersistenceContext;
导入javax.persistence.PersistenceContextType;
导入javax.persistence.Query;
导入org.springframework.transaction.annotation.Propagation;
导入org.springframework.transaction.annotation.Transactional;
导入org.slf4j.Logger;
导入org.slf4j.LoggerFactory;
/**
*此代码的部分内容已从JARVANA站点复制。
*
*@author Younis alomoush
*
*/
@事务性(传播=传播。必需)
公共抽象类AbstractMaqraaService实现了MaqraaService{
私有记录器Logger=LoggerFactory.getLogger(this.getClass());
private int defaultMaxResults=DEFAULT_MAX_RESULTS;
@PersistenceContext(类型=PersistenceContextType.TRANSACTION)
私人实体管理者;
/**
*{@link EntityManager},所有查询操作和
*在这个DAO中执行。
*
*@返回{@link EntityManager}
*/
公共实体管理器getEntityManager(){
返回em;
}
/*
*(非Javadoc)
*
*@see org.skyway.spring.util.dao.JpaDao#getTypes()
*/
公共抽象集>getTypes(){
Set>();
设置.添加(学生.班级);
返回集;
}
公共学生登记处学生(学生){
Annotation[]Annotation=StudentsService.class.getAnnotations();
System.out.println(注释);
归还此。商店(学生);
}
公共学生编辑学生(学生){
归还此。商店(学生);
}
公共作废注销学生(学生){
这个。移除(学生);
}
公共列表findAllStudents(){
返回此.executeQueryByName(“Student.findAll”);
}
}
如果您注意到方法register student已经提供了用于检查注释的代码,在这里我真正找到了@Transactional
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:
有人能帮我解决这个矛盾吗?注释继承的工作方式与方法或字段的继承基本相同
由于只能通过反射来访问注释,因此类中有两种基本方法:
getAnnotations()
返回当前类及其超类上的所有注释
getDeclaredAnnotations()
返回当前类上的所有注释
您链接的文章谈到的问题是,Method#getAnnotation(…)
访问该方法所定义的类的declaredAnnotations()
,如上所述,该类只返回该类中定义的注释,而不返回超类中定义的注释
这意味着,如果您重写用@Transactional
注释的其中一个方法,则必须在其中添加注释(或者如果框架也在类注释中查找,则应找到AbstractMaqraaService
上声明的@Transactional
).是,如果注释已添加到其中,则有可能。例如,注释继承了
从文档中:
指示注释类型是自动继承的。如果
继承的元批注存在于批注类型上
声明,用户查询类的注释类型
声明,而类声明对此没有注释
类型,则将自动查询该类的超类
注释类型。此过程将重复进行,直到生成注释为止
找到此类型的,或类层次结构(对象)的顶部为
达到。如果没有超类具有此类型的注释,则
查询将指示所讨论的类没有这样的注释
请注意,如果已注释的
类型用于注释除类以外的任何内容。还请注意
此元注释只会导致从中继承注释
超类;已实现接口上的注释无效
@Transactional
的文档:
离题:尽管在Java中,您不能对注释进行子类型划分。注意,@Inherited仅在应用于类(而不是方法或接口)时有效
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");
}
}
@Target(value={METHOD,TYPE})
@Retention(value=RUNTIME)
@Inherited
@Documented
public @interface Transactional