JPA中的修剪字符串字段

JPA中的修剪字符串字段

或者，您可以使用生命周期注释：

@Entitypublic class MyEntity {    @PostLoad    protected void repair(){        if(myStringProperty!=null)myStringProperty=myStringProperty.trim();    }    private String myStringProperty;    public String getMyStringProperty() {        return myStringProperty;    }    public void setMyStringProperty(String myStringProperty) {        this.myStringProperty = myStringProperty;    }}

如果在多个实体上发生这种情况，则可以创建一个自定义批注并编写一个专用的EntityListener。

注解

@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.FIELD)public @interface Trim {}

听众

public class TrimListener {    private final Map<Class<?>, Set<Field>> trimProperties =         new HashMap<Class<?>, Set<Field>>();    @PostLoad    public void repairAfterLoad(final Object entity) throws Exception {        for (final Field fieldToTrim : getTrimProperties(entity.getClass())) { final String propertyValue = (String) fieldToTrim.get(entity); if (propertyValue != null)     fieldToTrim.set(entity, propertyValue.trim());        }    }    private Set<Field> getTrimProperties(Class<?> entityClass) throws Exception {        if (Object.class.equals(entityClass)) return Collections.emptySet();        Set<Field> propertiesToTrim = trimProperties.get(entityClass);        if (propertiesToTrim == null) { propertiesToTrim = new HashSet<Field>(); for (final Field field : entityClass.getDeclaredFields()) {     if (field.getType().equals(String.class)         && field.getAnnotation(Trim.class) != null) {         field.setAccessible(true);         propertiesToTrim.add(field);     } } trimProperties.put(entityClass, propertiesToTrim);        }        return propertiesToTrim;    }}

现在使用注释所有相关的String字段，

@Trim

并在persistence.xml中将侦听器注册为默认实体侦听器：

<persistence-unit ..>    <!-- ... -->    <default-entity-listeners>      com.somepackage.TrimListener      and.maybe.SomeOtherListener    </default-entity-listeners></persistence-unit>