我在JSTL中有以下代码,可以在j2ee网站中检索学生图片
<c:if test="${student.studentPictureId != null}">
<a href="javascript:showImage('<c:out value="${student.studentId}"/>','<c:out value="${student.studentPictureId }"/>
</c:if>
我想使代码更通用
而不是打电话
student.studentPictureId
我想用Enum调用泛型函数:
学生班上的功能签名如下:
Student class
String getPictureId(PictureTypeEnum picture type)
所以最终的JSTL代码将是:
<c:if test="${student.getPictureId(PictureTypeEnum.StudentCard) != null}">
<a href="javascript:showImage('<c:out value="${student.studentId}"/>','<c:out value="${student.getPictureId(PictureTypeEnum.StudentCard)}"/>
</c:if>
我知道在打电话时
<c:out value="${student.studentPictureId }"/>
它基本上称为getter,student.getStudentPictureId() student.studentPictureId
但是可以调用学生对象方法并将参数传递给它吗?
答案 0 :(得分:1)
直接从JSTL调用方法是不可能的,所以我使用了一种hack:QuickMap:
public abstract class QuickMap<K,V> implements Map<K,V> {
@Override
public abstract V get(Object key);
@Override
public final int size() {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final boolean isEmpty() {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final boolean containsKey(Object key) {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final boolean containsValue(Object value) {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final V put(K key, V value) {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final V remove(Object key) {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final void putAll(Map<? extends K, ? extends V> m) {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final void clear() {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final Set<K> keySet() {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final Collection<V> values() {
throw new UnsupportedOperationException("Not supported yet.");
}
@Override
public final Set<Entry<K, V>> entrySet() {
throw new UnsupportedOperationException("Not supported yet.");
}
}
在您的情况下,我会在您的学生班中添加以下方法:
public Map<Object,String> getStudentPictureIds() {
return new QuickMap<Object,String>() {
@Override
public String get(Object k) {
PictureTypeEnum type;
if (k instanceof PictureTypeEnum) {
type = (PictureTypeEnum)k;
} else {
type = PictureTypeEnum.valueOf(k.toString());
}
return getStudentPictureId(type);
}
};
}
使用JSTL操作枚举并不容易,因此该方法也接受字符串。
您可以在JSP中使用它:
<c:out value="${student.pictureIds['StudentCard']}"/>