seminar/src/main/java/ru/ulstu/model/OffsetablePageRequest.java
2022-03-15 10:44:43 +04:00

120 lines
2.8 KiB
Java

package ru.ulstu.model;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import java.io.Serializable;
import java.util.Optional;
public class OffsetablePageRequest implements Pageable, Serializable {
private final int offset;
private final int count;
private final Sort sort;
public OffsetablePageRequest(int page, long pageSize) {
this(pageSize * page, pageSize, Sort.by("id"));
}
public OffsetablePageRequest(long offset, long count, Sort sort) {
if (offset < 0) {
throw new IllegalArgumentException("Offset value must not be less than zero!");
}
if (count < 1) {
throw new IllegalArgumentException("Count value must not be less than one!");
}
this.offset = (int) offset;
this.count = (int) count;
this.sort = sort;
}
@Override
public Sort getSort() {
return sort;
}
@Override
public Sort getSortOr(Sort sort) {
return Pageable.super.getSortOr(sort);
}
@Override
public int getPageSize() {
return count;
}
@Override
public boolean isPaged() {
return Pageable.super.isPaged();
}
@Override
public boolean isUnpaged() {
return Pageable.super.isUnpaged();
}
@Override
public int getPageNumber() {
return offset / count;
}
@Override
public long getOffset() {
return offset;
}
@Override
public boolean hasPrevious() {
return offset > 0;
}
@Override
public Optional<Pageable> toOptional() {
return Pageable.super.toOptional();
}
@Override
public Pageable next() {
return new OffsetablePageRequest(getOffset() + getPageSize(), getPageSize(), getSort());
}
@Override
public Pageable previousOrFirst() {
return hasPrevious() ? previous() : first();
}
public Pageable previous() {
return getOffset() == 0 ? this : new OffsetablePageRequest(getOffset() - getPageSize(), getPageSize(), getSort());
}
@Override
public Pageable first() {
return new OffsetablePageRequest(0, getPageSize(), getSort());
}
@Override
public Pageable withPage(int pageNumber) {
return null;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null || getClass() != obj.getClass()) {
return false;
}
final OffsetablePageRequest other = (OffsetablePageRequest) obj;
return this.offset == other.offset && this.count == other.count;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + offset;
result = prime * result + count;
return result;
}
}