Spring框架中PageImpl<T>类的源码如下：
/*
* Copyright 2008-2013 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.data.domain; import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List; /**
* Basic {@code Page} implementation.
*
* @param <T> the type of which the page consists.
* @author Oliver Gierke
*/
public class PageImpl<T> implements Page<T>, Serializable { private static final long serialVersionUID = 867755909294344406L; private final List<T> content = new ArrayList<T>();
private final Pageable pageable;
private final long total; /**
* Constructor of {@code PageImpl}.
*
* @param content the content of this page, must not be {@literal null}.
* @param pageable the paging information, can be {@literal null}.
* @param total the total amount of items available
*/
public PageImpl(List<T> content, Pageable pageable, long total) { if (null == content) {
throw new IllegalArgumentException("Content must not be null!");
} this.content.addAll(content);
this.total = total;
this.pageable = pageable;
} /**
* Creates a new {@link PageImpl} with the given content. This will result in the created {@link Page} being identical
* to the entire {@link List}.
*
* @param content must not be {@literal null}.
*/
public PageImpl(List<T> content) {
this(content, null, null == content ? 0 : content.size());
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getNumber()
*/
public int getNumber() {
return pageable == null ? 0 : pageable.getPageNumber();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getSize()
*/
public int getSize() {
return pageable == null ? 0 : pageable.getPageSize();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getTotalPages()
*/
public int getTotalPages() {
return getSize() == 0 ? 1 : (int) Math.ceil((double) total / (double) getSize());
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getNumberOfElements()
*/
public int getNumberOfElements() {
return content.size();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getTotalElements()
*/
public long getTotalElements() {
return total;
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#hasPreviousPage()
*/
public boolean hasPreviousPage() {
return getNumber() > 0;
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#isFirstPage()
*/
public boolean isFirstPage() {
return !hasPreviousPage();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#hasNextPage()
*/
public boolean hasNextPage() {
return getNumber() + 1 < getTotalPages();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#isLastPage()
*/
public boolean isLastPage() {
return !hasNextPage();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#nextPageable()
*/
public Pageable nextPageable() {
return hasNextPage() ? pageable.next() : null;
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#previousOrFirstPageable()
*/
public Pageable previousPageable() { if (hasPreviousPage()) {
return pageable.previousOrFirst();
} return null;
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#iterator()
*/
public Iterator<T> iterator() {
return content.iterator();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getContent()
*/
public List<T> getContent() {
return Collections.unmodifiableList(content);
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#hasContent()
*/
public boolean hasContent() {
return !content.isEmpty();
} /*
* (non-Javadoc)
* @see org.springframework.data.domain.Page#getSort()
*/
public Sort getSort() {
return pageable == null ? null : pageable.getSort();
} /*
* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() { String contentType = "UNKNOWN"; if (content.size() > 0) {
contentType = content.get(0).getClass().getName();
} return String.format("Page %s of %d containing %s instances", getNumber(), getTotalPages(), contentType);
} /*
* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) { if (this == obj) {
return true;
} if (!(obj instanceof PageImpl<?>)) {
return false;
} PageImpl<?> that = (PageImpl<?>) obj; boolean totalEqual = this.total == that.total;
boolean contentEqual = this.content.equals(that.content);
boolean pageableEqual = this.pageable == null ? that.pageable == null : this.pageable.equals(that.pageable); return totalEqual && contentEqual && pageableEqual;
} /*
* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() { int result = 17; result = 31 * result + (int) (total ^ total >>> 32);
result = 31 * result + (pageable == null ? 0 : pageable.hashCode());
result = 31 * result + content.hashCode(); return result;
}
}
在Spring框架中，要实现分页显示数据，可以使用PageImpl<T>这个类：
代码如下：
省略================
String pageindex = "" + (searchable.getPage().getPageNumber() * searchable.getPage().getPageSize() + 1);
String Spagesum = "" + searchable.getPage().getPageSize(); com.pcitc.modules.fos.appstream.wsclient.qry.ResponseBody responseBody = appStreamRepository
.appStreamQry(user, LSUtil.getLsNum(), streamEntity, pageinsex, pagesum);
// 视图部分
model.addAttribute("page", new PageImpl<Qrylist>(responseBody.getQrylist(), searchable.getPage(),
Long.parseLong(responseBody.getSumcount()))); setCommonData(model);
return viewName("moview");
省略======================