pagehelper是一個分頁插件,用來後端API進行分頁處理,pagehelper只需要pageNum(當前頁)和pageSize(頁大小)就可以自動實現查詢的分頁數據.只對緊接着後續一條查詢語句起作用.
項目運行成功後,查詢語句之前加 PageHelper.startPage(pageNum, pageSize)
即可實現分頁,PageHelper只對緊跟着的第一個SQL語句起作用.分頁成功後,實際分會的結果list類型是Page<E>
,可使用 PageInfo<E>
進行封裝,後文有相應源碼.
pagehelper可以與前端datatables或pagination插件配合使用.前端具體插件具體怎麼使用這裏不再介紹.
1.maven中引入依賴
<!-- 分頁插件 -->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.3</version>
</dependency>
<!-- entity插件 -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.18</version>
</dependency>
2.controller
@GetMapping("/testresult/{project}/{pageNum}/{pagesize}")
public ResponseEntity<TestResultResponse>
getPhaseSmokeResult(@PathVariable(value="pageNum",defaultValue="1")Integer pageNum,
@PathVariable(value="pageSize",defaultValue="6")Integer pageSize,
@PathVariable("project")String project){
log.debug("REST request to get {} phase smoke result from {} to {} ", project, pageNum, pageSize);
TestResultResponse response = smokeResultService.getPhaseSmokeResult(pageNum,pagesize,project);
return new ResponseEntity<>(response, HttpStatus.OK);
}
3.serviceImpl
@Override
public TestResultResponse getPhaseSmokeResult(Integer pageNum, Integer pagesize, String project) {
PageHelper.startPage(pageNum, pagesize);
List<SmokeResult> smokeResultList = smokeResultMapper.getPhaseSmokeResult(project);
PageInfo<SmokeResult> pageInfo = new PageInfo<>(smokeResultList);
TestResultResponse response = new TestResultResponse();
response.setProject(project).setPageInfo(pageInfo);
return response;
}
4.entity
TestResultResponse類
@Data
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
public class TestResultResponse {
private String project;
private String version;
private String starttime;
private String endtime;
private String total;
private PageInfo pageInfo;
}
5.PageInfo源碼
import com.github.pagehelper.Page;
import lombok.Data;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
@Data
public class PageInfo<T> implements Serializable{
private static final long serialVersionUID = 1L;
//當前頁
private int pageNum;
//每頁的數量
private int pageSize;
//當前頁的數量
private int size;
//由於startRow和endRow不常用,這裏說個具體的用法
//可以在頁面中"顯示startRow到endRow 共size條數據"
//當前頁面第一個元素在數據庫中的行號
private int startRow;
//當前頁面最後一個元素在數據庫中的行號
private int endRow;
//總記錄數
private long total;
//總頁數
private int pages;
//結果集
private List<T> list;
//前一頁
private int prePage;
//下一頁
private int nextPage;
//是否爲第一頁
private boolean isFirstPage = false;
//是否爲最後一頁
private boolean isLastPage = false;
//是否有前一頁
private boolean hasPreviousPage = false;
//是否有下一頁
private boolean hasNextPage = false;
//導航頁碼數,頁碼導航連續顯示的頁數
private int navigatePages;
//所有導航頁號
private int[] navigatepageNums;
//導航條上的第一頁
private int navigateFirstPage;
//導航條上的最後一頁
private int navigateLastPage;
public PageInfo() {
}
/**
* 包裝Page對象
*
* @param list
*/
public PageInfo(List<T> list) {
this(list, 8);
}
/**
* 包裝Page對象
*
* @param list page結果
* @param navigatePages 頁碼數量,頁碼導航連續顯示的頁數
*/
public PageInfo(List<T> list, int navigatePages) {
if (list instanceof Page) {
Page page = (Page) list;
this.pageNum = page.getPageNum();
this.pageSize = page.getPageSize();
this.pages = page.getPages();
this.list = page;
this.size = page.size();
this.total = page.getTotal();
//由於結果是>startRow的,所以實際的需要+1
if (this.size == 0) {
this.startRow = 0;
this.endRow = 0;
} else {
this.startRow = page.getStartRow() + 1;
//計算實際的endRow(最後一頁的時候特殊)
this.endRow = this.startRow - 1 + this.size;
}
} else if (list instanceof Collection) {
this.pageNum = 1;
this.pageSize = list.size();
this.pages = this.pageSize > 0 ? 1 : 0;
this.list = list;
this.size = list.size();
this.total = list.size();
this.startRow = 0;
this.endRow = list.size() > 0 ? list.size() - 1 : 0;
}
if (list instanceof Collection) {
this.navigatePages = navigatePages;
//計算導航頁
calcNavigatepageNums();
//計算前後頁,第一頁,最後一頁
calcPage();
//判斷頁面邊界
judgePageBoudary();
}
}
/**
* 計算導航頁
*/
private void calcNavigatepageNums() {
//當總頁數小於或等於導航頁碼數時
if (pages <= navigatePages) {
navigatepageNums = new int[pages];
for (int i = 0; i < pages; i++) {
navigatepageNums[i] = i + 1;
}
} else { //當總頁數大於導航頁碼數時
navigatepageNums = new int[navigatePages];
int startNum = pageNum - navigatePages / 2;
int endNum = pageNum + navigatePages / 2;
if (startNum < 1) {
startNum = 1;
//最前navigatePages頁
for (int i = 0; i < navigatePages; i++) {
navigatepageNums[i] = startNum++;
}
} else if (endNum > pages) {
endNum = pages;
//最後navigatePages頁
for (int i = navigatePages - 1; i >= 0; i--) {
navigatepageNums[i] = endNum--;
}
} else {
//所有中間頁
for (int i = 0; i < navigatePages; i++) {
navigatepageNums[i] = startNum++;
}
}
}
}
/**
* 計算前後頁,第一頁,最後一頁
*/
private void calcPage() {
if (navigatepageNums != null && navigatepageNums.length > 0) {
navigateFirstPage = navigatepageNums[0];
navigateLastPage = navigatepageNums[navigatepageNums.length - 1];
if (pageNum > 1) {
prePage = pageNum - 1;
}
if (pageNum < pages) {
nextPage = pageNum + 1;
}
}
}
/**
* 判定頁面邊界
*/
private void judgePageBoudary() {
isFirstPage = pageNum == 1;
// isLastPage = pageNum == pages;
isLastPage = pageNum == pages || pages == 0;
hasPreviousPage = pageNum > 1;
hasNextPage = pageNum < pages;
}
}
參考鏈接: