SpringBoot 把PageHelper分页信息返回给前端的方法步骤
作者:张紫娃
本文主要介绍了SpringBoot 把PageHelper分页信息返回给前端的方法步骤,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友们下面随着小编来一起学习学习吧
第1步:定义线程容器收纳HttpHeaders和HttpStatus
import org.springframework.http.HttpHeaders; import org.springframework.http.HttpStatus; public class ResponseUtils { private static ThreadLocal<HttpHeaders> ThreadLocalHeaders = new InheritableThreadLocal<>(); private static ThreadLocal<HttpStatus> ThreadLocalStatus = new InheritableThreadLocal<>(); public static void addHeaders(String key, String value) { if (ThreadLocalHeaders.get() == null) { ThreadLocalHeaders.set(new HttpHeaders()); } ThreadLocalHeaders.get().add(key, value); } public static void setResponseCode(HttpStatus httpStatus) { ThreadLocalStatus.set(httpStatus); } public static HttpHeaders getHeaders() { return ThreadLocalHeaders.get(); } public static HttpStatus getResponseCode() { return ThreadLocalStatus.get(); } public static void clear() { if (ThreadLocalHeaders.get() != null) { ThreadLocalHeaders.remove(); } if (ThreadLocalStatus.get() != null) { ThreadLocalStatus.remove(); } } }
第2步:分页信息 转储到 线程容器 方法的封装
import com.github.pagehelper.PageInfo; import com.zhangziwa.practisesvr.utils.response.ResponseUtils; public class PageHeaderUtils { private static final String PAGE_NUM = "page_num"; // 当前第几页 private static final String PAGE_SIZE = "page_size"; // 每页显示的条数 private static final String PREV_PAGE = "prev_page"; // 上一页页码 private static final String NEXT_PAGE = "next_page"; // 下一页页码 private static final String TOTAL_COUNT = "total_count"; // 总条数 private static final String TOTAL_PAGE = "total_page"; // 总页数 public static <E> void setPageHeader(PageInfo<E> page) { if (page == null) { return; } ResponseUtils.addHeaders(PAGE_NUM, String.valueOf(page.getPageNum())); ResponseUtils.addHeaders(PAGE_SIZE, String.valueOf(page.getPageSize())); ResponseUtils.addHeaders(TOTAL_COUNT, String.valueOf(page.getTotal())); ResponseUtils.addHeaders(TOTAL_PAGE, String.valueOf(page.getPages() == 0 ? 1 : page.getPages())); // page.getPages()=1表示就1页,前后页都不存在,故也算特殊场景.也为了page.getPages()+1和page.getPages()-1不会对[1,page.getPages()]越界 if (page.getPages() == 0 || page.getPages() == 1) { ResponseUtils.addHeaders(PREV_PAGE, ""); ResponseUtils.addHeaders(NEXT_PAGE, ""); } else if (page.getPageNum() == 1) { ResponseUtils.addHeaders(PREV_PAGE, ""); ResponseUtils.addHeaders(NEXT_PAGE, String.valueOf(page.getPages() + 1)); } else if (page.getPageNum() == page.getPages()) { ResponseUtils.addHeaders(PREV_PAGE, String.valueOf(page.getPages() - 1)); ResponseUtils.addHeaders(NEXT_PAGE, ""); } else { ResponseUtils.addHeaders(PREV_PAGE, String.valueOf(page.getPages() - 1)); ResponseUtils.addHeaders(NEXT_PAGE, String.valueOf(page.getPages() + 1)); } } }
第3步:分页查询,HttpHeaders和HttpStatus收集到线程容器中
public List<Student> listStudents(Integer pageNum, Integer PageSize) { PageHelper.startPage(PageUtils.getPageNum(pageNum), PageUtils.getPageSize(PageSize), PageUtils.isQueryTotalCount()); PageHelper.orderBy("age asc"); List<Student> students = userMapper.listStudents(); PageInfo<Student> studentPageInfo = PageInfo.of(students); // 收集分页信息到 ThreadLocal PageHeaderUtils.setPageHeader(studentPageInfo); // 收集HttpStatus到 ThreadLocal // ResponseUtils.setResponseCode(num2HttpStatus("200")); // 为了使用一下num2HttpStatus方法 ResponseUtils.setResponseCode(HttpStatus.OK); return students; }
public class HttpStatusUtils { public static HttpStatus num2HttpStatus(String num) { HttpStatus httpStatus = HttpStatus.NOT_FOUND; for (HttpStatus status : HttpStatus.values()) { if (Integer.parseInt(num) == status.value()) { return status; } } return httpStatus; } }
第4步:controller层需为@RestController Restful接口
@RestController @Slf4j public class SearchController { @Autowired UserService userService; @RequestMapping(value = "/getAllStudents", method = RequestMethod.GET) public List<Student> login() { List<Student> students = userService.listStudents(1, 10); students.forEach(System.out::println); return students; } }
第5步:线程容器收纳HttpHeaders和HttpStatus添加到ServerHttpResponse
@ControllerAdvice public class HttpResponseBodyAdvice implements ResponseBodyAdvice { @Override public boolean supports(MethodParameter returnType, Class converterType) { return true; } @Override public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class clazz, ServerHttpRequest request, ServerHttpResponse response) { HttpHeaders headers = response.getHeaders(); // 分页信息添加到ServerHttpResponse HttpHeaders headersContext = ResponseUtils.getHeaders(); if (nonNull(headersContext) && !headersContext.isEmpty()) { headers.addAll(headersContext); } // 状态码添加到ServerHttpResponse if (nonNull(ResponseUtils.getResponseCode())) { response.setStatusCode(ResponseUtils.getResponseCode()); } return body; } }
第6步:测试结果
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