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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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到此这篇关于SpringBoot 把PageHelper分页信息返回给前端的方法步骤的文章就介绍到这了,更多相关SpringBoot PageHelper分页信息返回内容请搜索脚本之家以前的文章或继续浏览下面的相关文章希望大家以后多多支持脚本之家! 

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