JavaWeb分页

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• 平时我们查询的必要参数是写在Dao层的，但这样是不合理的，Dao层只是用来访问和操作数据库，不应该包含其他信息，所以通用做法创建一个Page对象，将分页信息全部放到里面

Page对象

public class Page {
    
    private List<Object> list;  //存放查询的数据
    private int currentPage;    //当前页数
    private int pageSize;       //每页显示的数据条数
    private int totalRecord;    //总数据条数
    private int totalPage;      //总页数
    
    //构造函数，两个参数
    public Page(int currentPage, int pageSize) {
        super();
        this.currentPage = currentPage;
        this.pageSize = pageSize;
    }
    
    public List<Object> getList() {
        return list;
    }
    public void setList(List<Object> list) {
        this.list = list;
    }
    public int getCurrentPage() {
        return currentPage;
    }
    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
    public int getTotalRecord() {
        return totalRecord;
    }
    public void setTotalRecord(int totalRecord) {
        this.totalRecord = totalRecord;
    }
    public int getTotalPage() {
        return totalPage;
    }
    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }
}

Service层

public Page getPageData(int currentPage,int pageSize){
    
    Page page = new Page(currentPage,pageSize);
    
    //通过Dao层把查询数据放到Page对象中
    page.setTotalPage(pageDao.getTotalPage);
    page.setTotalRecord(pageDao.getTotalRecord);
    page.setList( pageDao.setList(currentPage,pageSize) );
    
    //返回Page给Web层
    return page;
}

Web层

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    //获取前端传过来的参数
    int currentPage = Integer.parseInt( request.getParameter("currentPage") );
    int pageSize = Integer.parseInt( request.getParameter("pageSize") );
    
    //处理Page的Service对象
    PageService pageService = new PageService();
    
    //返回数据给前端，这里应该返回Json对象
    Page page = pageService.getPageData(currentPage, pageSize);
    
    //阿里巴巴有个开源的jar包，fastJson可以Bean和Json互转，具体操作可以看下面链接
    return JSON.toJSONString(page);
}

FastJson 点这里看对象和Json互转