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Jetbrains全系列IDE稳定放心使用

在java项目中不使用mybatis的pageHelper进行数据分页:

1. 分页工具类编写：

import java.util.List;

public class PageModel<E> {
    //结果集
    private List<E> list;

    //查询记录数
    private int totalRecords;

    //每页多少条数据
    private int pageSize;

    //第几页
    private int pageNo;

    /**
     * 总页数
     * @return
     */
    public int getTotalPages() {
        return (totalRecords + pageSize - 1) / pageSize;
    }

    /**
     * 取得首页
     * @return
     */
    public int getTopPageNo() {
        return 1;
    }

    /**
     * 上一页
     * @return
     */
    public int getPreviousPageNo() {
        if (pageNo <= 1) {
            return 1;
        }
        return pageNo - 1;
    }

    /**
     * 下一页
     * @return
     */
    public int getNextPageNo() {
        if (pageNo >= getBottomPageNo()) {
            return getBottomPageNo();
        }
        return pageNo + 1;
    }

    /**
     * 取得尾页
     * @return
     */
    public int getBottomPageNo() {
        return getTotalPages();
    }

    public List<E> getList() {
        return list;
    }

    public void setList(List<E> list) {
        this.list = list;
    }

    public int getTotalRecords() {
        return totalRecords;
    }

    public void setTotalRecords(int totalRecords) {
        this.totalRecords = totalRecords;
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getPageNo() {
        return pageNo;
    }

    public void setPageNo(int pageNo) {
        this.pageNo = pageNo;
    }
}

2.数据库实体类

public class Demo {
    private  int id;
    private String name;

    public Demo(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

3.数据分页查询（下面为一个方法，类名为:JdbcService)

/**
 * 
 * @param pageNo 当前第几页
 * @param pageSize 每页显示数据量
 * @return
 * @throws SQLException
 */
public PageModel getDate(int pageNo, int pageSize) throws SQLException {
    String sql = "select * from demo limit ?,?";
    PageModel pageModel = null;
    PreparedStatement pstm = null;
    ResultSet rs = null;
    Demo demo = null;
    Connection connection = null;
    List<Demo> list = new ArrayList<>();
    try {
     //分页查询的数据
        connection = getDataSource().getConnection();
        pstm = connection.prepareStatement(sql);
        pstm.setInt(1, (pageNo - 1) * pageSize);
        pstm.setInt(2,  pageSize);
        rs = pstm.executeQuery();
        while (rs.next()) {
          list.add(new Demo(rs.getInt("id"),rs.getString("name")));
        }
      //查询总条数
        ResultSet resultSet1 = pstm.executeQuery("select count(*) from demo");
        int total = 0;
        if (resultSet1.next()) {
            total = resultSet1.getInt(1);
        }
        resultSet1.close();
     //将数据放到分页工具类中
        pageModel = new PageModel<>();
        pageModel.setPageNo(pageNo);
        pageModel.setPageSize(pageSize);
        pageModel.setTotalRecords(total);
        pageModel.setList(list);
    } catch (SQLException e) {
        e.printStackTrace();
    } finally {
        if (rs != null) {
            rs.close();
        }
        if (pstm != null) {
            pstm.close();
        }
        if (connection != null) {
            connection.close();
        }
    }
    if (connection==null){
        System.out.println("close");
    }
    if (connection!=null){
        System.out.println(connection);
    }
    return pageModel;
}

4.controller层调用数据（一个接口方法）

//注解注入
Autowired
private JdbcService jdbcService;
@GetMapping("/getDemo")
public PageModel getDemo(int pageNo, int pageSize){
    PageModel date = null;
        try {
        date = jdbcService.getDate(pageNo, pageSize);
    } catch (SQLException e) {
        e.printStackTrace();
    }
    return date;
}