javaWeb项目——简单的分页功能

实体类：Page.java

        定义变量：pageSize（每页显示的数量）、pageCurrent（当前页）、PageCount（总页数）、count（数据总条数）、list（数据列表）；

        setPageCount()方法，设置页数；

        Page(List<T> list,int pageCurrent,int count) 构造方法；

 

package entity;

import java.util.List;

public class Page<T> {
	private int pageSize=2;
	private int pageCurrent=1;
	private int pageCount;
	private int count;
	private List<T> list;
	
	public int getPageSize() {
		return pageSize;
	}
	public void setPageSize(int pageSize) {
		this.pageSize = pageSize;
	}
	public int getPageCurrent() {
		return pageCurrent;
	}
	public void setPageCurrent(int pageCurrent) {
		this.pageCurrent = pageCurrent;
	}
	public int getPageCount() {
		return pageCount;
	}
	public void setPageCount(int pageCount) {
		this.pageCount = count%pageSize==0? (count/pageSize):(count/pageSize+1);
	}
	public int getCount() {
		return count;
	}
	public void setCount(int count) {
		this.count = count;
	}
	public List<T> getList() {
		return list;
	}
	public void setList(List<T> list) {
		this.list = list;
	}
	
	public Page(List<T> list,int pageCurrent,int count){
		setList(list);
		setPageCurrent(pageCurrent);
		setPageSize(this.pageSize);
		setCount(count);
		setPageCount(this.pageCount);
	}

}

 

实现类：StudentServiceImpl.java——page方法

        定义的sql为子查询语句；

        调用Dao层方法；

    @Override
	public Page<Student> page(int pageCurrent) {
		// TODO Auto-generated method stub
		String sql="(select * from student order by code asc)";
		Page<Student> page=studentDao.page(sql,pageCurrent);
		return page;
	}

 

Dao类：StudentDao.java——page方法

 

        listSql查询数据列表，countSql查询数据条数；

        调用page构造方法，返回page对象；

public Page<Student> page(String sql,int pageCurrent){
		
		String listSql="select * from (select A.*,ROWNUM RN from"+sql+"A where ROWNUM<=?) where RN>?";
		String countSql="select count(1) from "+sql;
		List<Student> list =new ArrayList<Student>();
		Long count=0L;
		try{
			PreparedStatement ps=getConn().prepareStatement(listSql);
			ps.setInt(1, (pageCurrent-1)*2+2);
			ps.setInt(2, (pageCurrent-1)*2);
			ResultSet rs=ps.executeQuery();
			while(rs.next()){
				Student student=new Student();
				student.setStudentId(rs.getString("student_id"));
				student.setCode(rs.getString("code"));
				student.setStudentName(rs.getString("student_name"));
				list.add(student);
			}
			ps.close();
			closeConn();
			
			ps=getConn().prepareStatement(countSql);
			rs=ps.executeQuery();
			while(rs.next()){
				count=rs.getLong(1);
			}
			ps.close();
			closeConn();
		}catch(Exception e){
			e.printStackTrace();
		}
		Page<Student> page = new Page<Student>(list, pageCurrent, count.intValue());
		return page;
	}

 

action类：pageServlet.java

        调用page方法，获取page对象；

        拼接html，返回页面；

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		StudentService studentService=new StudentServiceImpl();
		int pageCurrent = Integer.valueOf(request.getParameter("pageCurrent")!=null?request.getParameter("pageCurrent"):"1");
		Page<Student> page = studentService.page(pageCurrent);
		List<Student> studentList=page.getList();
		
		StringBuffer html=new StringBuffer();
		html.append("<table align='center' border='1' cellspacing='0'><tr><td>学号</td><td>姓名</td></tr>");
		for(int i=0;i<studentList.size();i++){
			html.append("<tr><td>"+studentList.get(i).getCode()+"</td><td>"+studentList.get(i).getStudentName()+"</td></tr>");
		}
		html.append("</table><div align='center'>");
		if(pageCurrent>1){
			html.append("<a href='/student03/page?pageCurrent=1'>首页</a> ");
			html.append("<a href='/student03/page?pageCurrent="+(pageCurrent-1)+"'>上一页</a>  ");
		}
		for(int i=0;i<page.getPageCount();i++){
			html.append("<a href='/student03/page?pageCurrent="+(i+1)+"'>"+(i+1)+"</a>  ");
		}
		if(pageCurrent<page.getPageCount()){
			html.append("<a href='/student03/page?pageCurrent="+(pageCurrent+1)+"'>下一页</a>");
			html.append(" <a href='/student03/page?pageCurrent="+ page.getPageCount() +"'>末页</a> ");
		}
		html.append("第 【"+page.getPageCurrent()+"】页</div>");
		response.setContentType("text/html; charset=UTF-8");
		response.getWriter().write(html.toString());
	}