bootstarp java 分页实现 java分页思路

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人类新新 2023-08-18 13:47:45

文章标签 java 开发语言 mysql xml eclipse 文章分类 Java 后端开发

思维导图：

1. PageBean

2. 后台

3. junit

4、视图层：（PageTag）

1、准备工作：导入jar包：

2、utils包里的各个类，都有各自不同的作用：

3、标签库描述文件

4、jsp界面—booklist

思维导图：

bootstarp java 分页实现 java分页思路_xml

基于MySql数据库的通用分页

通用分页核心思路：将上一次查询请求再发一次，只不过页码变了
实现步骤：
1）先查询全部数据
   Junit测试
   baseDao<T>、CallBack<K>
2）通用分页实现
   pagebean

1. PageBean

分页三要素
page 页码视图层传递过来
rows 页大小视图层传递过来
total 总记录数后台查出来
pagination 是否分页视图层传递过来
getStartIndex() 基于MySql数据库分页，获取分页开始标记

2. 后台

2.1 entity
2.2 dao
BaseDao<T>
1）匿名内部接口
2）分页查询方法，接口方法传参
（返回：总记录数+指定页码并满足条件的记录集）
3）二次查询的条件要一致
getCountSql()/getPagerSql()

3. junit

java单元测试/白盒测试
setUp
tearDown
测试用例

Servlet中的init和destory方法只会运行一次
Junit中的setUp和tearDown方法是根据方法数量来决定的

4、视图层：（PageTag）

1、准备工作：
导入jar包：

2、建包建类：

2、utils包里的各个类，都有各自不同的作用：

连接数据库—DBHelper

package com.zking.pagination.util;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * 提供了一组获得或关闭数据库对象的方法
 * 
 */
public class DBHelper {
	private static String driver;
	private static String url;
	private static String user;
	private static String password;

	static {// 静态块执行一次，加载 驱动一次
		try {
			InputStream is = DBHelper.class
					.getResourceAsStream("/config.properties");

			Properties properties = new Properties();
			properties.load(is);

			driver = properties.getProperty("driver");
			url = properties.getProperty("url");
			user = properties.getProperty("user");
			password = properties.getProperty("pwd");

			Class.forName(driver);//classNotfoundException
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}
	}

	/**
	 * 获得数据连接对象
	 * 
	 * @return
	 */
	public static Connection getConnection() {
		try {
			Connection conn = DriverManager.getConnection(url, user, password);
			return conn;
		} catch (SQLException e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}
	}

	public static void close(ResultSet rs) {
		if (null != rs) {
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
				throw new RuntimeException(e);
			}
		}
	}

	public static void close(Statement stmt) {
		if (null != stmt) {
			try {
				stmt.close();
			} catch (SQLException e) {
				e.printStackTrace();
				throw new RuntimeException(e);
			}
		}
	}

	public static void close(Connection conn) {
		if (null != conn) {
			try {
				conn.close();
			} catch (SQLException e) {
				e.printStackTrace();
				throw new RuntimeException(e);
			}
		}
	}

	public static void close(Connection conn, Statement stmt, ResultSet rs) {
		close(rs);
		close(stmt);
		close(conn);
	}

	public static boolean isOracle() {
		return "oracle.jdbc.driver.OracleDriver".equals(driver);
	}

	public static boolean isSQLServer() {
		return "com.microsoft.sqlserver.jdbc.SQLServerDriver".equals(driver);
	}
	
	public static boolean isMysql() {
		return "com.mysql.jdbc.Driver".equals(driver);
	}

	public static void main(String[] args) {
		Connection conn = DBHelper.getConnection();
		DBHelper.close(conn);
		System.out.println("isOracle：" + isOracle());
		System.out.println("isSQLServer：" + isSQLServer());
		System.out.println("isMysql：" + isMysql());
		System.out.println("数据库连接(关闭)成功");
	}
}

中文乱码处理—EncodingFilter

package com.zking.pagination.util;

import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * 中文乱码处理
 * 
 */
public class EncodingFilter implements Filter {

	private String encoding = "UTF-8";// 默认字符集

	public EncodingFilter() {
		super();
	}

	public void destroy() {
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;

		// 中文处理必须放到 chain.doFilter(request, response)方法前面
		res.setContentType("text/html;charset=" + this.encoding);
		if (req.getMethod().equalsIgnoreCase("post")) {
			req.setCharacterEncoding(this.encoding);
		} else {
			Map map = req.getParameterMap();// 保存所有参数名=参数值(数组)的Map集合
			Set set = map.keySet();// 取出所有参数名
			Iterator it = set.iterator();
			while (it.hasNext()) {
				String name = (String) it.next();
				String[] values = (String[]) map.get(name);// 取出参数值[注：参数值为一个数组]
				for (int i = 0; i < values.length; i++) {
					values[i] = new String(values[i].getBytes("ISO-8859-1"),
							this.encoding);
				}
			}
		}

		chain.doFilter(request, response);
	}

	public void init(FilterConfig filterConfig) throws ServletException {
		String s = filterConfig.getInitParameter("encoding");// 读取web.xml文件中配置的字符集
		if (null != s && !s.trim().equals("")) {
			this.encoding = s.trim();
		}
	}

}

分页工具类—PageBean

package com.zking.pagination.util;

import java.io.Serializable;

public class PageBean implements Serializable {
	//当前页码，默认1
	private int page=1;
	//页面显示条数，默认10
	private int rows=10;
	//总记录数，默认0
	private int total=0;
	//是否分页标记，默认分页
	private boolean pagination=true;
	/**
	 * 基于Mysql分页，计算limit开始位置
	 * @return
	 */
	public int getStartIndex() {
		//page=1 (1-1)*10 limit 0,10
		//page=1 (2-1)*10 limit 10.10
		//.....
		return (this.page-1)*this.rows;
	}
	public int getPage() {
		return page;
	}
	public void setPage(int page) {
		this.page = page;
	}
	public int getRows() {
		return rows;
	}
	public void setRows(int rows) {
		this.rows = rows;
	}
	public int getTotal() {
		return total;
	}
	public void setTotal(int total) {
		this.total = total;
	}
	public boolean isPagination() {
		return pagination;
	}
	public void setPagination(boolean pagination) {
		this.pagination = pagination;
	}
	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
	}
	

}

写实体类—Book

package com.zking.pagination.entity;

import java.io.Serializable;

public class Book implements Serializable {
	private Integer book_id;
	private String book_name;
	private float book_price;
	private String book_type;
	public Integer getBook_id() {
		return book_id;
	}
	public void setBook_id(Integer book_id) {
		this.book_id = book_id;
	}
	public String getBook_name() {
		return book_name;
	}
	public void setBook_name(String book_name) {
		this.book_name = book_name;
	}
	public float getBook_price() {
		return book_price;
	}
	public void setBook_price(float book_price) {
		this.book_price = book_price;
	}
	public String getBook_type() {
		return book_type;
	}
	public void setBook_type(String book_type) {
		this.book_type = book_type;
	}
	public Book(Integer book_id, String book_name, float book_price, String book_type) {
		super();
		this.book_id = book_id;
		this.book_name = book_name;
		this.book_price = book_price;
		this.book_type = book_type;
	}
	public Book() {
		super();
		// TODO Auto-generated constructor stub
	}
	@Override
	public String toString() {
		return "Book [book_id=" + book_id + ", book_name=" + book_name + ", book_price=" + book_price + ", book_type="
				+ book_type + "]";
	}
	

}

dao方法—BookDao

package com.zking.pagination.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import com.zking.pagination.entity.Book;
import com.zking.pagination.util.DBHelper;
import com.zking.pagination.util.PageBean;
import com.zking.pagination.util.StringUtils;

public class BookDao extends BaseDao<Book>{
	//1.书本新增
	public int addBook(Book book) {
		int i=0;
		Connection con=null;
		PreparedStatement ps=null;
		try {
			//获取连接对象
			con=DBHelper.getConnection();
			//定义sql
			String sql="insert into T_book(book_name,"
					+ "book_price,book_type) values(?,?,?)";
			//创建执行对象
			ps=con.prepareStatement(sql);
			//赋值
			ps.setString(1, book.getBook_name());
			ps.setFloat(2, book.getBook_price());
			ps.setString(3, book.getBook_type());
			i=ps.executeUpdate();
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.close(con, ps, null);
		}
		return i;
		
	}
	//2.书本修改
	//3.书本删除
	//4.书本分页查询
	public List<Book> queryBookPager(Book book,PageBean pageBean){
		//定义SQL语句
		String sql="select book_id,book_name,book_price,book_type from t_book where 1=1";
		//拼接查询条件，按照书本名称模糊查询
		if(StringUtils.isNotBlank(book.getBook_name()))
			sql+=" and book_Name like '%"+book.getBook_name()+"%'";
		sql+=" order by book_id desc";
		return super.executeQuery(sql, pageBean, new CallBack<Book>() {
			
			@Override
			public List<Book> foreachRs(ResultSet rs) throws SQLException {
				List<Book> lst=new ArrayList<>();
				//定义Book对象
				Book book=null;
				//循环遍历结果集
				while(rs.next()) {
					book=new Book();
					book.setBook_id(rs.getInt("book_id"));
					book.setBook_name(rs.getString("book_name"));
					book.setBook_price(rs.getFloat("book_price"));
					book.setBook_type(rs.getString("book_type"));
					lst.add(book);
					}
				return lst;
			}
		});
		/*List<Book> lst=new ArrayList<Book>();
		Connection con=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		try {
			con=DBHelper.getConnection();
			
			String sql="select book_id,book_name,book_price,book_type from t_book where 1=1";
			if(StringUtils.isNotBlank(book.getBook_name()))
				sql+=" and book_Name like '%"+book.getBook_name()+"%'";
			sql+=" order by book_id desc";
			//创建执行对象
			ps=con.prepareStatement(sql);
			//执行sql语句
			rs=ps.executeQuery();
			//循环遍历结果集
			while(rs.next()) {
				book=new Book();
				book.setBook_id(rs.getInt("book_id"));
				book.setBook_name(rs.getString("book_name"));
				book.setBook_price(rs.getFloat("book_price"));
				book.setBook_type(rs.getString("book_type"));
				lst.add(book);
				}
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.close(con, ps, rs);
		}
		return lst;*/
		
	}
	//5.根据书本id查询单个书本对象信息
	
	

}

BaseDao

package com.zking.pagination.dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import com.zking.pagination.util.DBHelper;
import com.zking.pagination.util.PageBean;

public class BaseDao<T> {
	public static interface CallBack<k>{
		//只用于遍历ResultSet结果集
		public List<k> foreachRs(ResultSet rs) throws SQLException;
	}
	/**
	 * 通用分页方法（既支持分页，也支持不分页）
	 * @param sql 普通的SQL
	 * @param pageBean 分页对象
	 * @return 查询结果集
	 */
	public List<T> executeQuery(String sql,
			PageBean pageBean,CallBack<T> callBack){
		Connection conn=null;
		PreparedStatement stmt=null;
		ResultSet rs=null;
		
		try {
			//获取连接对象
			conn=DBHelper.getConnection();
			
			//根据pagebean分页对象判断是否分页
			if(null!=pageBean&&pageBean.isPagination()) {
				//1)根据满足条件查询总记录数
				String countsql=this.getCountSQL(sql);
				//创建执行对象
				stmt=conn.prepareStatement(countsql);
				//执行SQL语句并返回总记录数
				rs=stmt.executeQuery();
				//获取总记录数
				if(rs.next()) {
					pageBean.setTotal(rs.getInt(1));
				}
				
			    //2)根据满足条件查询分页结果集
				sql = this.getPagerSQL(sql, pageBean);
			}
			//创建执行对象
			stmt=conn.prepareStatement(sql);
			//查询结果集
			rs=stmt.executeQuery();
			return callBack.foreachRs(rs);
			
		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			DBHelper.close(conn, stmt, rs);
		}
		return null;
	}
	/**
	 * 将普通的SQL语句转换成查询总记录数的SQL语句
	 * select * from t_book
	 * select * from t_book where ...
	 * select book_id,book_name from t_book
	 * select book_id,book_name from t_book where ...
	 * ----->
	 * select count(0) from t_book where ...
	 * @param sql 普通的SQL
	 * @return 查询总记录数的SQL
	 */
	private String getCountSQL(String sql) {
		return "select count(0) from ("+sql+") temp";
	}
	/**
	 * 将普通的SQL语句转换成查询分页结果集的SQL语句
	 * select * from t_book
	 * select * from t_book where ...
	 * select book_id,book_name from t_book
	 * select book_id,book_name from t_book where ...
	 * ----->
	 * select * from t_book limit
	 * select * from t_book where 1=1 limit
	 * @param sql 普通的SQL
	 * @param PageBean 分页对象（包含当前页码和每页条数，用于计算分页的关键数据）
	 * @return
	 */
	private String getPagerSQL(String sql,PageBean PageBean) {
		return sql+" limit "+PageBean.getStartIndex()+","+PageBean.getRows();
	}

}

BookAction

package com.zking.pagination.action;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zking.pagination.dao.BookDao;
import com.zking.pagination.entity.Book;
import com.zking.pagination.util.PageBean;

/**
 * Servlet implementation class BookAction
 */

public class BookAction extends HttpServlet {
	
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		this.doPost(request, response);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String bookname=request.getParameter("bookname");
		//实例化Bookdao
		BookDao bookDao=new BookDao();
		//实例化Book
		Book book=new Book();
		book.setBook_name(bookname);
		//创建PageBean
		PageBean pageBean=new PageBean();
		//实现书本查询
		List<Book> books=bookDao.queryBookPager(book,pageBean);
		//将查询结果books保存到request作用域
		request.setAttribute("books", books);
		request.getRequestDispatcher("/booklist.jsp").forward(request, response);
	}

}

3、标签库描述文件

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>pagination</display-name>
  <!-- 中文乱码过滤器 -->
  <filter>
  <filter-name>encodingFilter</filter-name>
  <filter-class>com.zking.pagination.util.EncodingFilter</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>encodingFilter</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>
  <!-- 书本控制器 -->
  <servlet>
  <servlet-name>bookAction</servlet-name>
  <servlet-class>com.zking.pagination.action.BookAction</servlet-class>
  </servlet>
  <servlet-mapping>
  <servlet-name>bookAction</servlet-name>
  <url-pattern>/bookAction.action</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>

4、jsp界面—booklist

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<form action="bookAction.action" method="post">
	<label>书本名称：</label><input type="text" name="bookname"/>
	<input type="submit" value="查询"/>
	</form>
<table width="100%" border="1" cellpadding="0" cellspacing="0">
<tr>
<th>书本编号</th>
<th>书本名称</th>
<th>书本价格</th>
<th>书本类型</th>
</tr>
<c:forEach items="${books }" var="b">
<tr>
<td>${b.book_id }</td>
<td>${b.book_name }</td>
<td>${b.book_price}</td>
<td>${b.book_type }</td>
</tr>
</c:forEach>
</table>
</body>
</html>

结果展示：