簡單Java 多表聯查分頁顯示（初）
阿新 • • 發佈：2019-02-17
Java 多表聯查分頁顯示
操作步驟：
- 建立資料庫
- 使用Servlet 建立Java專案
- 編寫程式碼
1、資料庫 選用 Oracle
程式碼附上：
drop table Score;
drop table Student;
drop table Subject;
drop sequence seq_Student;
drop sequence seq_Score;
drop sequence seq_Subject;
create table Student
(
id int primary key,
name nvarchar2(50 2、頁面展示：index.jsp頁面
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
</head>
<body>
<form action="">
<table align="center" border="1" style="width: 400px; border-collapse: collapse; text-align: center;">
<tr>
<th>編號</th>
<th>姓名</th>
<th>年齡</th>
<th>愛好</th>
<th>成績</th>
<th>科目</th>
</tr>
<c:if test="${empty list}">
<c:redirect url="StudentInfoServlet.do"></c:redirect>
</c:if>
<c:forEach var="list" items="${sessionScope.list}">
<tr>
<td>${list.id }</td>
<td>${list.name }</td>
<td>${list.age }</td>
<td>${list.hobby }</td>
<td>${list.score }</td>
<td>${list.subject }</td>
</tr>
</c:forEach>
<tr>
<td colspan="6">
<a href="StudentInfoServlet.do?page=1">首頁</a>
<a href="StudentInfoServlet.do?page=${sessionScope.top }">上一頁</a>
<a href="StudentInfoServlet.do?page=${sessionScope.bottom }">下一頁</a>
<a href="StudentInfoServlet.do?page=${sessionScope.count }">末頁</a>
</td>
</tr>
</table>
</form>
</body>
</html>
3、建立Servlet StudentInfoServlet.java類
package servlet;
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 dao.StudentInfoDao;
import dao.impl.StudentInfoDaoImpl;
import entity.StudentInfo;
public class StudentInfoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset= utf-8");
request.setCharacterEncoding("utf-8");
StudentInfoDao stu = new StudentInfoDaoImpl();
int count = stu.count_ye();
Integer dang_ye = null;
if (request.getParameter("page") != null) {
dang_ye = Integer.parseInt(request.getParameter("page"));
} else {
dang_ye = 1;
}
List<StudentInfo> list = stu.getAll(dang_ye);
int top = 1;
int bottom = count;
if (dang_ye != 1) {
top = dang_ye - 1;
}
if (dang_ye != count) {
bottom = dang_ye + 1;
}
request.getSession().setAttribute("top", top);
request.getSession().setAttribute("bottom", bottom);
request.getSession().setAttribute("count", count);
request.getSession().setAttribute("list", list);
response.sendRedirect("index.jsp");
}
}
4、建立Dao層區
StudentInfoDao.java介面
package dao;
import java.util.List;
import entity.StudentInfo;
public interface StudentInfoDao {
public List<StudentInfo> getAll(int page);
public int count_ye();
}
實現類 StudentInfoDaoImpl.java介面實現類
package dao.impl;
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 dao.BaseDao;
import dao.StudentInfoDao;
import entity.StudentInfo;
public class StudentInfoDaoImpl extends BaseDao implements StudentInfoDao {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
public int count_ye() {
int count = 0;
int ye = 0;
String sql = "select count(*) from Student";
try {
conn = this.getConnection();
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
count = rs.getInt(1);
}
ye = count / 10;
if (count % 10 != 0) {
ye++;
}
} catch (SQLException e) {
e.printStackTrace();
}
return ye;
}
public List<StudentInfo> getAll(int page) {
List<StudentInfo> list = new ArrayList<StudentInfo>();
String sql = "select stu.*,sco.score as scoid,sub.name as subid from (select rownum as rn,s.* from (select * from Student order by id desc) s ) stu left join Score sco on stu.id = sco.id left join Subject sub on sub.id = sco.subid where stu.rn>? and stu.rn<=?";
int top = (page - 1) * 10;
int bottom = page * 10;
try {
conn = this.getConnection();
ps = conn.prepareStatement(sql);
ps.setInt(1, top);
ps.setInt(2, bottom);
rs = ps.executeQuery();
while (rs.next()) {
StudentInfo stu = new StudentInfo(rs.getInt("id"),
rs.getString("name"), rs.getInt("age"), rs.getString("hobby"), rs
.getInt("scoid"), rs.getString("subid"));
list.add(stu);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
this.getClose(conn, ps, rs);
}
return list;
}
}
BaseDao.java
package dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class BaseDao {
private static final String driver = "oracle.jdbc.driver.OracleDriver";
private static final String url = "jdbc:oracle:thin:@localhost:1521:accp11g";
private static final String name = "system";
private static final String pwd = "baiyu";
public Connection getConnection() {
Connection conn = null;
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, name, pwd);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public void getClose(Connection conn, Statement ps, ResultSet rs) {
try {
if (rs != null) {
rs.close();
}
if (ps != null) {
ps.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
實體類 StudentInfo.java
package entity;
import java.io.Serializable;
public class StudentInfo implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private String name;
private int age;
private String hobby;
private int score;
private String subject;
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;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getHobby() {
return hobby;
}
public void setHobby(String hobby) {
this.hobby = hobby;
}
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
public String getSubject() {
return subject;
}
public void setSubject(String subject) {
this.subject = subject;
}
public StudentInfo(int id, String name, int age, String hobby, int score,
String subject) {
super();
this.id = id;
this.name = name;
this.age = age;
this.hobby = hobby;
this.score = score;
this.subject = subject;
}
public StudentInfo(String name, int age, String hobby, int score,
String subject) {
super();
this.name = name;
this.age = age;
this.hobby = hobby;
this.score = score;
this.subject = subject;
}
public StudentInfo() {
super();
}
}