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丸趣 TV 小编给大家分享一下 Oracle 中 Java 分页功能有哪些，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
就如平时我们很在分页中看到的，分页的时候返回的不仅包括查询的结果集 (List)，而且还包括总的页数(pageNum)、当前第几页(pageNo) 等等信息，所以我们封装一个查询结果 PageModel 类，代码如下：
package com.bjpowernode.test;
import java.util.List;
public class PageModel E {
private List E list;
private int pageNo;
private int pageSize;
private int totalNum;
private int totalPage;
public List E getList() {
return list;
}
public void setList(List E list) {
this.list = list;
}
public int getPageNo() {
return pageNo;
}
public void setPageNo(int pageNo) {
this.pageNo = pageNo;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalNum() {
return totalNum;
}
public void setTotalNum(int totalNum) {
this.totalNum = totalNum;
setTotalPage((getTotalNum() % pageSize) == 0 ? (getTotalNum() / pageSize)
: (getTotalNum() / pageSize + 1));
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
// 获取第一页
public int getFirstPage() {
return 1;
}
// 获取最后页
public int getLastPage() {
return totalPage;
}
// 获取前页
public int getPrePage() {
if (pageNo 1)
return pageNo - 1;
return 1;
}
// 获取后页
public int getBackPage() {
if (pageNo totalPage)
return pageNo + 1;
return totalPage;
}
// 判断 首页 及‘前页 是否可用
public String isPreable() {
if (pageNo == 1)
return disabled
return
}
// 判断 尾页 及‘下页 是否可用
public String isBackable() {
if (pageNo == totalPage)
return disabled
return
}
}其中使用泛型是为了能使的该分页类能进行重用，比如在查询用户时可以封装 User 对象、在查询财务中的流向单时可以封装流向单 FlowCard 类。
我们以查询用户为例，用户选择查询条件，首先调用 Servlet 获取查询参数，然后请求业务逻辑层取得分页封装结果类。业务逻辑调用 Dao 层取得结果集、取得中记录数封装成分页类。最后 Servlet 将结果设置到 jsp 页面显示。
首先来讲解 Servlet，代码如下：
package com.bjpowernode.test;
import java.io.*;
import java.util.*;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import kane.UserInfo;
import kane.UserInfoManage;
import kane.PageModel;
public class UserBasicSearchServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private int pageSize = 0;
@Override
public void init(ServletConfig config) throws ServletException {
pageSize = Integer.parseInt(config.getInitParameter( pageSize));
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// 1. 取得页面参数并构造参数对象
int pageNo = Integer.parseInt(req.getParameter( pageNo));
String sex = req.getParameter( gender
String home = req.getParameter( newlocation
String colleage = req.getParameter( colleage
String comingyear = req.getParameter( ComingYear
UserInfo u = new UserInfo();
u.setSex(sex);
u.setHome(home);
u.setColleage(colleage);
u.setCy(comingyear);
// 2. 调用业务逻辑取得结果集
UserInfoManage userInfoManage = new UserInfoManage();
PageModel UserInfo pagination = userInfoManage.userBasicSearch(u,
pageNo, pageSize);
List UserInfo userList = pagination.getList();
// 3. 封装返回结果
StringBuffer resultXML = new StringBuffer();
try {
resultXML.append( ?xml version= 1.0 encoding= gb18030 ? /n
resultXML.append( root /n
for (Iterator UserInfo iterator = userList.iterator(); iterator
.hasNext();) {
UserInfo userInfo = iterator.next();
resultXML.append( data /n
resultXML.append(/t id + userInfo.getId() + /id /n
resultXML.append(/t truename + userInfo.getTruename()
+ / truename /n
resultXML.append(/t sex + userInfo.getSex() + /sex /n
resultXML.append(/t home + userInfo.getHome() + /home /n
resultXML.append( /data /n
}
resultXML.append( pagination /n
resultXML.append(/t total + pagination.getTotalPage()
+ /total /n
resultXML.append(/t start + pagination.getFirstPage()
+ /start /n
resultXML.append(/t end + pagination.getLastPage() + /end /n
resultXML.append(/t pageno + pagination.getPageNo()
+ /pageno /n
resultXML.append( /pagination /n
resultXML.append( /root /n
} catch (Exception e) {
e.printStackTrace();
}
writeResponse(req, resp, resultXML.toString());
}
public void writeResponse(HttpServletRequest request,
HttpServletResponse response, String result) throws IOException {
response.setContentType( text/xml
response.setHeader( Cache-Control , no-cache
response.setHeader( Content-Type , text/xml; charset=gb18030
PrintWriter pw = response.getWriter();
pw.write(result);
pw.close();
}
}其中 User 对象代码如下：
package com.bjpowernode.test;
import java.util.Date;
public class UserInfo {
private int id;
private String username;
private String password;
private String truename;
private String sex;
private Date birthday;
private String home;
private String colleage;
private String comingYear;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getTruename() {
return truename;
}
public void setTruename(String truename) {
this.truename = truename;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getHome() {
return home;
}
public void setHome(String home) {
this.home = home;
}
public String getColleage() {
return colleage;
}
public void setColleage(String colleage) {
this.colleage = colleage;
}
public String getCy() {
return comingYear;
}
public void setCy(String cy) {
this. comingYear= cy;
}
}接着是业务逻辑层代码，代码如下：
package com.bjpowernode.test;
import java.sql.Connection;
import kane.DBUtility;
import kane.PageModel;
public class UserInfoManage {
private UserInfoDao userInfoDao = null;
public UserInfoManage () {
userInfoDao = new UserInfoDao();
}
public PageModel UserInfo userBasicSearch(UserInfo u, int pageNo,
int pageSize) throws Exception {
Connection connection = null;
PageModel UserInfo pagination = new PageModel UserInfo
try {
connection = DBUtility.getConnection();
DBUtility.setAutoCommit(connection, false);
pagination.setList(userInfoDao.getUserList(u, pageNo, pageSize));
pagination.setPageNo(pageNo);
pagination.setPageSize(pageSize);
pagination.setTotalNum(userInfoDao.getTotalNum(u));
DBUtility.commit(connection);
} catch (Exception e) {
DBUtility.rollBack(connection);
e.printStackTrace();
throw new Exception();
} finally {
DBUtility.closeConnection();
}
return pagination;
}
}其中 DBUtility 为数据库的连接封装类。
最后是 Dao 层代码实现，代码如下：
package com.bjpowernode.test;
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 kane.UserInfo;
import kane.DBUtility;
public class UserInfoDao {
public List UserInfo getUserList(UserInfo userInfo, int pageNo,
int pageSize) throws Exception {
PreparedStatement pstmt = null;
ResultSet rs = null;
List UserInfo userList = null;
try {
String sql = select * from(select rownum num,u.* from(select * from user_info where sex = ? and home like
+ userInfo.getHome()
+ %
+ and colleage like
+ userInfo.getColleage()
+ %
+ and comingyear like
+ userInfo.getCy()
+ %
+ order by id) u where rownum =?) where num =?
userList = new ArrayList UserInfo
Connection conn = DBUtility.getConnection();
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, userInfo.getSex());
pstmt.setInt(2, pageNo * pageSize);
pstmt.setInt(3, (pageNo - 1) * pageSize + 1);
rs = pstmt.executeQuery();
while (rs.next()) {
UserInfo user = new UserInfo();
user.setId(rs.getInt( id));
user.setTruename(rs.getString( truename));
user.setSex(rs.getString( sex));
user.setHome(rs.getString( home));
userList.add(user);
}
} catch (SQLException e) {
e.printStackTrace();
throw new Exception(e);
} finally {
DBUtility.closeResultSet(rs);
DBUtility.closePreparedStatement(pstmt);
}
return userList;
}
public int getTotalNum(UserInfo userInfo) throws Exception {
PreparedStatement pstmt = null;
ResultSet rs = null;
int count = 0;
try {
String sql = select count(*) from user_info where sex=? and home like
+ userInfo.getHome()
+ %
+ and colleage like
+ userInfo.getColleage()
+ %
+ and comingyear like
+ userInfo.getCy()+ % +
Connection conn = DBUtility.getConnection();
pstmt = conn.prepareStatement(sql);
pstmt.setString(1, userInfo.getSex());
rs = pstmt.executeQuery();
if (rs.next()) {
count = rs.getInt(1);
}
} catch (SQLException e) {
e.printStackTrace();
throw new Exception(e);
} finally {
DBUtility.closeResultSet(rs);
DBUtility.closePreparedStatement(pstmt);
}
return count;
}
}最后就是 servlet 将得到的结果返回给 jsp 页面显示出来。
注：其中 DBUtility 代码是封装数据库连接操作的代码，如下：
1.package com.bjpowernode.test;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DBUtility {
private static ThreadLocal Connection threadLocal = new ThreadLocal Connection
public static Connection getConnection() {
Connection conn = null;
conn = threadLocal.get();
if (conn == null) {
try {
Class.forName( oracle.jdbc.driver.OracleDriver
conn = DriverManager.getConnection(
jdbc:oracle:thin:@localhost:1521:oracle , admin ,
admin
threadLocal.set(conn);
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
return conn;
}
// 封装设置 Connection 自动提交
public static void setAutoCommit(Connection conn, Boolean flag) {
try {
conn.setAutoCommit(flag);
} catch (SQLException e) {
e.printStackTrace();
}
}
// 设置事务提交
public static void commit(Connection conn) {
try {
conn.commit();
} catch (SQLException e) {
e.printStackTrace();
}
}
// 封装设置 Connection 回滚
public static void rollBack(Connection conn) {
try {
conn.rollback();
} catch (SQLException e) {
e.printStackTrace();
}
}
// 封装关闭 Connection、PreparedStatement、ResultSet 的函数
public static void closeConnection() {
Connection conn = threadLocal.get();
try {
if (conn != null) {
conn.close();
conn = null;
threadLocal.remove();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void closePreparedStatement(PreparedStatement pstmt) {
try {
if (pstmt != null) {
pstmt.close();
pstmt = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void closeResultSet(ResultSet rs) {
try {
if (rs != null) {
rs.close();
rs = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}使用 ThreadLocal 是为了保证事务的一致，使得同一个线程的所有数据库操作使用同一个 Connection。
以上是“Oracle 中 Java 分页功能有哪些”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注丸趣 TV 行业资讯频道！
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