就如平時我們很在分頁中看到的，分頁的時候返回的不僅包括查詢的結果集(List)，而且還包括總的頁數(pageNum)、當前第幾頁(pageNo)等等信息，所以我們封裝一個查詢結果PageModel類，代碼如下：
package com.bjpowernode.test;
import java.util.List;
public class PageModelE> {
private ListE> list;
private int pageNo;
private int pageSize;
private int totalNum;
private int totalPage;
public ListE> getList() {
return list;
}
public void setList(ListE> 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;
}
// 獲取第一頁
public int getFirstPage() {
return 1;
}
// 獲取最后頁
public int getLastPage() {
return totalPage;
}
// 獲取前頁
public int getPrePage() {
if (pageNo > 1)
return pageNo - 1;
return 1;
}
// 獲取后頁
public int getBackPage() {
if (pageNo totalPage)
return pageNo + 1;
return totalPage;
}
// 判斷'首頁'及‘前頁'是否可用
public String isPreable() {
if (pageNo == 1)
return "disabled";
return "";
}
// 判斷'尾頁'及‘下頁'是否可用
public String isBackable() {
if (pageNo == totalPage)
return "disabled";
return "";
}
}
其中使用泛型是為了能使的該分頁類能進行重用，比如在查詢用戶時可以封裝User對象、在查詢財務中的流向單時可以封裝流向單FlowCard類。
我們以查詢用戶為例，用戶選擇查詢條件，首先調用Servlet獲取查詢參數，然后請求業務邏輯層取得分頁封裝結果類。業務邏輯調用Dao層取得結果集、取得中記錄數封裝成分頁類。最后Servlet將結果設置到jsp頁面顯示。
首先來講解Servlet，代碼如下：
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.取得頁面參數并構造參數對象
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.調用業務邏輯取得結果集
UserInfoManage userInfoManage = new UserInfoManage();
PageModelUserInfo> pagination = userInfoManage.userBasicSearch(u,
pageNo, pageSize);
ListUserInfo> userList = pagination.getList();
// 3.封裝返回結果
StringBuffer resultXML = new StringBuffer();
try {
resultXML.append("?xml version='1.0' encoding='gb18030'?>/n");
resultXML.append("root>/n");
for (IteratorUserInfo> iterator = userList.iterator(); iterator
.hasNext();) {
UserInfo userInfo = iterator.next();
resultXML.append("data>/n");
resultXML.append("/tid>" + userInfo.getId() + "/id>/n");
resultXML.append("/ttruename>" + userInfo.getTruename()
+ "/ truename >/n");
resultXML.append("/tsex>" + userInfo.getSex() + "/sex>/n");
resultXML.append("/thome>" + userInfo.getHome() + "/home>/n");
resultXML.append("/data>/n");
}
resultXML.append("pagination>/n");
resultXML.append("/ttotal>" + pagination.getTotalPage()
+ "/total>/n");
resultXML.append("/tstart>" + pagination.getFirstPage()
+ "/start>/n");
resultXML.append("/tend>" + pagination.getLastPage() + "/end>/n");
resultXML.append("/tpageno>" + 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對象代碼如下：
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;
}
}
接著是業務邏輯層代碼，代碼如下：
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 PageModelUserInfo> userBasicSearch(UserInfo u, int pageNo,
int pageSize) throws Exception {
Connection connection = null;
PageModelUserInfo> pagination = new PageModelUserInfo>();
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為數據庫的連接封裝類。
最后是Dao層代碼實現，代碼如下：
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 ListUserInfo> getUserList(UserInfo userInfo, int pageNo,
int pageSize) throws Exception {
PreparedStatement pstmt = null;
ResultSet rs = null;
ListUserInfo> 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 ArrayListUserInfo>();
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將得到的結果返回給jsp頁面顯示出來。
注：其中DBUtility代碼是封裝數據庫連接操作的代碼，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 ThreadLocalConnection> threadLocal = new ThreadLocalConnection>();
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;
}
// 封裝設置Connection自動提交
public static void setAutoCommit(Connection conn, Boolean flag) {
try {
conn.setAutoCommit(flag);
} catch (SQLException e) {
e.printStackTrace();
}
}
// 設置事務提交
public static void commit(Connection conn) {
try {
conn.commit();
} catch (SQLException e) {
e.printStackTrace();
}
}
// 封裝設置Connection回滾
public static void rollBack(Connection conn) {
try {
conn.rollback();
} catch (SQLException e) {
e.printStackTrace();
}
}
// 封裝關閉Connection、PreparedStatement、ResultSet的函數
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是為了保證事務的一致，使得同一個線程的所有數據庫操作使用同一個Connection。
到此一個簡單的代碼實現就完成了。
總結
以上所述是小編給大家介紹的Oracle下的Java分頁功能，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對腳本之家網站的支持！
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