Oracle下的Java分页功能_动力节点Java学院整理

2023-09-26 13:42:05 68
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：
packagecom.bjpowernode.test;
importjava.util.List;
publicclassPageModel{
privateListlist;
privateintpageNo;
privateintpageSize;
privateinttotalNum;
privateinttotalPage;
publicListgetList(){
returnlist;
}
publicvoidsetList(Listlist){
this.list=list;
}
publicintgetPageNo(){
returnpageNo;
}
publicvoidsetPageNo(intpageNo){
this.pageNo=pageNo;
}
publicintgetPageSize(){
returnpageSize;
}
publicvoidsetPageSize(intpageSize){
this.pageSize=pageSize;
}
publicintgetTotalNum(){
returntotalNum;
}
publicvoidsetTotalNum(inttotalNum){
this.totalNum=totalNum;
setTotalPage((getTotalNum()%pageSize)==0?(getTotalNum()/pageSize)
:(getTotalNum()/pageSize+1));
}
publicintgetTotalPage(){
returntotalPage;
}
publicvoidsetTotalPage(inttotalPage){
this.totalPage=totalPage;
}
//获取第一页
publicintgetFirstPage(){
return1;
}
//获取最后页
publicintgetLastPage(){
returntotalPage;
}
//获取前页
publicintgetPrePage(){
if(pageNo>1)
returnpageNo-1;
return1;
}
//获取后页
publicintgetBackPage(){
if(pageNo
 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：


packagecom.bjpowernode.test;
importjava.io.*;
importjava.util.*;
importjavax.servlet.ServletConfig;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
importkane.UserInfo;
importkane.UserInfoManage;
importkane.PageModel;
publicclassUserBasicSearchServletextendsHttpServlet{
privatestaticfinallongserialVersionUID=1L;
privateintpageSize=0;
@Override
publicvoidinit(ServletConfigconfig)throwsServletException{
pageSize=Integer.parseInt(config.getInitParameter("pageSize"));
}
@Override
protectedvoiddoGet(HttpServletRequestreq,HttpServletResponseresp)
throwsServletException,IOException{
doPost(req,resp);
}
@Override
protectedvoiddoPost(HttpServletRequestreq,HttpServletResponseresp)
throwsServletException,IOException{
//1.取得页面参数并构造参数对象
intpageNo=Integer.parseInt(req.getParameter("pageNo"));
Stringsex=req.getParameter("gender");
Stringhome=req.getParameter("newlocation");
Stringcolleage=req.getParameter("colleage");
Stringcomingyear=req.getParameter("ComingYear");
UserInfou=newUserInfo();
u.setSex(sex);
u.setHome(home);
u.setColleage(colleage);
u.setCy(comingyear);
//2.调用业务逻辑取得结果集
UserInfoManageuserInfoManage=newUserInfoManage();
PageModelpagination=userInfoManage.userBasicSearch(u,
pageNo,pageSize);
ListuserList=pagination.getList();
//3.封装返回结果
StringBufferresultXML=newStringBuffer();
try{
resultXML.append("/n");
resultXML.append("/n");
for(Iteratoriterator=userList.iterator();iterator
.hasNext();){
UserInfouserInfo=iterator.next();
resultXML.append("/n");
resultXML.append("/t"+userInfo.getId()+"/n");
resultXML.append("/t"+userInfo.getTruename()
+"/n");
resultXML.append("/t"+userInfo.getSex()+"/n");
resultXML.append("/t"+userInfo.getHome()+"/n");
resultXML.append("/n");
}
resultXML.append("/n");
resultXML.append("/t"+pagination.getTotalPage()
+"/n");
resultXML.append("/t"+pagination.getFirstPage()
+"/n");
resultXML.append("/t"+pagination.getLastPage()+"/n");
resultXML.append("/t"+pagination.getPageNo()
+"/n");
resultXML.append("/n");
resultXML.append("/n");
}catch(Exceptione){
e.printStackTrace();
}
writeResponse(req,resp,resultXML.toString());
}
publicvoidwriteResponse(HttpServletRequestrequest,
HttpServletResponseresponse,Stringresult)throwsIOException{
response.setContentType("text/xml");
response.setHeader("Cache-Control","no-cache");
response.setHeader("Content-Type","text/xml;charset=gb18030");
PrintWriterpw=response.getWriter();
pw.write(result);
pw.close();
}
}
其中User对象代码如下：
packagecom.bjpowernode.test;
importjava.util.Date;
publicclassUserInfo{
privateintid;
privateStringusername;
privateStringpassword;
privateStringtruename;
privateStringsex;
privateDatebirthday;
privateStringhome;
privateStringcolleage;
privateStringcomingYear;
publicintgetId(){
returnid;
}
publicvoidsetId(intid){
this.id=id;
}
publicStringgetUsername(){
returnusername;
}
publicvoidsetUsername(Stringusername){
this.username=username;
}
publicStringgetPassword(){
returnpassword;
}
publicvoidsetPassword(Stringpassword){
this.password=password;
}
publicStringgetTruename(){
returntruename;
}
publicvoidsetTruename(Stringtruename){
this.truename=truename;
}
publicStringgetSex(){
returnsex;
}
publicvoidsetSex(Stringsex){
this.sex=sex;
}
publicDategetBirthday(){
returnbirthday;
}
publicvoidsetBirthday(Datebirthday){
this.birthday=birthday;
}
publicStringgetHome(){
returnhome;
}
publicvoidsetHome(Stringhome){
this.home=home;
}
publicStringgetColleage(){
returncolleage;
}
publicvoidsetColleage(Stringcolleage){
this.colleage=colleage;
}
publicStringgetCy(){
returncomingYear;
}
publicvoidsetCy(Stringcy){
this.comingYear=cy;
}
}
接着是业务逻辑层代码，代码如下：
packagecom.bjpowernode.test;
importjava.sql.Connection;
importkane.DBUtility;
importkane.PageModel;
publicclassUserInfoManage{
privateUserInfoDaouserInfoDao=null;
publicUserInfoManage(){
userInfoDao=newUserInfoDao();
}
publicPageModeluserBasicSearch(UserInfou,intpageNo,
intpageSize)throwsException{
Connectionconnection=null;
PageModelpagination=newPageModel();
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(Exceptione){
DBUtility.rollBack(connection);
e.printStackTrace();
thrownewException();
}finally{
DBUtility.closeConnection();
}
returnpagination;
}
}
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： 


packagecom.bjpowernode.test;
importjava.sql.Connection;
importjava.sql.PreparedStatement;
importjava.sql.ResultSet;
importjava.sql.SQLException;
importjava.util.ArrayList;
importjava.util.List;
importkane.UserInfo;
importkane.DBUtility;
publicclassUserInfoDao{
publicListgetUserList(UserInfouserInfo,intpageNo,
intpageSize)throwsException{
PreparedStatementpstmt=null;
ResultSetrs=null;
ListuserList=null;
try{
Stringsql="select*from(selectrownumnum,u.*from(select*fromuser_infowheresex=?andhomelike'"
+userInfo.getHome()
+"%"
+"'andcolleagelike'"
+userInfo.getColleage()
+"%"
+"'andcomingyearlike'"
+userInfo.getCy()
+"%"
+"'orderbyid)uwhererownum<=?)wherenum>=?";
userList=newArrayList();
Connectionconn=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()){
UserInfouser=newUserInfo();
user.setId(rs.getInt("id"));
user.setTruename(rs.getString("truename"));
user.setSex(rs.getString("sex"));
user.setHome(rs.getString("home"));
userList.add(user);
}
}catch(SQLExceptione){
e.printStackTrace();
thrownewException(e);
}finally{
DBUtility.closeResultSet(rs);
DBUtility.closePreparedStatement(pstmt);
}
returnuserList;
}
publicintgetTotalNum(UserInfouserInfo)throwsException{
PreparedStatementpstmt=null;
ResultSetrs=null;
intcount=0;
try{
Stringsql="selectcount(*)fromuser_infowheresex=?andhomelike'"
+userInfo.getHome()
+"%"
+"'andcolleagelike'"
+userInfo.getColleage()
+"%"
+"'andcomingyearlike'"
+userInfo.getCy()+"%"+"'";
Connectionconn=DBUtility.getConnection();
pstmt=conn.prepareStatement(sql);
pstmt.setString(1,userInfo.getSex());
rs=pstmt.executeQuery();
if(rs.next()){
count=rs.getInt(1);
}
}catch(SQLExceptione){
e.printStackTrace();
thrownewException(e);
}finally{
DBUtility.closeResultSet(rs);
DBUtility.closePreparedStatement(pstmt);
}
returncount;
}
}
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.packagecom.bjpowernode.test;    


importjava.sql.Connection;
importjava.sql.DriverManager;
importjava.sql.PreparedStatement;
importjava.sql.ResultSet;
importjava.sql.SQLException;
publicclassDBUtility{
privatestaticThreadLocalthreadLocal=newThreadLocal();
publicstaticConnectiongetConnection(){
Connectionconn=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(ClassNotFoundExceptione){
e.printStackTrace();
}catch(SQLExceptione){
e.printStackTrace();
}
}
returnconn;
}
//封装设置Connection自动提交
publicstaticvoidsetAutoCommit(Connectionconn,Booleanflag){
try{
conn.setAutoCommit(flag);
}catch(SQLExceptione){
e.printStackTrace();
}
}
//设置事务提交
publicstaticvoidcommit(Connectionconn){
try{
conn.commit();
}catch(SQLExceptione){
e.printStackTrace();
}
}
//封装设置Connection回滚
publicstaticvoidrollBack(Connectionconn){
try{
conn.rollback();
}catch(SQLExceptione){
e.printStackTrace();
}
}
//封装关闭Connection、PreparedStatement、ResultSet的函数
publicstaticvoidcloseConnection(){
Connectionconn=threadLocal.get();
try{
if(conn!=null){
conn.close();
conn=null;
threadLocal.remove();
}
}catch(SQLExceptione){
e.printStackTrace();
}
}
publicstaticvoidclosePreparedStatement(PreparedStatementpstmt){
try{
if(pstmt!=null){
pstmt.close();
pstmt=null;
}
}catch(SQLExceptione){
e.printStackTrace();
}
}
publicstaticvoidcloseResultSet(ResultSetrs){
try{
if(rs!=null){
rs.close();
rs=null;
}
}catch(SQLExceptione){
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。
到此一个简单的代码实现就完成了。
总结
以上所述是小编给大家介绍的Oracle下的Java分页功能，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对毛票票网站的支持！
Oracle下的Java分页功能_动力节点Java学院整理

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