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:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
|
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:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
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:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
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:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
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:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
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;
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
|
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。
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服务器之家网站的支持!