java常用公共代码二之分页代码的实现

二、分页代码实现：在项目中，分页是一个项目中必不可少的，它可以防止我们从​​数据库​​中进行大量数据查询时速度变慢，提高我们的查询效率

1、定义分页模型：PageModel

​

1. 1. 
      
2. package com.common.page;
3. 
   
4. import java.util.List;
5. 
   
6. /**
7. * 封装分页信息
8. * @author Administrator
9. *
10. */
11. public class PageModel<E> {
12. 
    
13. //结果集
14. private List<E> list;
15. 
    
16. //查询记录数
17. private int totalRecords;
18. 
    
19. //每页多少条数据
20. private int pageSize;
21. 
    
22. //第几页
23. private int pageNo;
24. 
    
25. /**
26. * 总页数
27. * @return
28. */
29. public int getTotalPages() {
30. return (totalRecords + pageSize - 1) / pageSize;
31. }
32. 
    
33. /**
34. * 取得首页
35. * @return
36. */
37. public int getTopPageNo() {
38. return 1;
39. }
40. 
    
41. /**
42. * 上一页
43. * @return
44. */
45. public int getPreviousPageNo() {
46. if (pageNo <= 1) {
47. return 1;
48. }
49. return pageNo - 1;
50. }
51. 
    
52. /**
53. * 下一页
54. * @return
55. */
56. public int getNextPageNo() {
57. if (pageNo >= getBottomPageNo()) {
58. return getBottomPageNo();
59. }
60. return pageNo + 1;
61. }
62. 
    
63. /**
64. * 取得尾页
65. * @return
66. */
67. public int getBottomPageNo() {
68. return getTotalPages();
69. }
70. 
    
71. public List<E> getList() {
72. return list;
73. }
74. 
    
75. public void setList(List<E> list) {
76. this.list = list;
77. }
78. 
    
79. public int getTotalRecords() {
80. return totalRecords;
81. }
82. 
    
83. public void setTotalRecords(int totalRecords) {
84. this.totalRecords = totalRecords;
85. }
86. 
    
87. public int getPageSize() {
88. return pageSize;
89. }
90. 
    
91. public void setPageSize(int pageSize) {
92. this.pageSize = pageSize;
93. }
94. 
    
95. public int getPageNo() {
96. return pageNo;
97. }
98. 
    
99. public void setPageNo(int pageNo) {
100. this.pageNo = pageNo;
101. }
102. }
     1. 
        

2、分页测试：在MySQL中建立admin表，里面有字段id、name、password

3、简历Admin的实体bean类：

​

1. 1. 
      
2. package com.common.page;
3. 
   
4. public class Admin {
5. private int id;
6. private String name;
7. private String password;
8. public int getId() {
9. return id;
10. }
11. public void setId(int id) {
12. this.id = id;
13. }
14. public String getName() {
15. return name;
16. }
17. public void setName(String name) {
18. this.name = name;
19. }
20. public String getPassword() {
21. return password;
22. }
23. public void setPassword(String password) {
24. this.password = password;
25. }
26. 
    
27. }
    1. 
       

4、测试调用：​

1. 1. 
      
2. package com.common.page;
3. 
   
4. import java.sql.Connection;
5. import java.sql.PreparedStatement;
6. import java.sql.ResultSet;
7. import java.sql.SQLException;
8. import java.util.ArrayList;
9. import java.util.List;
10. 
    
11. import com.common.db.DbUtil;
12. 
    
13. public class Client {
14. public static PageModel findAdmins(int pageNo,int pageSize){
15. Connection conn=DbUtil.getConnection();
16. String sql="select * from admin limit ?,?";
17. PageModel pageModel=null;
18. PreparedStatement pstm=null;
19. ResultSet rs=null;
20. Admin admin=null;
21. List<Admin> list=new ArrayList<Admin>();
22. try {
23. pstm=conn.prepareStatement(sql);
24. pstm.setInt(1, (pageNo-1)*pageSize);
25. pstm.setInt(2, pageNo*pageSize);
26. rs=pstm.executeQuery();;
27. while(rs.next()){
28. admin=new Admin();
29. admin.setId(rs.getInt("a_id"));
30. admin.setName(rs.getString("a_name"));
31. admin.setPassword(rs.getString("a_pwd"));
32. list.add(admin);
33. }
34. ResultSet rs2=pstm.executeQuery("select count(*) from admin");
35. int total=0;
36. if(rs2.next()){
37. total=rs2.getInt(1);
38. }
39. pageModel=new PageModel();
40. pageModel.setPageNo(pageNo);
41. pageModel.setPageSize(pageSize);
42. pageModel.setTotalRecords(total);
43. pageModel.setList(list);
44. } catch (SQLException e) {
45. e.printStackTrace();
46. }finally{
47. DbUtil.close(conn);
48. DbUtil.close(pstm);
49. DbUtil.close(rs);
50. }
51. return pageModel;
52. }
53. 
    
54. public static void main(String[] args) {
55. PageModel pageModel=Client.findAdmins(2,4);
56. List<Admin> list=pageModel.getList();
57. for(Admin a:list){
58. System.out.print("ID:"+a.getId()+",用户名:"+a.getName()+",密码:"+a.getPassword());
59. System.out.println();
60. }
61. System.out.print("当前页:"+pageModel.getPageNo()+" ");
62. System.out.print("共"+pageModel.getTotalPages()+"页 ");
63. System.out.print("首页:"+pageModel.getTopPageNo()+" ");
64. System.out.print("上一页:"+pageModel.getPreviousPageNo()+" ");
65. System.out.print("下一页:"+pageModel.getNextPageNo()+" ");
66. System.out.print("尾页:"+pageModel.getBottomPageNo()+" ");
67. System.out.print("共"+pageModel.getTotalRecords()+"条记录");
68. System.out.println();
69. }
70. 
    
71. }
    1. 
       

这样分页效果就实现了，我们要实现分页效果，只要传入相应的参数和相应的数据库执行语句即可实现，希望大家能灵活运用。