JSP分页(MySql+c3p0+dbutils)
来源：互联网
作者：佚名
时间：2015-02-16 17:27
为什么要对数据进行分页？当数据较多时，页面就会变的很庞大，不仅会影响到用户的使用，而且还有加重服务器的负担。下面简单的实现了数据的分页。第一步：导入相
为什么要对数据进行分页？当数据较多时，页面就会变的很庞大，不仅会影响到用户的使用，而且还有加重服务器的负担。下面简单的实现了数据的分页。
第一步：导入相应的jar包
需要导入c3p0，dbutils,mysql驱动等jar包。
第二步：创建数据库和表, 配置c3p0， 创建工具类，User类
创建数据库，并准备测试数据(可以自行生成)
create database contacts;
use contacts;
create table users(
id varchar(32),
username varchar(36),
password varchar(36),
constraint user_pk primary key(id)
);
c3p0-config.xml
30000
30
2
30
10
2
50
3
com.mysql.jdbc.Driver
root
123456
1000
30
2
30
5
2
50
3
com.mysql.jdbc.Driver
root
123456
DataSourceUtil.java
package cn.zq.util;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class DataSourceUtil {
private static DataSource ds;
static{
ds = new ComboPooledDataSource("contacts");
}
public static DataSource getDataSource(){
return ds;
}
public static Connection getConnection() throws SQLException{
return ds.getConnection();
}
}
User.java
package cn.zq.domain;
public class User {
private String id;
private String username;
private String password;
public User() {}
public User(String id, String username, String password) {
this.id = id;
this.username = username;
this.password = password;
}
public void setId(String id) {
this.id = id;
}
public void setUsername(String username) {
this.username = username;
}
public void setPassword(String password) {
this.password = password;
}
public String toString() {
return "User [id=" + id + ", username=" + username + ", password="
+ password + "]";
}
public String getId() {
return id;
}
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
}
第三步：创建并配置servlet，创建显示页面
UserServlet.java
package cn.zq.servlet;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import cn.zq.domain.User;
import cn.zq.util.DataSourceUtil;
public class UserServlet extends HttpServlet {
public void init() throws ServletException {
try {
Class.forName("cn.zq.util.DataSourceUtil");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//which page to show.
String pn = request.getParameter("pn");
int pageNum = 1;
try{
pageNum = Integer.parseInt(pn);
}catch(Throwable t){
//ignore
}
int pageSize = 10;
QueryRunner run = new QueryRunner(DataSourceUtil.getDataSource());
try {
String sql = "SELECT COUNT(1) from users";
int totalRecord = run.query( sql, new ScalarHandler() )
.intValue();
System.err.println("totalRecord = " + totalRecord);
//(11 + ( 10 -1))/10
int pageCount = (totalRecord + (pageSize - 1)) / pageSize;
if(pageNum < 0){
pageNum = 1;
}
if(pageNum > pageCount){
pageNum = pageCount;
}
//0, 10 10, 20
int m = (pageNum - 1)*pageSize;
int n = pageSize;
sql = "SELECT * FROM users LIMIT ?, ?";
List userList = run.query(sql, new BeanListHandler(User.class), m, n);
//分页显示多少个页号
int no = 10;
int beginPageIndex = 0;
int endPageIndex = 0;
if(pageCount <= no){
beginPageIndex = 1;
endPageIndex = pageNum;
}else{
beginPageIndex = pageNum - no/2;
endPageIndex = beginPageIndex + (no -1);
if(beginPageIndex < 1){
beginPageIndex = 1;
endPageIndex = no;
}
if(endPageIndex > pageCount){
endPageIndex = pageCount;
beginPageIndex = endPageIndex - (no - 1);
}
}
request.setAttribute("pageCount", pageCount);
request.setAttribute("totalRecord", totalRecord);
request.setAttribute("pageNum", pageNum);
request.setAttribute("beginPageIndex", beginPageIndex);
request.setAttribute("endPageIndex", endPageIndex);
request.setAttribute("userList", userList);
request.getRequestDispatcher("/page/user.jsp")
.forward(request, response);;
} catch (Exception e) {
e.printStackTrace();
}
}
}
)
)
