javathead的简单介绍
本篇文章给大家谈谈javathead，以及对应的知识点，希望对各位有所帮助，不要忘了收藏本站喔。
本文目录一览：
- 1、java 线程4个方法sleep()、wait()、notify()、notifyAll()中哪些方法会抛出异常？什么异常？
- 2、用java将数据导出到wps表格中，怎么实现
- 3、JAVA中Thead cannot be resolved to a type怎么解决 程序如下
- 4、Java如何做动态表格？
- 5、java 用什么实现 FIFO队列？
- 6、java数据库操作问题（上一条数据、下一条数据）
java 线程4个方法sleep()、wait()、notify()、notifyAll()中哪些方法会抛出异常？什么异常？
Thead的sleep方法会抛出InterruptedException异常
Object的wait方法会抛出IllegalMonitorStateException，InterruptedException异常
Object的notify方法会抛出IllegalMonitorStateException异常
Object的notifyAll方法会抛出IllegalMonitorStateException异常
用java将数据导出到wps表格中，怎么实现
一:页面图片显示预览：
1）如下图：
2）点击导出按钮后预览：
3）最终生成的excel表格图片预览：
二：代码演示：
说明：执行操作时，请先引进导出excel表格的jar文件包。
找到导出按钮所执行的js方法，在java后天查看该方法的实现即可。
1）jsp代码：
[html] view plaincopyprint?
%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%
%@taglib prefix="s" uri="/struts-tags" %
%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%
html
head
base href="%=basePath%"
title驾校合格率排名/title
link href="jsp/commonstyle/css/tabStyle.css" rel="stylesheet" type="text/css"
link rel="STYLESHEET" type="text/css" href="%=basePath%jsp/hgltj/js/tablesort.css"
script type="text/javascript" src="%=basePath%jsp/system/common/js/publicColor.js"/script
script type="text/javascript" src="jsp/commonstyle/js/js/My97DatePicker/WdatePicker.js" defer="defer"/script
script type="text/javascript" src="%=basePath%jsp/hgltj/js/tablesort.js"/script
script language="JavaScript"
function load()
{
//根据分辨率设置表格大小
maxw=document.getElementById("maintb").offsetWidth;
if(maxw824){//1024分辨率未展开
mainbox.width="98%";
} else if(maxw1013){//1024分辨率展开
mainbox.width="98%";
} else if(maxw1081){//1280分辨率未展开
mainbox.width="95%";
} else if(maxw1270){//1280分辨未展开
mainbox.width="95%";
}else{//1280以上分辨展开
mainbox.width="98%";
}
}
/script
script
function overIt(){
var the_obj = event.srcElement;
if(the_obj.tagName.toLowerCase() == "td"){
the_obj=the_obj.parentElement;
the_obj.oBgc=the_obj.currentStyle.backgroundColor;
the_obj.oFc=the_obj.currentStyle.color;
the_obj.style.backgroundColor='#4073C4';
the_obj.style.color='#ffffff';
the_obj.style.textDecoration='underline';
}
}
function outIt(){
var the_obj = event.srcElement;
if(the_obj.tagName.toLowerCase() == "td"){
the_obj=the_obj.parentElement;
the_obj.style.backgroundColor=the_obj.oBgc;
the_obj.style.color=the_obj.oFc;
the_obj.style.textDecoration='';
}
}
function serch(){
document.getElementById("formName").action="%=basePath %hgltj.action?method=getHglpm";
document.getElementById("formName").submit();
}
function tbbt(){
var jzrq=document.getElementById("jzrqId").value;
//var jxmc=document.getElementById("jxmcId").value;
window.open('%=basePath %hgltj.action?method=getHglpmTbtjjxkshgl.jzrq='+jzrq+'tjjxkshgl.zt='+1,'','height=650,width=1250,top=150,left=200,toobar=no,menubar=no,scrollbars=yes,resizable=no,location=no,');
}
function openwd(){
document.getElementById("formName").action="%=basePath %hgltj.action?method=downJxhglPm";
document.getElementById("formName").submit();
}
/script
/head
BODY onLoad="load()" style="background: url(images/cont_bg.gif); background-repeat: repeat-y"
input type="hidden" name="method" value="getDriverInfoList"/
table border="0" width="100%" cellspacing="0" cellpadding="0" id="maintb"
tr
td align="center"
table width="90%" border="0" cellspacing="0" cellpadding="0" id="mainbox" style="background:url(jsp/commonstyle/images/usermessage_02.gif); background-repeat:repeat-x;"
!--宽度可变内容框--
tr
td width="33" height="27" style=" background:url(jsp/commonstyle/images/usermessage_01.gif); background-position:left; background-repeat:no-repeat;" /td
td width="965" class="style1"font color="black"驾校合格率排名/font/td
td width="14" height="27" style=" background:url(jsp/commonstyle/images/usermessage_03.gif); background-position:right; background-repeat:no-repeat;" /td
/tr
tr
td colspan="3"
!--页面主体内容开始--
!--查询条件--
form action="" name="formName" method="post" style="margin:0px" id="formName" theme="simple"
table width="100%" border="0" cellpadding="0" cellspacing="0" style="border-collapse:collapse;" id="tj" align="center"
tr align="left"
td class="tjbg1" style="text-align: left"
!-- input type="hidden" id="method" name="method" value="getHglpm"/ --
统计日期：
input type="text" name="tjjxkshgl.jzrq" id="jzrqId" value="s:property value="tjjxkshgl.jzrq"/" onclick="WdatePicker({skin:'whyGreen',dateFmt:'yyyy-MM'})"/
!-- 驾校名称：
s:select id="jxmcId" name="tjjxkshgl.jxxh" value="tjjxkshgl.jxxh" list="schoolList" listKey="jxxh" listValue="jxmc" headerKey="" headerValue="--请选择--" theme="simple"/s:select --
input name="input" value=" 统 计 " type="button" class="normalbtn" onClick="serch()" style="margin-bottom: 5px" /
input name="input" type="button" value=" 合格率图表 " onclick="tbbt()" class="normalbtn" style="margin-bottom: 5px" /
input id="Button1" type="button" value=" 导 出 " onclick="openwd();" class="normalbtn" style="margin-bottom: 5px" /
/td
/tr
/table!--查询结果--
/form
!--查询结果--
table width="100%" border="0" cellpadding="4" cellspacing="1" bgcolor="#abcfff" id="cxjg" align="center"
thead
tr class="tbtitle"
td width="4%" align="center" class="t1"名次/td
td width="8%" align="center" class="t1"名称/td
td class="t1" width="5%" align="center"科目一/td
td class="t1" width="5%" align="center"科目二/td
td class="t1" width="5%" align="center"科目三/td
td class="t1" width="5%" align="center"平均合格率/td
td class="t1" width="5%" align="center"操作/td
/tr
/thead
s:iterator id="jxhgl" value="jxhelpmList" status="st"
tr class="changeColor" onMouseOver="overIt()" onMouseOut="outIt()" style="cursor: hand" align="center"
tds:property value="#st.index+1"//td
tds:property value="#jxhgl.jxmc"//td
tds:property value="#jxhgl.km1hgl"//td
tds:property value="#jxhgl.km2hgl"//td
tds:property value="#jxhgl.km3hgl"//td
tds:property value="#jxhgl.avghgl"/%/td
td
a href="javascript:" onclick="openWin('%=basePath %hgltj.action?method=getTbForJxxhtjjxkshgl.jxxh=s:property value="#jxhgl.jxxh"/tjjxkshgl.zt=1','',1250,750);"图表/a
/td
/tr
/s:iterator
/table
/table
/td
/tr
/table
/body
/html
2）java代码演示：
[java] view plaincopyprint?
/**
* 驾校合格率导出excel图表
*/
//response.getOutputStream();// 取得输出流
response.reset();// 清空输出流
String tmptitle = "驾校合格率排名"; // 标题
response.setHeader("Content-disposition", "attachment; filename="+new String(tmptitle.getBytes(),"iso8859-1")+".xls");// 设定输出文件头
response.setContentType("application/vnd.ms-excel");// 定义输出类型
wbook = Workbook.createWorkbook(os); // 建立excel文件
WritableSheet wsheet = wbook.createSheet(tmptitle, 0); // sheet名称
// 设置excel标题
//cellFormat.setBackground(Colour.AQUA);
cellFormat.setFont(wfont);
label.setCellFormat(cellFormat);
wsheet.addCell(label);
//wsheet.addCell(new Label(0, 0, tmptitle, wcfFC));
wsheet.setRowView(0,500); //第一行高度
wsheet.mergeCells(0, 0, 6, 1); //合并单元格(第一列的第一行和第七列的第二行合并)
//wsheet.mergeCells(0, 1, 9, 1);
// wsheet.mergeCells(0, 2, 0, 4);
// wsheet.mergeCells(1, 2, 3, 2);
// wsheet.mergeCells(4, 2, 6, 2);
// wsheet.mergeCells(7, 2, 9, 2);
wsheet.setColumnView(0,10); //宽度
wsheet.setColumnView(1,25); //宽度
wsheet.setColumnView(2,10); //宽度
wsheet.setColumnView(3,10); //宽度
wsheet.setColumnView(4,10); //宽度
wsheet.setColumnView(5,10); //宽度
// 开始生成主体内容
wfont = new jxl.write.WritableFont(WritableFont.ARIAL, 14,WritableFont.BOLD,false, UnderlineStyle.NO_UNDERLINE,Colour.BLACK);
wcfFC = new WritableCellFormat(wfont);
wsheet.addCell(new Label(0, 2, "名次",wcfFC));
wsheet.addCell(new Label(1, 2, "驾校名称",wcfFC));
wsheet.addCell(new Label(2, 2, "科目一",wcfFC));
wsheet.addCell(new Label(3, 2, "科目二",wcfFC));
wsheet.addCell(new Label(4, 2, "科目三",wcfFC));
wsheet.addCell(new Label(5, 2, "合格率",wcfFC));
int count=jxhelpmList.size();
if(count0){ ////判断集合是否不为0
TjJxkshgl tjhgl=null;
for(int i=0;ijxhelpmList.size();i++){
tjhgl=(TjJxkshgl)jxhelpmList.get(i);
wsheet.addCell(new Label(0, i+3, (i+1)+""));
wsheet.addCell(new Label(1, i+3, tjhgl.getJxmc()));
wsheet.addCell(new Label(2, i+3, tjhgl.getKm1hgl()));
wsheet.addCell(new Label(3, i+3, tjhgl.getKm2hgl()));
wsheet.addCell(new Label(4, i+3, tjhgl.getKm3hgl()));
wsheet.addCell(new Label(5, i+3, tjhgl.getAvghgl()));
}
JAVA中Thead cannot be resolved to a type怎么解决 程序如下
代码编译错误了
Thread t =new Thead(); --------------------后面的改成new Thread(); 少写了个r
Java如何做动态表格？
一、动态加载表格
1.首先在html中为表格的添加位置设置id
即是在html的body标签内部写一个div标签表明表格要添加到此div的内部。如下
div id="tdl"div
2.在javascript中写添加表格的语句
若在当前html文件中，则写在script标签内部，如
代码如下:
script type="text/javascript"
document.getElementById("tbl").innerHTML="tabletrtd/td/tr/table" //此处添加的表格可根据自己需要创建
/script
若是通过引入js文件，则在js文件（假设是test.js）中直接写如下语句
代码如下:
document.getElementById("tbl").innerHTML="tabletrtd/td/tr/table"
然后再引入自己的html文件
代码如下:
script type="text/javascript" src="test.js"/script
二、 动态添加表格行
1.首先在html中为表格行的添加位置设置id，此位置必须是tbody内部（不是特别准确，但根据我的测试就得到此结论，有其他的方法请留言，谢谢），如下
代码如下:
table
thead/thead
tfoottfoot //tfoot与thead是与tbody配套使用，但我在写的时候，没用也可以。
tbody id="rows"/tbody
/table
[\s\S ]*\n
2.在javascript内容中，要先创建行和单元格，再在.tbody中添加行，如下
[code]
row=document.createElement("tr"); //创建行
td1=document.createElement("tr"); //创建单元格
td1.appendChild(document.createTextNode("content")); //为单元格添加内容
row.appendChild(td1); //将单元格添加到行内
document.getElementById("rows").append(row); //将行添加到tbody中
java 用什么实现 FIFO队列？
java使用数据结构来实现FIFO先进先出的队列，实例如下：
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package linkedlisttest;
import java.util.ArrayList;
import java.util.Deque;
import java.util.LinkedList;
import java.util.List;
/**
*
* @author Vicky.H
* @email eclipser@163.com
*/
public class FIFOTest {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
FIFOA fifo = new FIFOImplA(5);
for (int i = 0; i 20; i++) {
A a = new A("A:" + i);
A head = fifo.addLastSafe(a);
System.out.println(i + "\thead:" + head + "\tsize:" + fifo.size());
}
System.out.println("---------------");
System.out.println("弹出数据");
ListA polls = fifo.setMaxSize(3);
for (A a : polls) {
System.out.println("\thead:" + a);
}
System.out.println("剩余数据");
for (A a : fifo) {
System.out.println("\thead:" + a);
}
System.out.println(fifo.size());
}
}
interface FIFOT extends ListT, DequeT, Cloneable, java.io.Serializable {
/**
* 向最后添加一个新的，如果长度超过允许的最大值，则弹出一个 *
*/
T addLastSafe(T addLast);
/**
* 弹出head，如果Size = 0返回null。而不同于pop抛出异常
* @return
*/
T pollSafe();
/**
* 获得最大保存
*
* @return
*/
int getMaxSize();
/**
* 设置最大存储范围
*
* @return 返回的是，因为改变了队列大小，导致弹出的head
*/
ListT setMaxSize(int maxSize);
}
class FIFOImplT extends LinkedListT implements FIFOT {
private int maxSize = Integer.MAX_VALUE;
private final Object synObj = new Object();
public FIFOImpl() {
super();
}
public FIFOImpl(int maxSize) {
super();
this.maxSize = maxSize;
}
@Override
public T addLastSafe(T addLast) {
synchronized (synObj) {
T head = null;
while (size() = maxSize) {
head = poll();
}
addLast(addLast);
return head;
}
}
@Override
public T pollSafe() {
synchronized (synObj) {
return poll();
}
}
@Override
public ListT setMaxSize(int maxSize) {
ListT list = null;
if (maxSize this.maxSize) {
list = new ArrayListT();
synchronized (synObj) {
while (size() maxSize) {
list.add(poll());
}
}
}
this.maxSize = maxSize;
return list;
}
@Override
public int getMaxSize() {
return this.maxSize;
}
}
class A {
private String name;
public A() {
}
public A(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "A{" + "name=" + name + '}';
}
}
java数据库操作问题（上一条数据、下一条数据）
给你个思路吧：
lt;%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%gt;
lt;%@ taglib prefix="s" uri="/struts-tags" %gt;
lt;%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%gt;
lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"gt;
lt;htmlgt;
lt;headgt;
lt;base href="lt;%=basePath%gt;"gt;
lt;titlegt;My JSP 'list.jsp' starting pagelt;/titlegt;
lt;meta http-equiv="content-type" content="text/html;charset=utf-8"gt;
lt;meta http-equiv="pragma" content="no-cache"gt;
lt;meta http-equiv="cache-control" content="no-cache"gt;
lt;meta http-equiv="expires" content="0"gt;
lt;meta http-equiv="keywords" content="keyword1,keyword2,keyword3"gt;
lt;meta http-equiv="description" content="This is my page"gt;
lt;!--
lt;link rel="stylesheet" type="text/css" href="styles.css"gt;
--gt;
lt;stylegt;
.row0{
background: #AABBFF;
}
.row1{
background: #FFAABB;
}
lt;/stylegt;
lt;/headgt;
lt;bodygt;
lt;divgt;lt;span style="color:red;"gt;请用list.action访问该页面lt;/spangt;lt;/divgt;
lt;table width="100%" border="1px solid black" cellpadding="0" cellspacing="0"gt;
lt;captiongt;用户列表及操作lt;/captiongt;
lt;theadgt;
lt;trgt;
lt;th width="20%"gt;IDlt;/thgt;
lt;th width="20%"gt;用户名lt;/thgt;
lt;th width="20%"gt;密码lt;/thgt;
lt;th width="20%"gt;是否可用lt;/thgt;
lt;th width="20%"gt;操作lt;/thgt;
lt;/trgt;
lt;/theadgt;
lt;tbodygt;
lt;s:iterator value="%{users}" status="s"gt;
lt;tr class="row${s.index%2 }"gt;
lt;tdgt;${id }lt;/tdgt;
lt;tdgt;${username }lt;/tdgt;
lt;tdgt;${password }lt;/tdgt;
lt;tdgt;${valid }lt;/tdgt;
lt;tdgt;
lt;a href="delete.action?id=${id }amp;p.page=${p.page }" onclick="return confirm('确定删除？')"gt;删除lt;/agt;
lt;a href="load.action?id=${id }amp;p.page=${p.page }"gt;修改lt;/agt;
lt;/tdgt;
lt;/trgt;
lt;/s:iteratorgt;
lt;/tbodygt;
lt;/tablegt;
lt;divgt;
lt;form action="list.action"gt;
lt;s:if test="%{p.page != 1}"gt;
lt;a href="list.action?p.page=1"gt;首页lt;/agt;
lt;/s:ifgt;
lt;s:elsegt;
lt;a style="color:#ccc;"gt;首页lt;/agt;
lt;/s:elsegt;
lt;s:if test="%{p.page != 1}"gt;
lt;a href="list.action?p.page=${p.page-1 }"gt;上一页lt;/agt;
lt;/s:ifgt;
lt;s:if test="%{p.page != p.totalPage}"gt;
lt;a href="list.action?p.page=${p.page+1 }"gt;下一页lt;/agt;
lt;/s:ifgt;
lt;s:if test="%{p.page != p.totalPage}"gt;
lt;a href="list.action?p.page=${p.totalPage }"gt;末页lt;/agt;
lt;/s:ifgt;
lt;s:elsegt;
lt;a style="color:#ccc;"gt;末页lt;/agt;
lt;/s:elsegt;
lt;spangt;第${p.page }页/共${p.totalPage }页lt;/spangt;
lt;spangt;跳lt;input id="page" name="p.page" style="width:30px;"gt;页lt;/spangt;
lt;input type="submit" value="go"gt;
lt;/formgt;
lt;/divgt;
lt;divgt;
lt;input type="button" value="添加用户" onclick="window.location='add.jsp'"/gt;
lt;/divgt;
lt;/bodygt;
lt;/htmlgt;
package com.action;
import java.util.ArrayList;
import java.util.List;
import com.dao.UserDao;
import com.dao.UserDaoImpl;
import com.opensymphony.xwork2.ActionSupport;
import com.pojo.User;
import com.util.Pagination;
public class UserAction extends ActionSupport{
private UserDao dao = new UserDaoImpl();
private Listlt;Usergt; users = new ArrayListlt;Usergt;();
private User user;
private int id;
private Pagination p = new Pagination();
public String list(){
System.out.println("======================list.action");
try {
System.out.println("list:"+p.getPage()+p.getPageSize());
dao.getMaxPage(p);
users = dao.list(p);
return "success";
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "failed";
}
public String add(){
System.out.println("======================add.action");
try {
dao.add(user);
return "success";
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "failed";
}
public String delete(){
System.out.println("======================delete.action");
try {
dao.delete(id);
return "success";
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "failed";
}
public String load(){
System.out.println("======================load.action");
try {
user = dao.findUserById(id);
return "success";
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "failed";
}
public String modify(){
System.out.println("======================modify.action");
try {
user.setId(id);//设置user的id为所要修改的id
dao.update(user);
return "success";
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return "failed";
}
public Listlt;Usergt; getUsers() {
return users;
}
public void setUsers(Listlt;Usergt; users) {
this.users = users;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public Pagination getP() {
return p;
}
public void setP(Pagination p) {
this.p = p;
}
}
package com.util;
/**
* 分页
* @author yun
*
*/
public class Pagination {
private int pageSize = 3;//每页显示几条数据
private int totalPage = Integer.MAX_VALUE;//共多少页
private int page = 1;//第几页
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
if(pageSize lt;= 0){
pageSize = 3;
}
this.pageSize = pageSize;
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
if(totalPage lt;=0){
totalPage = 1;
}
this.totalPage = totalPage;
//下面的setPage(page)一定要有，因为totalPage是查询出来的，这会影响page的值。
//如：原来有12页数据，现在查询出来的只有2页，那么page大于2的页应该就不存在了
setPage(page);
}
public int getPage() {
return page;
}
public void setPage(int page) {
System.out.println("=========totalPage:"+totalPage);
if(page lt;= 0){
page = 1;
}
if(page gt; totalPage){
page = totalPage;
}
this.page = page;
}
}
package com.dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.pojo.User;
import com.util.DBUtil;
import com.util.Pagination;
public class UserDaoImpl implements UserDao {
public void add(User u) throws Exception {
int id = searchMaxId();//获得id值，相当于id = seq.nextval()
System.out.println("获得id值=============="+id);
u.setId(id);
String sql = "insert into s_user(id,username,password,valid) " +
" values(?,?,?,?)";
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, u.getId());
pstmt.setString(2, u.getUsername());
pstmt.setString(3, u.getPassword());
pstmt.setString(4, u.getValid());
System.out.println("打印sql："+sql+"\t参数:["+u.getId()+","+u.getUsername()+","+u.getPassword()+","+u.getValid()+"]");
pstmt.executeUpdate();
DBUtil.close(pstmt);
DBUtil.close(conn);
}
/**
* 查询记录中最大的id，如果没有就默认为1，有就+1返回
* @return
*/
private int searchMaxId() {
int id = 1;
String sql = "select max(id) mid from s_user";
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = DBUtil.getConnection();
stmt = conn.createStatement();
System.out.println("打印sql："+sql);
rs = stmt.executeQuery(sql);
if(rs.next()){
id = rs.getInt("mid")+1;//有结果，就+1
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return id;
}
public void delete(int id) throws Exception {
String sql = "delete from s_user where id = ?";
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
System.out.println("打印sql："+sql+"\t参数：["+id+"]");
pstmt.executeUpdate();
DBUtil.close(pstmt);
DBUtil.close(conn);
}
public User findUserById(int id) throws Exception {
User u = null;
String sql = "select * from s_user where id = ?";
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, id);
System.out.println("打印sql："+sql+"\t参数：["+id+"]");
ResultSet rs = pstmt.executeQuery();
if(rs.next()){
u = new User();
u.setId(rs.getInt("id"));
u.setUsername(rs.getString("username"));
u.setPassword(rs.getString("password"));
u.setValid(rs.getString("valid"));
}
DBUtil.close(rs);
DBUtil.close(pstmt);
DBUtil.close(conn);
return u;
}
public Listlt;Usergt; list() throws Exception {
Listlt;Usergt; list = new ArrayListlt;Usergt;();
String sql = "select id,username,password,valid from s_user order by id";
Connection conn = DBUtil.getConnection();
Statement stmt = conn.createStatement();
System.out.println("打印sql："+sql);
ResultSet rs = stmt.executeQuery(sql);
while(rs.next()){
int id = rs.getInt("id");
String username = rs.getString("username");
String password = rs.getString("password");
String valid = rs.getString("valid");
User u = new User();
u.setId(id);
u.setUsername(username);
u.setPassword(password);
u.setValid(valid);
list.add(u);
}
DBUtil.close(rs);
DBUtil.close(stmt);
DBUtil.close(conn);
return list;
}
public Listlt;Usergt; list(Pagination p) throws Exception {
Listlt;Usergt; list = new ArrayListlt;Usergt;();
String sql = "select * from (select ini.*,rownum rn from " +
"(select id,username,password,valid from s_user order by id) ini " +
"where rownum lt;= ?) where rn gt;= ? ";
int begin = p.getPageSize()*(p.getPage()-1)+1;//10*(3-1)+1=21 1-10 11-20 21-30
int end = p.getPageSize()*p.getPage();//10*3=30
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, end);
pstmt.setInt(2, begin);
System.out.println("打印sql："+sql+"\t参数：["+end+","+begin+"]");
ResultSet rs = pstmt.executeQuery();
while(rs.next()){
int id = rs.getInt("id");
String username = rs.getString("username");
String password = rs.getString("password");
String valid = rs.getString("valid");
User u = new User();
u.setId(id);
u.setUsername(username);
u.setPassword(password);
u.setValid(valid);
list.add(u);
}
DBUtil.close(rs);
DBUtil.close(pstmt);
DBUtil.close(conn);
return list;
}
public void update(User u) throws Exception {
String sql = "update s_user set username=?,password=?,valid=? where id=?";
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setString(1, u.getUsername());
pstmt.setString(2, u.getPassword());
pstmt.setString(3, u.getValid());
pstmt.setInt(4, u.getId());
System.out.println("打印sql："+sql+"\t参数:["+u.getUsername()+","+u.getPassword()+","+u.getValid()+","+u.getId()+"]");
pstmt.executeUpdate();
DBUtil.close(pstmt);
DBUtil.close(conn);
}
/**
* 设置最大页
* @param p
* @throws SQLException
*/
public void getMaxPage(Pagination p) throws SQLException{
String sql = "select count(*) from s_user";
Connection conn = DBUtil.getConnection();
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery(sql);
if(rs.next()){
int s = rs.getInt(1);//一共有多少条数据
int n = p.getPageSize();//每页大小
int t = (s+n-1)/n;
p.setTotalPage(t);//共有多少页
}
DBUtil.close(rs);
DBUtil.close(stmt);
DBUtil.close(conn);
}
/**
* 测试UserDaoImpl
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
UserDaoImpl impl = new UserDaoImpl();
int size = impl.list().size();
System.out.println("size======"+size);//size======0
}
}
总体来说，这是一个翻页查询问题。
上一条，下一条如果是两个按钮的话，就要写javascript去异步发送请求了，请求时来带上参数，参数为当前的页数减一（上一条），或加一（下一条）。然后就是写查询语句了。
如：
public ListUser list(Pagination p) throws Exception {
ListUser list = new ArrayListUser();
String sql = "select * from (select ini.*,rownum rn from " +
"(select id,username,password,valid from s_user order by id) ini " +
"where rownum = ?) where rn = ? ";
int begin = p.getPageSize()*(p.getPage()-1)+1;//10*(3-1)+1=21 1-10 11-20 21-30
int end = p.getPageSize()*p.getPage();//10*3=30
Connection conn = DBUtil.getConnection();
PreparedStatement pstmt = conn.prepareStatement(sql);
pstmt.setInt(1, end);
pstmt.setInt(2, begin);
System.out.println("打印sql："+sql+"\t参数：["+end+","+begin+"]");
ResultSet rs = pstmt.executeQuery();
while(rs.next()){
int id = rs.getInt("id");
String username = rs.getString("username");
String password = rs.getString("password");
String valid = rs.getString("valid");
User u = new User();
u.setId(id);
u.setUsername(username);
u.setPassword(password);
u.setValid(valid);
list.add(u);
}
DBUtil.close(rs);
DBUtil.close(pstmt);
DBUtil.close(conn);
return list;
}
同理，还是要去查询，然后得到两条记录，还是要传参数的。
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发布于：2022-11-29，除非注明，否则均为原创文章，转载请注明出处。