建目錄coreservlets,將兩個servlets放在這個目錄中,在coreservlet的上級目錄
運行:
javac coreservlets/HelloServlet3.java
package coreservlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
/** Simple servlet for testing the use of packages
* and utilities from the same package.
* <P>
* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/
public class HelloServlet3 extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Hello (3)";
out.println(ServletUtilities.headWithTitle(title) +
"<BODY BGCOLOR=\"#FDF5E6\">\n" +
"<H1>" + title + "</H1>\n" +
"</BODY></HTML>");
}
}
package coreservlets;
import javax.servlet.*;
import javax.servlet.http.*;
/** Some simple timesavers. Note that most are static methods.
* <P>
* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/
public class ServletUtilities {
public static final String DOCTYPE =
"<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0 " +
"Transitional//EN\">";
public static String headWithTitle(String title) {
return(DOCTYPE + "\n" +
"<HTML>\n" +
"<HEAD><TITLE>" + title + "</TITLE></HEAD>\n");
}
/** Read a parameter with the specified name, convert it
* to an int, and return it. Return the designated default
* value if the parameter doesn't exist or if it is an
* illegal integer format.
*/
public static int getIntParameter(HttpServletRequest request,
String paramName,
int defaultValue) {
String paramString = request.getParameter(paramName);
int paramValue;
try {
paramValue = Integer.parseInt(paramString);
} catch(NumberFormatException nfe) { // null or bad format
paramValue = defaultValue;
}
return(paramValue);
}
public static double getDoubleParameter
(HttpServletRequest request,
String paramName,
double defaultValue) {
String paramString = request.getParameter(paramName);
double paramValue;
try {
paramValue = Double.parseDouble(paramString);
} catch(NumberFormatException nfe) { // null or bad format
paramValue = defaultValue;
}
return(paramValue);
}
/** Replaces characters that have special HTML meanings
* with their corresponding HTML character entities.
*/
// Note that Javadoc is not used for the more detailed
// documentation due to the difficulty of making the
// special chars readable in both plain text and HTML.
//
// Given a string, this method replaces all occurrences of
// '<' with '<', all occurrences of '>' with
// '>', and (to handle cases that occur inside attribute
// values), all occurrences of double quotes with
// '"' and all occurrences of '&' with '&'.
// Without such filtering, an arbitrary string
// could not safely be inserted in a Web page.
public static String filter(String input) {
if (!hasSpecialChars(input)) {
return(input);
}
StringBuffer filtered = new StringBuffer(input.length());
char c;
for(int i=0; i<input.length(); i++) {
c = input.charAt(i);
switch(c) {
case '<': filtered.append("<"); break;
case '>': filtered.append(">"); break;
case '"': filtered.append("""); break;
case '&': filtered.append("&"); break;
default: filtered.append(c);
}
}
return(filtered.toString());
}
private static boolean hasSpecialChars(String input) {
boolean flag = false;
if ((input != null) && (input.length() > 0)) {
char c;
for(int i=0; i<input.length(); i++) {
c = input.charAt(i);
switch(c) {
case '<': flag = true; break;
case '>': flag = true; break;
case '"': flag = true; break;
case '&': flag = true; break;
}
}
}
return(flag);
}
}
posted @
2005-08-17 11:34 my java 閱讀(1028) |
評論 (1) |
編輯 收藏/*
字符串分拆函數
--調用示例
select * from dbo.fsplit('a;adf;fd;ed;dh',';')
select * from dbo.fsplit('a,,adf,,fd,,ed,,dh',',,')
鄒建 2003.07*/
--檢查函數是否存在
if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[fsplit]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[fsplit]
GO
--創建字符串分拆的函數
create function fsplit(
@str varchar(8000) --要分拆的字符串
,@spli varchar(10) --字符串分隔符
)
returns @re table(istr varchar(8000))
as
begin
declare @i int,@splen int
select @splen=len(@spli)
,@i=charindex(@spli,@str)
while @i>0
begin
insert into @re values(left(@str,@i-1))
select @str=substring(@str,@i+@splen,8000)
,@i=charindex(@spli,@str)
end
if @str<>'' insert into @re values(@str)
return
end
select * from dbo.fsplit(123|abc|000|777','|')
posted @
2005-07-26 10:24 my java 閱讀(573) |
評論 (0) |
編輯 收藏在Windows編程中可以調用SetTimer在指定窗口安裝定時器(Timer)，定時器可以在指定的時間間隔周期性回調用戶指定的方法，用來執行周期性的任務，如果想取消定時器，可以調用KillTimer取消。但是在java標準包里中并沒有這種類。下面介紹的這個類包可以實現上述功能。
下面是接口，需要支持定時器功能的類要實現這個接口：
TimerClient.java
package com.ly.util;
/**
* TimerClient Interface
*
* @version 1.0, 8 October 1995
*
*/
public interface TimerClient
{
void timerEvent(int id);
}
下面是定時器的實現，包括三個類：TimerCtl,TimerTask,TimerTasks。其中TimerTask用來描述定時器信息。TimerTasks是一個TimerTask的列表，這樣我們就可以同時在一個應用中安插多個定時器。TimerCtl是定時器控制類，是個線程，不停地檢查TimerTasks中是否有TimerTask到期，要是有TimerTask到達指定的時間，則回調TimerTask指定的TimerClient的timerEvent接口。
TimerCtl.java
package com.ly.util;
import java.util.Vector;
import java.util.Enumeration;
//import com.borland.jb.util.Diagnostic;
/**
* Timer Component
*
* Note:
* - The successful operation of this timer requires clients to execute simple, short
* code snippets when called back by the engine. Otherwise the queue's delivery
* mechanism will be held up
*
* Further work:
* - When Thread.Interrupt is implemented we can switch from the busy wait model to
* the calculated wait model. Without the interrupt the thread waits for the
* calculated interval before waking up. This is a problem if another shorter
* request arrives. For now we'll assume the minimum resolution of the timer is
* 100ms.
*
* @version 1.0, 2 October 1995
*
*/
public class TimerCtl
{
static TimerTasks timerTasks;
public TimerCtl() {
}
/*
* Start a timer running
*/
public static void startTimer(TimerClient client, int eventId, long delay, boolean repeat) {
// create the timer if necessary
if (timerTasks == null) {
timerTasks = new TimerTasks();
timerTasks.start();
}
//Diagnostic.out.println("TIMER: startTimer"+eventId);
// add the new task to the queue
timerTasks.add(client, eventId, delay, repeat);
}
/*
* Stop a timer
*/
public static void stopTimer(TimerClient client, int eventId) {
//Diagnostic.out.println("TIMER: stopTimer"+eventId);
if(timerTasks != null)
timerTasks.end(client, eventId);
}
}
class TimerTasks extends Thread
{
Vector tasks = new Vector();
boolean suspended = false;
boolean sleeping = false;
/**
* Thread task runner
*/
public void run() {
// Loop forever
while (true) {
long sleepTime = 0;
// Ensure that the tasks class is protected
synchronized (tasks) {
//Diagnostic.out.println("TIMER: Tick");
// Scan the job list for any jobs which may fire.
// Mark one-shot jobs for deletion
// Calculate the maximum time we can sleep for
sleepTime = scan();
// Delete DeletePending jobs. DeletePending jobs result from one-shots which have
// been sent, and repeat jobs which have been cancelled. Jobs may have been
// cancelled during the Scan process.
purge();
}
// Suspend timer if necessary
if (tasks.size() == 0) {
//Diagnostic.out.println("TIMER: Suspend");
try {
synchronized(this) {
suspended = true;
wait();
}
}
catch (InterruptedException e) {
}
}
else {
//Diagnostic.out.println("TIMER: Suggested Sleeping for "+sleepTime);
if (sleepTime >= 0) {
try {
sleeping = true;
sleep(sleepTime);
sleeping = false;
}
catch (InterruptedException i) {
//Diagnostic.out.println("TIMER: Caught me napping");
}
}
}
}
}
/**
* Add a new task
*/
public void add(TimerClient client, int eventId, long delay, boolean repeat) {
TimerTask t = new TimerTask(client, eventId, delay, repeat);
synchronized (tasks) {
tasks.addElement((Object)t);
}
// Want instant response - wake the thread if it's napping
// unfortunately the interrupt() method is not working
// if (sleeping)
// interrupt();
if (suspended) {
synchronized(this) {
notify();
//Diagnostic.out.println("TIMER: Resume");
suspended = false;
}
}
}
/**
* Find the job and mark it for deletion
*/
public void end(TimerClient client, int eventId) {
synchronized (tasks) {
for (int i = 0; i < tasks.size(); i++) {
TimerTask t = (TimerTask)tasks.elementAt(i);
//if (!t.deletePending && t.client == client && t.eventId == eventId)
if (t.deletePending == false && t.client == client && t.eventId == eventId) {
// JPBS - if we don't reset 'repeat', deletePending will be set again
t.repeat = false;
t.deletePending = true;
break;
}
}
}
}
/**
* Clear out all the dead wood
*/
void purge() {
for (int i = 0; i < tasks.size(); i++) {
TimerTask t = (TimerTask)tasks.elementAt(i);
if (t.deletePending) {
//Diagnostic.out.println("TIMER: purged");
tasks.removeElementAt(i);
i--;
}
}
}
long scan() {
// The value added to the current time determines the MAX time until
// the next scan
// This is 100 now since thread.interrupt() is not implemented
long nextTime = System.currentTimeMillis() + 100;
for (int i = 0; i < tasks.size(); i++) {
TimerTask t = (TimerTask)tasks.elementAt(i);
// if not already deletePending, test (and possibly send the event)
// as a result, the job may be flagged for deletion.
// May also be a non-repeating job and so require self deletion
if (!t.deletePending)
t.test();
// if the task didn't get deleted - see what it contributes to the time
if (!t.deletePending)
nextTime = Math.min(nextTime, t.timeNext);
//Diagnostic.out.println("TIMER: Scanning "+t.eventId+" "+(t.deletePending == true ? "DEL" : ""));
}
return nextTime - System.currentTimeMillis();
}
}
class TimerTask
{
TimerClient client;
int eventId;
long timePrev;
long timeDelay;
long timeNext;
boolean repeat;
boolean deletePending;
public TimerTask(TimerClient client, int eventId, long timeDelay, boolean repeat) {
this.client = client;
this.eventId = eventId;
this.timeDelay = timeDelay;
this.repeat = repeat;
// schedule the next click - now + delay
timeNext = System.currentTimeMillis() + timeDelay;
deletePending = false;
//Diagnostic.out.println("TIMER: Adding New Task");
}
public void test() {
if (System.currentTimeMillis() >= timeNext) {
//Diagnostic.out.println("TIMER: fire");
// Fire the event
client.timerEvent(eventId);
// Update the next time
timeNext = System.currentTimeMillis() + timeDelay;
deletePending = !repeat;
}
}
}
下面是一個使用例子
TimerTest.java
package com.ly.util;
import java.io.*;
import java.util.*;
import com.ly.util.*;
/**
* Title:
* Description:
* Copyright: Copyright (c) 2001
* Company: http://dozb.blogchina.com
* @author dozb
* @version 1.0
*/
public class TimerTest implements TimerClient{
public TimerTest()
{
starttime();
}
public void timerEvent(int id)
{
System.out.println("timerEvent...");
}
public void starttime()
{
TimerCtl.startTimer(this,1,5*1000,true);
}
public void stoptime()
{
TimerCtl.stopTimer(this,1);
}
public static void main(String[] args)
{
new TimerTest();
try
{
Thread.sleep(200000);
}catch(Exception e)
{
}
}
}
通過這種方式，可以高效地使用socket通訊，在異步socket版本沒有發布以前，不失是一種解決問題的方法。:)
posted @
2005-07-26 09:00 my java 閱讀(5822) |
評論 (1) |
編輯 收藏