Web信息系统毕业论文中英文资料外文翻译文献

中英文资料翻译With

thepopularity

of

theInter

NET

applications,

avarietyofWeb

InformationSystem

Hasbecome

a

pressing

issue.

Establish

the

essence

of

Web

informationsystems

Developmentofa

Web

repository

(database

asthecoreof

avarietyof

Web

letter

Informationstorage)

asthecore

Web

applications.

Currently,theWeb

repositorydevelopment

technology

Operation

of

awiderangeof

differentcharacteristics.

Variousperiods

atalllevels,

avarietyofpurposes

Technology

co-exist,

dizzying

mirror

chaos,itisdifficultto

choose.

More

popular

Java

ofSer

vet

Web

repository

development

program

amorepractical

Of

choice.Servlet

is

running

the

applet

ontheWebserver,

canbecompleted

Xu

Multi-client

Applet

cannotcomplete

thework,whichruns

ontheserver

and

clients

No

end,donot

download

donot

by

the

client

securityrestrictions,

the

running

speed

GreatlyincreasedAndApplet

running

in

a

browser

and

extend

the

browser's

ability

similar

Like,

Serv

thelet

run

in

theWeb

server

to

enable

Java

Serv

thelet

engine

Andexpand

the

capacity

of

the

server.

Therefore,wecansay

Serv

thelet

is

run

in

Applet

onaWebserver,

Serv

thelet

JavaServletAPI

And

Jav

a

program

of

classes

andpackages.Servlet

access

modelServ

thelet,therearethree

accessmodels:

(1)

anaccess

model

1

browserto

Webserver

to

issue

a

retrieval

request.

2

theWeb

server

after

receiptoftherequest,

the

request

forwardedtothe

Servletengine.

3Serlet

engine

toperformtherequested

the

Servlet

and

directly

throughJDBC4Servlet

throughJDBC

toretrieve

searchresults

to

generate

the

html

pageand

Page

backto

the

Webserver.

5

theWeb

server

thepage

is

sent

backtothebrowser.(2)Thesecond

access

model

1

browserto

Webserver

to

issue

a

retrieval

request.

2

theWeb

serverreceivestherequest

afterthe

request

forwardedto

the

ofSer

v

theletengine.

3Servlet

engine

toperformthe

request

the

the

Servlet

and

retrieve

sent

Ja,

vabean

access

to

the

data.

4data

access

the

Javabean

searchabledatabase

throughJDBC

information

And

fromthesearchresults

stored

in

itself.

5Servlet

remove

searchresults

from

the

data

access

Javabean

generate

Html

pageand

Ht

mlof

page

backtothe

w

eb

server.

6

theWeb

server

thepage

is

sent

backtothebrowser.(3)

Thethird

accessmodel1A

browser

issue

a

retrieval

request

totheWebserver.

2

Web

serverreceivestherequest

afterthe

request

forwardedto

the

ofSer

v

thelet

engine.

OfSer

vlet

engine

toperformtherequested

Servlet

directly

throughJDBC

inspection

3The

cable

databaseand

searchresults

arestoredinthe

resultisstored

the

Javabean

into.Javabean,

4.

Ser

v

thelet

from

the

resultsarestored

to

remove

the

searchresults

and

JSPfiles

to

format

the

output

page.2

Servlet

functionalityand

lifecycleServlet

functions(1)

Create

andreturn

dynamicWebpages

based

on

customerrequests.

(2)

create

canbeembeddedinto

existing

HTMLpages

aspartof

HTML

Page(HT

fragment)

of

theML.

(3)

and

other

serverresources

(includingdatabases

and

applications

based

on

the

Jav

a

Program)

tocommunicate.

(4)

to

handle

multiple

client

connections,receiving

the

input

of

more

than

one

client,and

Theresults

broadcastto

multipleclients.

For

example,Ser

vlet

isamulti-participant

Gameserver.

(5)

ofMIM

E

type

filter

information

on

the

specialhandling,suchas

image

Conversionand

server-side

include

(SSI).

(6)

custom

processing

available

to

allserversin

thestandard

routine.2.2ServletlifecycleServlet

lifecycle

begins

with

itinto

the

Webserver'smemory

And

end

in

the

terminationor

re-loaded

Serv

thelet.load.Load

the

servlet

atthefollowing

times:Ifyouhaveconfigured

automatic

load

option,and

then

start

the

Webserver

automaticallyloadedAfter

the

start

of

the

Webserver,

the

client

Serv

thelet

issued

for

the

first

time,please

Demand.Reload

Serv

thelet.Loaded

Servlet,Webservers

tocreatea

servletinstance,

and

Servlet's

init()method

is

called.

Servlet

initialization

parameters

in

the

initializationphase,

The

number

ispassed

totheServlet

configurationobject.SERVLET〉callthe

servlet

in

the

JSPfiles.Call

in

the

JSP

file

format

used

by

the

Servlet

and

HTML

page

tocall

exactlythesame.Andthe

principles

areidentical.

Only

reconcile

its

dynamic

JSP

fileisnota

staticHTML

page.inanASPfile

calls

the

servlet.Ifyou

Micr

oso

ft

I

nt

ernet

Informatio

n-Ser

ver

(II

S)

onthe

legacy

oftheASPfile,

and

cannotbe

ASPfiles

transplanted

into

a

JSPfile,

youcanuse

the

ASPfile

to

ofSer

vlet

iscalled.Butitmustbe

through

a

special

ActiveX

control,

anASPfile

isonlythrough

itcan

callthe

servlet.Servlet

Howto

use

ConnectionManager

toefficientlymanage

thedatabaseconnectionthefunctionality

of

the

ConnectionManager.For

non-Webapplications,

Web-based

application

accesstothedatabase

willleadtohigher

and

unpredictable

overhead,whichis

dueto

morefrequent

Webusers

connectanddisconnect.Normallyconnected

to

theresourcesused

and

disconnectfromthedatabasewillfarexceed

the

resources

used

in

the

retrieval.ConnectionManager

functionis

tominimize

the

additional

occupancy

of

the

usersof

the

database

resources

toachieve

thebestperformance

of

databaseaccess.ConnectionManager

sharing

overhead

throughtheestablishmentof

the

connectionpoolwillconnect

users

Servlet

available

tomultipleusers

request.In

other

words,eachuserrequest

onlythe

connect/

disconnect

with

asmallportion

of

the

overhead

costs.Initialresources

toestablish

the

connection

of

the

buffer

pool,

the

rest

of

the

connect/

disconnectoverhead

isnotbig,because

thisisonly

reuse

the

existing

connection.Serv

thelet

inthefollowingmanner

usingthe

connectionpool:

When

a

user

through

Request

Web

Serv

thelet

thelet

Serv

use

anexisting

connection

fromthebufferpool

Next,

thismeansthat

the

userrequests

donotcause

the

connectiontothedatabasesystem

overhead.

In

After

the

termination

of

serv

thelet

it

connect

toreturn

to

the

pool

forits

ConnectionManager

The

Servlet.

Thus,

the

user

request

doesnotcause

thedatabase

isdisconnected

Ofsystemoverhead.

ConnectionManager

alsoallowsusers

to

beabletocontrol

the

concurrency

of

thedatabaseproducts

even

Then

thenumber.

When

the

database

licenseagreement

limit

the

numberofusers,

thisfeature

is

Veryuseful.

Create

abuffer

pool

forthedatabase,and

connectionmanagement

Buffering

pool

"maximum

numberofconnections"

parameter

setto

the

database

productlicense

limit

Given

maximumnumberofusers.

Ifyouuse

otherprograms

without

ConnectionManagerconnections

Database,youcannot

guaranteethatthemethod

is

effective.thestructureof

theConnectionManager.ConnectionManagerconnectionpooltomaintainaconnectiontoaspecificdatabaseisopen.

Step1:WhenthefirstServthelettryingtoConnectionManagercommunicationsisloadedbytheJavaApplicationServerConnectionManager.

AslongastheJavaapplicationserverrunningtheConnectionManagerhasbeenloaded.Step2:TheJavaapplicationserverpassestherequesttoaservlet.

Step3:ServletConnectionManagerrequestsaconnectionfromthepool.

Stepfour:thebufferpooltoServletallocatedapoolofexistingidleconnection.

Step5:servlettousetoconnectadirectdialoguewiththedatabase,thisprocessisthestandardAPIforaparticulardatabase.

Step6:thedatabasethroughServlettheconnectionreturnsdata.

Step7:WhentheServletendtocommunicatewiththedatabase,servletconnectionsreturnedtotheconnectionmanagerpoolforotherservletuses.Step8:ServletJavaapplicationservertotheusersendsbackresponse.Servletrequestsaconnection,ifthebufferpool,thereisnoidleconnection,thentheconnectionmanagerdirectlycommunicatewiththedatabase.

ConnectionManagerwill:Step9:tothedatabaserequestsanewconnection.

Step10:Addconnectionstothebufferpool.

Ifthebufferpoolisconnectedtotheprescribedceiling,connecttotheserver

Willnotbeanewconnectiontojointhebufferpool

(3)theperformancecharacteristicsoftheConnectionManager.

Bufferpooltocreateanewconnectionisahighoverheadtasks,newconnectionswillusetheresourcesonthedatabase.

Therefore,theConnectionManagerthebestuseofexistingconnectionsofthebufferpooltomeettherequestoftheServlet.

Meanwhile,theconnectingtube

Theprocessormustbeasmuchaspossibletominimizethebufferpoolidleconnections,becausethisisagreatwasteofsystemresources.

ConnectionManagerServtheletwiththeimplementationoftheseminimizeandmaximizetask.

ConnectionManagertomaintaineachconnectionverificationtimestamp,andrecentlyusedtagsandusethelogo.

WhentheaServletfirsttheconnection,connectionverificationtimestamp,andmostrecenttimestampissettothecurrenttime,theconnectionisbeingusedflagissettotrue.ConnectionManagercanberemovedfromaServtheletalong-unusedconnections,thislengthoftimespecifiedbytheConnectionManager,thelongestcycleparameters.ConnectionManagercanviewrecentlyusedmarkisbeingusedtoconnect.

Ifthetimebetweenthemostrecentlyusedtimeandtimedifferenceisgreaterthanthelongestcycleconfigurationparameters,theconnectionwillbeconsideredtobearesidualconnection,whichindicatesServthelettakeitsdiscontinuedornoresponse.

ResidualconnectionwillbereturnedtothepoolforotherServlet,itisbeingusedflagissettofalse,authenticationandtimestampissettothecurrenttime.

IfServletisreadywithinalongerperiodoftimetousetheconnectionwiththedatabaseseveraltimes

Communications,youmustcodetotheServthelet,sothateachtimeyouusetoconnect

Confirmthatitstilloccupiesthisconnection.

ConnectionManagercanberemovedfromthebufferpoolidleconnections,becausethey

Wouldbeawasteofresources.

Inordertodeterminewhichconnectionisidle,ConnectionManagerwillcheck

Investigationconnectedthesignandtimestamp,thisoperationisconnectedbyperiodicaccessto

Bufferpoolinformation.

ConnectionManagercheckshavenotbeenanyServletmake

Withtheconnections(theseconnectionsistousethelogoisfalse).

Ifyouhaverecentlyused

Betweentimeandthecurrenttimedifferenceexceedsamaximumidletimeconfigurationparameters,the

Thattheconnectionisidle.

Idleconnectionwillberemovedfromthebufferpool,downto

Minimumnumberofconnectionsconfigurationparameterspecifiesthelowerlimitvalue.翻译：随着Internet的普及应用,各种Web信息系统的建立已成为一个迫在眉睫的问题。建立Web信息系统的实质就是开发一个以Web信息库(以数据库为核心的多种Web信息存储)为核心的Web应用系统。目前,Web信息库开发技术的种类繁多,特点各异。各个时期、各个层面、各种用途的技术并存,令人眼花镜乱,难以选择。而目前较为流行的基于JavaServet技术就是Web信息库开发方案的一种比较实用的的选择。Servlet是运行在Web服务器上的Applet,可以完成许多客户Applet不能完成的工作,它运行在服务器上,与客户端无任何关系,不用下载不用受到客户端安全限制,运行速度大大提高。与Applet运行在浏览器上并扩展浏览器的能力相类似,Servlet运行在启用JavaServlet引擎的Web服务器上并扩展该服务器的能力。因此,可以说Servlet就是运行在Web服务器上的Applet,Servlet就是使用JavaServletAPI及相关类和软件包的Java程序。1Servlet的访问模型Servlet有三种访问模型:(1)第一种访问模型。1浏览器向Web服务器发出检索请求。2Web服务器收到请求后将请求转交给Servlet引擎。3Servlet引擎执行所请求的Servlet并通过JDBC直接检索数据库中的信息。4Servlet通过JDBC取回检索结果生成html页面并将页面送回Web服务器。5Web服务器将页面发送回浏览器。(2)第二种访问模型1浏览器向Web服务器发出检索请求。2Web服务器收到请求后将请求转交给Servlet引擎。3Servlet引擎执行所请求的Servlet并将检索式发送给数据访问Javabean。4数据访问Javabean通过JDBC检索数据库中的信息并将从检索结果存储在自身之中。5Servlet从数据访问Javabean中取出检索结果生成Html页面并将Html页面返回给web服务器。6Web服务器将页面发送回浏览器。(3)第三种访问模型(见图3)。1浏览器向Web服务器发出检索请求。2Web服务器收到请求后将请求转交给Servlet引擎。3Servlet引擎执行所请求的Servlet直接通过JDBC检索数据库并将检索结果存储在结果存储Javabean之中。4Servlet从结果存储Javabean中取出检索结果并用JSP文件格式化输出页面。5将格式化后的输出页面发送给Web服务器。6Web服务器将页面发送回浏览器。2Servlet的功能与生命周期2.1Servlet的功能(1)创建并返回一个基于客户请求的动态Web页面。(2)创建可嵌入到现有HTML页面中的一部分HTML页面(HTML片段)。(3)与其它服务器资源(包括数据库和基于Java的应用程序)进行通信。(4)处理多个客户机的连接,接收多个客户机的输入,并将结果广播到多个客户机上。例如,Servlet可以是多参与者的游戏服务器。(5)对特殊的处理采用MIME类型过滤资料,例如图像转换和服务器端包括(SSI)。(6)将定制的处理提供给所有服务器的标准例行程序。例如,Servlet可以修改如何认证用户。2.2Servlet的生命周期Servlet的生命周期始于将它装入Web服务器的内存时,并在终止或重新装入Servlet时结束。(1)装入。在下列时刻装入Servlet:1如果已配置自动装入选项,则在启动Web服务器时自动装入。2在Web服务器启动后,客户机首次向Servlet发出请求时。3重新装入Servlet时。装入Servlet后,Web服务器创建一个Servlet实例并且调用Servlet的init()方法。在初始化阶段,Servlet初始化参数被传递给Servlet配置对象。(2)终止。当Web服务器不再需要Servlet,或重新装入Servlet的新实例时,服务器会调用Servlet的destroy()方法,将其从内存中删除。3如何调用Servlet调用Servlet的方法共有五种:在URL中调用、在窗体〈Form〉标记中调用、在HTML页面中调用、在JSP文件中调用、在ASP文件中调用。下面将逐项加以介绍。(1)在URL中调用Servlet。只需在浏览器中输入格式像http:∥yourwebservername/servletpath/servletname一样的ServletURL地址即可。其中:yourwebservername是指Servlet所在的Web服务器名,servletpath是指Servlet的路径,servletname是指Servlet的真实名字或别名。(2)在〈FORM〉标记中调用Servlet。在〈FORM〉标记中调用Servlet使用户能在Web页面上输入资料,并将输入资料提交给Servlet。Servlet将根据提交的方法不同,采用不同的方式接收资料。例如:<FORMMETHOD=“POST/GET”ACTION=“/servletpath/servletname”>{放置文本输入区域标记、按钮和其它标识}〈/FORM〉(3)在HTML页面中调用Servlet。使用〈SERVLET〉标记与使用〈FORM〉标记一样,无需创建一个完整的HTML页面。作为替代,Servlet的输出仅是HTML页面的一部分(HTML片段),且被动态嵌入到原来HTML页面中的其它静态文本中。所有这些都发生在服务器上,且发送给用户的仅是结果HTML页面。原始HTML页面中包含〈SERVLET〉和〈/SERVLET〉标记。Servlet将在这两个标记中被调用,且Servlet的响应将覆盖这两个标记间的所有东西和标记本身。例如:〈SERVLETNAME=“myservlet”CODE=“myservlet.class”CODEBASE=“url”initparam=“value”〉〈PARAMNAME=“parm1”VALUE=“value1”〉〈PARAMNAME=“parm2”VALUE=“value2”〉⋯⋯〈/SERVLET〉(4)在JSP文件中调用Servlet。在JSP文件中调用Servlet所采用的格式与HTML页1面中调用完全一样。而且原理也完全相同。只不过调和它的是动态的JSP文件不是静态的HTML页面而已。(5)在ASP文件中调用Servlet。如果您在MicrosoftInternetInformationServer(ⅡS)上有遗留的ASP文件,并且无法将ASP文件移植成JSP文件时,您可用ASP文件来调用Servlet。但必须通过一个特殊的ActiveX控制,ASP文件只有通过它才能调用Servlet。4Servlet如何利用连接管理器高效地管理数据库连接(1)连接管理器的功能。相对于非Web应用程序,基于Web的应用程序对数据库的访问会导致更高的和不可预料的系统开销,这是由于Web用户更为频繁的连接和断开。通常连接与断开数据库连接所用的资源将远远超过检索时所用的资源。连接管理器的功能就是尽可能地减少用户对数据库资源的额外占用,实现数据库访问的最佳效能。连接管理器通过建立用户Servlet可用的连接缓冲池将连接的系统开销分摊给多个用户请求。换言之,每个用户请求仅占用连接/断开连接所用系统开销成本的一小部分。在使用初始资源建立缓冲池中的连接后,其余连接/断开连接所用的系统开销就不大了,因为这只是重复使用已有的连接而已。Servlet以如下方式使用连接缓冲池:当一个用户通过Web向Servlet请求时,Servlet从缓冲池使用一个已有的连接,这意味着用户请求不会引起数据库的连接系统开销。在Serv