Web信息系統(tǒng)畢業(yè)論文中英文資料外文翻譯文獻(xiàn)

中英文資料翻譯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.翻譯：隨著Internet的普及應(yīng)用,各種Web信息系統(tǒng)的建立已成為一個(gè)迫在眉睫的問題。建立Web信息系統(tǒng)的實(shí)質(zhì)就是開發(fā)一個(gè)以Web信息庫(kù)(以數(shù)據(jù)庫(kù)為核心的多種Web信息存儲(chǔ))為核心的Web應(yīng)用系統(tǒng)。目前,Web信息庫(kù)開發(fā)技術(shù)的種類繁多,特點(diǎn)各異。各個(gè)時(shí)期、各個(gè)層面、各種用途的技術(shù)并存,令人眼花鏡亂,難以選擇。而目前較為流行的基于JavaServet技術(shù)就是Web信息庫(kù)開發(fā)方案的一種比較實(shí)用的的選擇。Servlet是運(yùn)行在Web服務(wù)器上的Applet,可以完成許多客戶Applet不能完成的工作,它運(yùn)行在服務(wù)器上,與客戶端無任何關(guān)系,不用下載不用受到客戶端安全限制,運(yùn)行速度大大提高。與Applet運(yùn)行在瀏覽器上并擴(kuò)展瀏覽器的能力相類似,Servlet運(yùn)行在啟用JavaServlet引擎的Web服務(wù)器上并擴(kuò)展該服務(wù)器的能力。因此,可以說Servlet就是運(yùn)行在Web服務(wù)器上的Applet,Servlet就是使用JavaServletAPI及相關(guān)類和軟件包的Java程序。1Servlet的訪問模型Servlet有三種訪問模型:(1)第一種訪問模型。1瀏覽器向Web服務(wù)器發(fā)出檢索請(qǐng)求。2Web服務(wù)器收到請(qǐng)求后將請(qǐng)求轉(zhuǎn)交給Servlet引擎。3Servlet引擎執(zhí)行所請(qǐng)求的Servlet并通過JDBC直接檢索數(shù)據(jù)庫(kù)中的信息。4Servlet通過JDBC取回檢索結(jié)果生成html頁(yè)面并將頁(yè)面送回Web服務(wù)器。5Web服務(wù)器將頁(yè)面發(fā)送回瀏覽器。(2)第二種訪問模型1瀏覽器向Web服務(wù)器發(fā)出檢索請(qǐng)求。2Web服務(wù)器收到請(qǐng)求后將請(qǐng)求轉(zhuǎn)交給Servlet引擎。3Servlet引擎執(zhí)行所請(qǐng)求的Servlet并將檢索式發(fā)送給數(shù)據(jù)訪問Javabean。4數(shù)據(jù)訪問Javabean通過JDBC檢索數(shù)據(jù)庫(kù)中的信息并將從檢索結(jié)果存儲(chǔ)在自身之中。5Servlet從數(shù)據(jù)訪問Javabean中取出檢索結(jié)果生成Html頁(yè)面并將Html頁(yè)面返回給web服務(wù)器。6Web服務(wù)器將頁(yè)面發(fā)送回瀏覽器。(3)第三種訪問模型(見圖3)。1瀏覽器向Web服務(wù)器發(fā)出檢索請(qǐng)求。2Web服務(wù)器收到請(qǐng)求后將請(qǐng)求轉(zhuǎn)交給Servlet引擎。3Servlet引擎執(zhí)行所請(qǐng)求的Servlet直接通過JDBC檢索數(shù)據(jù)庫(kù)并將檢索結(jié)果存儲(chǔ)在結(jié)果存儲(chǔ)Javabean之中。4Servlet從結(jié)果存儲(chǔ)Javabean中取出檢索結(jié)果并用JSP文件格式化輸出頁(yè)面。5將格式化后的輸出頁(yè)面發(fā)送給Web服務(wù)器。6Web服務(wù)器將頁(yè)面發(fā)送回瀏覽器。2Servlet的功能與生命周期2.1Servlet的功能(1)創(chuàng)建并返回一個(gè)基于客戶請(qǐng)求的動(dòng)態(tài)Web頁(yè)面。(2)創(chuàng)建可嵌入到現(xiàn)有HTML頁(yè)面中的一部分HTML頁(yè)面(HTML片段)。(3)與其它服務(wù)器資源(包括數(shù)據(jù)庫(kù)和基于Java的應(yīng)用程序)進(jìn)行通信。(4)處理多個(gè)客戶機(jī)的連接,接收多個(gè)客戶機(jī)的輸入,并將結(jié)果廣播到多個(gè)客戶機(jī)上。例如,Servlet可以是多參與者的游戲服務(wù)器。(5)對(duì)特殊的處理采用MIME類型過濾資料,例如圖像轉(zhuǎn)換和服務(wù)器端包括(SSI)。(6)將定制的處理提供給所有服務(wù)器的標(biāo)準(zhǔn)例行程序。例如,Servlet可以修改如何認(rèn)證用戶。2.2Servlet的生命周期Servlet的生命周期始于將它裝入Web服務(wù)器的內(nèi)存時(shí),并在終止或重新裝入Servlet時(shí)結(jié)束。(1)裝入。在下列時(shí)刻裝入Servlet:1如果已配置自動(dòng)裝入選項(xiàng),則在啟動(dòng)Web服務(wù)器時(shí)自動(dòng)裝入。2在Web服務(wù)器啟動(dòng)后,客戶機(jī)首次向Servlet發(fā)出請(qǐng)求時(shí)。3重新裝入Servlet時(shí)。裝入Servlet后,Web服務(wù)器創(chuàng)建一個(gè)Servlet實(shí)例并且調(diào)用Servlet的init()方法。在初始化階段,Servlet初始化參數(shù)被傳遞給Servlet配置對(duì)象。(2)終止。當(dāng)Web服務(wù)器不再需要Servlet,或重新裝入Servlet的新實(shí)例時(shí),服務(wù)器會(huì)調(diào)用Servlet的destroy()方法,將其從內(nèi)存中刪除。3如何調(diào)用Servlet調(diào)用Servlet的方法共有五種:在URL中調(diào)用、在窗體〈Form〉標(biāo)記中調(diào)用、在HTML頁(yè)面中調(diào)用、在JSP文件中調(diào)用、在ASP文件中調(diào)用。下面將逐項(xiàng)加以介紹。(1)在URL中調(diào)用Servlet。只需在瀏覽器中輸入格式像http:∥yourwebservername/servletpath/servletname一樣的ServletURL地址即可。其中:yourwebservername是指Servlet所在的Web服務(wù)器名,servletpath是指Servlet的路徑,servletname是指Servlet的真實(shí)名字或別名。(2)在〈FORM〉標(biāo)記中調(diào)用Servlet。在〈FORM〉標(biāo)記中調(diào)用Servlet使用戶能在Web頁(yè)面上輸入資料,并將輸入資料提交給Servlet。Servlet將根據(jù)提交的方法不同,采用不同的方式接收資料。例如:<FORMMETHOD=“POST/GET”ACTION=“/servletpath/servletname”>{放置文本輸入?yún)^(qū)域標(biāo)記、按鈕和其它標(biāo)識(shí)}〈/FORM〉(3)在HTML頁(yè)面中調(diào)用Servlet。使用〈SERVLET〉標(biāo)記與使用〈FORM〉標(biāo)記一樣,無需創(chuàng)建一個(gè)完整的HTML頁(yè)面。作為替代,Servlet的輸出僅是HTML頁(yè)面的一部分(HTML片段),且被動(dòng)態(tài)嵌入到原來HTML頁(yè)面中的其它靜態(tài)文本中。所有這些都發(fā)生在服務(wù)器上,且發(fā)送給用戶的僅是結(jié)果HTML頁(yè)面。原始HTML頁(yè)面中包含〈SERVLET〉和〈/SERVLET〉標(biāo)記。Servlet將在這兩個(gè)標(biāo)記中被調(diào)用,且Servlet的響應(yīng)將覆蓋這兩個(gè)標(biāo)記間的所有東西和標(biāo)記本身。例如:〈SERVLETNAME=“myservlet”CODE=“myservlet.class”CODEBASE=“url”initparam=“value”〉〈PARAMNAME=“parm1”VALUE=“value1”〉〈PARAMNAME=“parm2”VALUE=“value2”〉??〈/SERVLET〉(4)在JSP文件中調(diào)用Servlet。在JSP文件中調(diào)用Servlet所采用的格式與HTML頁(yè)1面中調(diào)用完全一樣。而且原理也完全相同。只不過調(diào)和它的是動(dòng)態(tài)的JSP文件不是靜態(tài)的HTML頁(yè)面而已。(5)在ASP文件中調(diào)用Servlet。如果您在MicrosoftInternetInformationServer(ⅡS)上有遺留的ASP文件,并且無法將ASP文件移植成JSP文件時(shí),您可用ASP文件來調(diào)用Servlet。但必須通過一個(gè)特殊的ActiveX控制,ASP文件只有通過它才能調(diào)用Servlet。4Servlet如何利用連接管理器高效地管理數(shù)據(jù)庫(kù)連接(1)連接管理器的功能。相對(duì)于非Web應(yīng)用程序,基于Web的應(yīng)用程序?qū)?shù)據(jù)庫(kù)的訪問會(huì)導(dǎo)致更高的和不可預(yù)料的系統(tǒng)開銷,這是由于Web用戶更為頻繁的連接和斷開。通常連接與斷開數(shù)據(jù)庫(kù)連接所用的資源將遠(yuǎn)遠(yuǎn)超過檢索時(shí)所用的資源。連接管理器的功能就是盡可能地減少用戶對(duì)數(shù)據(jù)庫(kù)資源的額外占用,實(shí)現(xiàn)數(shù)據(jù)庫(kù)訪問的最佳效能。連接管理器通過建立用戶Servlet可用的連接緩沖池將連接的系統(tǒng)開銷分?jǐn)偨o多個(gè)用戶請(qǐng)求。換言之,每個(gè)用戶請(qǐng)求僅占用連接/斷開連接所用系統(tǒng)開銷成本的一小部分。在使用初始資源建立緩沖池中的連接后,其余連接/斷開連接所用的系統(tǒng)開銷就不大了,因?yàn)檫@只是重復(fù)使用已有的連接而已。Servlet以如下方式使用連接緩沖池:當(dāng)一個(gè)用戶通過Web向Servlet請(qǐng)求時(shí),Servlet從緩沖池使用一個(gè)已有的連接,這意味著用戶請(qǐng)求不會(huì)引起數(shù)據(jù)庫(kù)的連接系統(tǒng)開銷。在Serv