Web信息系统毕业论文中英文资料外文翻译文献.doc

中英文资料翻译

With the popularity of the Inter NET applications, a variety of Web Information System
Has become a pressing issue. Establish the essence of Web information systems
Development of a Web repository (database as the core of a variety of Web letter
Information storage) as the core Web applications. Currently, the Web repositorydevelopment technology
Operation of a wide range of different characteristics. Various periods at all levels, a variety of purposes
Technology co-exist, dizzying mirror chaos, it is difficult to choose. More popular
Java of Ser vet Web repository development program a more practical
Of choice.
Servlet is running the applet on the Web server, can be completed Xu
Multi-client Applet can not complete the work, which runs on the server and clients
No end, do not download do not by the client security restrictions, the running speed
Greatly increased
And Applet running in a browser and extend the browser's ability similar
Like, Serv the let run in the Web server to enable Java Serv the let engine
And expand the capacity of the server. Therefore, we can say Serv the let is run in
Applet on a Web server, Serv the let Jav a Ser vlet API
And Jav a program of classes and packages.
1 Servlet access model
2 Serv the let, there are three access models:
(1) an access model 
1 browser to Web server to issue a retrieval request.
2 the Web server after receipt of the request, the request forwarded to the  Servle tengine.
3 Serlet engine to perform the requested the Ser vlet and directly through JDBC
4Servlet throughJDBC toretrieve search results to generate the html page and
Page back to the Web server.
5 the Web server the page is sent back to the browser.
(2)The second access model 
1 browser to Web server to issue a retrieval request.
2 the Web server receives the request after the request forwarded to the of Ser v the letengine.
3 Serv let engine to perform the request the the Ser vlet and retrieve sent
Ja, vabean access to the data.
4data access the Ja vabean searchable database through JDBC information
And from the search results stored in itself.
5Servlet remove search results from the data access Javabean generate
Html page and Ht ml of page back to the w eb server.
6 the Web server the page is sent back to the browser.

(3) The third access model
1 A browser issue a retrieval request to the Web server.
2  Web server receives the request after the request forwarded to the of Ser v the let engine.
Of Ser vlet engine to perform the requested Servlet directly through JDBC inspection
3 The cable database and search results are stored in the result is stored the Jav abean into.Javabean,
 4. Ser v the let from the results are stored to remove the search results and
JSP files to format the output page.
2 Servlet functionality and life cycle
2.1 Servlet functions
(1) Create and return dynamic Web pages based on customer requests.
(2) create can be embedded into existing HTML pages as part of HTML
Page (HT fragment) of the ML.
(3) and other server resources (including databases and applications based on the Jav a
Program) to communicate.
(4) to handle multiple client connections, receiving the input of more than one client, and
The results broadcast to multiple clients. For example, Ser vlet is a multi-participant
Game server.
(5) of MIM E type filter information on the special handling, such as image
Conversion and server-side include (SSI).
(6) custom processing available to all servers in the standard routine.
2.2Servlet lifecycle
Servlet life cycle begins with it into the Web server's memory
And end in the termination or re-loaded Serv the let.
(1) load.
Load the servlet at the following times:
1. If you have configured automatic load option, and then start the Web server automatically loaded
2. After the start of the Web server, the client Serv the let issued for the first time, please
Demand.
3. Reload Serv the let.
Loaded Servlet, Web servers to create a servlet instance, and
Servlet's init () method is called. Servlet initialization parameters in the initialization phase,
The number is passed to the Servlet configuration object.
(2) terminate
When the Web server no longer needs the servlet, or reload Servlet
A new instance of the server calls Serv the let's destroy () method, remove it from the
Memory deleted.
3 How to call Servlet
Method of Ser vlet is called Total five kinds: call in the URL in the form
m> Tag call, call, in HT the ML page in the JSP files
Call, call in an ASP file. The following itemized to be introduced.
(1) call the servlet in the URL.
Simply input format in the browser as http: ∥ yo ur webser ver
the same the ser vlet name name / servlet path / servlet the URL to
The site canbe. Ofwhich:your webser ver name is to refer to the Servlet where theWeb server name, the servlet path is the path refers to the Servlet, the servletThe name refers to the Servlet real name or an alias.
(2) call the Servlet t data on the Web page, andinput data submitted to the vlet of Ser.Serv the let will be submitted to receive data in different ways.For example:  {place the text input area tags, buttons and other logos}
(3) in the HTML page to call the servlet.
Use  mark  tags, no need to create a complete HTML page.Instead,the servlet output isonly part of the HTMLpage (HTML fragment) and dynamicallyembedded into the static text in the original HTML page.All this happened on the server andsent to the user only the resulting HTML page.
  tag contained in the original HTML page.Servlet will be invoked in these two markers and the Ser vlet response will cover these two markersbetween all things and mark itself, for example:
〈S
ERVLET NAME= “my serv let ”CODE= “my serv let .
class”CODEBASE= u r l”initpar am= “v alue”〉
〈PARAM NAME= “parm1”VALU E= “v alue1”〉
〈PARAM NAME= “parm2”VALU E= “v alue2”〉
⋯⋯
〈/
SERVLET 〉
(4) call the servlet in the JSP files.
Call in the JSP file format used by the Servlet and HTML page to call exactly the same.Andthe principles are identical. Only reconcile its dynamic JSP file is not a static HTML page.
(5) in an ASP file calls the servlet.
If you Micr oso ft I nt ernet Informatio n-Ser ver (II S) on the legacy of the ASP file, and can not be ASP files transplanted into a JSP file, you can use the ASP file to of Ser vlet iscalled.But it must be through a special ActiveX control, an ASP file is only through it can callthe servlet.
4 Servlet Howto use ConnectionManager to efficiently manage the database connection
(1) the functionality of the Connection Manager.
For non-Web applications, Web-based application access to the database will lead tohigher and unpredictable overhead, which is due to more frequent Web users connect anddisconnect.Normally connected to the resources used and disconnect from the databasewill far exceed the resources used in the retrieval.Connection Manager function is to minimize the additional occupancy of the users of the database resources to achieve thebest performance of database access.
Connection Manager sharing overhead through the establishment of the connection poolwill connect users Servlet available to multiple users request.In other words, each userrequest only the connect / disconnect with a small portion of the overhead costs.Initialresources to establish the connection of the buffer pool, the rest of the connect / disconnectoverhead is not big, because this is only reuse the existing connection.
Serv the let in the following manner using the connection pool: When a user through
Request Web Serv the let the let Serv use an existing connection from the buffer pool
Next, this means that the user requests do not cause the connection to the databasesystem overhead. In
After the termination of serv the let it connect to return to the pool for its Connection Manager
The Ser vlet. Thus, the user request does not cause the database is disconnected
Of system overhead.
Connection Manager also allows users to be able to control the concurrency of thedatabase products even
Then the number. When the database license agreement limit the number of users, this feature is
Very useful. Create a buffer pool for the database, and connection management
Buffering pool "maximum number of connections" parameter set to the database product license limit
Given maximum number of users. If you use other programs without Connection Managerconnections
Database, you can not guarantee that the method is effective.
(2) the structure of the Connection Manager.
(3) Connection Manager connection pool to maintain a connection to a specific database is open. Step 1: When the first Serv the let trying to Connection Manager communications is loaded by the Java Application Server Connection Manager. As long as the Java application server running the Connection Manager has been loaded. Step 2: The Java application server passes the request to a servlet. Step 3: Servlet Connection Manager requests a connection from the pool. Step four: the buffer pool to Ser vlet allocated a pool of existing idle connection. Step 5: servlet to use to connect a direct dialogue with the database, this process is the standard API for a particular database. Step 6: the database through Ser vlet the connection returns data. Step 7: When the Servlet end to communicate with the database, servlet connections returned to the connection manager pool for other servlet uses. Step 8: Servlet Jav a application server to the user sends back response.Servlet requests a connection, if the buffer pool, there is no idle connection, then the connection manager directly communicate with the database. Connection Manager will: Step 9: to the database requests a new connection. Step 10: Add connections to the buffer pool. If the buffer pool is connected to the prescribed ceiling, connect to the server
Will not be a new connection to join the buffer pool
(3) the performance characteristics of the Connection Manager.
Buffer pool to create a new connection is a high overhead tasks, new connections will use the resources on the database. Therefore, the Connection Manager the best use of existing connections of the buffer pool to meet the request of the Servlet. Meanwhile, the connecting tube
The processor must be as much as possible to minimize the buffer pool idle connections, because this is a great waste of system resources. Connection Manager Serv the let with the implementation of these minimize and maximize task. Connection Manager to maintain each connection verification time stamp, and recently used tags and use the logo. When the a Ser vlet first the connection, connection verification time stamp, and most recent time stamp is set to the current time, the connection is being used flag is set to true.Connection Manager can be removed from a Serv the let a long-unused connections, this length of time specified by the Connection Manager, the longest cycle parameters.Connection Manager can view recently used mark is being used to connect. If the time between the most recently used time and time difference is greater than the longest cycle configuration parameters, the connection will be considered to be a residual connection, which indicates Serv the let take its discontinued or no response. Residual connection will be returned to the pool for other Ser vlet, it is being used flag is set to false, authentication and time stamp is set to the current time.
If Ser vlet is ready within a longer period of time to use the connection with the database several times
Communications, you must code to the Serv the let, so that each time you use to connect
Confirm that it still occupies this connection.
Connection Manager can be removed from the buffer pool idle connections, because they
Would be a waste of resources. In order to determine which connection is idle, Connection Manager will check
Investigation connected the sign and time stamp, this operation is connected by periodic access to
Buffer pool information. Connection Manager checks have not been any Ser vlet make
With the connections (these connections is to use the logo is false). If you have recently used
Between time and the current time difference exceeds a maximum idle time configuration parameters, the
That the connection is idle. Idle connection will be removed from the buffer pool, down to
Minimum number of connections configuration parameter specifies the lower limit value.
翻译：随着Inter net 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Java Ser vet 技术就是Web 信息库开发方案的一种比较实用的的选择。Serv let 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, Serv let 运行在启用Java Serv let 引擎的Web 服务器上并扩展该服务器的能力。因此, 可以说Serv let 就是运行在Web 服务器上的Applet, Serv let 就是使用Jav a Ser vlet API
及相关类和软件包的Jav a 程序。1　Servlet 的访问模型
Serv let 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。
2 Web 服务器收到请求后将请求转交给Ser vlet 引擎。
3 Serv let 引擎执行所请求的Ser vlet 并通过JDBC 直接检索数据库中的信息。
4Ser vlet 通过JDBC 取回检索结果生成html 页面并将页面送回Web 服务器。
5 Web 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。
2 Web 服务器收到请求后将请求转交给Ser v let 引擎。
3Serv let 引擎执行所请求的Ser vlet 并将检索式发送给数据访问Ja vabean。
4数据访问Ja vabean 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。
5 Ser vlet 从数据访问Javabean 中取出检索结果生成Html 页面并将Ht ml 页面返回给w eb 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。
2 Web 服务器收到请求后将请求转交给Ser v let 引擎。
3 Ser vlet 引擎执行所请求的Serv let 直接通过JDBC 检索数据库并将检索结果存储在结果存储Jav abean 之中。
4 Ser v let 从结果存储Jav abea n 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。
6 Web 服务器将页面发送回浏览器。
2　Servlet 的功能与生命周期
　　2. 1　Ser vlet 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HTM L
页面( HT ML 片段) 。
( 3) 与其它服务器资源( 包括数据库和基于Jav a 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, Ser vlet 可以是多参与者
的游戏服务器。
( 5) 对特殊的处理采用MIM E 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, Ser vlet 可以修改如何认证用户。
　　2. 2　Ser vlet 的生命周期
Serv let 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Serv let 时结束。
( 1) 装入。
在下列时刻装入Ser vlet:
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Serv let 发出请求时。
3 重新装入Serv let 时。
装入Serv let 后,Web 服务器创建一个Ser vlet 实例并且调用Serv let 的init( ) 方法。在初始化阶段, Serv let 初始化参数被传递给Serv let 配置对象。
( 2) 终止。
当Web 服务器不再需要Serv let , 或重新装入Ser vlet 的新实例时, 服务器会调用Serv let 的destr oy ( ) 方法, 将其从内存中删除。
3　如何调用Servlet
调用Ser vlet 的方法共有五种: 在URL 中调用、在窗体〈Form〉标记中调用、在HT ML 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Serv let。
只需在浏览器中输入格式像http: ∥yo ur webser vername / serv let path/ ser vlet name 一样的Serv let URL 地址即可。其中: yo ur webser ver name 是指Serv let 所在的Web 服务器名, serv let pat h 是指Serv let 的路径, ser vlet
name 是指Serv let 的真实名字