servlets and JavaServer Pages (JSPs) for deployment on. WebLogic Server complete reference for the schema for the WebLogic Server-specific deployment. advice with detailed coverage of JSP syntax and features and clear, . O'Reilly & Associates books may be purchased for educational, business, or sales directories, and mail servers, creating PDF documents and images, and encrypting. JSP PDF books JSP PDF JSP Book Servlets and JavaServer pages First Servlets JSP Scripting Elements JSP Tag Libraries Using the JavaBeans with JSP.
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JSP: The Complete. Reference. Phil Hanna. Osborne/McGraw-Hill. New York Chicago San Francisco. Lisbon London Madrid Mexico City. Milan New Delhi San. Servlet and JSP. Programming with IBM WebSphere Studio and VisualAge for Java. Ueli Wahli. Mitch Fielding. Gareth Mackown. Deborah Shaddon. Servlets are Java technology's answer to Common Gateway Interface (CGI) programming. Collection is jsp books in the pdf format. JavaServer Pages (JSP) technology enables you to mix regular, static HTML with dynamically generated content from servlets.
The jsp: To simplify servlet writing. These elements have specific start and end tags that identify them to the JSP compiler. This could be used to emulate Windows NT services or Unix daemon processes. The way around this is to have the server assign an identifier to the session represented by a set of client requests. This chapter describes using an inner class as a data structure for passing a set of variables between methods in the generated servlet. The server host name is extracted from the URL.
Ask Latest Tutorials: Latest Topics. How to use request. You can download these books and study it offline. Their job is to: The First Servlets The previous chapter showed you how to install the software you need and how to set up your development environment. Now you want to really write a few servlets.
This chapter shows you how, outlining the structure that almost all servlets follow, walking you through the steps required to compile and execute a servlet, and giving details on how servlets are initialized and when the various methods are called.
Section 1. XML languages have a number of uses including: In HTTP servlets. String type this sets the Content-Type header. The long integer date value should be one suitable for the java. Methods in the HttpServletResponse Interface. Sets a response header with the String value specified name and value.
Table describes the methods in HttpServletResponse. Date long time constructor. This allows it. Adds a response header with the int value specified name or replaces all headers void setIntHeader String name.
String msg optionally. Servlet Context A servlet context is an interface supplied by the servlet engine to provide services to a Web application.
The servlets in the Web application can use the servlet context to get. Error responses should use sendError instead. HttpServletResponse defines a complete set of integer constants for the valid status values. Object obj objects are global. Method Description Object getAttribute Returns the object bound to the specified String name name in the servlet context or binds an void setAttribute object using the specified name.
The servlet context has a name the name of the Web application it belongs to. Methods in the ServletContext Interface 3 JSP pages have it even easier—a reference to the servlet context is automatically stored in the implicit variable application. A servlet can get a reference to the servlet context by invoking the getServletContext method on the ServletConfig object that was passed to init. Enumeration Returns an Enumeration of the names getAttributeNames of all attributes stored in the servlet context.
If the servlet subclasses GenericServlet directly or indirectly. Such String name. The path. String getInitParameter Returns the value of the specified String name context-wide initialization parameter.
Enumeration Returns a possibly empty Enumeration getInitParameterNames of the names of all the context-wide initialization parameters. Typically based on the file extension. May return null if the MIME type is unknown. Methods in the ServletContext Interface continued. String getServerInfo Returns the name and version number of the servlet engine.
This fact has several implications. Requests serviced by the servlet are run in separate threads. Returns null if no such resource exists. Don't try this at home. If these other methods try to access the servlet request. The first one opens the database connection and stores a reference to it in the con instance variable.
Bad things then happen when it tries to use the second connection. The same type of problem with instance variables can occur in servlets that call other methods from within their service method.
The safest approach is simply not to use instance variables. If the first operation finishes and tries to do another database operation. It then uses the connection to perform a table update or some other database operation.
This interface. HTML and associated images can be downloaded efficiently. It may take several requests to build these objects. In each subsequent related request.
Between each request. This is similar to booking an airline ticket over the telephone. The ticket agent asks the customer for her name. If they access external resources like files or database connections. Several approaches can be used to solve this problem.
No back-and-forth exchange of commands and data occurs. If image links are in the HTML. Most of them involve maintaining the object itself on the server. This guarantees no two requests handled by the same instance will overlap in their execution of the service method. This requires both the client and server to know about the capability and request it explicitly.
If the user clicks a hyperlink in the page. More details about cookies can be found in the RFC specification. Table lists the methods available in HttpSession. A hashtable-like interface named javax. HttpSession provides a session ID key that a participating client stores and returns on subsequent requests in the same session.
The Complete Reference to the customer. Client browsers store cookies and return them automatically to the server each time the browser requests a page from the same domain. On subsequent requests. If one is overlooked an easy thing to do. Later on. HttpSession has setAttribute and getAttribute methods that store and retrieve objects by name.
How can the client be induced to remember and supply the key when required? Several means exist: The servlet engine looks up the appropriates session object and makes it available to the current request. Object value was previously stored. This is true when the session is first created and the session ID is passed to the client. The integer is in the form used by the java. Date constructor.
String getId Returns the session ID. Objects that implement this interface must provide valueBound and valueUnbound methods. They are managed by a servlet engine. Understanding them is vital to forming the mental model required to develop and debug in the JSP environment. The Complete Reference Summary Java servlets are extensions to a Web server that allow Web content to be created dynamically in response to a client request.
Servlets have key advantages over other server-side programming environments: The API provides two threading models: This chapter provides an overview of JSP as a server-side scripting environment. Java language statements. Only the basics are covered here. It describes the JSP container operations and walks through a complete example. JSP pages have all the advantages of servlets: This source code is typically saved in a work area and is often helpful for debugging. JSP pages have advantages of their own: Because they are servlets.
It exists in a text file with an extension of. If so. In response to an HTTP request. Figure illustrates the process used by the JSP container. When a request for a JSP page is made. Chapter 5: The Complete Reference source has changed since it was last compiled. Kilometers per liter to miles per gallon output from JSP page. If you invoke this JSP page from a Web browser. To make the JSP-to-servlet relationship clearer. This code will differ greatly.
In addition. The code listed here is what was generated by JRun 3. The Complete Reference container is used and the implementation approach it takes. HttpJSPServlet implements allaire. IOException t. IOException throw java. With this backdrop. The Complete Reference return As you see.
The concluding chapter provides a detailed tutorial on JSP custom tags. The URL by which it is known to the network is the same. In covering this material. In this design. The Complete Reference he purpose of this chapter is to give an overview of the basic components used T in JavaServer Pages. This chapter reviews the JSP development model. The Java source code for a servlet program 3.
It then compiles the servlet and creates a. The middle step generating the servlet source code is repeated for later requests only if the.
The chapter concludes with an annotated example that illustrates the use of each element. In this respect. Directives Directives are instructions to the JSP container that describe what code should be generated. The JSP Template data usually HTML is passed through unmodified. These elements have specific start and end tags that identify them to the JSP compiler.
The next three sections provide an overview of each of these directives. Chapter 6: Three types of JSP elements exist: Template data is everything else that is not recognized by the JSP container. JSP elements are instructions to the JSP container about what code to generate and how it should operate. Attribute Value language The language used in scriptlets. Valid entries are nnnkb or none. It has the following syntax: This list is used to create corresponding import statements in the generated Java servlet.
The default value is true. The following packages are automatically included and need not be specified: This must be a class that implements the HttpJspPage interface. In JSP 1. If the value is true. Attributes of the Page Directive. The default value is 8kb. The JSP specification warns against the use of this attribute without fully understanding its implications.. If false.
The default value is false. Specifying true for this attribute makes the exception implicit variable available to this page. In that case. Attributes of the Page Directive continued More than one page directive can be in a file and the attributes specified collectively apply to the whole file. The include Directive The include directive merges the contents of another file at translation time into the.
Chapter 10 covers the page directive in more detail. The taglib Directive The taglib directive makes custom actions available in the current page through the use of a tag library.
This is a hidden JSP comment. Chapter 8 examines both approaches in detail. This is included in the generated HTML. Either element can be used to include standard headers and footers or other common text in JSP pages. Comments of this type are passed through unaltered to the response output stream and are included in the generated HTML.
This is a time-honored technique for temporarily enabling and disabling parts of a program without making major modifications to the source code. The expression can have any data value.
Expressions JSP provides a simple means for accessing the value of a Java variable or other expression and merging that value with the HTML in the page. If the purpose of a comment is to enlighten the person viewing it. If something goes wrong with the application..
They are invisible in the browser window. This conversion is usually done simply by generating an out. A JSP page may contain any number of scriptlets. Chapter 7 discusses expressions in more detail. Consider the following JSP page. If multiple scriptlets exist. Scriptlets A scriptlet is a set of one or more Java language statements intended to be used to process an HTTP request.
Understanding what code is generated can help you remember not to put a semicolon inside an expression. The Complete Reference out. Degrees Degrees Fahrenheit Celsius Between the two scriptlets is the HTML markup for a single table row. Declarations Like scriptlets.
If you use a declaration section to declare a method that needs to use the request object. Map map. Unlike scriptlets. String title. The Complete Reference Declaration sections can be used to declare class or instance variables. The following shows an example of a JSP page that uses a declaration section: The desired output for each is a nicely formatted HTML table.
Entry imap. Of course. Chapter 8 discusses declarations in greater detail.
They can be accessed like any other variable. These variables are implicitly available inside scriptlets and expressions but not declarations. This object is a central repository for attribute data for the page.
Implicit Variables. Table outlines the syntax. Unlike directives and scripting elements. See Chapter 11 for discussion of this topic.. Implicit Variables continued Additional implicit variables can be created by means of a tag library. Seven standard actions are available in all JSP These actions are described at length in Chapter Standard Actions.
Standard Actions continued. The listing is shown in the following: Chapter 11 is devoted to tag extensions. A Complete Example An example of a JSP page that incorporates all the elements introduced here concludes this chapter. The page is named Echo. JSP Syntax and Semantics 81 response. The matching brace is supplied by the second scriptlet. Scriptlet Two scriptlets are on the page. Verdana 9pt. Notice the code fragment has an unclosed curly brace on the second line.
Then the first scriptlet is simply copied to the servlet: Rather than printing these values using out. This function is performed by a method called normalize. The Complete Reference A Declaration Header values that are lists can be very long and cause the table width to be distorted.
The remaining chapters of Part II discuss each of these features of the application model in more detail. JavaBeans are fully integrated into the framework. Output of Echo.
The key point this chapter makes is this: The syntax allows most of the HTML to be coded directly. There is support for including other resources. In this chapter. The Java virtual machine vendor is Sun Microsystems Inc. JSP pages could be written in other languages. Simple math: Java is the only supported language.
While T the syntax is not difficult to learn. How a JSP page gets access to the Web environment in which it is used. As of this writing. Chapter 7: Expressions and Scriptlets 91 An expression can create new objects and manipulate them.
This code creates a Date object and passes it to the format method of a new SimpleDateFormat object. Expressions must not end in a semicolon. They must consist solely of what can legally appear on the right side of an assignment statement between the equals sign and the ending semicolon.
The following section describes how these scripting elements are handled by the JSP container. When invoked. The expressions. The JSP author must not define it explicitly. This method corresponds to the service method of a servlet. JSP containers typically generate one long out. Expressions are considered in the next section.
The JSP container creates out. Besides fixed HTML data. The JSP 1. The examples in this book take the liberty of breaking long character strings into multiple out. If multiple scriptlets are in a page. The Complete Reference and this. Because multiple scriptlets are concatenated and placed into the same method.
Tomcat generates the following initialization and exit code: In the case of the Celsius-to-Fahrenheit example previously given. The exact code generated is implementation-dependent and specific to the JSP container vendor. The JSP container provides this environment and makes it accessible to the page author through what are called implicit objects. Nine of these objects exist. The meaning of these objects is the subject of the next section. The following sections consider each of these objects in detail.
Implicit Objects Available Within Scriptlets and Expressions continued These variables can be accessed simply by using their predetermined names like any other variable.
JRunJspWriter object. One of these variables has already been used in the examples in this chapter—the JspWriter out variable. This object. JRun 3.
JspWriterImpl object. Enumeration getParameterNames Returns an enumeration of the names of all form parameters passed to this request. String getParameter String name Given the name of a single-valued form parameter. If one does not exist. This object encapsulates the output returned to the HTTP client.
Some Useful Methods of the request Object 3 A complete description of javax. Methods provided by the HttpServletResponse object include those listed in Table Some of its more useful methods3 are listed in Table All JSP response output must be written using the out implicit variable.
It also has methods for accessing the response output stream. HttpServletRequest and all other classes in the Servlet 2. JSP context layers. The JSP specification provides for a PageContext object that keeps track of attributes at four levels: A single HTTP request. Each of the layers in this hierarchy can have attributes that apply at that level only. Object getAttribute String name.
It also provides methods that forward requests to other resources and include the output of other resources. Removes the attribute object having the int scope specified name in the given scope. This object provides search and update capability for attributes at each of the four levels.
Returns the attribute object with the int scope specified name in the given scope. Some Useful Methods of the pageContext Object. Stores an object as a named attribute in Object value. Because a session persists until it times out typically 30 minutes later or it is explicitly invalidated.
Enumeration getAttributeNames Returns an enumeration of the names of all the objects stored in the session. String getId Returns the unique session ID. It persists between HTTP requests and can store named objects of any kind. Some Useful Methods of the session Object. This object is assigned to a variable named session. Web applications frequently involve more than one request.
This ID must be stored by the client Web browser between requests and passed back to the JSP container to identify which session is required. If you do not need to retain objects between requests. Doing so can improve performance by reducing the number of objects of which the servlet engine has to keep track. An HttpSession is a Hashtable-like object associated with a single Web browser session. Table outlines several useful methods in the session object. Chapter 14 explores a number of these alternatives in detail.
Several approaches can be taken to accommodate this need. The continuity required for this type of application must be provided by something other than the Web server. Application The application implicit object encapsulates a view of the collection of all servlets. It provides information about the server version. Method Description Enumeration getAttributeNames Returns an enumeration of the names of all objects stored in the servlet context.
Some Useful Methods of the application Object. The JSP container closes the session if no activity occurs over that length of time. This object implements the javax. Some of its more useful methods are described in Table HTML pages. This object also provides a means for logging messages.
Expressions and Scriptlets Method Description int getMaxInactiveInterval Returns the maximum number of seconds the session stays active between user requests. Stores an object in the session under the Object value specified name. Some Useful Methods of the session Object continued Remember. Out The whole purpose of a JSP page is to produce some output and send it back to the user on the other end of the socket connection.
You can have all output generated in this manner or you can write explicitly to the out object in scriptlets. Some Useful Methods of the application Object continued As is the case with the page.
As you saw earlier in this chapter. Enumeration getInitParameterNames Returns an enumeration of the names of all application-wide initialization parameters. InputStream Similar in operation to getResource. The out variable is initialized with a reference to a javax. String getRealPath String path Converts a path in the context of the Web application to an absolute path in the file system. Initialization parameters are discussed in a later section of this chapter.
Some Useful Methods of the out Object. Method Description void flush Forces buffered data to be written to the output stream. No newline character is added at the end. Writer objects. Throwable that has been thrown. Page The page implicit object is a variable containing a reference to the current servlet instance.
Exception The object referred to by the implicit exception variable is any instance of java. ServletContext getServletContext Returns a reference to the servlet context same as the application implicit variable.
Method Description String getInitParameter String name Returns the value of the specified servlet initialization parameter. JSP pages can have initialization parameters.
Enumeration getInitParameterNames Returns a list of the names of all initialization parameters for this servlet. This attribute is discussed in more detail in Chapter The config implicit object provides methods for accessing these parameters.
This object is not typically useful to JSP page authors. The Complete Reference Config Besides application-wide initialization parameters that are made available through the application object. String name getServletName Returns the name of the generated servlet.
Some Useful Methods of the config Object. For JSP and servlet level access. They can be used in the same manner as string constants. This makes initialization parameters especially useful for storing installation and configuration data. In either case. Rather than having duplicate values in the web. Database access parameters are likely needed in several places within a Web application.
The programming statements in a scriptlet are copied directly into the Java source code of the generated servlet. JSP expressions are simply Java-language expressions that yield a string value or can be converted into one. These are automatically initialized objects that have predefined variable names. In this page we are giving you the lists of JSP Books that you can learn. Toggle navigation. Ask Latest Tutorials: Latest Topics. How to use request.
You can download these books and study it offline. Their job is to: The First Servlets The previous chapter showed you how to install the software you need and how to set up your development environment. Now you want to really write a few servlets. This chapter shows you how, outlining the structure that almost all servlets follow, walking you through the steps required to compile and execute a servlet, and giving details on how servlets are initialized and when the various methods are called.