【正文】 rent scheme are limited. As follows: pidly developing and testing. The JSP technology is designed to meet such requirements. The JSP specification is a Web server, application server, trading system and develop extensive cooperation between the tool suppliers. From this standard to develop the existing integration and balance of Java programming environment (for example, Java Servlet and JavaBeans) support techniques and tools. The result is a kind of new and developing method based on Web applications, using ponentbased application logic page designers with powerful functions. Overall Semantics of a JSP Page A JSP page implementation class defines a _jspService() method mapping from the request to the response object. Some details of this transformation are specific to the scripting language used (see Chapter , “Scripting”). Most details are not language specific and are described in this chapter. The content of a JSP page is devoted largely to describing the data that is written into the output stream of the response. (The JSP container usually sends this data back to the client.) The description is based on a JspWriter object that is exposed through the implicit object out (see Section , “Implicit Objects”). Its value varies: Initially, out is a new JspWriter object. This object may be different from the stream object returned from (), and may be considered to be interposed on the latter in order to implement buffering (see Section , “The page Directive”). This is the initial out object. JSP page authors are prohibited from writing directly to either the PrintWriter or OutputStream associated with the ServletResponse. The JSP container should not invoke () until the time when the first portion of the content is to be sent to the client. This enables a number of uses of JSP, including using JSP as a language to “glue” actions that deliver binary content, or reliably forwarding to a servlet, or change dynamically the content type of the response before generating content. See Chapter , “Internationalization Issues”. Within the body of some actions, out may be temporarily reassigned to a different (nested) instance of a JspWriter object. Whether this is the case depends on the details of the action’s semantics. Typically the content of these temporary streams is appended to the stream previously referred to by out, and out is subsequently reassigned to refer to the previous (nesting) stream. Such nested streams are always buffered, and require explicit flushing to a nesting stream or their contents will be discarded. If the initial out JspWriter object is buffered, then depending upon the value of the autoFlush attribute of the page directive, the content of that buffer will either be automatically flushed out to the ServletResponse output stream to obviate overflow, or an exception shall be thrown to signal buffer overflow. If the initial out JspWriter is unbuffered, then content written to it will be passed directly through to the ServletResponse output stream. A JSP page can also describe what should happen when some specific events occur. In JSP , the only events that can be described are the initialization and the destruction of the page. These events are described using “wellknown method names” in declaration elements.. JavaScript is used for the first kind is browser, the dynamic general purpose of client scripting language. Netscape first proposed in 1995, but its JavaScript LiveScript called. Then quickly Netscape LiveScript renamed JavaScript, Java developers with them from the same issued a statement. A statement Java and JavaScript will plement each other, but they are different, so the technology of the many dismissed the misunderstanding of the two technologies. JavaScript to create user interface control provides a scripting language. In fact, in the browser into the JavaScript code logic. It can support such effect: when the cursor on the Web page of a mobile user input validation or transform image. Microsoft also write out their JavaScript version and the JScript called. Microsof