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Created by Fang on March 23, 2010 03:50:11    Last update: August 18, 2010 21:59:52
This is a simple web application with a single servlet and a single JSP page. It is intended to be a test bed for JSTL tags. You may want to store all syntax, rules, and exceptions in your head, but in my opinion nothing beats a simple test program that allows you play with it all you want. So here it is (build with Maven ). Prerequisites: Maven: http://maven.apache.org/ . You don't need any prior knowledge of Maven, but you need to install the binary. JBoss: http://jboss.org/jbossas/downloads/ , or Tomcat: http://tomcat.apache.org/ if you don't run the SQL tests. You need to know how to deploy a web application (shh! Don't tell your boss it's just copying a file to the deployment folder). Steps: The directory...
Created by Fang on August 18, 2010 20:07:46    Last update: August 18, 2010 20:11:36
JSTL uses XPath expressions as a concise notation to specify or select parts of an XML document. JSTL provides EL like expressions to access web application data and comes with the core function library of the XPath specification. Accessing Web Application Data XPath Expression Mapping $foo pageContext.findAttribute("foo") $param:foo request.getParameter("foo") $header:foo request.getHeader("foo") $cookie:foo maps to the cookie's value for name foo $initParam:foo application.getInitParameter("foo") $pageScope:foo pageContext.getAttribute("foo", PageContext.PAGE_SCOPE) $requestScope:foo pageContext.getAttribute("foo", PageContext.REQUEST_SCOPE) $sessionScope:foo pageContext.getAttribute("foo", PageContext.SESSION_SCOPE) $applicationScope:foo pageContext.getAttribute("foo", PageContext.APPLICATION_SCOPE) For example, to find the bar element whose x attribute equals the value of the HTTP request parameter named paramName : /foo/bar[@x=$param:paramName] Java Type to XPath Type Mappings XPath Type Java Type java.lang.Boolean boolean java.lang.Number number java.lang.String string Object exported by <x:parse> node-set Please note that JSTL, as of version 1.2,...
Created by Fang on July 26, 2010 19:18:28    Last update: August 18, 2010 19:13:02
The tags <c:import> The <c:import> tag imports the contents of a URL and expose that in one of three ways: Import contents from a URL and write it out to the page (url may be relative or absolute): <c:import url="theUrl" /> Import contents from a URL and save it to a scoped variable string named by the var attribute. Use the scope attribute to define the scope of the exported variable. <c:import url="theUrl" var="importTest" scope="ses... Import a URL and expose to a Reader object named by the varReader attribute. The scope attribute does not apply. The varReader scoped variable can only be accessed within the body of <c:import> . <c:import url="theUrl" varReader="theReader"/> <c:url> The <c:url> tag constructs a URL and writes it out to the...
Created by Fang on August 16, 2010 22:00:05    Last update: August 16, 2010 22:12:25
The tags <sql:update> Executes SQL INSERT , UPDATE , DELETE statements, or SQL DDL statements. Syntax: <sql:update sql="sqlUpdate" [dataSource="d... or, put the SQL within the element body: <sql:update [dataSource="dataSource"] [v... Attributes: Name Dynamic? Type Description sql true String SQL update statement. dataSource true javax.sql.DataSource or String Data source associated with the database to update. A String value represents a relative path to a JNDI resource or the parameters for the JDBC DriverManager class. var false String Name of the exported scoped variable for the result of the database update. The type of the scoped variable is java.lang.Integer . scope false String Scope of var. Defaults to "page". <sql:transaction> Establishes a transaction context for <sql:query> and <sql:update> subtags. Syntax: <sql:transaction [dataSource="dataSource"] ... where...
Created by Fang on August 16, 2010 21:44:41    Last update: August 16, 2010 22:01:46
The tags <sql:query> Queries a database. Syntax: <sql:query sql="sqlQuery" var="varName" [scope... or, put the query within the element body: <sql:query var="varName" [scope="{page|req... Attributes: Name Dynamic? Type Description sql true String SQL query statement. dataSource true javax.sql.DataSource or String Data source associated with the database to query. A String value represents a relative path to a JNDI resource or the JDBC parameters for the DriverManager class. maxRows true int The maximum number of rows to be included in the query result. If not specified, or set to -1, no limit on the maximum number of rows is enforced. startRow true int The returned Result object includes the rows starting at the specified index. The first row of the original query result set is at index...
Created by Fang on August 03, 2010 19:50:51    Last update: August 03, 2010 19:50:51
The tags <fmt:message> Writes out a formatted message for the current locale and resource bundle, or stores the resulting message to a scoped variable (when the var attribute is specified). Syntax: <fmt:message key="messageKey" [bundle="resourc... Or, with parameters in body: <fmt:message key="messageKey" [bundle="resourc... <fmt:bundle> Creates a resource bundle for the contained body. Syntax: <fmt:bundle basename="basename" [prefix="prefi... <fmt:setBundle> Sets a resource bundle in a scoped variable, which may be used later by <fmt:message> . Syntax: <fmt:setBundle basename="basename" [var="varNa... <fmt:param> This is used inside a <fmt:message> tag to specify a replacement parameter. <fmt:param value="theParameterValue"/> or <fmt:param>The Parameter Value</fmt:param> Test it Make these additions to the expanded test application : Create 3 resource bundles and place them under src\main\resources . messages_en.properties : label.login=Login label.username=User Name ... messages_es.properties :...
Created by voodoo on July 30, 2010 14:53:33    Last update: July 30, 2010 14:54:52
The -d switch for cURL sends HTTP POST with data from the command line. To verify the data being posted, this is a CGI script that echos the data back: #!C:/perl/bin/perl.exe ## ## echo -- echos ... Examples: POST data from command line: C:\>curl -d input1=value1^&input1=value2 http://lo... POST data from stdin (with @ before the - symbol): C:\>curl -d @- http://localhost/cgi-bin/echo.pl ... POST data from a file (with @ before the - symbol and input redirect): C:\tmp>cat data.txt abcd 1234 xyz ... For some reason, @ with file name didn't work as expected: C:\tmp>curl -d @data.txt http://localhost/cgi-bin/... One thing to notice is that cURL removes the new line characters when posting (thus the echo back is only one line instead of three). This can...
Created by voodoo on July 11, 2009 15:14:55    Last update: July 29, 2010 22:45:48
cURL is a command line tool for transferring files with URL syntax. The main purpose and use for cURL is to automate unattended file transfers or sequences of operations. It's really easy to see HTTP headers with curl: C:\>curl --head http://www.google.com HTTP/1.0 ... or, headers and page together (dump headers to stdout): $ curl --dump-header - http://www.google.com HTTP/... Download openssl from openssl.org: curl http://www.openssl.org/source/openssl-0.9.6m.... C:\>curl --help Usage: curl [options...] <url> ...
Created by voodoo on July 21, 2010 16:10:47    Last update: July 21, 2010 16:10:47
Google news RSS does not like curl: C:\> curl --dump-header - -o NUL http://news.googl... Switch the agent to HotJava with the -A option: C:\> curl -A "HotJava/1.1.2 FCS" --dump-header - -...
Created by Fang on April 04, 2010 04:12:14    Last update: July 21, 2010 14:52:58
The tags <c:if> The <c:if> tag may be used with or without body content: <!-- Without body content, used to export vari... In my opinion, the version without body content is pretty much useless (the <c:set> tag is a lot more meaningful for this purpose). If body content exists, it is inserted into the page if the testCondition is true . Optional attributes var and scope may be specified. If var is specified, a variable whose name is the value of var is exported to the associated scope ( pageScope if no scope is specified). The type of the exported variable is Boolean and its value is the value of the testCondition . <c:choose>, <c:when>, <c:otherwise> These tags imitate the Java control structure if...else...
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