EN
Spring Boot - pre-compile JSP files (Tomcat Server)
8 points
In this short article, we would like to show how to pre-compile *.jsp files in Spring Boot application that uses Tomcat Server inside.
Problem:
*.jspfiles are compiled by Tomcat Server when they are first time used.
Solution: it is necessary to prepare some controller that imports existing
*.jspfiles without executing them - it will force compilation.
The below code shows how to implement JSP files pre-compiler, which should be run always after the Spring Boot Application is started.
Project structure:
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/C/2
|3
+-- example-spring-boot-application/4
|5
+-- src/6
| |7
| +-- main/8
| |9
| +-- java/com/example/10
| | |11
| | +-- controllers/12
| | | |13
| | | +-- JspCompilerController.java14
| | |15
| | +-- SpringBootWebApplication.java16
| |17
| +-- webapp/WEB-INF/jsp18
| |19
| +-- about.jsp20
| +-- jsp_compiler.jsp21
| +-- gallery.jsp22
| +-- index.jsp23
| +-- login.jsp24
| +-- reister.jsp25
| +-- users.jsp26
|27
+-- pom.xmlIt is necessary to run pre-compilation by opening preapared link:
https://my-domain.com/jsp-compilerto run pre-compiler on deloyment,http://localhost/jsp-compilerto run locally developed project if needed.
JspCompilerController.java file:
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package com.example.controllers;2
3
import org.springframework.stereotype.Controller;4
import org.springframework.web.bind.annotation.RequestMapping;5
import org.springframework.web.bind.annotation.RequestMethod;6
7
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public class JspCompilerController {9
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(value = {"/jsp-compiler"}, method = RequestMethod.GET)11
public String getJspCompiler() {12
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return "jsp_compiler";14
}15
}jsp_compiler.jsp file:
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<% page contentType="text/html;charset=UTF-8" language="java" %>2
<% page import="java.io.IOException" %>3
<% page import="java.util.Set" %>4
<% page import="java.util.Iterator" %>5
<%!6
private void compileJspFile(7
ServletContext context,8
JspWriter output,9
HttpServletRequest request,10
HttpServletResponse response,11
String file12
) throws IOException {13
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output.print("<div class=\"file\"><code>" + file + "</code> ");15
16
try {17
RequestDispatcher dispatcher = context.getRequestDispatcher(file);18
19
if (dispatcher == null) {20
output.print("<span class=\"error\">not found!</span>");21
} else {22
dispatcher.include(request, response);23
output.print("<span class=\"success\">pre-compiled!</span>");24
}25
} catch (Exception ex) {26
output.print("<span class=\"error\">error!</span>");27
}28
29
output.print("</div>");30
output.flush();31
}32
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private void compileJspFiles(34
ServletContext context,35
JspWriter output,36
HttpServletRequest request,37
HttpServletResponse response,38
String directory39
) throws IOException {40
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Set<String> files = context.getResourcePaths(directory);42
Iterator<String> iterator = files.iterator();43
44
while (iterator.hasNext()) {45
String file = iterator.next();46
47
if (file.endsWith(".jsp")) {48
compileJspFile(context, output, request, response, file);49
continue;50
}51
52
if (file.endsWith("/")) {53
compileJspFiles(context, output, request, response, file);54
continue;55
}56
}57
}58
%>59
<html>60
<head>61
<title>JSP files pre-compilation</title>62
<style>63
64
div.files {65
border: 1px solid gray;66
}67
68
span.error {69
background: #ce4545;70
color: #800000;71
}72
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span.success {74
background: #4ece45;75
color: green;76
}77
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div.summary {79
margin: 20px 0 0 0;80
background: #4ece45;81
color: green;82
}83
84
</style>85
</head>86
<body>87
<div class="files">88
<%89
ServletContext context = pageContext.getServletContext();90
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HttpServletRequest wrapper = new HttpServletRequestWrapper(request) {92
public String getQueryString() {93
/*94
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`jsp_precompile` parameter added to URL forces JSP pre-compliation:96
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?jsp_precompile98
?jsp_precompile=true99
?jsp_precompile=false100
?some-parameter=here&jsp_precompile=true101
?some-parameter=here&jsp_precompile=false102
103
e.g.104
https://my-domain.com/path/to/api?jsp_precompile=true105
will force returned JSP view recompliation.106
107
*/108
return "jsp_precompile"; // required to run jsp files pre-compilation only109
};110
};111
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compileJspFiles(context, out, wrapper, response, "/WEB-INF/jsp");113
%>114
</div>115
<div class="summary">Done!</div>116
</body>117
</html>