STORY:
I was setting up a Spring powered web application for testing.
I edited the configurations files (*.xml) to add in some new configuration for testing / POC.
The following error is shown when I deployed the WAR file in tomcat
org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 40 in XML document from ServletContext resource [/WEB-INF/applicationContext.xml] is invalid; nested exception is org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'bean'. One of '{"http://www.springframework.org/schema/beans":description, "http://www.springframework.org/schema/beans":meta, "http://www.springframework.org/schema/beans":constructor-arg, "http://www.springframework.org/schema/beans":property, "http://www.springframework.org/schema/beans":qualifier, "http://www.springframework.org/schema/beans":lookup-method, "http://www.springframework.org/schema/beans":replaced-method, WC[##other:"http://www.springframework.org/schema/beans"]}' is expected.

SOLUTION:
As highlighted above, there is error in the mentioned XML file.
After I opened the XML file, I found that is some missed-closed bean definition ABOVE the mentioned line (Line 40 in XML).
The error bean definition as below:

<bean id="accountManager" class="alfred.sandbox.AccountManager">

Added in a BLACK SLASH “/” to close the bean definition properly will solve the error:

<bean id="accountManager" class="alfred.sandbox.AccountManager"/>

STORY:
I was trying to add AOP to an existing web application. The AOP configuration I added is:

<aop:aspectj-autoproxy />

SOLUTION:
Add the AspectJ library to the classpath. The required AspectJ library are:
1. aspectjrt
2. aspectjweaver

My webapps is using Maven, so I added the dependencies to pom.xml as below:

<!-- AspectJ -->
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjrt</artifactId>
    <version>1.6.11</version>
</dependency>
<dependency>
    <groupId>org.aspectj</groupId>
    <artifactId>aspectjweaver</artifactId>
    <version>1.6.11</version>
</dependency>

Solution
I use grep with option “-an” which will print out the file name and line number of the found string.
The command below will search for text “my text” from all XML files in my current working directory.

grep -an "my text" *.xml

15 Practical GREP, resource

1. Generate SSL key for your computer.

$JAVA_HOME/bin/keytool -genkey -alias tomcat -keyalg RSA -keystore /path/to/my/keystore

2. Edit server.xml
- Open ../tomcat/conf/server.xml
- Uncomment following lines and add in “keystoreFile” and “keystorePass”

 <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
               maxThreads="150" scheme="https" secure="true"
               keystoreFile="/path/to/my/keystore" keystorePass="password"
               clientAuth="false" sslProtocol="TLS" />

3. You are DONE. You can try to access HTTPS with Port 8443 now.
Eg: https://www.example.com/SecretResource/1234567

Reference: Tomcat 6.0 SSL Configuration, here.

My environment:
Apache Tomcat v6.0.32
Sun Java v1.6.0_21
Red Hat 4.1.2-50

public void printMap(Map mp) {
    Iterator it = mp.entrySet().iterator();
    while (it.hasNext()) {
        Map.Entry pairs = (Map.Entry)it.next();
        System.out.println("Key:" + pairs.getKey() + ", Value:" + pairs.getValue());
    }
}

Reference Source

I started a simple web apps project to try out Spring 3.0. The web apps is pretty simple, a REST server alike. Client init HTTP calls to the web apps with specific Servlet name and parameter, the web apps will returns the result JSON with Plain text mode. Since I am using Spring MVC, the result is printed with JSTL.

Sample call from client: http://myserver.com/getUser?userId=001

Expected result from server:
{“name”:”Bob”,”age”:”30″,”gender”:”male”}

I get what I expected when I test my web apps with browser.

But the ‘interesting’ comes when I test it with little Java Post program (use HttpClient, init HTTP call and inspect the result).
I did not get the expected result, I get below:
{"name":"Bob","age":"30","gender":"male"}

All double-quat / quotation being replaced with ", its clearly the contain is being HTML encoded.

Below are my trouble-shooting steps:
Step 1. Check tomcat configuration
- Ensure the tomcat UTF-8 by default. More info
Step 2. Check web apps JSPs
- Ensure all JSP are UTF-8 as default encoding.

But both Step 1 & 2 does not fix my problem yet.
Step 3. Google “jstl without html encoded”
- Finally, I get the answer
- add in escapeXML properties when printing the result in JSTL
Before: <c:out value="${result}" />
After: <c:out value="${result}" escapeXml=”false”/>
Tutorial – Output with / without Encode

Lesson Learn:
When you want to print a PLAIN TEXT with JSTL, do remember to include escapeXML="false" to ensure that end user will get the actual expected result without HTML/XML encoded.

STORY:
I am starting a new webapps recently, since its a new webapps, I decided to use the latest Spring version 3.1.0.M2. Everything looks fine when the development is still in standalone environment. After dive into the development, the webapps I’m working on need to ‘talk’ to some other existing components in the system. After I have integrated my webapps with the existing components and I restart my tomcat, I get the error java.lang.NoSuchMethodError: org.springframework.core.GenericTypeResolver.resolveTypeArguments(Ljava/lang/Class;Ljava/lang/Class;)[Ljava/lang/Class;

First of all, for Java developer, when you see ‘NoSuchMethodError’, you will directly check the existence of the mentioned method in your JAR file. But ‘sadly’ the mentioned class file and method is there.

SOLUTION:
Thanks to Google, I got my answer in Spring Forum. The answer is pretty simple, I have more than 1 version of Spring in the classpath. As mentioned earlier, the new webapps is running on latest Spring (v3.1.0.M2) but the existing components I integrates with only running on Spring v2.5. So, pls ensure that there is only ONE SPRING VERSION in your classpath.

Story:
Ok, I hits the above error when I try to loop through the request parameters, and print out all parameter Key and Value.
The ClassCastException is a general exception, it will be thrown when you try to cast an Apple to an Orange. Thats simple!
When the first time I read this exception message, "[Ljava.lang.String; cannot be cast to java.lang.String", I though there is some typo in the compiler
What is the difference between "[Ljava.lang.String" and "java.lang.String"?
From the wording itself, quite straight forward. The later do not have "[L", but what is the "[L"?
Thanks for some stupid errors I hit before, I recall that the "[L" is the representation of Array object!

CODE / SOLUTION:
Here is the way I used to print out all parameter Key and Value. I'm not sure its a correct / best way, but its works!

Map paramMap = request.getParameterMap();
Iterator iter = paramMap.entrySet().iterator();
while(iter.hasNext()) {
    Entry<String, String[]> entry =  (Entry<String, String[]>) iter.next();
    String key = entry.getKey();
    String value = entry.getValue()[0];
    logger.debug("key[{}] value[{}]", key, value);
}

In normal case, we have to call to a class extending ActionForm before you’re going to the next JSP page. For cases that you do not need any action to perform before you reach that JSP, you can call the class org.apache.struts.actions.ForwardAction. So that, you only have to prepare the JSP file and do the configuration in struts-config.xml as below.

<action-mappings>
    ....
    <action path="/ForwardLogin"
        parameter="/WEB-INF/pages/login/login.jsp"
        type="org.apache.struts.actions.ForwardAction"
        scope="request"
        validate="false"/>
    ....
<action-mappings>

The solution that I’m going to share here is COPY from netty5.
I feel that its very useful especially to those who is not familiar with terminal,
coz everything can be done by few mouse clicks.

1. Move your pointer to the top-left corner of your desktop.
2. Click on “Applications” > “Accessories” > “Terminal”. A terminal will be pop up.
3. On the Terminal, click on “Edit” > “Profiles..”. A small windows named “Profile” will be pop up and a “Default” profile is selected by default.
4. Click on “Edit” in the Profile window. Another small window will be pop up.
5. Click on “General” tab, UNCHECK the “Terminal bell”, and close all poped up windows. And you’re done. no more “beeeep” or “tuuuuu” sounds

FYI, I’m using Ubuntu 9.04 at the moment.