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Created by Fang on March 30, 2012 10:07:25    Last update: March 08, 2013 13:41:57
After a user resets a password, I want to force the user to change the password before she gets access to secured content. This is usually done with a servlet filter. But with Spring MVC, you can also use a HandlerInterceptor . According to Spring JavaDoc: HandlerInterceptor is basically similar to a Servlet 2.3 Filter, but in contrast to the latter it just allows custom pre-processing with the option of prohibiting the execution of the handler itself, and custom post-processing. Filters are more powerful, for example they allow for exchanging the request and response objects that are handed down the chain. Note that a filter gets configured in web.xml, a HandlerInterceptor in the application context. As a basic guideline, fine-grained handler-related preprocessing tasks are candidates...
Created by Dr. Xi on June 22, 2011 07:33:45    Last update: June 22, 2011 11:57:54
Demo code for CSV parsing with OpenCSV . Java code: import java.io.*; import au.com.bytecode.opencs... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The parser: Escaped quote and backslash correctly Ignored spaces before the quotation mark - sometimes (see below) Counted spaces after the right quotation mark till the comma as content, including the right quotation mark (bug). Ignored improperly quoted item - silently (third line) Indeed, the OpenCSV parser has a problem with spaces: Input: "Smith, Jack", "210-345-8888" "Smith, J... Result: Line 1 has 2 values: | Smith, Jack| |210-3......
Created by Dr. Xi on June 22, 2011 09:42:35    Last update: June 22, 2011 11:39:40
Demo code for CSV parsing with Skife CSV . Java code: import java.io.*; import java.util.*; import... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| | CLAS... The parser worked correctly. But notice that it counts the spaces outside of the quotes significant, and doing so consistently. One more test for spaces: "Smith, Jack" , "210-345-8888" "Smith, Jack"... Result: Line 1 has 2 values: | Smith, Jack | | 210... Add a new line in item two: "One", "Two ", "Three" Result: Line 1 has 2 values: |One| | Two| L...
Created by Dr. Xi on June 21, 2011 15:41:51    Last update: June 22, 2011 11:33:36
Demo code for CSV parsing with Apache Commons CSV parser . Java code: import java.io.*; import org.apache.commons.csv... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... Result: Line 1 has 11 values: |psmith01| |CLASS2B|... The parser worked correctly. Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... Result: Line 1 has 4 values: |psmith01 abc| |CLASS... The third line is invalid input, but throwing a Java IOException is a bit grave. Also, the parser is not able to escape a backslash. Add a new line in item two: "One", "Two ", "Three" Result: Line 2 has 3 values: |One| |Two | |...
Created by Dr. Xi on June 21, 2011 15:54:00    Last update: June 22, 2011 11:33:09
Demo code for CSV parsing with SuperCSV parser . Java code: import java.io.*; import java.util.List; imp... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... The parser messed up on all three lines: Line 1 has 5 values: |psmith01 abc| |CLASS... Using two lines input: "psmith01 abc", "CLASS2B " , " Peter... It generates an exception: Line 1 has 5 values: |psmith01 abc| |CLASS... Add a new line in item two: "One", "Two ", "Three" Result: Line 2 has 3 values: |One| |Two | |...
Created by Dr. Xi on June 22, 2011 07:12:02    Last update: June 22, 2011 11:32:02
Demo code for CSV parsing with OstermillerUtils . Java code: import java.io.*; import java.util.List; imp... Test with a simple CSV file: psmith01,CLASS2B,Peter Smith 1,YEAR2,1,N,ADVANCED,... The parser worked correctly: Line 1 has 11 values: |psmith01| |CLASS2B|... Test with a more complicated CSV file: "psmith01 abc", "CLASS2B " , " Peter... The parser messed up on all three lines: Line 1 has 6 values: |psmith01 abc| | "CLA... Putting a space before the first quote: "Smith, Jack","210-345-8888" It dismissed the quotes: Line 1 has 3 values: | "Smith| | Jack"| ... Add a new line in item two: "One", "Two ", "Three" Result: Line 1 has 2 values: |One| | "Two| ...
Created by alfa on June 07, 2011 11:34:26    Last update: June 07, 2011 11:36:37
This is an example that uses dynamic proxies to trace method calls (in logging) and print out elapsed times for them. Because dynamic proxies can only be generated for interfaces, the service classes must be implemented with interface-implementation pairs. Create services A and B. A.java : public interface A { public void service1()... AImpl.java : import java.util.Random; public class AImpl... B.java : public interface B { public void service1()... BImpl.java : public class BImpl implements B { public vo... The call trace proxy: import java.lang.reflect.*; class TraceProx... The performance proxy: import java.lang.reflect.*; class Performan... The service factory: import java.lang.reflect.*; public class Se... The test class: public class Test { public static void main... The output: Entering AImpl.service1 Entering BImpl.service1... The above example has no information...
Created by alfa on June 03, 2011 12:36:14    Last update: June 03, 2011 12:36:14
Thread local storage is typically used to associate state with a thread (e.g., a user ID or Transaction ID). This example, coming from Java API doc , assigns a unique id to each thread that calls getCurrentThreadId() . The actual usage is demonstrated with the Java concurrency package. import java.util.concurrent.Future; import java...
Created by alfa on May 27, 2011 11:19:29    Last update: May 31, 2011 07:56:26
This is a utility to convert a string value to one of the primitive type values. It is useful in Java reflection code where the value comes in as a string (e.g., from XML parsing), and the type of the value cannot be decided until runtime. import java.util.*; import java.lang.reflect.*;... Note: This method can be extended to convert string to more complex types by writing a converter for the destination type. For example, to convert string to date: public class DateConverter { public static ... Usage: Date d = (Date) ConvertUtil.convert("10/12/2010", ...
Created by Dr. Xi on October 26, 2010 16:07:40    Last update: October 26, 2010 16:07:40
This is a more generic version, which can be expanded to accommodate additional file signatures. import java.io.*; import java.util.*; pu...
Created by Dr. Xi on July 29, 2010 18:46:57    Last update: July 29, 2010 18:48:15
This is an example of using java.beans.XMLEncoder and java.beans.XMLDecoder to serialize/deserialize Java objects to XML. Java code TestXMLEncoder.java: import java.io.*; import java.beans.XMLEncoder;... SimpleBean.java: public class SimpleBean { private String na... CompositeBean.java: public class CompositeBean { private Simple... NotABean.java: public class NotABean { private String name... Test Output By default, only Java beans can be serialized using XMLEncoder . Exception occurs when you try to deserialize an object which is not a Java bean. Errors actually occur when you try to serialize, but they are ignored. As a result, an XML file is generated by the serialization but the file is useless! Console output: C:\>java TestXMLEncoder Testing simple bean ... simplebean.xml: <?xml version="1.0" encoding="UTF-8"?> <java v... compositebean.xml: <?xml version="1.0" encoding="UTF-8"?> <java v... nodefault.xml: <?xml version="1.0" encoding="UTF-8"?> <java v......