Skip to main content

Spring Framework Annotation- Part 1

To make the annotation work, you need to

<context:component-scan
base-package="com.xxx.bar">
</context:component-scan>

The <context:component-scan> element
does everything that <context:annotation-config> does, plus it configures
Spring to automatically discover beans and declare them for you. What this means is
that most (or all) of the beans in your Spring application can be declared and wired
without using <bean>.




Spring's very own annotation:
@Autowired
@Qualifier
@Value

The @Inject annotation from JSR-000330 Dependency Injection for Java 


The @Resource annotation from JSR-000250 Common Annotations for the Java(tm) Platform ("Specification") : The Resource annotation is used to declare a reference to a resource. It can be specified on a class, methods or on fields. When the annotation is applied on a field or method, the container will inject an instance of the requested resource into the application when the application is initialized. If the annotation is applied to a class, the annotation declares a resource that the application will look up at runtime.


  • Usage of @Autowired



Accessor

@Autowired
public voidsetInstrument(Instrument instrument){
this.instrument=instrument;
}
Now you can get rid of the <property> element that wires the Instrumentalist with
an instrument

 Method 

@Autowired
public void heresYourInstrument(Instrument instrument){
      this.instrument=instrument;
}

 Constructor

@Autowired
public Instrumentalist(Instrument instrument){
this.instrument=instrument;
}
Properties
@Autowired
private Instrument instrument;

you can directly annotate properties and do away with the setter
methods altogether;

@Autowired(required=false)
private Instrument instrument;
Here, Spring will try to wire the instrument property. But if no bean of type
Instrument can be found, then no problem. The property will be left null.

  • Usage of @Qualifier
@Autowired
@Qualifier("guitar")
private Instrument instrument;
As shown here, the @Qualifier annotation will try to wire in a bean whose ID matches
guitar. It’s important to know that @Qualifier is really about narrowing the selection of autowire candidate beans.

  • Usage of @Value
@Value("Eruption")
private String song;
Here we’re wiring a String value into a String property

  • Usage of @Inject
@Inject
private Instrument instrument;
Just like @Autowired, @Inject can be used to autowire properties, methods, and con-
structors. Unlike @Autowired, @Inject doesn’t have a required attribute. Therefore,
@Inject-annotated dependencies are expected to be fulfilled, failing with an excep-
tion if they’re not.

  • QUALIFYING @INJECTED PROPERTIES
@Inject
@Named("guitar")
private Instrumentinstrument;
The key difference between Spring’s @Qualifier and JSR-330’s @Named is one of
semantics.




Comments

Popular posts from this blog

Stretch a row if data overflows in jasper reports

It is very common that some columns of the report need to stretch to show all the content in that column. But  if you just specify the property " stretch with overflow' to that column(we called text field in jasper report world) , it will just stretch that column and won't change other columns, so the row could be ridiculous. Haven't find the solution from internet yet. So I just review the properties in iReport one by one and find two useful properties(the bold highlighted in example below) which resolve the problems.   example:
<band height="20" splitType="Stretch"> <textField isStretchWithOverflow="true" pattern="" isBlankWhenNull="true"> <reportElement stretchType="RelativeToTallestObject" mode="Opaque" x="192" y="0" width="183" height="20"/> <box leftPadding="2"> <pen lineWidth="0.25"/> …

JasperReports - Configuration Reference

Live - solving the jasper report out of memory and high cpu usage problems

I still can not find the solution. So I summary all the things and tell my boss about it. If any one knows the solution, please let me know.


Symptom: 1.The JVM became Out of memory when creating big consumption report 2.Those JRTemplateElement-instances is still there occupied even if I logged out the system
Reason:         1. There is a large number of JRTemplateElement-instances cached in the memory 2.The clearobjects() method in ReportThread class has not been triggered when logging out
Action I tried:      About the Virtualizer: 1.Replacing the JRSwapFileVirtualizer with JRFileVirtualizer 2.Not use any FileVirtualizer for cache the report in the hard disk Result: The japserreport still creating the a large number of JRTemplateElement-instances in the memory     About the work around below,      I tried: item 3(in below work around list) – result: it helps to reduce  the size of the JRTemplateElement Object                Item 4,5 – result : it helps a lot to reduce the number of  JRTemplateE…