STRUTS2 Custom type converter detailed

STRUTS2 type conversions are based on OGNL expressions, because the requested arguments are strings, and Java itself is a strongly typed language, which requires converting strings to other types. This is done mainly through the following 2 steps:

1. Implement your own type converter (overriding the Convertvalue method) first by implementing the Typecoverter interface or inheriting the Defaulttypeconverter implementation class (which implements the Typecoverter interface)

(1) Typecoverter interface:

    Public interfacetypeconberter{public
       Object convertvalue (Map context,object target,member member,string Propertyname,object value, Class totype)  
       {}
    }

Because the Typecoverter interface is too complex, the OGNL project also provides a class that implements the interface:defaulttypeconverter.

(2) Defaulttypeconverter interface:

    public class Usertypeconvert extends Defaulttypeconverter {
      @Override the public 
      Object Convertvalue (map< String, object> context, Object value,   Class totype) {return 
          null;
      }
    ｝

Where the context is the contexts of the type transformation environment, value is the parameter that needs to be converted, and the ToType is the converted target type.

Eg: date format conversion

Loginaction.java:

   public class Loginaction {
     private Date birthday;
     Public Date Getbirthday () {return
         birthday;
     } 
     public void Setbirthday (Date birthday) {
         this.birthday = birthday;
     } 
     Public String Execute () throws unsupportedencodingexception{return
         "Success";
      }
   }

Datetypeconvert.java:

   public class Usertypeconvert extends Defaulttypeconverter  { 
     @Override the public 
     Object Convertvalue (map< String, object> context, Object value, Class totype) 
     {
        SimpleDateFormat dateformat = new SimpleDateFormat (" YyyyMMdd "); 
        try{
            if (ToType = = Date.class) { 
               String [] datevalue = (string []) value; 
               Return Dateformat.parse (datevalue[0]); 
            else if (ToType = = String.class) { 
               Date DateValue = (date) value;
               Return Dateformat.format (DateValue); 
            } 
        catch (ParseException e) { 
            e.printstacktrace (); 
       }
       return null; 
     }
    }

2. Register the converter in a Web application so that the Struts 2 framework can use that type of converter.

There are 3 types of registration for type converters:

(1) Register the local type converter: it only works on the properties of an action.

(2) Registers a converter of the global type: valid for all action.

(3) Use JDK1.5 annotation to register the converter.

Local type converter:

Place the actionname-conversion.properties under the package of the action class that needs to take effect, where ActionName is the class name of the action that needs to be converted, followed by the-conversion.

Content: The type to be converted = The full class name of the type converter. Note: The type converter is required to add a package name, and the last can not add punctuation

Loginaction-conversion.properties:

    Birthday =convert. Usertypeconvert

Global type converter:

Place the Xwork-conversion.properties file under Web-inf/class. The file name is fixed.

Content: Types to be converted = Full class names of type converters

Xwork-conversion.properties:

    Java.util.Date = Convert. Usertypeconvert