Struts2 + jquery. Validate framework to check whether the user name exists

On the project registration page, you need to determine whether the user name exists. This method is implemented using the remote method of the jquery verification framework.

1. js script:

Jquery. validator. addmethod ("usename", function (value, element ){

Return this. Optional (element) | value. length> = 4
& Value. Length <= 12 & (// D/. Test (value) |/[A-Z]
/I. Test (value) ;}, "the user name should contain 4-12 numbers and letters ");

$ ("Form"). Validate ({

Rules :{

Username :{

Required: True,

Remote: "checkuseravailable. Action" // check whether the user name exists.

}

},

Messages :{

Username :{

Required: "Enter the user name ",

Remote: "This user name has been registered" // Div displayed on the page when false is returned in the background

}

}

});

2. Java code:

Because jquery's remote method only allows true or false to be returned, when false is returned, the message content is output: "This user name has been registered ". There are two methods to implement struts2:

(1) using the response instance of the httpservletresponse object, the Java code is as follows:

String text = "true ";

If (memberservice. findbyusername (member. GetUserName ())! = NULL ){

TEXT = "false"; // if the user name already exists, false is output.

}

Httpservletresponse response = servletactioncontext. getresponse ();

Response. setcontenttype ("text/plain; charset = UTF-8 ");

Response. getwriter (). Write (text );

Return NULL;

Struts. xml configuration: you do not need to configure the <result> output item. The disadvantage of this method is that it depends on httpservletresponse.

(2) stream return type using struts2:

Boolean cansign = true;

// Whether the user name exists in the Database

If (memberservice. findbyusername (member. GetUserName ())! = NULL ){

Cansign = false; // indicates that the API exists and false is returned.

}

Inputstream = new bytearrayinputstream (cansign. tostring (). getbytes (); // convert true or false to a stream and provide the getter Method for inputstream.

Return success;

Struts. xml configuration:

<Result type = "stream">

<Param name = "contenttype"> text/plain </param>

<Param name = "inputname"> inputstream </param>

</Result>

The above contenttype cannot use the text/html type, or you do not need to configure this item. The default value is the text/plain type.