Jakarta Struts Cookbook

9.3. Using Exception Error Codes

Problem

You want to use an exception class that accepts a logical error code or key and optional arguments that can be used to display a localized error message.

Solution

Use or extend my ErrorCodeException, shown in Example 9-6.

Example 9-6. Exception that accepts a numeric error code

package com.oreilly.strutsckbk.ch09;

public class ErrorCodeException extends Exception {
    
    public ErrorCodeException(int code) {
        this.code = code;
    }
    public ErrorCodeException(int code, Object[] args) {
        this.code = code;
        this.args = args;
    }
    public ErrorCodeException(int code, Object[] args, String msg) {
        super(msg);
        this.code = code;
        this.args = args;
    }
    public ErrorCodeException(int code, Object[] args, String msg, 
                                                  Throwable cause) {
        super(msg, cause);
        this.code = code;
        this.args = args;
    }

    public int getCode( ) {
        return code;
    }

    public Object[] getArgs( ) {
        return args;
    }
    private Object[] args;
    private int code;
}

Use my ErrorCodeExceptionHandler, shown in Example 9-7, to handle these exception types.

Example 9-7. Exception handler for the ErrorCodeException

package com.oreilly.strutsckbk.ch09; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.Globals; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; import org.apache.struts.action.ActionMessage; import org.apache.struts.action.ExceptionHandler; ...