FAQ

Here are some common issues you may encountered.

How to Access Servlet Objects

All Servlet objects (ServletContext, HttpSession, HttpServletRequest, HttpServletResponse) are always available because they are arealy bind to ThreadLocal and can be retrieved using following code:

ActionContext ctx = ActionContext.getActionContext();
ServletContext servletContext = ctx.getServletContext();
HttpSession httpSession = ctx.getHttpSession();
HttpServletRequest httpServletRequest = ctx.getHttpServletRequest();
HttpServletResponse httpServletResponse = ctx.getHttpServletResponse();

How to Set Character Encoding

WebWind always uses UTF-8 as default character encoding if possible, which supports international applications.

If you want to specify another character encoding, use TextRenderer:

@Mapping("/hello")
public Renderer hello() {
    return new TextRenderer("<h1>Hello, world</h1>", "iso-8859-1");
}

If you use JSP, the character encoding is set in your JSP file:

<%@page contentType="text/html;charset=UTF-8" %>

Please note that the default character encoding of JSP is ISO-8859-1 according to the JSP standards.

If you use Velocity, the character encoding is specified in /WEB-INF/velocity.properties:

# the velocity template file encoding:
input.encoding=UTF-8

# the output encoding:
output.encoding=UTF-8

If the encoding is not specified, WebWind will automatically use UTF-8 for both input.encoding and output.encoding.

How to Generate Dynamic Text Content

The TextRenderer can be used to output any text:

@Mapping("/hello/$1")
public Renderer alert(String name) {
    TextRenderer renderer = new TextRenderer("hello, " + name + "!");
    renderer.setContentType("text/plain");
    return renderer;
}

If you want to send text as JavaScript, use JavaScriptRender which set the content type as 'application/x-javascript' automatically.

How to Generate Dynamic Binary Content

If you want to output dynamic binary file such as PDF, JPG, etc., you can use BinaryRender:

@Mapping("/download/pdf")
public Renderer download() {
    byte[] data = generateBinaryContent(); // build your binary content here
    BinaryRenderer renderer = new BinaryRenderer(data);
    renderer.setContentType("application/pdf");
    return renderer;
}

If you do not specify the content type, WebWind will use the default MIME type application/octet-stream for binary file.

How to Send a Redirect

You do not need to operate HttpServletResponse object. Just return a String starts with 'redirect:':

@Mapping("/redirect")
public String redirect() {
    return "redirect:/index.jsp";
}

How to Inject a ServletContext Object

If you use Guice as IoC container, you may want to inject the ServletContext for some reason:

public class MyClass {
    @Inject ServletContext servlectContext;
}

You can get the ServletContext instance in your module. If the module class implements the org.expressme.wind.guice.ServletContextAware interface, WebWind will call setServletContext(ServletContext) to pass the ServletContext instance:

public class MyModule implements Module, org.expressme.wind.guice.ServletContextAware {

    private ServletContext servletContext;

    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
    }

    public void configure(Binder binder) {
        // bind the ServletContext:
        binder.bind(ServletContext.class).toInstance(this.servletContext);
        // bind others...
    }
}

If you use Spring, just implements ServletContextAware provided by Spring API:

public class MyClass implements org.springframework.web.context.ServletContextAware {

    private ServletContext servletContext;

    public void setServletContext(ServletContext servletContext) {
        this.servletContext = servletContext;
    }
}

Keep Updating

Please leave a comment if you have more questions.