renderresponseimpl.java

GridSphere 门户 提供一个基于 portlet 的高级开放源代码门户。GridSphere 是在欧盟提供基金的 GridLab 项目下开发的

/*
 * @author <a href="mailto:[e-mail]">Jason Novotny</a>
 * @version $Id: RenderResponseImpl.java 4988 2006-08-04 09:57:48Z novotny $
 */
package org.gridsphere.portlet.impl;

import org.gridsphere.services.core.user.User;

import javax.portlet.PortletURL;
import javax.portlet.RenderResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;
import java.util.SortedSet;


/**
 * The <CODE>RenderResponse</CODE> defines an object to assist a portlet in
 * sending a response to the portal.
 * It extends the <CODE>PortletResponse</CODE> interface to provide specific
 * render response functionality to portlets.<br>
 * The portlet container creates a <CODE>RenderResponse</CODE> object and
 * passes it as argument to the portlet's <CODE>render</CODE> method.
 *
 * @see javax.portlet.RenderRequest
 * @see javax.portlet.PortletResponse
 */
public class RenderResponseImpl extends PortletResponseImpl implements RenderResponse {

    protected String contentType = null;  // needed as servlet 2.3 does not have a response.getContentType
    protected boolean hasWriter = false;
    protected boolean hasOutputStream = false;

    /**
     * Constructs an instance of SportletResponse using an
     * <code>HttpServletResponse</code> as a proxy
     *
     * @param req the <code>HttpServletRequest</code>
     * @param res the <code>HttpServletResponse</code>
     */
    public RenderResponseImpl(HttpServletRequest req, HttpServletResponse res) {
        super(req, res);
    }

    // Jakarta Pluto method
    private String stripCharacterEncoding(String type) {
        int xs = type.indexOf(';');
        String strippedType;
        if (xs == -1) {
            strippedType = type;
        } else {
            strippedType = type.substring(0, xs);
        }
        return strippedType.trim();
    }

    /**
     * Returns the MIME type that can be used to contribute
     * markup to the render response.
     * <p/>
     * If no content type was set previously using the {@link #setContentType} method
     * this method retuns <code>null</code>.
     *
     * @return the MIME type of the response, or <code>null</code>
     *         if no content type is set
     * @see #setContentType
     */
    public String getContentType() {
        // in servlet 2.4 we could simply use this:
        // return this._getHttpServletResponse().getContentType();
        return contentType;
    }


    /**
     * Creates a portlet URL targeting the portlet. If no portlet mode,
     * window state or security modifier is set in the PortletURL the
     * current values are preserved. If a request is triggered by the
     * PortletURL, it results in a render request.
     * <p/>
     * The returned URL can be further extended by adding
     * portlet-specific parameters and portlet modes and window states.
     * <p/>
     * The created URL will per default not contain any parameters
     * of the current render request.
     *
     * @return a portlet render URL
     */
    public PortletURL createRenderURL() {
        PortletURLImpl portletURL = new PortletURLImpl(req, (HttpServletResponse) this.getHttpServletResponse(), true);
        portletURL.setRender("");
        return portletURL;
    }

    /**
     * Creates a portlet URL targeting the portlet. If no portlet mode,
     * window state or security modifier is set in the PortletURL the
     * current values are preserved. If a request is triggered by the
     * PortletURL, it results in an action request.
     * <p/>
     * The returned URL can be further extended by adding
     * portlet-specific parameters and portlet modes and window states.
     * <p/>
     * The created URL will per default not contain any parameters
     * of the current render request.
     *
     * @return a portlet action URL
     */
    public PortletURL createActionURL() {
        PortletURLImpl portletURL = new PortletURLImpl(req, this.getHttpServletResponse(), false);
        portletURL.setAction("");
        return portletURL;
    }

    /**
     * The value returned by this method should be prefixed or appended to
     * elements, such as JavaScript variables or function names, to ensure
     * they are unique in the context of the portal page.
     *
     * @return the namespace
     */
    public String getNamespace() {
        // this is done due to an issue with MyFaces using getNamespace
        String pid = ((String) req.getAttribute(SportletProperties.PORTLETID)).replace('#', '_');
        return "gridsphere_" + pid + "_" + (String) req.getAttribute(SportletProperties.COMPONENT_ID);
    }

    /**
     * This method sets the title of the portlet.
     * <p/>
     * The value can be a text String
     *
     * @param title portlet title as text String or resource URI
     */
    public void setTitle(String title) {
        if (title == null) title = "Unknown portlet title";
        req.setAttribute(SportletProperties.PORTLET_TITLE, title);
    }

    /**
     * Sets the MIME type for the render response. The portlet must
     * set the content type before calling {@link #getWriter} or
     * {@link #getPortletOutputStream}.
     * <p/>
     * Calling <code>setContentType</code> after <code>getWriter</code>
     * or <code>getOutputStream</code> does not change the content type.
     *
     * @param type the content MIME type
     * @throws java.lang.IllegalArgumentException
     *          if the given type is not in the list returned
     *          by <code>PortletRequest.getResponseContentTypes</code>
     * @see javax.portlet.RenderRequest#getResponseContentTypes
     * @see #getContentType
     */
    public void setContentType(String type) {
        if (type == null) throw new IllegalArgumentException("supplied MIME type is null!");
        String mimeType = stripCharacterEncoding(type);
        SortedSet<String> types = (SortedSet<String>) req.getAttribute(SportletProperties.PORTLET_MIMETYPES);
        if (types != null) {
            if (!types.contains(type)) throw new IllegalArgumentException("Unsupported portlet mimeType: " + type);
        }
        this.getHttpServletResponse().setContentType(mimeType);
        this.contentType = mimeType;
    }


    /**
     * Returns the name of the charset used for
     * the MIME body sent in this response.
     * <p/>
     * <p>See <a href="http://ds.internic.net/rfc/rfc2045.txt">RFC 2047</a>
     * for more information about character encoding and MIME.
     *
     * @return a <code>String</code> specifying the
     * name of the charset, for
     * example, <code>ISO-8859-1</code>
     */
    public String getCharacterEncoding() {
        return this.getHttpServletResponse().getCharacterEncoding();
    }


    /**
     * Returns a PrintWriter object that can send character
     * text to the portal.
     * <p/>
     * Before calling this method the content type of the
     * render response must be set using the {@link #setContentType}
     * method.
     * <p/>
     * Either this method or {@link #getPortletOutputStream} may be
     * called to write the body, not both.
     *
     * @return a <code>PrintWriter</code> object that
     *         can return character data to the portal
     * @throws java.io.IOException if an input or output exception occurred
     * @throws java.lang.IllegalStateException
     *                             if the <code>getPortletOutputStream</code> method
     *                             has been called on this response,
     *                             or if no content type was set using the
     *                             <code>setContentType</code> method.
     * @see #setContentType
     * @see #getPortletOutputStream
     */
    public java.io.PrintWriter getWriter() throws java.io.IOException {
        if ((contentType == null) || (hasOutputStream))
            throw new IllegalStateException("A writer has already been obtained or the content type has not been set!");
        hasWriter = true;
        return this.getHttpServletResponse().getWriter();
    }


    /**
     * Returns the locale assigned to the response.
     *
     * @return Locale of this response
     */
    public java.util.Locale getLocale() {
        Locale locale = (Locale) this.req.getSession(true).getAttribute(User.LOCALE);
        if (locale != null) return locale;
        locale = this.req.getLocale();
        if (locale != null) return locale;
        return Locale.ENGLISH;
    }


    /**
     * Sets the preferred buffer size for the body of the response.
     * The portlet container will use a buffer at least as large as
     * the size requested.
     * <p/>
     * This method must be called before any response body content is
     * written; if content has been written, or the portlet container
     * does not support buffering, this method may throw an
     * <code>IllegalStateException</code>.
     *
     * @param size the preferred buffer size
     * @throws java.lang.IllegalStateException
     *          if this method is called after
     *          content has been written, or the
     *          portlet container does not support buffering
     * @see #getBufferSize
     * @see #flushBuffer
     * @see #isCommitted
     * @see #reset
     */
    public void setBufferSize(int size) {
        throw new IllegalStateException("portlet container does not support buffering");
    }


    /**
     * Returns the actual buffer size used for the response.  If no buffering
     * is used, this method returns 0.
     *
     * @return the actual buffer size used
     * @see #setBufferSize
     * @see #flushBuffer
     * @see #isCommitted
     * @see #reset
     */
    public int getBufferSize() {
        return 0;
    }


    /**
     * Forces any content in the buffer to be written to the client.  A call
     * to this method automatically commits the response.
     *
     * @throws java.io.IOException if an error occured when writing the output
     * @see #setBufferSize
     * @see #getBufferSize
     * @see #isCommitted
     * @see #reset
     */
    public void flushBuffer() throws java.io.IOException {
        this.getHttpServletResponse().flushBuffer();
    }


    /**
     * Clears the content of the underlying buffer in the response without
     * clearing properties set. If the response has been committed,
     * this method throws an <code>IllegalStateException</code>.
     *
     * @throws java.lang.IllegalStateException
     *          if this method is called after
     *          response is comitted
     * @see #setBufferSize
     * @see #getBufferSize
     * @see #isCommitted
     * @see #reset
     */
    public void resetBuffer() {
        this.getHttpServletResponse().resetBuffer();
    }

    /**
     * Returns a boolean indicating if the response has been
     * committed.
     *
     * @return a boolean indicating if the response has been
     * committed
     * @see #setBufferSize
     * @see #getBufferSize
     * @see #flushBuffer
     * @see #reset
     */
    public boolean isCommitted() {
        return this.getHttpServletResponse().isCommitted();
    }


    /**
     * Clears any data that exists in the buffer as well as the properties set.
     * If the response has been committed, this method throws an
     * <code>IllegalStateException</code>.
     *
     * @throws java.lang.IllegalStateException
     *          if the response has already been
     *          committed
     * @see #setBufferSize
     * @see #getBufferSize
     * @see #flushBuffer
     * @see #isCommitted
     */
    public void reset() {
        this.getHttpServletResponse().reset();
    }


    /**
     * Returns a <code>OutputStream</code> suitable for writing binary
     * data in the response. The portlet container does not encode the
     * binary data.
     * <p/>
     * Before calling this method the content type of the
     * render response must be set using the {@link #setContentType}
     * method.
     * <p/>
     * Calling <code>flush()</code> on the OutputStream commits the response.
     * <p/>
     * Either this method or {@link #getWriter} may be called to write the body, not both.
     *
     * @throws java.lang.IllegalStateException
     *                             if the <code>getWriter</code> method
     *                             has been called on this response, or
     *                             if no content type was set using the
     *                             <code>setContentType</code> method.
     * @throws java.io.IOException if an input or output exception occurred
     * @return a <code>OutputStream</code> for writing binary data
     * @see #setContentType
     * @see #getWriter
     */
    public java.io.OutputStream getPortletOutputStream() throws java.io.IOException {
        if ((contentType == null) || (hasWriter))
            throw new IllegalStateException("A writer has already been obtained or the content type has not been set!");
        hasOutputStream = true;
        return this.getHttpServletResponse().getOutputStream();
    }

}