Struts example source code file (File.java)

This example Struts source code file (File.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

file, file, form, form, html, html, http, request, response, servlet, string, string, struts, strutstagattribute, template, this, ui, uibean

The Struts File.java source code

/*
 * $Id: File.java 651946 2008-04-27 13:41:38Z apetrelli $
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.struts2.components;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.views.annotations.StrutsTag;
import org.apache.struts2.views.annotations.StrutsTagAttribute;

import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

/**
 * <!-- START SNIPPET: javadoc -->
 * Renders an HTML file input element.
 * <!-- END SNIPPET: javadoc -->
 *
 * <p/> Examples
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * <s:file name="anUploadFile" accept="text/*" />
 * <s:file name="anohterUploadFIle" accept="text/html,text/plain" />
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 */
@StrutsTag(
    name="file",
    tldTagClass="org.apache.struts2.views.jsp.ui.FileTag",
    description="Render a file input field",
    allowDynamicAttributes=true)
public class File extends UIBean {
    private final static Logger LOG = LoggerFactory.getLogger(File.class);

    final public static String TEMPLATE = "file";

    protected String accept;
    protected String size;

    public File(ValueStack stack, HttpServletRequest request, HttpServletResponse response) {
        super(stack, request, response);
    }

    protected String getDefaultTemplate() {
        return TEMPLATE;
    }

    public void evaluateParams() {
        super.evaluateParams();

        Form form = (Form) findAncestor(Form.class);
        if (form != null) {
            String encType = (String) form.getParameters().get("enctype");
            if (!"multipart/form-data".equals(encType)) {
                // uh oh, this isn't good! Let's warn the developer
                LOG.warn("Struts has detected a file upload UI tag (s:file) being used without a form set to enctype 'multipart/form-data'. This is probably an error!");
            }

            String method = (String) form.getParameters().get("method");
            if (!"post".equalsIgnoreCase(method)) {
                // uh oh, this isn't good! Let's warn the developer
                LOG.warn("Struts has detected a file upload UI tag (s:file) being used without a form set to method 'POST'. This is probably an error!");
            }
        }

        if (accept != null) {
            addParameter("accept", findString(accept));
        }

        if (size != null) {
            addParameter("size", findString(size));
        }
    }

    @StrutsTagAttribute(description="HTML accept attribute to indicate accepted file mimetypes")
    public void setAccept(String accept) {
        this.accept = accept;
    }

    @StrutsTagAttribute(description="HTML size attribute", required=false, type="Integer")
    public void setSize(String size) {
        this.size = size;
    }
}