Struts example source code file (ChartResult.java)

This example Struts source code file (ChartResult.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

actioninvocation, chartresult, default_type, default_value, exception, http, integer, io, jfreechart, jfreechart, no, no, nullpointerexception, nullpointerexception, request, response, servlet, string, string

The Struts ChartResult.java source code

/*
 * $Id: ChartResult.java 817318 2009-09-21 16:55:09Z musachy $
 *
 * 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.dispatcher;

import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;

import java.io.OutputStream;

import javax.servlet.http.HttpServletResponse;

/**
 * <!-- START SNIPPET: description -->
 * <p/>
 * A custom Result type for chart data. Built on top of
 * <a href="http://www.jfree.org/jfreechart/" target="_blank">JFreeChart. When executed
 * this Result will write the given chart as a PNG or JPG to the servlet output stream.
 * <p/>
 * <!-- END SNIPPET: description -->
 * <p/>
 * <b>This result type takes the following parameters:
 * <p/>
 * <!-- START SNIPPET: params -->
 * <p/>
 * <ul>
 * <p/>
 * <li>value - the name of the JFreeChart object on the ValueStack, defaults to 'chart'.
 * <p/>
 * <li>type - the render type for this chart. Can be jpg (or jpeg) or png. Defaults to png.
 * <p/>
 * <li>width (required) - the width (in pixels) of the rendered chart.
 * <p/>
 * <li>height (required) - the height (in pixels) of the rendered chart.
 * <p/>
 * </ul>
 * <!-- END SNIPPET: params -->
 * <p/>
 * <b>Example:
 * <p/>
 * <pre>
 * public class ExampleChartAction extends ActionSupport {
 *
 *	    private JFreeChart chart;
 *
 *	    public String execute() throws Exception {
 *		    // chart creation logic...
 *		    XYSeries dataSeries = new XYSeries(new Integer(1)); // pass a key for this serie
 *		    for (int i = 0; i <= 100; i++) {
 *			    dataSeries.add(i, RandomUtils.nextInt());
 *		    }
 *		    XYSeriesCollection xyDataset = new XYSeriesCollection(dataSeries);
 *
 *		    ValueAxis xAxis = new NumberAxis("Raw Marks");
 *		    ValueAxis yAxis = new NumberAxis("Moderated Marks");
 *
 *		    // set my chart variable
 *		    chart =
 *			    new JFreeChart( "Moderation Function", JFreeChart.DEFAULT_TITLE_FONT,
 *				    new XYPlot( xyDataset, xAxis, yAxis, new StandardXYItemRenderer(StandardXYItemRenderer.LINES)),
 *				    false);
 *		    chart.setBackgroundPaint(java.awt.Color.white);
 *
 *		    return SUCCESS;
 *	    }
 * 
 *      // this method will get called if we specify <param name="value">chart</param>
 *	    public JFreeChart getChart() {
 *		    return chart;
 *	    }
 *  }
 *
 * <result name="success" type="chart">
 *   <param name="value">chart</param>
 *   <param name="type">png</param>
 *   <param name="width">640</param>
 *   <param name="height">480</param>
 * </result>
 * <!-- END SNIPPET: example -->

*/ public class ChartResult extends StrutsResultSupport { private final static Logger LOG = LoggerFactory.getLogger(ChartResult.class); private static final long serialVersionUID = -6484761870055986612L; private static final String DEFAULT_TYPE = "png"; private static final String DEFAULT_VALUE = "chart"; private JFreeChart chart; // the JFreeChart to render private boolean chartSet; String height, width; String type = DEFAULT_TYPE; // supported are jpg, jpeg or png, defaults to png String value = DEFAULT_VALUE; // defaults to 'chart' // CONSTRUCTORS ---------------------------- public ChartResult() { super(); } public ChartResult(JFreeChart chart, String height, String width) { this.chart = chart; this.height = height; this.width = width; } // ACCESSORS ---------------------------- public String getHeight() { return height; } public void setHeight(String height) { this.height = height; } public String getWidth() { return width; } public void setWidth(String width) { this.width = width; } public String getType() { return type; } public void setType(String type) { this.type = type; } public String getValue() { return value; } public void setValue(String value) { this.value = value; } public JFreeChart getChart() { return chart; } public void setChart(JFreeChart chart) { this.chartSet = true; this.chart = chart; } // OTHER METHODS ----------------------- // Required by com.opensymphony.xwork2.Result /** * Executes the result. Writes the given chart as a PNG or JPG to the servlet output stream. * * @param invocation an encapsulation of the action execution state. * @throws Exception if an error occurs when creating or writing the chart to the servlet output stream. */ public void doExecute(String finalLocation, ActionInvocation invocation) throws Exception { initializeProperties(invocation); if (!chartSet) // if our chart hasn't been set (by the testcase), we'll look it up in the value stack chart = (JFreeChart) invocation.getStack().findValue(value, JFreeChart.class); if (chart == null) // we need to have a chart object - if not, blow up throw new NullPointerException("No JFreeChart object found on the stack with name " + value); // make sure we have some value for the width and height if (height == null) throw new NullPointerException("No height parameter was given."); if (width == null) throw new NullPointerException("No width parameter was given."); // get a reference to the servlet output stream to write our chart image to HttpServletResponse response = ServletActionContext.getResponse(); OutputStream os = response.getOutputStream(); try { // check the type to see what kind of output we have to produce if ("png".equalsIgnoreCase(type)) { response.setContentType("image/png"); ChartUtilities.writeChartAsPNG(os, chart, getIntValueFromString(width), getIntValueFromString(height)); } else if ("jpg".equalsIgnoreCase(type) || "jpeg".equalsIgnoreCase(type)) { response.setContentType("image/jpg"); ChartUtilities.writeChartAsJPEG(os, chart, getIntValueFromString(width), getIntValueFromString(height)); } else throw new IllegalArgumentException(type + " is not a supported render type (only JPG and PNG are)."); } finally { if (os != null) os.flush(); } } /** * Sets up result properties, parsing etc. * * @param invocation Current invocation. * @throws Exception on initialization error. */ private void initializeProperties(ActionInvocation invocation) throws Exception { if (height != null) { height = conditionalParse(height, invocation); } if (width != null) { width = conditionalParse(width, invocation); } if (type != null) { type = conditionalParse(type, invocation); } if ( type == null) { type = DEFAULT_TYPE; } } private Integer getIntValueFromString(String value) { try { return Integer.parseInt(value); } catch (Exception e) { LOG.error("Specified value for width or height is not of type Integer...", e); return null; } } }