Java tutorial
/* * $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</a>. 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:</b> * <p/> * <!-- START SNIPPET: params --> * <p/> * <ul> * <p/> * <li><b>value</b> - the name of the JFreeChart object on the ValueStack, defaults to 'chart'.</li> * <p/> * <li><b>type</b> - the render type for this chart. Can be jpg (or jpeg) or png. Defaults to png.</li> * <p/> * <li><b>width (required)</b> - the width (in pixels) of the rendered chart.</li> * <p/> * <li><b>height (required)</b> - the height (in pixels) of the rendered chart.</li> * <p/> * </ul> * <!-- END SNIPPET: params --> * <p/> * <b>Example:</b> * <p/> * <pre><!-- START SNIPPET: example --> * 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 --></pre> */ 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; } } }