org.apache.struts2.dispatcher.ChartResult Maven / Gradle / Ivy
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*
* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* KIND, either express or implied. See the License for the
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*/
package org.apache.struts2.dispatcher;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import org.apache.struts2.result.StrutsResultSupport;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import java.io.OutputStream;
import javax.servlet.http.HttpServletResponse;
/**
*
*
* A custom Result type for chart data. Built on top of
* JFreeChart. When executed
* this Result will write the given chart as a PNG or JPG to the servlet output stream.
*
*
*
* This result type takes the following parameters:
*
*
*
*
*
* - value - the name of the JFreeChart object on the ValueStack, defaults to 'chart'.
*
* - type - the render type for this chart. Can be jpg (or jpeg) or png. Defaults to png.
*
* - width (required) - the width (in pixels) of the rendered chart.
*
* - height (required) - the height (in pixels) of the rendered chart.
*
*
*
*
* 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>
*
*
*/
public class ChartResult extends StrutsResultSupport {
private final static Logger LOG = LogManager.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;
}
}
}
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