JasperReport+Servlet Web施用之：打印预览

打印预览与打印的准备工作是一样的，第一，二，三，四，五步请参照：JasperReport+Servlet Web应用之：打印?

不同之处在于：我们同样要写一个预览的applet如下：

import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.URL;

import javax.swing.JOptionPane;

import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.JasperPrintManager;
import net.sf.jasperreports.engine.util.JRLoader;

public class JRViewApplet extends javax.swing.JApplet {
	private URL url = null;

	private JasperPrint jasperPrint = null;

	public JRViewApplet() {

	}

	public void init() {
		String strUrl = getParameter("REPORT_URL");
		if (strUrl != null) {
			try {
				url = new URL(getCodeBase(), strUrl);
			} catch (Exception e) {
				StringWriter swriter = new StringWriter();
				PrintWriter pwriter = new PrintWriter(swriter);
				e.printStackTrace(pwriter);
				JOptionPane.showMessageDialog(this, swriter.toString());
			}
		} else {
			JOptionPane.showMessageDialog(this, "Source URL not specified");
		}
	}

	@Override
	public void start() {
		// initComponents();
		if (url != null) {
			try {
				if (jasperPrint == null) {
					jasperPrint = (JasperPrint) JRLoader.loadObject(url);
				}
				if (jasperPrint != null) {
					ViewerFrame viewerFrame = new ViewerFrame(this
							.getAppletContext(), jasperPrint);
					viewerFrame.show();
				} else {
					JOptionPane.showMessageDialog(this, "空报表！");
				}
			} catch (Exception e) {
				StringWriter swriter = new StringWriter();
				PrintWriter pwriter = new PrintWriter(swriter);
				e.printStackTrace(pwriter);
				JOptionPane.showMessageDialog(this, swriter.toString());
			}
		} else {
			JOptionPane.showMessageDialog(this, "Source URL not specified");
		}
	}

	private void initComponents() {
		pnlMain = new javax.swing.JPanel();
		btnPrint = new javax.swing.JButton();
		btnView = new javax.swing.JButton();

		// btnPrint.setText("打印报表");
		// btnPrint.addActionListener(new java.awt.event.ActionListener() {
		// public void actionPerformed(java.awt.event.ActionEvent evt) {
		// btnPrintActionPerformed(evt);
		// }
		// });

		// pnlMain.add(btnPrint);

		btnView.setText("预览报表");
		btnView.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				btnViewActionPerformed(evt);
			}
		});

		pnlMain.add(btnView);

		getContentPane().add(pnlMain, java.awt.BorderLayout.WEST);

	}

	/**
	 * 预览报表
	 * 
	 * @param evt
	 */
	protected void btnViewActionPerformed(java.awt.event.ActionEvent evt) {
		if (url != null) {
			try {
				if (jasperPrint == null) {
					jasperPrint = (JasperPrint) JRLoader.loadObject(url);
				}
				if (jasperPrint != null) {
					ViewerFrame viewerFrame = new ViewerFrame(this
							.getAppletContext(), jasperPrint);
					viewerFrame.show();
				} else {
					JOptionPane.showMessageDialog(this, "空报表！");
				}
			} catch (Exception e) {
				StringWriter swriter = new StringWriter();
				PrintWriter pwriter = new PrintWriter(swriter);
				e.printStackTrace(pwriter);
				JOptionPane.showMessageDialog(this, swriter.toString());
			}
		} else {
			JOptionPane.showMessageDialog(this, "Source URL not specified");
		}
	}

	/**
	 * 打印报表
	 * 
	 * @param evt
	 */
	protected void btnPrintActionPerformed(java.awt.event.ActionEvent evt) {
		if (url != null) {
			if (jasperPrint == null) {
				try {
					jasperPrint = (JasperPrint) JRLoader.loadObject(url);
				} catch (Exception e) {
					StringWriter swriter = new StringWriter();
					PrintWriter pwriter = new PrintWriter(swriter);
					e.printStackTrace(pwriter);
					JOptionPane.showMessageDialog(this, swriter.toString());
				}
			}
			if (jasperPrint != null) {
				final JasperPrint print = jasperPrint;

				Thread thread = new Thread(new Runnable() {
					public void run() {
						try {
							JasperPrintManager.printReport(print, true);
						} catch (Exception e) {
							StringWriter swriter = new StringWriter();
							PrintWriter pwriter = new PrintWriter(swriter);
							e.printStackTrace(pwriter);
							JOptionPane.showMessageDialog(null, swriter
									.toString());
						}
					}
				});

				thread.start();
			} else {
				JOptionPane.showMessageDialog(this, "空报表！");
			}
		} else {
			JOptionPane.showMessageDialog(this, "Source URL not specified");
		}
	}

	private javax.swing.JPanel pnlMain;

	private javax.swing.JButton btnView;

	private javax.swing.JButton btnPrint;

}

?它还需要两个辅助类：如下：

public class JRViewerPlus extends JRViewer {

	protected JButton btnPlus = new javax.swing.JButton();

	public JRViewerPlus(JasperPrint jrPrint) throws JRException {
		super(jrPrint);

		tlbToolBar.remove(btnSave);
		tlbToolBar.remove(btnReload);

		btnPlus = new javax.swing.JButton();
		btnPlus.setToolTipText("Plus...");
		btnPlus.setText("Plus...");
		btnPlus.setPreferredSize(new java.awt.Dimension(80, 23));
		btnPlus.setMaximumSize(new java.awt.Dimension(80, 23));
		btnPlus.setMinimumSize(new java.awt.Dimension(80, 23));
		btnPlus.addActionListener(new java.awt.event.ActionListener() {
			public void actionPerformed(java.awt.event.ActionEvent evt) {
				btnPlusActionPerformed(evt);
			}
		});
		tlbToolBar.add(btnPlus, 0);
	}

	protected void setZooms() {
		this.zooms = new int[] { 33, 66, 100, 133, 166, 200, 233 };
		this.defaultZoomIndex = 2;
	}

	protected void btnPlusActionPerformed(java.awt.event.ActionEvent evt) {
		JOptionPane
				.showMessageDialog(
						this,
						"I just wanted to let you know that you can extend the JRViewer to customize it.\n The button you have pushed was added this way.");
	}

}

?

public class ViewerFrame extends javax.swing.JFrame implements
		JRHyperlinkListener {
	private AppletContext appletContext = null;

	public ViewerFrame(AppletContext appletContext, JasperPrint jasperPrint)
			throws JRException {
		initComponents();

		this.appletContext = appletContext;

		JRViewerPlus viewer = new JRViewerPlus(jasperPrint);
		viewer.addHyperlinkListener(this);
		this.pnlMain.add(viewer, BorderLayout.CENTER);
	}
	public void gotoHyperlink(JRPrintHyperlink hyperlink) {
		switch (hyperlink.getHyperlinkType()) {
		case JRHyperlink.HYPERLINK_TYPE_REFERENCE: {
			try {
				this.appletContext.showDocument(new URL(hyperlink
						.getHyperlinkReference()), "_blank");
			} catch (MalformedURLException e) {
				JOptionPane.showMessageDialog(this, e.getMessage());
			}
			break;
		}
		case JRHyperlink.HYPERLINK_TYPE_LOCAL_ANCHOR:
		case JRHyperlink.HYPERLINK_TYPE_LOCAL_PAGE: {
			break;
		}
		case JRHyperlink.HYPERLINK_TYPE_REMOTE_ANCHOR:
		case JRHyperlink.HYPERLINK_TYPE_REMOTE_PAGE: {
			JOptionPane
					.showMessageDialog(this,
							"Implement your own JRHyperlinkListener to manage this type of event.");
			break;
		}
		case JRHyperlink.HYPERLINK_TYPE_NONE:
		default: {
			break;
		}
		}
	}

	private void initComponents() {
		pnlMain = new javax.swing.JPanel();

		setTitle("JasperViewer");
		setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
		pnlMain.setLayout(new java.awt.BorderLayout());

		getContentPane().add(pnlMain, java.awt.BorderLayout.CENTER);

		pack();
		java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit()
				.getScreenSize();
		setSize(new java.awt.Dimension(400, 300));
		setLocation((screenSize.width - 400) / 2, (screenSize.height - 300) / 2);
	}

	private javax.swing.JPanel pnlMain;

}

?

说明：这三个类可以在jasperReport自带的demo中获得，只需做小小的改动就可以了。

?

同样还需要这三个类的编译后的class文件放到WebRoot/applet下面。将jasperreports-3.5.2-applet.jar,commons-logging-1.0.2.jar,commons-collections-2.1.jar三个包加进去。该applet所需要调用的servlet和servlet配置请见：http://zmx.iteye.com/admin/blogs/572812

?

页面调用的applet写法或js动态产生applet如下：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
	<head>
		<title>打印窗口</title>
	</head>
	<script language="javascript"> 
	<!-- 
		function openView() 
		{ 
			var url = "../JRPrintServlet"; 
			document.write('<APPLET ID="JrPrt" CODE = "JRViewApplet.class" CODEBASE = "applets" ARCHIVE = "jasperreports-3.5.2-applet.jar,commons-logging-1.0.2.jar,commons-collections-2.1.jar" WIDTH = "0" HEIGHT = "0">'); 
			document.write('<PARAM NAME = "type" VALUE="application/x-java-applet;version=1.2.2">'); 
			document.write('<PARAM NAME = "scriptable" VALUE="false">'); 
			document.write('<PARAM NAME = "REPORT_URL" VALUE ="'+url+'">'); 
			document.write('</APPLET>'); 
		}
		--> 
	</script>
	<body bgcolor="#FFFFFF">
		<input type="button" value="测试预览" onclick="openView();">
		<!-- 
		 <APPLET CODE="JRViewApplet.class" CODEBASE = "applets"
			ARCHIVE = "jasperreports-3.5.2-applet.jar,commons-logging-1.0.2.jar,commons-collections-2.1.jar"
			WIDTH="300" HEIGHT="40">
			</XMP>
			<PARAM NAME=CODE VALUE="JRViewApplet.class">
			<PARAM NAME = ARCHIVE VALUE = "jasperreports-3.5.2-applet.jar,commons-logging-1.0.2.jar,commons-collections-2.1.jar" >
			<PARAM NAME="type" VALUE="application/x-java-applet;version=1.2.2">
			<PARAM NAME="scriptable" VALUE="false">
			<PARAM NAME="REPORT_URL" VALUE="../JRPrintServlet">
		</APPLET>
		  -->
	</body>
</html>

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