Java Swing快速构建窗体应用程序

　　以前接触java感觉其在桌面开发上,总是不太方便,没有一个好的拖拽界面布局工具,可以快速构建窗体. 最近学习了一下NetBeans IDE 8.1,感觉其窗体设计工具还是很不错的 , 就尝试一下做了一个窗体应用程序. 总体下来,感觉和winform开发相差也不大,只是一些具体的设置或者语法有些差异,可以通过查阅相关资料进行掌握:

1 应用结构

新建一个java应用程序JavaApp,并创建相关的包及文件,其中简单实现了一个登录界面(JDBC 访问MYSQL数据库),登录成功后跳转到主界面.在主界面上单击菜单,可以打开子窗体.java swing自带的JTabbedPane没有显示关闭按钮的功能,这里在com.mkmis.controls包下自定义了一个TabbedPane控件,可以实现带关闭按钮的页签面板.应用结构如下图所示:

2 登陆界面设计

在IDE中新建一个Login的JFrame窗体,单击[设计]视图,可以将组件面板中的相关控件拖放到界面上,和Vistual Studio的操作差别不大,就是界面显示效果较差,不及Vistual Studio.用户名文本框用的文本字段,密码框用的是口令字段控件.登录和退出按钮用的是按钮控件.

设计完成后,单击运行按钮,界面效果如下图所示:

3 相关属性设置

Java Swing的很多属性设置用的方法,而NET用的属性.例如设置窗体标题,java swing用的是setTitle().另外窗体居中用的是setLocationRelativeTo(getOwner()). 获取文本框的值为getText()方法,如下代码所示:

    public Login() {        
        initComponents();
        setTitle("登录");   
        setDefaultCloseOperation(EXIT_ON_CLOSE);   
        setVisible(true);     
        setResizable(false);   
        setLocationRelativeTo(getOwner()); //居中显示

    }

 private void btnLoginActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    if(this.txtUserName.getText()!="" && this.txtPWD.getText().toString()!="")
    {
        Connection conn = DBConnection.getConnection();
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = conn.prepareStatement(
　　　　　　　　　"select * from users where UserName = ? and password = ?");
            ps.setString(1,this.txtUserName.getText());// 
            ps.setString(2, this.txtPWD.getText());
            rs = ps.executeQuery();
            while (rs.next()) {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setUsername(rs.getString("UserName"));
                user.setPassword(rs.getString("password"));
                
                System.out.println(user.toString());
                //跳转页面
                FrameMain frm=new FrameMain(user.getUsername());
                frm.setVisible(true);
                this.dispose();//关闭当前窗体
                                
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBConnection.closeResultSet(rs);
            DBConnection.closeStatement(ps);
            DBConnection.closeConnection(conn);
        }
            
     }
 }                                       

 显示一个窗体是设置其setVisiable(true);关闭一个窗体用的dispose();在登录界面想着输完用户名和密码后,按enter键可以自动登录,在网上搜下,发现了一个变通的方法,就是监听密码框的keypressed事件,当然需要验证一下用户名和密码是否为空(此处未加验证!),如下代码所示:

   private void txtPWDKeyPressed(java.awt.event.KeyEvent evt) {                                  
        // TODO add your handling code here:
        if(evt.getKeyCode()==KeyEvent.VK_ENTER)
        {
            //调用登录事件
            btnLoginActionPerformed(null);
            
        }
    }        

 4 主界面

登录成功后,单击左边的树叶节点,通过反射动态实例化窗体(实际上菜单应该从数据库加载)并显示,主界面如下:

 图表控件用的是JFreeChart控件,默认显示中文有乱码情况,需要设置显示中文处的字体进行解决.另外设置主界面显示最大化的代码为this.setExtendedState(this.getExtendedState()|JFrame.MAXMIZED_BOTH).为了让某个控件可以随着窗体大小变化而自动调整,需要设置其水平和垂直自动调整.

    public FrameMain(){
        initComponents();
         setLocationRelativeTo(getOwner()); //居中显示
         this.setExtendedState(this.getExtendedState()|JFrame.MAXIMIZED_BOTH );
　　　　　　　//最大化 window
         LoadTree();
      
    }
    public FrameMain(String uname){
        initComponents();
         setLocationRelativeTo(getOwner()); //居中显示
         this.setExtendedState(this.getExtendedState()|JFrame.MAXIMIZED_BOTH );
         LoadTree();
         this.lblUser.setText("欢迎 "+uname+ " 登录!");
      
    }

 主界面在初始化时,调用LoadTree方法来填充左边的菜单树,如下所示:

    private void LoadTree()
    {
        //自定义控件,支持关闭按钮
        jTabbedPane1.setCloseButtonEnabled(true);
 
        DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("软件部");
        node1.add(new DefaultMutableTreeNode("产品部"));
        node1.add(new DefaultMutableTreeNode("测试部"));
        node1.add(new DefaultMutableTreeNode("设计部"));
 
        DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("销售部");
        node2.add(new DefaultMutableTreeNode("jack"));
        node2.add(new DefaultMutableTreeNode("Lily"));
        node2.add(new DefaultMutableTreeNode("Smith"));
 
        DefaultMutableTreeNode top = new DefaultMutableTreeNode("职员管理");
           
       
        top.add(new DefaultMutableTreeNode("总经理"));
        top.add(node1);
        top.add(node2);
       
        //JTree tree=new JTree(top);       
        DefaultTreeModel model = new DefaultTreeModel (top);     
        this.jTree1.setModel(model);
       //jTree1.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION)      
       //set jframe icon
       try
           
       {
       Image icon= ImageIO.read(this.getClass().getResource("/images/Icon.png"));
       tabIcon = createImageIcon("/images/Icon.png", "tab icon");
      
       this.setIconImage(icon);
       }
       catch(IOException ex)
       {
           
           System.out.println(ex);
                   
       }
    
    }

 在Tree的值变化事件中,通过class.forName()和 cls.newInstance()反射动态实例化窗体,代码如下:

    private void jTree1ValueChanged(javax.swing.event.TreeSelectionEvent evt) {                                    
        // TODO add your handling code here:
     
       DefaultMutableTreeNode node = (DefaultMutableTreeNode) 
　　　　　　　　jTree1.getLastSelectedPathComponent();

        if (node == null){
            //Nothing is selected.  
             return;
        }

        Object nodeInfo = node.getUserObject();
        String item = (String) nodeInfo;

        if (node.isLeaf()) {
            String item1 = (String) nodeInfo;
            // this.setTitle(item1);
            //File f = new File("client.jar");
            //URLClassLoader cl = new URLClassLoader(new URL[]{f.toURI().toURL(), null});
            //Class<?> clazz = cl.loadClass("epicurus.Client");
            //Method main = clazz.getMethod("main", String[].class);
            //main.invoke(null, new Object[]{new String[]{}});
            try {
                Class cls = Class.forName("com.mkmis.forms.JIFrame1");
                javax.swing.JInternalFrame frm =
　　　　　　　　　　　　　　　　(javax.swing.JInternalFrame) cls.newInstance();
                 frm.setVisible(true);

                //jTabbedPane1.addTab(" "+item1+"  ",null,frm);
                jTabbedPane1.addTab(" "+item1+"  ",this.tabIcon,frm);

             }
             catch (Throwable e) {
                System.err.println(e);
             }
        } else {
            System.out.println("not leaf");
        }
    }       

 在javaswing中的路径也和net不同,下面定义了一个创建ImageIcon的方法:

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected ImageIcon createImageIcon(String path,String description) {
        java.net.URL imgURL = getClass().getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL, description);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

 5 JDBC MYSQL代码

package com.mkmis.db;

import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;


public class DBConnection {

    public static Connection getConnection() {
        Properties props = new Properties();
        FileInputStream fis = null;
        Connection con = null;
        try {
            fis = new FileInputStream("db.properties");
            props.load(fis);
            //
            Class.forName(props.getProperty("DB_DRIVER_CLASS"));
            // 
            con = DriverManager.getConnection(props.getProperty("DB_URL"), props.getProperty("DB_USERNAME"), props.getProperty("DB_PASSWORD"));
        } catch (IOException | SQLException | ClassNotFoundException e) {
            e.printStackTrace();
        }
        return con;
    }

    // �ر�ResultSet
    public static void closeResultSet(ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
                rs = null;
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    //Statement
    public static void closeStatement(Statement stm) {
        if (stm != null) {
            try {
                stm.close();
                stm = null;
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    //PreparedStatement
    public static void closePreparedStatement(PreparedStatement pstm) {
        if (pstm != null) {
            try {
                pstm.close();
                pstm = null;
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    //Connection
    public static void closeConnection(Connection con) {
        if (con != null) {
            try {
                con.close();
                con = null;
            } catch (SQLException e) {
                e.printStackTrace();
            }
            con = null;
        }
    }

}

 6 图表窗体代码

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package com.mkmis.forms;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.StandardChartTheme;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.block.BlockBorder;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
//import org.jfree.ui.ApplicationFrame;
//import org.jfree.ui.RefineryUtilities;
/**
 *
 * @author wangming
 */
public class JIFrame1 extends javax.swing.JInternalFrame {

    /**
     * Creates new form JIFrame1
     */
    public JIFrame1() {
        initComponents();
        //hiding title bar of JInternalFrame       
        ((javax.swing.plaf.basic.BasicInternalFrameUI)this.getUI()).setNorthPane(null);
        this.setBackground(Color.white);
        
        CategoryDataset dataset = createDataset();
        JFreeChart chart = createChart(dataset);
        ChartPanel chartPanel = new ChartPanel(chart);
        chartPanel.setFillZoomRectangle(true);
        chartPanel.setMouseWheelEnabled(true);
        chartPanel.setPreferredSize(new Dimension(500, 270));
        setContentPane(chartPanel);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        setBorder(null);
        setClosable(true);
        setMaximizable(true);
        setResizable(true);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 410, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 285, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        

        private static final long serialVersionUID = 1L;

    static {
        // set a theme using the new shadow generator feature available in
        // 1.0.14 - for backwards compatibility it is not enabled by default
        ChartFactory.setChartTheme(new StandardChartTheme("JFree/Shadow",
                true));
    }

    /**
     * Creates a new demo instance.
     *
     * @param title  the frame title.
     */
    public JIFrame1(String title) {
        super(title);
        CategoryDataset dataset = createDataset();
        JFreeChart chart = createChart(dataset);
        ChartPanel chartPanel = new ChartPanel(chart);
        chartPanel.setFillZoomRectangle(true);
        chartPanel.setMouseWheelEnabled(true);
        chartPanel.setPreferredSize(new Dimension(500, 270));
        setContentPane(chartPanel);
    }

    /**
     * Returns a sample dataset.
     *
     * @return The dataset.
     */
    private static CategoryDataset createDataset() {
        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.addValue(7445, "JFreeSVG", "Warm-up");
        dataset.addValue(24448, "Batik", "Warm-up");
        dataset.addValue(4297, "JFreeSVG", "Test");
        dataset.addValue(21022, "Batik", "Test");
        return dataset;
    }

    /**
     * Creates a sample chart.
     *
     * @param dataset  the dataset.
     *
     * @return The chart.
     */
    private static JFreeChart createChart(CategoryDataset dataset) {
        //中文乱码,设置字体
        Font font=new Font("微软雅黑",Font.BOLD,18);//测试是可以的
      
      
       
       
        JFreeChart chart = ChartFactory.createBarChart("性能: JFreeSVG 对比 Batik", null /* x-axis label*/, 
                "毫秒" /* y-axis label */, dataset);
        //中文乱码,设置字体
        chart.getTitle().setFont(font);

        chart.addSubtitle(new TextTitle("在SVG中产生1000个图表"));
        chart.setBackgroundPaint(Color.white);
        CategoryPlot plot = (CategoryPlot) chart.getPlot();
         NumberAxis rangeAxis = (NumberAxis) plot.getRangeAxis();
         rangeAxis.setLabelFont(font);

         CategoryAxis domainAxis = plot.getDomainAxis();
         domainAxis.setLabelFont(font);
        // ******************************************************************
        //  More than 150 demo applications are included with the JFreeChart
        //  Developer Guide...for more information, see:
        //
        //  >   http://www.object-refinery.com/jfreechart/guide.html
        //
        // ******************************************************************

      
        rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
        BarRenderer renderer = (BarRenderer) plot.getRenderer();
        renderer.setDrawBarOutline(false);
        chart.getLegend().setFrame(BlockBorder.NONE);
        return chart;
    }

    /**
     * Starting point for the demonstration application.
     *
     * @param args  ignored.
     */
//    public static void main(String[] args) {
//        BarChartDemo1 demo = new BarChartDemo1("JFreeChart: BarChartDemo1.java");
//        demo.pack();
//        RefineryUtilities.centerFrameOnScreen(demo);
//        demo.setVisible(true);
//    }

    // Variables declaration - do not modify                     
    // End of variables declaration                   
}

 运行此app,一定要引入需要的库,mysql jdbc驱动和jfreechart库