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