Swing 之 JTable 使表头标题和表格内容居中

封装的DButil.java，负责数据库连接：

/* * To change this template, choose Tools | Templates * and open the template in the editor. */package com.ethan.util;import java.sql.*;import java.util.logging.Level;import java.util.logging.Logger;/** * * @author Administrator */public class DBUtil {        private static final String url = "jdbc:mysql://localhost:3306/test";    private static final String username = "root";    private static final String password = "";           //private DBUtil dbUtil = null;        private DBUtil() {            }            static {        try {            Class.forName("com.mysql.jdbc.Driver");        } catch (ClassNotFoundException ex) {            Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);        }    }        public static Connection getConn() {        try {            return  DriverManager.getConnection(url,username,password);                    } catch (SQLException ex) {            Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);        }        return null;    }        public static PreparedStatement getPstmt(Connection conn, String sql) {        try {            return conn.prepareStatement(sql);        } catch (SQLException ex) {            Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);        }                return null;    }        public static ResultSet getRs(PreparedStatement pstmt) {        try {            return pstmt.executeQuery();        } catch (SQLException ex) {            Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);        }                return null;    }        public static void close(Connection conn,Statement stmt, ResultSet rs) {        if(conn!=null) {            try {                conn.close();                conn = null;            } catch (SQLException ex) {                Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);            } finally {                if(stmt!=null) {                    try {                        stmt.close();                        stmt = null;                    } catch (SQLException ex) {                        Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);                    } finally {                        if(rs!=null) {                            try {                                rs.close();                                rs = null;                            } catch (SQLException ex) {                                Logger.getLogger(DBUtil.class.getName()).log(Level.SEVERE, null, ex);                            } finally {                                conn = null;                                stmt = null;                            }                                                    }                                            }                                    }             }        }    }}

下边是采用netbeans 新建的JFrame, 拖拉控件到面板上：

/* * To change this template, choose Tools | Templates * and open the template in the editor. */package jtable;import com.ethan.util.DBUtil;import java.awt.Color;import java.awt.Dimension;import java.sql.*;import java.util.logging.Level;import java.util.logging.Logger;import javax.swing.JFrame;import javax.swing.JTable;import javax.swing.SwingConstants;import javax.swing.table.DefaultTableCellRenderer;import javax.swing.table.JTableHeader;import javax.swing.table.TableCellRenderer;/** * * @author Administrator */public class TestJTableFrame extends javax.swing.JFrame {    /**     * Creates new form TestJTableFrame     */    public TestJTableFrame() {         initComponents();         setTitle("使用数组填充数据");                setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                        //getContentPane().add(scrollPane,BorderLayout.CENTER);                String sql = "select * from student";        Connection conn = DBUtil.getConn();        PreparedStatement pstmt = DBUtil.getPstmt(conn, sql);        ResultSet rs = DBUtil.getRs(pstmt);        ResultSetMetaData data;                //二维数组的维数写死了         String[][] values = new String[3][3];         String[] columns = null;        try {            data = rs.getMetaData();            columns = new String[data.getColumnCount()];            for(int i=0;i<columns.length;i++) {                columns[i] = data.getColumnName(i+1);                System.out.println(columns[i]);            }                                               for(int i=0;i<values.length;i++) {                //每一条记录，每一行                    if(rs.next()) {                        //每一列                        for( int j=0;j<values[i].length;j++) {                        //values[i] = {rs.getObject("id").toString(),rs.getObject("sid").toString(),rs.getObject("name").toString()};                        values[i][j] = rs.getString(j+1);                    }                }                                            }                       DBUtil.close(conn, pstmt, rs);        } catch (SQLException ex) {            Logger.getLogger(ArrayCreateTableFrame.class.getName())                    .log(Level.SEVERE, null, ex);        }               this.setSize(new Dimension(400, 300));          //public Window getOwner() returns the owner of this windowsetLocationRelativeTo(getOwner());                jTable1 = null;        jTable1 = new CusJTable(values,columns);                        //产生水平滚动条       // jTable1.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);        jTable1.setSelectionBackground(Color.GREEN);                DefaultTableCellRenderer tcr = new DefaultTableCellRenderer();// 设置table内容居中        // tcr.setHorizontalAlignment(JLabel.CENTER);        tcr.setHorizontalAlignment(SwingConstants.CENTER);// 这句和上句作用一样        jTable1.setDefaultRenderer(Object.class, tcr);            jTable1.setForeground(Color.RED);                jTable1.setRowHeight(50);      //jScrollPane1.setViewportView(null);        jScrollPane1.setViewportView(jTable1);    }            private class CusJTable extends JTable {        public CusJTable(String[][] values, String[] columns) {            super(values, columns);        }                 @Override         public JTableHeader getTableHeader() {                    JTableHeader tableHeader = super.getTableHeader();            tableHeader.setReorderingAllowed(false);//表格列不可移动            DefaultTableCellRenderer hr = (DefaultTableCellRenderer) tableHeader                    .getDefaultRenderer();            hr.setHorizontalAlignment(DefaultTableCellRenderer.CENTER);//列名居中            return tableHeader;        }//        @Override//        public TableCellRenderer getDefaultRenderer(Class<?> columnClass) {//            DefaultTableCellRenderer cr = (DefaultTableCellRenderer) super.getDefaultRenderer(columnClass);//            //            cr.setHorizontalAlignment(DefaultTableCellRenderer.CENTER);//            return cr;//        }                //单元格可编辑        @Override        public boolean isCellEditable(int row, int column) {            return false;        }    }    /**     * 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() {        jScrollPane1 = new javax.swing.JScrollPane();        jTable1 = new javax.swing.JTable();        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);        jTable1.setModel(new javax.swing.table.DefaultTableModel(            new Object [][] {                {null, null, null, null},                {null, null, null, null},                {null, null, null, null},                {null, null, null, null}            },            new String [] {                "Title 1", "Title 2", "Title 3", "Title 4"            }        ));        jScrollPane1.setViewportView(jTable1);        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());        getContentPane().setLayout(layout);        layout.setHorizontalGroup(            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()                .addContainerGap(15, Short.MAX_VALUE)                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 375, javax.swing.GroupLayout.PREFERRED_SIZE)                .addContainerGap())        );        layout.setVerticalGroup(            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()                .addContainerGap(15, Short.MAX_VALUE)                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 275, javax.swing.GroupLayout.PREFERRED_SIZE)                .addContainerGap())        );        pack();    }// </editor-fold>    /**     * @param args the command line arguments     */    public static void main(String args[]) {        /*         * Set the Nimbus look and feel         */        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">        /*         * If Nimbus (introduced in Java SE 6) is not available, stay with the         * default look and feel. For details see         * http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html         */        try {            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {                if ("Nimbus".equals(info.getName())) {                    javax.swing.UIManager.setLookAndFeel(info.getClassName());                    break;                }            }        } catch (ClassNotFoundException ex) {            java.util.logging.Logger.getLogger(TestJTableFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);        } catch (InstantiationException ex) {            java.util.logging.Logger.getLogger(TestJTableFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);        } catch (IllegalAccessException ex) {            java.util.logging.Logger.getLogger(TestJTableFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);        } catch (javax.swing.UnsupportedLookAndFeelException ex) {            java.util.logging.Logger.getLogger(TestJTableFrame.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);        }        //</editor-fold>        /*         * Create and display the form         */        java.awt.EventQueue.invokeLater(new Runnable() {            public void run() {                new TestJTableFrame().setVisible(true);            }        });    }    // Variables declaration - do not modify    private javax.swing.JScrollPane jScrollPane1;    private javax.swing.JTable jTable1;    // End of variables declaration}//如果自己重写  public TableCellRenderer getDefaultRenderer(Class<?> columnClass) 就会出一下异常。//请高手多多指教了！/* * Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: javax.swing.JTable$BooleanRenderer cannot be cast to javax.swing.table.DefaultTableCellRendererat jtable.TestJTableFrame$CusJTable.getDefaultRenderer(TestJTableFrame.java:125)at javax.swing.plaf.synth.SynthTableUI.installRendererIfPossible(SynthTableUI.java:102)at javax.swing.plaf.synth.SynthTableUI.installDefaults(SynthTableUI.java:93)at javax.swing.plaf.basic.BasicTableUI.installUI(BasicTableUI.java:1351)at javax.swing.JComponent.setUI(JComponent.java:662)at javax.swing.JTable.setUI(JTable.java:3574) */