使用TextAreaRenderer在JTable單元格中居中對齊文本

Question

我正在使用TextAreaRenderer來對我的JTable單元格中的文字進行自動換行。但是，我的項目規範要求能夠將文本居中（水平和垂直）。我無法弄清楚如何做到這一點。

因爲我已經使用了TextAreaRenderer其中extends JTextArea，我無法延長DefaultTableCellRenderer這是需要訪問setHorizontalAlignment()和setVerticalAlignment()方法（見這個問題，回答：How to center in JTable cell a value?）。我無法執行DefaultTableCellRenderer，因爲它不是接口。

SSCCE與我使用的TextAreaRenderer：

import java.awt.Component; 
import java.util.Enumeration; 
import java.util.HashMap; 
import java.util.Iterator; 
import java.util.Map; 
import javax.swing.JFrame; 
import javax.swing.JScrollPane; 
import javax.swing.JTable; 
import javax.swing.JTextArea; 
import javax.swing.table.DefaultTableCellRenderer; 
import javax.swing.table.DefaultTableModel; 
import javax.swing.table.TableCellRenderer; 
import javax.swing.table.TableColumn; 
import javax.swing.table.TableColumnModel; 

public class Test { 

    public static void main(String args[]) { 
     JFrame frame = new JFrame(); 
     JTable table = new JTable(); 
     JScrollPane jsp = new JScrollPane(table); 
     Object[][] data = new Object[2][2]; 
     data[0][0] = 1; 
     data[0][1] = "Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. Super long text just to illustrate word wrap. "; 
     data[1][0] = 2; 
     data[1][1] = "Two Lines/Two Lines"; 
     String[] headers = new String[]{"Digit", "Text"}; 
     table.setModel(new DefaultTableModel(data, headers) { 

      @Override 
      public Class<?> getColumnClass(int columnIndex) { 
       switch(columnIndex){ 
        case 1: return Integer.class; 
        case 2: return String.class; 
        default: return Object.class; 
       } 
      } 
     }); 
     table.getColumnModel().getColumn(1).setCellRenderer(new TextAreaRenderer()); 
     frame.add(jsp); 
     frame.pack(); 
     frame.setLocationByPlatform(true); 
     frame.setVisible(true); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    } 



    static class TextAreaRenderer extends JTextArea implements TableCellRenderer { 

     private final DefaultTableCellRenderer adaptee = new DefaultTableCellRenderer(); 
     /** map from table to map of rows to map of column heights */ 
     private final Map cellSizes = new HashMap(); 


     public TextAreaRenderer() { 
      setLineWrap(true); 
      setWrapStyleWord(true); 
     } 

     public Component getTableCellRendererComponent(
       JTable table, Object obj, boolean isSelected, 
       boolean hasFocus, int row, int column) { 

      // set the colours, etc. using the standard for that platform 
      adaptee.getTableCellRendererComponent(table, obj, 
        isSelected, hasFocus, row, column); 
      setForeground(adaptee.getForeground()); 
      setBackground(adaptee.getBackground()); 
      setBorder(adaptee.getBorder()); 
      setFont(adaptee.getFont()); 
      setText(adaptee.getText()); 


      // This line was very important to get it working with JDK1.4 
      TableColumnModel columnModel = table.getColumnModel(); 
      setSize(columnModel.getColumn(column).getWidth(), 100000); 
      int height_wanted = (int) getPreferredSize().getHeight(); 
      addSize(table, row, column, height_wanted); 
      height_wanted = findTotalMaximumRowSize(table, row); 
      if (height_wanted != table.getRowHeight(row)) { 
       table.setRowHeight(row, height_wanted); 
      } 
      return this; 
     } 

     @SuppressWarnings("unchecked") 
     private void addSize(JTable table, int row, int column, int height) { 
      Map rows = (Map) cellSizes.get(table); 
      if (rows == null) { 
       cellSizes.put(table, rows = new HashMap()); 
      } 
      Map rowheights = (Map) rows.get(new Integer(row)); 
      if (rowheights == null) { 
       rows.put(new Integer(row), rowheights = new HashMap()); 
      } 
      rowheights.put(new Integer(column), new Integer(height)); 
     } 

     /** 
     * Look through all columns and get the renderer. If it is 
     * also a TextAreaRenderer, we look at the maximum height in 
     * its hash table for this row. 
     */ 
     private int findTotalMaximumRowSize(JTable table, int row) { 
      int maximum_height = 0; 
      Enumeration columns = table.getColumnModel().getColumns(); 
      while (columns.hasMoreElements()) { 
       TableColumn tc = (TableColumn) columns.nextElement(); 
       TableCellRenderer cellRenderer = tc.getCellRenderer(); 
       if (cellRenderer instanceof TextAreaRenderer) { 
        TextAreaRenderer tar = (TextAreaRenderer) cellRenderer; 
        maximum_height = Math.max(maximum_height, 
          tar.findMaximumRowSize(table, row)); 
       } 
      } 
      return maximum_height; 
     } 

     private int findMaximumRowSize(JTable table, int row) { 
      Map rows = (Map) cellSizes.get(table); 
      if (rows == null) { 
       return 0; 
      } 
      Map rowheights = (Map) rows.get(new Integer(row)); 
      if (rowheights == null) { 
       return 0; 
      } 
      int maximum_height = 0; 
      for (Iterator it = rowheights.entrySet().iterator(); 
        it.hasNext();) { 
       Map.Entry entry = (Map.Entry) it.next(); 
       int cellHeight = ((Integer) entry.getValue()).intValue(); 
       maximum_height = Math.max(maximum_height, cellHeight); 
      } 
      return maximum_height; 
     } 
    } 
} 

Answer 1

你需要有一個使用JTextPane中，沒有一個JTextArea渲染器，然後設置文檔的樣式屬性。

即

static class TextAreaRenderer extends JTextPane implements TableCellRenderer { 

    private final DefaultTableCellRenderer adaptee = new DefaultTableCellRenderer(); 
    /** map from table to map of rows to map of column heights */ 
    private final Map cellSizes = new HashMap(); 

    public TextAreaRenderer() { 
    // !! setLineWrap(true); 
    // setWrapStyleWord(true); 

    StyledDocument doc = getStyledDocument(); 
    SimpleAttributeSet center = new SimpleAttributeSet(); 
    StyleConstants.setAlignment(center, StyleConstants.ALIGN_CENTER); 
    doc.setParagraphAttributes(0, doc.getLength(), center, false); 
    } 

如需更多信息，請參閱（和贊成票）camickr的回答here。