Jtable表头换行显示

在jtable渲染表头时,由于有些表头字体较多,需要折行显示,但jtable没有自动折行的功能,所以自己实现表头的渲染器.

有两种方案实现表头的折行渲染:

1、渲染器继承自JTextArea,实现TableCellRenderer接口，具体代码如下：

Java代码




import java.awt.Component; import java.awt.Dimension; import java.util.Enumeration; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import javax.swing.JTable; import javax.swing.JTextArea; import javax.swing.UIManager; import javax.swing.table.DefaultTableCellRenderer; import javax.swing.table.JTableHeader; import javax.swing.table.TableCellRenderer; import javax.swing.table.TableColumn; import javax.swing.table.TableColumnModel; public class TextAreaHeaderRenderer 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 TextAreaHeaderRenderer() { setLineWrap(true); setWrapStyleWord(true); setHighlighter(null); } public Component getTableCellRendererComponent( // JTable table, Object obj, boolean isSelected, boolean hasFocus, int row, int column) { // 设置表头渲染时的一些属性参数 JTableHeader header = table.getTableHeader(); setForeground(header.getForeground()); setBackground(header.getBackground()); setFont(header.getFont()); setText(obj.toString()); setBorder(UIManager.getBorder("TableHeader.cellBorder")); // This line was very important to get it working with JDK1.4 TableColumnModel columnModel = table.getColumnModel(); int width = columnModel.getColumn(column).getWidth(); setSize(width, 100000); int height_wanted = (int) getPreferredSize().getHeight(); addSize(table, column, height_wanted); height_wanted = findTotalMaximumRowSize(table, column); if (height_wanted != header.getHeight()) { // 设置JTextArea的大小 this.setSize(new Dimension(width, height_wanted)); } return this; } private void addSize(JTable table, int column, int height) { Map cols = (Map) cellSizes.get(table); if (cols == null) { cellSizes.put(table, cols = new HashMap()); } Map rowheights = (Map) cols.get(new Integer(column)); if (rowheights == null) { cols.put(new Integer(column), 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 column) { int maximum_height = 0; Enumeration columns = table.getColumnModel().getColumns(); while (columns.hasMoreElements()) { TableColumn tc = (TableColumn) columns.nextElement(); TableCellRenderer cellRenderer = tc.getHeaderRenderer(); if (cellRenderer instanceof TextAreaHeaderRenderer) { TextAreaHeaderRenderer tar = (TextAreaHeaderRenderer) cellRenderer; maximum_height = Math.max(maximum_height, tar .findMaximumRowSize(table, column)); } // System.out.println("aaa"); } return maximum_height; } private int findMaximumRowSize(JTable table, int column) { Map rows = (Map) cellSizes.get(table); if (rows == null) return 0; Map rowheights = (Map) rows.get(new Integer(column)); 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; } }

import java.awt.Component;
import java.awt.Dimension;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;
import javax.swing.table.TableColumnModel;

public class TextAreaHeaderRenderer 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 TextAreaHeaderRenderer() {
setLineWrap(true);
setWrapStyleWord(true);
setHighlighter(null);
}

public Component getTableCellRendererComponent(
//
JTable table, Object obj, boolean isSelected, boolean hasFocus,
int row, int column) {
// 设置表头渲染时的一些属性参数
JTableHeader header = table.getTableHeader();
setForeground(header.getForeground());
setBackground(header.getBackground());
setFont(header.getFont());
setText(obj.toString());
setBorder(UIManager.getBorder("TableHeader.cellBorder"));
// This line was very important to get it working with JDK1.4
TableColumnModel columnModel = table.getColumnModel();
int width = columnModel.getColumn(column).getWidth();
setSize(width, 100000);
int height_wanted = (int) getPreferredSize().getHeight();
addSize(table, column, height_wanted);
height_wanted = findTotalMaximumRowSize(table, column);
if (height_wanted != header.getHeight()) {
// 设置JTextArea的大小
this.setSize(new Dimension(width, height_wanted));
}
return this;
}

private void addSize(JTable table, int column, int height) {
Map cols = (Map) cellSizes.get(table);
if (cols == null) {
cellSizes.put(table, cols = new HashMap());
}
Map rowheights = (Map) cols.get(new Integer(column));
if (rowheights == null) {
cols.put(new Integer(column), 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 column) {
int maximum_height = 0;
Enumeration columns = table.getColumnModel().getColumns();
while (columns.hasMoreElements()) {
TableColumn tc = (TableColumn) columns.nextElement();
TableCellRenderer cellRenderer = tc.getHeaderRenderer();
if (cellRenderer instanceof TextAreaHeaderRenderer) {
TextAreaHeaderRenderer tar = (TextAreaHeaderRenderer) cellRenderer;
maximum_height = Math.max(maximum_height, tar
.findMaximumRowSize(table, column));
}
// System.out.println("aaa");
}
return maximum_height;
}

private int findMaximumRowSize(JTable table, int column) {
Map rows = (Map) cellSizes.get(table);
if (rows == null)
return 0;
Map rowheights = (Map) rows.get(new Integer(column));
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;
}
}

此种渲染器的缺点是没有办法实现居中对齐。

2、因为JLabel可以解析html中的br，所以利用这个特点，可以动态构建显示的标题，在换行处添加<br>标记，实现换行显示，代码如下：

Java代码




import java.awt.Component;
import java.awt.Dimension;
import java.awt.FontMetrics;

import javax.swing.JLabel;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableColumnModel;

public class HeaderRendererHh extends DefaultTableCellRenderer {

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

JTableHeader header = table.getTableHeader();
setForeground(header.getForeground());
setBackground(header.getBackground());
setFont(header.getFont());
setOpaque(true);
setBorder(UIManager.getBorder("TableHeader.cellBorder"));

// 得到列的宽度
TableColumnModel columnModel = table.getColumnModel();
int width = columnModel.getColumn(column).getWidth();

value = getShowValue(value.toString(), width);
setText(value.toString());
setSize(new Dimension(width, this.getHeight()));

setHorizontalAlignment(JLabel.CENTER);

return this;
}

private Object getShowValue(String value, int colWidth) {
// 根据当前的字体和显示值得到需要显示的宽度
FontMetrics fm = this.getFontMetrics(this.getFont());
int width = fm.stringWidth(value.toString());
int test = fm.stringWidth("好");
System.out.println(test * value.length());
System.out.println(width);
if (width < colWidth) {
return value;
}
StringBuffer sb = new StringBuffer("<html>");
char str;
int tempW = 0;
for (int i = 0; i < value.length(); i++) {
str = value.charAt(i);
tempW += fm.charWidth(str);
if (tempW > colWidth) {
sb.append("<br>");
tempW = 0;
}
sb.append(str);
}
sb.append("</html>");
return sb.toString();
}
}

import java.awt.Component;
import java.awt.Dimension;
import java.awt.FontMetrics;

import javax.swing.JLabel;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.JTableHeader;
import javax.swing.table.TableColumnModel;

public class HeaderRendererHh extends DefaultTableCellRenderer {

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

JTableHeader header = table.getTableHeader();
setForeground(header.getForeground());
setBackground(header.getBackground());
setFont(header.getFont());
setOpaque(true);
setBorder(UIManager.getBorder("TableHeader.cellBorder"));

// 得到列的宽度
TableColumnModel columnModel = table.getColumnModel();
int width = columnModel.getColumn(column).getWidth();

value = getShowValue(value.toString(), width);
setText(value.toString());
setSize(new Dimension(width, this.getHeight()));

setHorizontalAlignment(JLabel.CENTER);

return this;
}

private Object getShowValue(String value, int colWidth) {
// 根据当前的字体和显示值得到需要显示的宽度
FontMetrics fm = this.getFontMetrics(this.getFont());
int width = fm.stringWidth(value.toString());
int test = fm.stringWidth("好");
System.out.println(test * value.length());
System.out.println(width);
if (width < colWidth) {
return value;
}
StringBuffer sb = new StringBuffer("<html>");
char str;
int tempW = 0;
for (int i = 0; i < value.length(); i++) {
str = value.charAt(i);
tempW += fm.charWidth(str);
if (tempW > colWidth) {
sb.append("<br>");
tempW = 0;
}
sb.append(str);
}
sb.append("</html>");
return sb.toString();
}
}

两种方法在使用时只要给对应的列添加headerRenderer就可以了，如：

Java代码




HeaderRendererHh renderer = new HeaderRendererHh();
TableColumnModel cmodel = table.getColumnModel();
for (int i = 0; i < cmodel.getColumnCount(); i++) {
cmodel.getColumn(i).setHeaderRenderer(renderer);
}

下面方法是根据上面第二中方法来做的，因为我的表头换行的时候加了换行符号\n，方法如下：

import java.awt.Component;

import java.awt.Dimension;

import java.awt.Font;

import java.awt.FontMetrics;

import javax.swing.JLabel;

import javax.swing.JTable;

import javax.swing.UIManager;

import javax.swing.table.DefaultTableCellRenderer;

import javax.swing.table.JTableHeader;

import javax.swing.table.TableColumnModel;

public class HeaderRendererHh extends DefaultTableCellRenderer {

public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected,

boolean hasFocus, int row, int column) {

JTableHeader header = table.getTableHeader();

setForeground(header.getForeground());

setBackground(header.getBackground());

// setFont(header.getFont());

setFont(new Font(null, Font.BOLD, 13));

setOpaque(true);

setBorder(UIManager.getBorder("TableHeader.cellBorder"));

// 得到列的宽度

TableColumnModel columnModel = table.getColumnModel();

int width = columnModel.getColumn(column).getWidth();

value = getShowValue(value.toString(), width);

setText(value.toString());

setSize(new Dimension(width, this.getHeight()));

setHorizontalAlignment(JLabel.CENTER);

return this;

}

private Object getShowValue(String value, int colWidth) {

// 根据当前的字体和显示值得到需要显示的宽度

FontMetrics fm = this.getFontMetrics(this.getFont());

int width = fm.stringWidth(value.toString());

StringBuffer sb = new StringBuffer("<html>");

char str;

int tempW = 0;

for (int i = 0; i < value.length(); i++) {

str = value.charAt(i);

tempW += fm.charWidth(str);

char linebreak = '\n';

if (str == linebreak) {

sb.append("<br>");

tempW = 0;

}

sb.append(str);

}

sb.append("</html>");

return sb.toString();

}

}

在java文件中使用以上方法代码如下

HeaderRendererHh headrenderer = new HeaderRendererHh();// 设置Head居中

TableColumnModel cmodel = tabledata.getColumnModel();

for (int i = 0; i < cmodel.getColumnCount(); i++) {

cmodel.getColumn(i).setHeaderRenderer(headrenderer);

}
http://weibaojun.iteye.com/blog/524507