ch06.html

java2高级编程

<a name="pgfId-1087782"></a>    for (int i=0; i &lt; openItems.length; i++) {</pre>
					<pre class="CODE">

<a name="pgfId-1087783"></a>       //Populate the open item nodes with the open item data,</pre>
					<pre class="CODE">

<a name="pgfId-1087784"></a>       //i.e., auction ids
       opennodes[i] = new DefaultMutableTreeNode(openItems[i]); </pre>
					<pre class="CODE">

<a name="pgfId-1087785"></a>       //Add the open items under the Open Auction parent node
       nodes[2].add(opennodes[i]);
    }</pre>
					<pre class="CODE">

<a name="pgfId-1087786"></a>    //Finally, create the tree model from the nodes created above</pre>
					<pre class="CODE">

<a name="pgfId-1087787"></a>    //and then create the tree

    DefaultTreeModel model=new DefaultTreeModel(nodes[0]);
    tree = new JTree(model);
    JScrollPane scroll = new JScrollPane(tree);
    getContentPane().add(scroll, BorderLayout.CENTER);
    findPanel= new JPanel();
    findField= new JTextField(10);
    findButton= new JButton(&quot;find&quot;);</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087789"></a>//API Ref: <a name="48732"></a>void addActionListener(ActionListener l)</pre>
					<pre class="CODE">

<a name="pgfId-1087794"></a>    <a name="marker-1087790"></a><a name="marker-1087791"></a><a name="marker-1087792"></a><a name="marker-1087793"></a>findButton.addActionListener (new ActionListener() {</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087796"></a>//API Ref: <a name="12167"></a>void actionPerformed(ActionEvent e)</pre>
					<pre class="CODE">

<a name="pgfId-1087801"></a>     <a name="marker-1087797"></a><a name="marker-1087798"></a><a name="marker-1087799"></a>public void <a name="marker-1087800"></a>actionPerformed (ActionEvent e) {
        String field=findField.getText(); 
        if (field != null) {</pre>
					<pre class="CODE">

<a name="pgfId-1087802"></a>          //Search for the node whose label matches the search string
          findNode(findField.getText());
        } else {
          return;
        } 
      }
    });
    findPanel.add(findField);
    findPanel.add(findButton);
    getContentPane().add(findPanel, BorderLayout.SOUTH);
  }                                                               
  public void findNode(String field) {</pre>
					<pre class="CODE">

<a name="pgfId-1087803"></a>    //Get an enumeration list of all the nodes.</pre>
					<pre class="CODE">

<a name="pgfId-1087804"></a>    //The ordering is generated by starting from the root</pre>
					<pre class="CODE">

<a name="pgfId-1087805"></a>    //to the end of each branch, and to the end of</pre>
					<pre class="CODE">

<a name="pgfId-1087806"></a>    //the next branch including any nodes not visited before.</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087808"></a>//API Ref: <a name="77673"></a>Enumeration depthFirstEnumeration() </pre>
					<pre class="CODE">

<a name="pgfId-1087811"></a>    <a name="marker-1087809"></a><a name="depthFirstEnumeration method"></a>Enumeration e = nodes[0].depthFirstEnumeration(); 
    Object currNode; 
    while (e.hasMoreElements()) {
      currNode = e.nextElement(); 
      if (currNode.toString().equals(field)) { </pre>
					<pre class="CODE">

<a name="pgfId-1087812"></a>       //Does the node match our search string? If so, generate</pre>
					<pre class="CODE">

<a name="pgfId-1087813"></a>       //a path object to highlight the matching node</pre>
					<pre class="CODE">

<a name="pgfId-1087814"></a>       //with a call to setSelectionRow.</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087816"></a>//API Ref: <a name="58137"></a>TreePath(Object singlePath)</pre>
					<pre class="CODE">

<a name="pgfId-1087821"></a>       <a name="marker-1087817"></a><a name="javax.swing.tree.TreePath class"></a><a name="TreePath class"></a><a name="TreePath constructor"></a>TreePath path=new 
                TreePath(((DefaultMutableTreeNode)currNode).getPath());</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087823"></a>//API Ref: <a name="11684"></a>void makeVisible(TreePath path)</pre>
					<pre class="CODE">

<a name="pgfId-1087828"></a>       <a name="marker-1087824"></a><a name="javax.swing.JTree class"></a><a name="JTree class"></a><a name="makeVisible method"></a>tree.makeVisible(path);</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087830"></a>//API Ref: <a name="72169"></a>void setSelectionRow(int row)</pre>
					<pre class="CODE">

<a name="pgfId-1087833"></a>       <a name="marker-1087831"></a><a name="setSelectionRow method"></a>tree.setSelectionRow(tree.getRowForPath(path));  
       return;
      } 
    } 
  }</pre>
					<pre class="CODE">

<a name="pgfId-1087834"></a>  public static void main(String[] args) {
    SimpleSearchTree frame = new SimpleSearchTree();</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087836"></a>//API Ref: <a name="27085"></a>void addWindowListener(WindowListener l)</pre>
					<pre class="CODE">

<a name="pgfId-1087841"></a>    <a name="marker-1087837"></a><a name="marker-1087838"></a><a name="marker-1087839"></a><a name="marker-1087840"></a>frame.addWindowListener( new WindowAdapter() {</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087843"></a>//API Ref: <a name="64689"></a>void windowClosing(WindowEvent e)</pre>
					<pre class="CODE">

<a name="pgfId-1087848"></a>      <a name="marker-1087844"></a><a name="marker-1087845"></a><a name="marker-1087846"></a><a name="marker-1087847"></a>public void windowClosing( WindowEvent e ) {
        System.exit(0);
      }
    });
    frame.setVisible(true);
    frame.pack();
    frame.setSize(300,150);
  }                          
}</pre>
					<p class="Body"><a name="pgfId-1087849"></a><em class="CODE">JTree</em> , <em class="CODE">JTable</em> , and <em class="CODE">JList</em> are probably the most common components you will want to customize. But you can use models such as <em class="CODE">SingleSelectionModel</em> for general data manipulation. The <em class="CODE">SingleSelectionModel</em> class lets you specify how data is selected in a component. <a name="render"></a></p>
					<p class="Body"><a name="pgfId-1087853"></a><em class="Bold">Custom Cell Rendering. </em><a name="marker-1087851"></a><a name="marker-1087852"></a>As you learned above, many components have a default cell renderer to paint each element in a table, tree, or list. The default cell renderer is usually a <em class="CODE">JLabel</em> and displays a <em class="CODE">String</em> representation of the data element.</p>
					<p class="Body"><a name="pgfId-1087855"></a>A simple custom cell renderer can extend the <em class="CODE">Default&lt;type&gt;CellRenderer</em> <a name="marker-1087854"></a>class to provide additional customization in the <em class="CODE">get&lt;type&gt;CellRenderer</em> <a name="marker-1087856"></a>. The <em class="CODE">DefaultTableCellRenderer</em> and <em class="CODE">DefaultTreeCellRenderer</em> components both use a <em class="CODE">JLabel</em> to render the cell. This means any customization that can be applied to a <em class="CODE">JLabel</em> can also be used in the <em class="CODE">JTable</em> or <em class="CODE">JTree</em> cell.</p>
					<p class="Body"><a name="pgfId-1087857"></a>For example, the following renderer sets the background color of the component if the auction item has received a high number of bids:</p>
					<pre class="CODE">
<a name="pgfId-1087858"></a>class CustomRenderer extends DefaultTableCellRenderer {</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087860"></a>//API Ref: <a name="86315"></a>Component getTableCellRendererComponent(JTable table, Object value, 
           boolean isSelected, boolean hasFocus, int row, int column)</pre>
					<pre class="CODE">

<a name="pgfId-1087865"></a>  <a name="marker-1087861"></a><a name="javax.swing.table.DefaultTableCellRenderer class"></a><a name="DefaultTableCellRenderer class"></a><a name="getTableCellRendererComponent method"></a>public Component getTableCellRendererComponent(JTable table,Object value,
                   boolean isSelected, boolean hasFocus, int row, 
                   int column) {
    Component comp = super.getTableCellRendererComponent(table,
                     value,isSelected, hasFocus, row,column);
      JLabel label = (JLabel)comp;</pre>
					<pre class="CODE">

<a name="pgfId-1087866"></a>       //Does the auction item have 30 or more bids. If so display</pre>
					<pre class="CODE">

<a name="pgfId-1087867"></a>       //a hot item image
      if(((Integer)value).intValue() &gt;= 30) {</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087869"></a>//API Ref: <a name="47804"></a>void setIcon(Icon icon)</pre>
					<pre class="CODE">

<a name="pgfId-1087874"></a>        <a name="marker-1087870"></a><a name="marker-1087871"></a><a name="marker-1087872"></a><a name="marker-1087873"></a>label.setIcon(new ImageIcon(&quot;Hot.gif&quot;));
      } else {
        label.setIcon(new ImageIcon(&quot;Normal.gif&quot;));
      }
      return label;                   
   }
}                            </pre>
					<p class="Body"><a name="pgfId-1087875"></a>The renderer is set on a column like this:</p>
					<pre class="CODE">
<a name="pgfId-1087876"></a>  CustomRenderer custom = new CustomRenderer();
  custom.setHorizontalAlignment(JLabel.CENTER);
  scrollColumnModel.getColumn(2).setCellRenderer(custom);</pre>
					<p class="Body"><a name="pgfId-1087877"></a>If the component being displayed inside the <em class="CODE">JTable</em> column requires more functionality than is available using a <em class="CODE">JLabel</em> , you can create your own <em class="CODE">TableCellRenderer</em> . This next code example uses a <em class="CODE">JButton</em> as the renderer cell.</p>
					<pre class="CODE">
<a name="pgfId-1087878"></a>class CustomButtonRenderer extends JButton implements TableCellRenderer {
   public CustomButtonRenderer() {
     setOpaque(true);
   }</pre>
					<pre class="CODE-caption">

<a name="pgfId-1087880"></a>//API Ref: <a name="57671"></a>Component getTableCellRendere