做两个文件过滤器。
import java.io.FileFilter
class FolderFilter extends FileFilter{
public boolean accept(File f){
return f.isDirectory()
}
}
class FilesFilter extends FileFilter{
public boolean accept(File f){
return f.isFile()
}
}
在调用listFiles()取子项目时，先new一个FolderFilter做参数调用listFiles，得到的子项目就是目录。
new一个FilesFilter做参数调用listFiles得到的就是子文件。
import java.awt.BorderLayoutimport java.awt.Component
import java.io.File
import java.util.*
import javax.swing.*
import javax.swing.border.EmptyBorder
import javax.swing.filechooser.FileSystemView
import javax.swing.tree.DefaultTreeCellRenderer
import javax.swing.tree.TreeNode
/**
* @author Kirill Grouchnikov
*/
public class FileTreePanel extends JPanel {
/**
* File system view.
*/
protected static FileSystemView fsv = FileSystemView.getFileSystemView()
/**
* Renderer for the file tree.
*
* @author Kirill Grouchnikov
*/
private static class FileTreeCellRenderer extends DefaultTreeCellRenderer {
/**
* Icon cache to speed the rendering.
*/
private Map<String, Icon>iconCache = new HashMap<String, Icon>()
/**
* Root name cache to speed the rendering.
*/
private Map<File, String>rootNameCache = new HashMap<File, String>()
/*
* (non-Javadoc)
*
* @see javax.swing.tree.DefaultTreeCellRenderer#getTreeCellRendererComponent(javax.swing.JTree,
* java.lang.Object, boolean, boolean, boolean, int, boolean)
*/
@Override
public Component getTreeCellRendererComponent(JTree tree, Object value,
boolean sel, boolean expanded, boolean leaf, int row,
boolean hasFocus) {
FileTreeNode ftn = (FileTreeNode) value
File file = ftn.file
String filename = ""
if (file != null) {
if (ftn.isFileSystemRoot) {
// long start = System.currentTimeMillis()
filename = this.rootNameCache.get(file)
if (filename == null) {
filename = fsv.getSystemDisplayName(file)
this.rootNameCache.put(file, filename)
}
// long end = System.currentTimeMillis()
// System.out.println(filename + ":" + (end - start))
} else {
filename = file.getName()
}
}
JLabel result = (JLabel) super.getTreeCellRendererComponent(tree,
filename, sel, expanded, leaf, row, hasFocus)
if (file != null) {
Icon icon = this.iconCache.get(filename)
if (icon == null) {
// System.out.println("Getting icon of " + filename)
icon = fsv.getSystemIcon(file)
this.iconCache.put(filename, icon)
}
result.setIcon(icon)
}
return result
}
}
/**
* A node in the file tree.
*
* @author Kirill Grouchnikov
*/
private static class FileTreeNode implements TreeNode {
/**
* Node file.
*/
private File file
/**
* Children of the node file.
*/
private File[] children
/**
* Parent node.
*/
private TreeNode parent
/**
* Indication whether this node corresponds to a file system root.
*/
private boolean isFileSystemRoot
/**
* Creates a new file tree node.
*
* @param file
*Node file
* @param isFileSystemRoot
*Indicates whether the file is a file system root.
* @param parent
*Parent node.
*/
public FileTreeNode(File file, boolean isFileSystemRoot, TreeNode parent) {
this.file = file
this.isFileSystemRoot = isFileSystemRoot
this.parent = parent
this.children = this.file.listFiles()
if (this.children == null)
this.children = new File[0]
}
/**
* Creates a new file tree node.
*
* @param children
*Children files.
*/
public FileTreeNode(File[] children) {
this.file = null
this.parent = null
this.children = children
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#children()
*/
public Enumeration<?>children() {
final int elementCount = this.children.length
return new Enumeration<File>() {
int count = 0
/*
* (non-Javadoc)
*
* @see java.util.Enumeration#hasMoreElements()
*/
public boolean hasMoreElements() {
return this.count <elementCount
}
/*
* (non-Javadoc)
*
* @see java.util.Enumeration#nextElement()
*/
public File nextElement() {
if (this.count <elementCount) {
return FileTreeNode.this.children[this.count++]
}
throw new NoSuchElementException("Vector Enumeration")
}
}
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#getAllowsChildren()
*/
public boolean getAllowsChildren() {
return true
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#getChildAt(int)
*/
public TreeNode getChildAt(int childIndex) {
return new FileTreeNode(this.children[childIndex],
this.parent == null, this)
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#getChildCount()
*/
public int getChildCount() {
return this.children.length
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#getIndex(javax.swing.tree.TreeNode)
*/
public int getIndex(TreeNode node) {
FileTreeNode ftn = (FileTreeNode) node
for (int i = 0i <this.children.lengthi++) {
if (ftn.file.equals(this.children[i]))
return i
}
return -1
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#getParent()
*/
public TreeNode getParent() {
return this.parent
}
/*
* (non-Javadoc)
*
* @see javax.swing.tree.TreeNode#isLeaf()
*/
public boolean isLeaf() {
return (this.getChildCount() == 0)
}
}
/**
* The file tree.
*/
private JTree tree
/**
* Creates the file tree panel.
*/
public FileTreePanel() {
this.setLayout(new BorderLayout())
File[] roots = File.listRoots()
FileTreeNode rootTreeNode = new FileTreeNode(roots)
this.tree = new JTree(rootTreeNode)
this.tree.setCellRenderer(new FileTreeCellRenderer())
this.tree.setRootVisible(false)
final JScrollPane jsp = new JScrollPane(this.tree)
jsp.setBorder(new EmptyBorder(0, 0, 0, 0))
this.add(jsp, BorderLayout.CENTER)
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame("File tree")
frame.setSize(500, 400)
frame.setLocationRelativeTo(null)
frame.add(new FileTreePanel())
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
frame.setVisible(true)
}
})
}
}
Java中使用递归算法实现查找树形结构中所有父级和子级节点，用递归加一个全局变量标记是否已经找到，然后返回。
截取后面的一段例子：
if (list[i].ID.Equals(id) || found)
found = true
return
拓展资料
递归查询子级节点
1.一个节点可能有多个子级节点，每个自己节点可能还有更多的子级节点。
2.所以递归时的参数用一个list来接受，首先遍历参数list，分别查询pid为参数id的对象。
3.每一个参数id所查询返回的数据是一个对象的list。
4.遍历list获取符合条件的对象的id值，一份存到temp中用作递归的参数，并存到全局变量中用来获取所有符合条件的id。
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