Question

Java递归如何正确输出树形菜单

Answer 1

首先我们要建立树节点的类：
[java]
view
plain
copy
package
com.tree;
public
class
Node
{
private
Integer
id;
private
Integer
parentId;
private
String
name;
private
String
link;
public
Integer
getId()
{
return
id;
}
public
void
setId(Integer
id)
{
this.id
=
id;
}
public
Integer
getParentId()
{
return
parentId;
}
public
void
setParentId(Integer
parentId)
{
this.parentId
=
parentId;
}
public
String
getName()
{
return
name;
}
public
void
setName(String
name)
{
this.name
=
name;
}
public
String
getLink()
{
return
link;
}
public
void
setLink(String
link)
{
this.link
=
link;
}
}
输出树形菜单类：
[java]
view
plain
copy
package
com.tree;
import
java.util.ArrayList;
import
java.util.List;
public
class
Tree
{
private
StringBuffer
html
=
new
StringBuffer();
private
List<Node>
nodes;
public
Tree(List<Node>
nodes){
this.nodes
=
nodes;
}
public
String
buildTree(){
html.append("<ul>");
for
(Node
node
:
nodes)
{
Integer
id
=
node.getId();
if
(node.getParentId()
==
)
{
html.append("\r\n<li
id='"
+
id
+
"'>"
+
node.getName()+
"</li>");
build(node);
}
}
html.append("\r\n</ul>");
return
html.toString();
}
private
void
build(Node
node){
List<Node>
children
=
getChildren(node);
if
(!children.isEmpty())
{
html.append("\r\n<ul>");
for
(Node
child
:
children)
{
Integer
id
=
child.getId();
html.append("\r\n<li
id='"
+
id
+
"'>"
+
child.getName()+
"</li>");
build(child);
}
html.append("\r\n</ul>");
}
}
private
List<Node>
getChildren(Node
node){
List<Node>
children
=
new
ArrayList<Node>();
Integer
id
=
node.getId();
for
(Node
child
:
nodes)
{
if
(id.equals(child.getParentId()))
{
children.add(child);
}
}
return
children;
}
}