Swing布局管理器

1、概述布局管理器的工作过程protected void addImpl(Component comp, Object constraints, int index) /*当我们删除组件时，要调用这个方法，而它要遍布容器内的所有组件，然后根据索引值调用remove(int *index)方法。*/public void remove(Component comp) /*根据索引值删除容器的组件,可以看到该方法调用了布局管理器的removeLayoutComponent()*/public void remove(int index) synchronized (getTreeLock() if (

2、index < 0 | index >= ncomponents) throw new ArrayIndexOutOfBoundsException(index);Component comp = componentindex;synchronized (getTreeLock() if (layoutMgr != null) /*通知布局管理器已经add了组件 */ if (layoutMgr instanceof LayoutManager2) (LayoutManager2)layoutMgr).addLayoutComponent(comp, constraints); e

3、lse if (constraints instanceof String) layoutMgr.addLayoutComponent(String)constraints, comp); synchronized (getTreeLock() if (comp.parent = this) Component component = ponent; for (int i = ncomponents; -i >= 0; ) if (componenti = comp) remove(i); if (layoutMgr != null) layoutMgr.removeLayoutComp

4、onent(comp); if (valid) invalidate(); /*返回容器当前的布局管理器*/public LayoutManager getLayout() /*这个是我们经常调用的方法,设置容器的布局管理器*/public void setLayout(LayoutManager mgr) public void doLayout() /让布局管理器进行布局组件Deprecatedpublic void layout() /* Invalidates the container. The container and all parents above it are marke

5、d as needing* to be laid out. This method can be called often, so it needs to execute quickly. */public void invalidate() LayoutManager layoutMgr = this.layoutMgr;/*取得容器的首选大小*/public Dimension getPreferredSize() return layoutMgr; layoutMgr = mgr; if (valid) invalidate(); layout(); LayoutManager layo

6、utMgr = this.layoutMgr; if (layoutMgr != null) layoutMgr.layoutContainer(this); if (layoutMgr instanceof LayoutManager2) LayoutManager2 lm = (LayoutManager2) layoutMgr; lm.invalidateLayout(this); super.invalidate(); return preferredSize(); 3Deprecatedpublic Dimension preferredSize() Dimension dim =

7、prefSize;if (dim = null | !(isPreferredSizeSet() | isValid() synchronized (getTreeLock() prefSize = (layoutMgr != null) ? layoutMgr.preferredLayoutSize(this) : super.preferredSize();dim = prefSize;if (dim != null)return new Dimension(dim);elsereturn dim;/*取得容器的最小大小*/public Dimension getMinimumSize()

8、 Deprecatedpublic Dimension minimumSize() Dimension dim = minSize;if (dim = null | !(isMinimumSizeSet() | isValid() synchronized (getTreeLock() minSize = (layoutMgr != null) ? layoutMgr.minimumLayoutSize(this) : super.minimumSize(); return minimumSize(); dim = minSize; if (dim != null)return new Dim

9、ension(dim);elsereturn dim;/*取得容器的最大大小*/布局管理器的实现AWT标准布局管理器自定义布局管理器import java.awt.Dimension;import java.awt.Insets;import java.awt.LayoutManager;/* author tianyistar*/public class ColumnLayout implements LayoutManager private int xInset = 5;private int yInset = 5;private int yGap = 2;public void add

10、LayoutComponent(String s, Component c) public void layoutContainer(Container c) Insets insets = c.getInsets();int height = yInset + insets.top;Component children = c.getComponents();Dimension compSize = null;for (int i = 0; i < children.length; i+) compSize = childreni.getPreferredSize();children

11、i.setSize(compSize.width, compSize.height);childreni.setLocation(xInset + insets.left, height);height += compSize.height + yGap;public Dimension minimumLayoutSize(Container c) /确定此容器的 insets，它指示容器边框的大小。Insets insets = c.getInsets();/Insets 对象是容器边界的表示形式。/它指定容器必须在其各个边缘留出的空间。这个空间可以是边界、空白空间或标题。 int height = yInset + insets.top;int width = 0 + insets.left + insets.right;Component children = c.getComponents();Dimension compSize = null;for (int i = 0; i < children.length; i+) compSize = childreni.getPreferredSize();height += compSize.height + yGap;width = Math.max(width, compSize.