📅 最后修改于: 2020-11-10 04:48:39 🧑 作者: Mango
布局是指容器内组件的布置。换句话说，可以说布局是将组件放置在容器内的特定位置。布局控件的任务由布局管理器自动完成。
布局管理器自动将所有组件放置在容器内。即使您不使用布局管理器，组件仍将由默认布局管理器定位。可以手动布置控件，但是由于以下两个原因，这变得非常困难。
处理容器内的大量控件非常繁琐。
通常，当我们需要排列组件的宽度和高度信息时，不会给出它们。
Java提供了各种布局管理器来定位控件。大小，形状和排列之类的属性在一个布局管理器之间会有所不同。当applet或应用程序窗口的大小发生变化时，组件的大小，形状和排列也会相应地发生变化，即，布局管理器会适应appletviewer或应用程序窗口的大小。
布局管理器与每个Container对象关联。每个布局管理器都是实现LayoutManager接口的类的对象。
以下是定义布局管理器功能的接口。
| Sr.No. | Interface & Description |
|---|---|
| 1 | LayoutManager
The LayoutManager interface declares those methods which need to be implemented by the class, whose object will act as a layout manager. |
| 2 | LayoutManager2
The LayoutManager2 is the sub-interface of the LayoutManager. This interface is for those classes that know how to layout containers based on layout constraint object. |
以下是使用AWT设计GUI时常用的控件列表。
| Sr.No. | LayoutManager & Description |
|---|---|
| 1 | BorderLayout
The borderlayout arranges the components to fit in the five regions: east, west, north, south, and center. |
| 2 | CardLayout
The CardLayout object treats each component in the container as a card. Only one card is visible at a time. |
| 3 | FlowLayout
The FlowLayout is the default layout. It layout the components in a directional flow. |
| 4 | GridLayout
The GridLayout manages the components in the form of a rectangular grid. |
| 5 | GridBagLayout
This is the most flexible layout manager class. The object of GridBagLayout aligns the component vertically, horizontally, or along their baseline without requiring the components of the same size. |
| 6 | GroupLayout
The GroupLayout hierarchically groups the components in order to position them in a Container. |
| 7 | SpringLayout
A SpringLayout positions the children of its associated container according to a set of constraints. |