实战SWT布局

标准的SWT布局类

FillLayout：在容器中以相同的大小单行或单列的排列组件

RowLayout：以单行或多行的方式使用几个选项(fill,wrap,spacing,justify,type)定制组件的排列方式

GridLayout：类似于swing的GridLayout的方式以格子的方式排列组件

FormLayout（SWT 2.0的新特性）：通过定义组件四个边的“粘贴”位置来排列组件，被引用的相对的组件可以父组件，也可以是同一容器中的其它组件。

在SWT中，可以由用户自定义布局类。

在简单的布局中，使用FillLayout和RowLayout也许就够用了，也比较简单。但是通常的布局都比较复杂，而且要求很精确。无论复杂程度如何，都可以由GridLayout或FormLayout来完成。通常GridLayout与FormLayout可以做成同样的效果，但是使用FormLayout更有效，不会像GridLayout产生resize导致的布局错位，也更简单。下面通过一个例子简单介绍FormLayout的使用。

布局效果

布局实施

1.首先定义窗口和它的空白边

Display.getDefault().dispose(); //移去平台核心启动画面

display = new Display();

shell = new Shell(display, SWT.TITLE);

FormLayout layout = new FormLayout();

layout.marginHeight = 10;

layout.marginWidth = 20;

shell.setLayout(layout);

shell.setText("用户登录");

2.创建窗口上的元素，其中下面的两个button由一个使用RowLayout的组件来包容。

name = new Label(shell, SWT.NONE);

name.setText("用户名");

nameText = new Text(shell, SWT.SINGLE SWT.BORDER);

pass = new Label(shell, SWT.NONE);

pass.setText("密码");

passText = new Text(shell, SWT.SINGLE SWT.BORDER);

passText.setEchoChar(´*´);

passText.setTabs(2);

bottom = new Composite(shell, SWT.NONE);

RowLayout rowLayout = new RowLayout();

rowLayout.justify = true; //justify定义组件在容器中分散开，效果类似于swing的FlowLayout

bottom.setLayout(rowLayout);

3.定义name标签的位置。它的顶边离父组件（窗口shell）的空白边距离是父组件clientArea（除空白边以外的空间）高度(height)的15%，偏移的点数(points)为0。

FormData data = new FormData();

data.top = new FormAttachment(15, 0);

name.setLayoutData(data);

4.定义name文本输入的位置。它的顶边在name标签的中心位置（这不是正确的表达，但程序是这样解释，事实上它的中心位置与name标签在同一条水平线上），左边距name标签的右边有10个点。

data = new FormData();

data.top = new FormAttachment(name, 0, SWT.CENTER);

data.left = new FormAttachment(name, 10, SWT.RIGHT);

nameText.setLayoutData(data);

5.定义pass标签的位置。它的顶边距name标签的底边有10个点数的偏移。

data = new FormData();

data.top = new FormAttachment(name, 10, SWT.BOTTOM);

pass.setLayoutData(data);

6.定义pass文本输入的位置。它的顶边在name标签的中心位置（同上），左边与name文本框的左边对齐。

data = new FormData();

data.top = new FormAttachment(pass, 0, SWT.CENTER);

data.left = new FormAttachment(nameText, 0, SWT.LEFT);

passText.setLayoutData(data);

7.定义bottom组件的位置。它的顶边距pass标签的底边15个点数，左边与pass标签的左边对齐，右边与pass文本输入的右边对齐。

data = new FormData();

data.top = new FormAttachment(pass, 15, SWT.BOTTOM);

data.left = new FormAttachment(pass, 0, SWT.LEFT);

data.right = new FormAttachment(passText, 0, SWT.RIGHT);

bottom.setLayoutData(data);

完整的源码

import org.eclipse.swt.SWT;

import org.eclipse.swt.events.SelectionAdapter;

import org.eclipse.swt.events.SelectionEvent;

import org.eclipse.swt.graphics.Rectangle;

import org.eclipse.swt.layout.FormAttachment;

import org.eclipse.swt.layout.FormData;

import org.eclipse.swt.layout.FormLayout;

import org.eclipse.swt.layout.RowLayout;

import org.eclipse.swt.widgets.Button;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Display;

import org.eclipse.swt.widgets.Label;

import org.eclipse.swt.widgets.Shell;

import org.eclipse.swt.widgets.Text;

import cn.com.efly.clientframe.core.Hook;

/**

* @author efly

* @version 1.0.0,11/22/02

*/

public final class LoginUI {

private Display display;

private Shell shell;

private Composite bottom;

private Label name;

private Label pass;

private Text nameText;

private Text passText;

private Button ok;

private Button exit;

private Rectangle clientArea;

private RootHook rootHook;

public LoginUI(Hook hook) {

rootHook = (RootHook) hook;

}

/**

* 显示登陆界面

*/

public void show() {

Display.getDefault().dispose();

display = new Display();

clientArea = display.getClientArea();

shell = new Shell(display, SWT.TITLE);

FormLayout layout = new FormLayout();

layout.marginHeight = 10;

layout.marginWidth = 20;

shell.setLayout(layout);

shell.setText("用户登录");

name = new Label(shell, SWT.NONE);

name.setText("用户名");

nameText = new Text(shell, SWT.SINGLE SWT.BORDER);

pass = new Label(shell, SWT.NONE);

pass.setText("密码");

passText = new Text(shell, SWT.SINGLE SWT.BORDER);

passText.setEchoChar(´*´);

passText.setTabs(2);

bottom = new Composite(shell, SWT.NONE);

RowLayout rowLayout = new RowLayout();

rowLayout.justify = true;

bottom.setLayout(rowLayout);

ok = new Button(bottom, SWT.PUSH);

ok.setText("确定");

ok.addSelectionListener(new SelectionAdapter() {

public void widgetSelected(SelectionEvent event) {

ok();

}

});

exit = new Button(bottom, SWT.PUSH);

exit.setText("取消");

exit.addSelectionListener(new SelectionAdapter() {

public void widgetSelected(SelectionEvent event) {

cancel();

}

});

FormData data = new FormData();

data.top = new FormAttachment(15, 0);

name.setLayoutData(data);

data = new FormData();

data.top = new FormAttachment(name, 0, SWT.CENTER);

data.left = new FormAttachment(name, 10, SWT.RIGHT);

nameText.setLayoutData(data);

data = new FormData();

data.top = new FormAttachment(name, 10, SWT.BOTTOM);

pass.setLayoutData(data);

data = new FormData();

data.top = new FormAttachment(pass, 0, SWT.CENTER);

data.left = new FormAttachment(nameText, 0, SWT.LEFT);

passText.setLayoutData(data);

data = new FormData();

data.top = new FormAttachment(pass, 15, SWT.BOTTOM);

data.left = new FormAttachment(pass, 0, SWT.LEFT);

data.right = new FormAttachment(passText, 0, SWT.RIGHT);

bottom.setLayoutData(data);

shell.pack();

Rectangle shellBounds = shell.getBounds();

shell.setLocation(

(clientArea.width - shellBounds.width) / 2,

(clientArea.height - shellBounds.height) / 2);

shell.open();

while (!shell.isDisposed()) {

if (!display.readAndDispatch())

display.sleep();

}

}

private void dispose() {

display.dispose();

}

private void cancel() {

dispose();

}

private void ok() {

verify();

}

private void verify() {

rootHook.runPlatform();

}

public static void main(String[]){

new LoginUI(null).show();

}

}