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GridBagLayout练习
摘自http://blog.csdn.net/qq_18989901/article/details/52403737
GridBagLayout的用法
GridBagLayout是面板设计中最复杂的布局工具，当然用的好的话也是最方便的。
本文主要通过设计一个计算器界面的方式，来学习GridBagLayout的使用。最终的效果如下图所示：
GridBagLayout其组件的摆放都是有GridBagConstraints控制的。可以将需要设计的界面划分成许多个纵横的小网格，每个网格里面最多放置一个组件，一个组件可以占用多个网格。
网格的定义是由gridx和gridy定义的，前者表示横坐标，后者表示纵坐标，坐标是从0开始，从整个面板的左上角开始算起，所以在上图中，按钮7所在的位置gridx=0，gridy=0;以此类推，后面所有的网格位置都可以这样定义；
但是图中网格的宽度和高度是由什么定义的呢？答案是gridwidth和gridheight，为1表示占用一个网格，为2表示占用两个网格，如上图中"+"的gridwidth=1，gridheight=2；
知道这两个，就可以大体把网格划分清楚，每一个的具体位置也就有了着落。有朋友会说，我也是这样写的，但是组件怎么就那么小呢？那是因为GridBaglayout里面还有一项参数weight，她控制着组件随着面板的变化自身的变化情况，默认情况下weightx=0,weighty=0，意思是组件大小固定，不管面板如何变，自身就那么大，但是如果想让组件随面板变化的话，可以设置weightx和weighty，设置为浮点数也行，其值代表着变化的大小，也就是你宽度设为2，高度设为1的话，拉大面板会使组件越变越宽。
这三个是比较重要的Constraints，另外，还有insets，其有四个参数，表示其上左下右和相邻组件的最小间隔；ipadx和ipady表示组件间距，默认是0（其和insets不同读者可以自己摸索一下）；fill参数表示当网格区域比组件大的伤害，组件是以何种方式填充区域，是全方位还是水平或竖直；anchor是区域比组件大时，组件应该显示在区域的哪个方位，西北还是东南；
下面是我实现面板显示部分的所有代码：
1 package com.wst.bj; 2 3 import java.awt.GridBagConstraints; 4 import java.awt.GridBagLayout; 5 import java.awt.Insets; 6 7 import javax.swing.JButton; 8 import javax.swing.JFrame; 9 import javax.swing.JPanel; 10 import javax.swing.JTextField; 11 12 public class GridBagTest2 { 13 14 private JFrame jframe = new JFrame(); 15 private JButton bt1 = new JButton("1"); 16 private JButton bt2 = new JButton("2"); 17 private JButton bt3 = new JButton("3"); 18 private JButton bt4 = new JButton("4"); 19 private JButton bt5 = new JButton("5"); 20 private JButton bt6 = new JButton("6"); 21 private JButton bt7 = new JButton("7"); 22 private JButton bt8 = new JButton("8"); 23 private JButton bt9 = new JButton("9"); 24 private JButton bt0 = new JButton("0"); 25 private JButton btdot = new JButton("."); 26 private JButton btsignleft = new JButton("("); 27 private JButton btsignright = new JButton(")"); 28 private JButton btp = new JButton("+"); 29 private JButton btm = new JButton("-"); 30 private JButton btmp = new JButton("*"); 31 private JButton btd = new JButton("/"); 32 private JButton bte = new JButton("="); 33 private JButton bt = new JButton("00"); 34 private JButton btclear = new JButton("cl"); 35 private JTextField textField = new JTextField(); 36 37 public GridBagTest2() { 38 init(); 39 } 40 41 private void init() 42 { 43 FrameUtil.initFram(jframe, 300, 400); 44 JPanel jpanel = createPanel(); 45 jframe.add(jpanel); 46 } 47 48 49 private JPanel createPanel(){ 50 JPanel panel = new JPanel(); 51 52 GridBagLayout gbl = new GridBagLayout(); 53 GridBagConstraints gbs = new GridBagConstraints(); 54 panel.setLayout(gbl); 55 56 panel.add(bt7);panel.add(bt8);panel.add(bt9);panel.add(btp); 57 panel.add(bt4);panel.add(bt5);panel.add(bt6); 58 // panel.add(bt1);panel.add(bt2);panel.add(bt9);panel.add(btp); 59 panel.add(bt1);panel.add(bt2);panel.add(bt3);panel.add(btm); 60 panel.add(bt0);panel.add(btdot); 61 panel.add(btsignleft);panel.add(btsignright);panel.add(bte);panel.add(btmp); 62 panel.add(btclear);panel.add(bt); panel.add(btd); 63 panel.add(textField); 64 65 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 66 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 67 gbs.gridx=0;gbs.gridy=0; 68 gbl.setConstraints(bt7, gbs); 69 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 70 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 71 gbs.gridx=1;gbs.gridy=0; 72 gbl.setConstraints(bt8, gbs); 73 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 74 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 75 gbs.gridx=2;gbs.gridy=0; 76 gbl.setConstraints(bt9, gbs); 77 78 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=2; 79 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 80 gbs.gridx=3;gbs.gridy=0; 81 gbl.setConstraints(btp, gbs); 82 83 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 84 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 85 gbs.gridx=0;gbs.gridy=1; 86 gbl.setConstraints(bt4, gbs); 87 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 88 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 89 gbs.gridx=1;gbs.gridy=1; 90 gbl.setConstraints(bt5, gbs); 91 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 92 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 93 gbs.gridx=2;gbs.gridy=1; 94 gbl.setConstraints(bt6, gbs); 95 96 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 97 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 98 gbs.gridx=0;gbs.gridy=2; 99 gbl.setConstraints(bt1, gbs); 100 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 101 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 102 gbs.gridx=1;gbs.gridy=2; 103 gbl.setConstraints(bt2, gbs); 104 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 105 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 106 gbs.gridx=2;gbs.gridy=2; 107 gbl.setConstraints(bt3, gbs); 108 109 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=2; 110 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 111 gbs.gridx=3;gbs.gridy=2; 112 gbl.setConstraints(btm, gbs); 113 114 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=2;gbs.gridheight=1; 115 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 116 gbs.gridx=0;gbs.gridy=3; 117 gbl.setConstraints(bt0, gbs); 118 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 119 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 120 gbs.gridx=2;gbs.gridy=3; 121 gbl.setConstraints(btdot, gbs); 122 123 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 124 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 125 gbs.gridx=0;gbs.gridy=4; 126 gbl.setConstraints(btsignleft, gbs); 127 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 128 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 129 gbs.gridx=1;gbs.gridy=4; 130 gbl.setConstraints(btsignright, gbs); 131 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=2; 132 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 133 gbs.gridx=2;gbs.gridy=4; 134 gbl.setConstraints(bte, gbs); 135 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 136 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 137 gbs.gridx=3;gbs.gridy=4; 138 gbl.setConstraints(btmp, gbs); 139 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 140 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 141 gbs.gridx=0;gbs.gridy=5; 142 gbl.setConstraints(btclear, gbs); 143 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 144 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 145 gbs.gridx=1;gbs.gridy=5; 146 gbl.setConstraints(bt, gbs); 147 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=1;gbs.gridheight=1; 148 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 149 gbs.gridx=3;gbs.gridy=5; 150 gbl.setConstraints(btd, gbs); 151 152 gbs.fill=GridBagConstraints.BOTH;gbs.gridwidth=4;gbs.gridheight=3; 153 gbs.insets=new Insets(5, 5, 5, 5);gbs.weightx=1;gbs.weighty=1; 154 gbs.gridx=0;gbs.gridy=6; 155 gbl.setConstraints(textField, gbs); 156 157 return panel; 158 } 159 }
GridBagLayout练习
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