Java AWT SpringLayout用法及代码示例

AWT(抽象窗口工具包)中的 SpringLayout 类根据一组布局约束将子级布局到其关联容器。每个约束都由一个 Spring 对象表示，该对象控制两个组件边之间的垂直或水平距离。边可以属于容器的任何子容器，也可以属于容器本身。默认情况下，SpringLayout 创建约束，使其关联组件具有最小值、首选值、最大值和实际值。

构造函数：

• SpringLayout():用于构造新的SpringLayout 类。

常用方法：

• void addLayoutComponent(Component com, Object cons):如果约束是一个实例SpringLayout.Constraints，将约束与指定组件相关联。
• getLayoutAlignmentX(容器c)：用于返回 0.5f(居中)。
• getLayoutAlignmentY(容器c)：用于返回 0.5f(居中)。
• getConstraint((字符串边名称，组件 c):返回控制组件的指定边与其父级的上边或左边之间距离的弹簧。
• getConstraint(组件c)：返回指定组件的约束。
• 布局容器(容器父级)：用于布置指定的容器。

以下示例程序旨在说明 SpringLayout 类：

• 程序1:下面的程序将组件排列在一个J框架。我们创建 1J标签名为“的组件标签”并创建一个 1文本字段名为“文本域”并创建 2 个类，一个是JFrame类另一个是SpringLayout 类然后将它们添加到J框架通过方法add()。我们使用设置框架的可见性setvisible()方法。布局是通过使用设置的setLayout()方法。

  
  // Java program to show Example of SpringLayout. 
  // in java. Importing different Package. 
  import java.awt.Container; 
  import javax.swing.JFrame; 
  import javax.swing.JLabel; 
  import javax.swing.JTextField; 
  import javax.swing.SpringLayout; 
    
  // construct a class springdemo 
  public class Springdemo { 
    
      // It is used to create and show GUI 
      private static void createAndShowGUI() 
      { 
    
          // Creating Object of "JFrame" class 
          JFrame frame = new JFrame("MySpringDemp"); 
    
          // Function to set default  
          // close operation of JFrame. 
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    
          // to get content pane 
          Container contentPane = frame.getContentPane(); 
    
          // Creating Object of "Springlayout" class 
          SpringLayout layout = new SpringLayout(); 
    
          // to set content pane 
          contentPane.setLayout(layout); 
    
          // Initialization of object  
          // "label" of JLabel class. 
          JLabel label = new JLabel("Label: "); 
    
          // Initialization of object  
          // "label" of JLabel class. 
          JTextField textField = new JTextField("Enter the text ", 15); 
    
          // to add content pane of JLabel 
          contentPane.add(label); 
    
          // to add content pane of JTextField 
          contentPane.add(textField); 
    
          // It is used to put the layout 
          // constraint in JFrame using springLayout class 
          layout.putConstraint(SpringLayout.WEST, label,  
                     6, SpringLayout.WEST, contentPane); 
                       
          layout.putConstraint(SpringLayout.NORTH, label,  
                     6, SpringLayout.NORTH, contentPane); 
                       
          layout.putConstraint(SpringLayout.WEST, textField, 
                               6, SpringLayout.EAST, label); 
                                 
          layout.putConstraint(SpringLayout.NORTH, textField,  
                         6, SpringLayout.NORTH, contentPane); 
                           
          layout.putConstraint(SpringLayout.EAST, contentPane,  
                             6, SpringLayout.EAST, textField); 
                               
          layout.putConstraint(SpringLayout.SOUTH, contentPane,  
                             6, SpringLayout.SOUTH, textField); 
    
          // Function to pack the JFrame. 
          frame.pack(); 
    
          // Function to set visible status of JFrame. 
          frame.setVisible(true); 
      } 
        
      // Main Method 
      public static void main(String[] args) 
      { 
          javax.swing.SwingUtilities.invokeLater(new Runnable()  
          { 
                
              // create a class 
              public void run() 
              { 
                  // to create and show GUI 
                  createAndShowGUI(); 
              } 
          }); 
      } 
  } 

  输出：
• 程序2:下面的程序将组件排列在一个J框架。我们创建 1 个类，名为“弹簧布局类”并创建一个 4J按钮名为“的组件b1”，“b2”，“b3”，“b4”，“b5”，然后将它们添加到J框架通过方法add()。我们使用以下方法设置框架的可见性setvisible()。布局设置为setLayout()方法。

  
  // Java program to show Example of SpringLayout. 
  // in java. Importing different Package. 
  import java.awt.*; 
  import javax.swing.*; 
    
  // construct a class Springclassdemo 
  public class Springclassdemo { 
        
      // Main Method 
      public static void main(String[] arguments) 
      { 
    
          // main window 
          // Function to set the default look  
          // and feel decorated status of JFrame. 
          JFrame.setDefaultLookAndFeelDecorated(true); 
    
          // Creating Object of "JFrame" class 
          JFrame frame = new JFrame("SpringLayoutExample Example"); 
    
          // Function to set the default  
          // close operation status of JFrame 
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    
          // Function to set the  
          // size status of JFrame 
          frame.setSize(300, 200); 
    
          // to get the content pane 
          Container content = frame.getContentPane(); 
    
          // Creating Object of "SpringLayout" class 
          SpringLayout layout = new SpringLayout(); 
    
          // to set the layout class 
          frame.setLayout(layout); 
    
          // Initialization of object  
          // "b1" of JButton class. 
          Component b1 = new JButton("GEEKS"); 
    
          // Initialization of object  
          // "b2" of JButton class. 
          Component b2 = new JButton("GFG"); 
    
          // Initialization of object 
          // "b3" of JButton class. 
          Component b3 = new JButton("JAVA"); 
    
          // Initialization of object 
          // "b4" of JButton class. 
          Component b4 = new JButton("Sudo Placement"); 
    
          // Adding the JButton "b1" on frame 
          frame.add(b1); 
    
          // Adding the JButton "b2" on frame 
          frame.add(b2); 
    
          // Adding the JButton "b3" on frame 
          frame.add(b3); 
    
          // Adding the JButton "b4" on frame 
          frame.add(b4); 
    
          // It is used to put the layout 
          // constraint in JFrame using  
          // springLayout class on b1 JButton 
          layout.putConstraint(SpringLayout.WEST, b1,  
                     25, SpringLayout.WEST, content); 
                       
          layout.putConstraint(SpringLayout.NORTH, b1,  
                      10, SpringLayout.NORTH, content); 
    
          // It is used to put the layout 
          // constraint in JFrame using  
          // springLayout class on b2 JButton 
          layout.putConstraint(SpringLayout.WEST, b2,  
                     50, SpringLayout.WEST, content); 
                       
          layout.putConstraint(SpringLayout.NORTH, b2, 
                          10, SpringLayout.SOUTH, b1); 
    
          // It is used to put the layout 
          // constraint in JFrame using  
          // springLayout class on b3 JButton 
          layout.putConstraint(SpringLayout.WEST, b3,  
                     75, SpringLayout.WEST, content); 
                       
          layout.putConstraint(SpringLayout.NORTH, b3,  
                          10, SpringLayout.SOUTH, b2); 
    
          // It is used to put the layout 
          // constraint in JFrame using  
          // springLayout class on b4 JButton 
          layout.putConstraint(SpringLayout.WEST, b4,  
                          15, SpringLayout.EAST, b1); 
                            
          layout.putConstraint(SpringLayout.NORTH, b4, 
                      10, SpringLayout.NORTH, content); 
    
          // Function to set the 
          // visible status of JFrame 
          frame.setVisible(true); 
      } 
  } 

  输出：
  

注意：上述程序可能无法在在线 IDE 中运行。请使用离线编译器。

参考： https://docs.oracle.com/javase/7/docs/api/javax/swing/SpringLayout.html