Java AWT SpringLayout用法及代碼示例

AWT(抽象窗口工具包)中的 SpringLayout 類根據一組布局約束將子級布局到其關聯容器。每個約束都由一個 Spring 對象表示，該對象控製兩個組件邊之間的垂直或水平距離。邊可以屬於容器的任何子容器，也可以屬於容器本身。默認情況下，SpringLayout 創建約束，使其關聯組件具有最小值、首選值、最大值和實際值。

構造函數：

• SpringLayout():用於構造新的SpringLayout 類。

常用方法：

• void addLayoutComponent(Component com, Object cons):如果約束是一個實例SpringLayout.Constraints，將約束與指定組件相關聯。
• getLayoutAlignmentX(容器c)：用於返回 0.5f(居中)。
• getLayoutAlignmentY(容器c)：用於返回 0.5f(居中)。
• getConstraint((字符串邊名稱，組件 c):返回控製組件的指定邊與其父級的上邊或左邊之間距離的彈簧。
• getConstraint(組件c)：返回指定組件的約束。
• 布局容器(容器父級)：用於布置指定的容器。

以下示例程序旨在說明 SpringLayout 類：

• 程序1:下麵的程序將組件排列在一個J框架。我們創建 1J標簽名為“的組件標簽”並創建一個 1文本字段名為“文本域”並創建 2 個類，一個是JFrame類另一個是SpringLayout 類然後將它們添加到J框架通過方法add()。我們使用設置框架的可見性setvisible()方法。布局是通過使用設置的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(); 
              } 
          }); 
      } 
  } 

  輸出：
• 程序2:下麵的程序將組件排列在一個J框架。我們創建 1 個類，名為“彈簧布局類”並創建一個 4J按鈕名為“的組件b1”，“b2”，“b3”，“b4”，“b5”，然後將它們添加到J框架通過方法add()。我們使用以下方法設置框架的可見性setvisible()。布局設置為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); 
      } 
  } 

  輸出：
  

注意：上述程序可能無法在在線 IDE 中運行。請使用離線編譯器。

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