import java.lang.reflect.Field; import javax.swing.JFrame; import javax.swing.BorderFactory; import java.awt.event.ActionListener; import java.awt.event.ActionEvent; import javax.swing.JTextField; import javax.swing.JButton; import javax.swing.JLabel; import javax.swing.JTextArea; import javax.swing.JScrollPane; import javax.swing.border.TitledBorder; import javax.swing.JPanel; import javax.swing.JOptionPane; import java.awt.BorderLayout; import java.awt.AWTEvent; import java.awt.Component; import java.awt.Container; import java.awt.Color; import javax.swing.text.JTextComponent; import javax.swing.UIManager; import java.awt.Dimension; import java.awt.Toolkit; import java.lang.reflect.Modifier; import java.lang.reflect.Constructor; import java.lang.reflect.Method; public class ViewClassInfoFrame extends JFrame implements ActionListener{ //输入类名单行文本框 private JTextField classNameField = new JTextField(); //查看类信息按钮 private JButton viewInfoButtom = new JButton(); //提示输入类名的标签 private JLabel hintLabel = new JLabel(); //显示类信息的多行文本框 private JTextArea InfoTextArea = new JTextArea(); //滚动容器，不能独立存在 private JScrollPane infoScrollPane = new JScrollPane(); //一个标题边框，提示结果信息 private TitledBorder titledBorder; //容器，可以盛放其他控件，不能单独存在 private JPanel upPanel = new JPanel(); private JPanel centerPanel = new JPanel(); //容器的布局管理器，边界划分，分为东南西北中，默认为CENTER private BorderLayout mainFrameBorderLayout = new BorderLayout(); private BorderLayout centerFrameBorderLayout = new BorderLayout(); private BorderLayout upFrameBorderLayout = new BorderLayout(); //通过构造函数创建对象实例时，初始化窗口和窗口中的组件 public ViewClassInfoFrame(){ //java.awt.Component，激活当前的窗口事件省略了this // enableEvents(AWTEvent.WINDOW_EVENT_MASK); init(); //初始化窗口 //java.awt.Container，当前窗口中GUI重新布局,生效 // validate(); } private void init(){ //初始化文本输入框 classNameField.setFont(new java.awt.Font("Dialog", 0, 15)); classNameField.setSelectedTextColor(java.awt.Color.WHITE); classNameField.setText(""); //清空文本 //初始化按钮和标签 viewInfoButtom.setFont(new java.awt.Font("Dialog", 0, 13)); viewInfoButtom.setText("查看类信息"); //将按钮事件注册到监听队列 viewInfoButtom.addActionListener(this); hintLabel.setFont(new java.awt.Font("Dialog", 0, 17)); hintLabel.setText("请输入完整的类名："); //初始化文本域，不可编辑，初始为空 InfoTextArea.setFont(new java.awt.Font("Dialog", 0, 13)); InfoTextArea.setEditable(false); InfoTextArea.setText(""); //初始化标题框，因为BorderFactory.createEtchedBorder()是静态方法，所以没有生成实例变量对象 titledBorder = new TitledBorder(javax.swing.BorderFactory.createEtchedBorder(Color.white, new Color(134,134,134)), "结果信息"); //初始化滚动容器--包含标题边框 infoScrollPane.setBorder(titledBorder); //向滚动容器中的视口或悬窗(观看的窗口)添加多行文本框组件 infoScrollPane.getViewport().add(InfoTextArea,null); //利用布局管理器将容器放入容器 upPanel.setLayout(upFrameBorderLayout); upPanel.add(hintLabel, BorderLayout.NORTH); upPanel.add(classNameField, BorderLayout.CENTER); upPanel.add(viewInfoButtom, BorderLayout.SOUTH); //将滚动容器和内部的组件放到centerPanel面板 centerPanel.setLayout(centerFrameBorderLayout); centerPanel.add(infoScrollPane, BorderLayout.CENTER); //获取当前窗口的内容容器,设置布局管理器 this.getContentPane().setLayout(mainFrameBorderLayout); this.setSize(new Dimension(650, 560)); this.setTitle("使用反射机制查看java的类信息"); //向窗口内容容器中添加容器 this.getContentPane().add(upPanel, BorderLayout.NORTH); this.getContentPane().add(centerPanel, BorderLayout.CENTER); //设置当前顶级容器操作的默认操作 this.getRootPane().setDefaultButton(viewInfoButtom); //进程监听窗口的关闭事件 this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); } //实现ActionListener接口，处理鼠标事件，方法一定要是public public void actionPerformed(ActionEvent e){ //从文本输入框获取输入的内容 String className = classNameField.getText(); StringBuffer buf = new StringBuffer(); try{ //利用反射获取类型系的背景是不知道类具体信息，仅知道类名或全限名(包路径+类名) Class c = Class.forName(className); buf.append(" /**类的声明**/ "); buf.append(getClassStatement(c)); buf.append(" "); buf.append(" /**字段**/ "); buf.append(getClassFields(c)); buf.append(" "); buf.append(" /**构造函数**/ "); buf.append(getClassConstructors(c)); buf.append(" "); buf.append(" /**方法**/ "); buf.append(getClassMethods(c)); buf.append(" "); }catch(Exception e1){ //调用对话框展示提示信息 JOptionPane.showMessageDialog(this, "没找到该类："+e1.getMessage()); } //在多行文本框中展示类信息 InfoTextArea.setText(buf.toString()); } //获取类的声明信息 private String getClassStatement(Class c){ StringBuffer buf = new StringBuffer(); if(c. getName().equals("java.lang.Object")){ buf.append("public class Object{"); }else{ String superClass = c.getSuperclass().getName(); buf.append("public class ").append(c.getName()); buf.append(" extends ").append(superClass).append(" {"); } return buf.toString(); } //获取Field信息 private String getClassFields(Class c){ StringBuffer buf = new StringBuffer(); Field[] fields = c.getDeclaredFields(); for(Field f:fields){ //将Field的访问控制符转换为String类型 String modifier = Modifier.toString(f.getModifiers()); String type = f.getType().getName(); buf.append(modifier).append(" ").append(type).append(" ").append(f.getName()).append("; "); } return buf.toString(); } //获取构造函数信息 private String getClassConstructors(Class c){ Constructor[] constructors = c.getDeclaredConstructors(); StringBuffer buf = new StringBuffer(); for(Constructor con:constructors){ //获取构造器的访问控制符 String modifier = Modifier.toString(con.getModifiers()); buf.append(modifier).append(" ").append(con.getName()).append(" ("); //获取构造函数所有参数类型 Class[] paremeters = con.getParameterTypes(); for(int i=0;i<paremeters.length;i++){ if(i==(paremeters.length-1)){ buf.append(paremeters[i].getName()); } else{ buf.append(paremeters[i].getName()).append(", "); } } buf.append(")"); Class[] excepTypes = con.getExceptionTypes(); for(int i=0;i<excepTypes.length;i++){ if(i==0){ buf.append("throws "); } if(i==(excepTypes.length-1)){ buf.append(excepTypes[i].getName()); }else{buf.append(excepTypes[i].getName()).append(", ");} } buf.append(" "); } return buf.toString(); } //获取所有方法信息 private String getClassMethods(Class c){ Method[] methods = c.getDeclaredMethods(); StringBuffer buf = new StringBuffer(); for(Method method:methods){ String modifier = Modifier.toString(method.getModifiers()); String type = method.getReturnType().getName(); String name = method.getName(); buf.append(modifier).append(" ").append(type).append(" ").append(name).append("("); Class[] parameters = method.getParameterTypes(); for(int i=0;i<parameters.length;i++){ if(i==0){ buf.append(parameters[i].getName()).append(", "); } if(i==(parameters.length-1)){ buf.append(parameters[i].getName()); }else{buf.append(parameters[i].getName()).append(", ");} } buf.append(") "); Class[] excepTypes = method.getExceptionTypes(); for(int i=0;i<excepTypes.length;i++){ if(i==0){ buf.append("throws ").append(excepTypes[i].getName()); } if(i==(excepTypes.length-1)){ buf.append(excepTypes[i].getName()); }else{buf.append(excepTypes[i].getName()).append(", ");} } buf.append(" "); } return buf.toString(); } public static void main(String[] args){ //设置界面的外观，为系统外观 // try{ // UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); // }catch(Exception e){ // e.printStackTrace(); // } ViewClassInfoFrame frame = new ViewClassInfoFrame(); //获取屏幕分辨率，使窗体居中 Dimension screenSize = Toolkit. getDefaultToolkit().getScreenSize(); Dimension frameSize = frame.getSize(); if(frameSize.height > screenSize.height){ frameSize.height = screenSize.height; } if(frameSize.width > screenSize.width){ frameSize.width = screenSize.width; } frame.setLocation((screenSize.width - frameSize.width)/2, (screenSize.height - frameSize.height)/2); frame.setVisible(true); } }
执行结果：
