corejava第10版

2019-05-22 19:31:49 +08:00
1 parent 2021c3c227
commit 6165543dd3
@@ -0,0 +1,126 @@
+package reflection;
+
+import java.util.*;
+import java.lang.reflect.*;
+
+/**
+ * This program uses reflection to print all features of a class.
+ * @version 1.1 2004-02-21
+ * @author Cay Horstmann
+ */
+public class ReflectionTest
+{
+   public static void main(String[] args)
+   {
+      // read class name from command line args or user input
+      String name;
+      if (args.length > 0) name = args[0];
+      else
+      {
+         Scanner in = new Scanner(System.in);
+         System.out.println("Enter class name (e.g. java.util.Date): ");
+         name = in.next();
+      }
+
+      try
+      {
+         // print class name and superclass name (if != Object)
+         Class cl = Class.forName(name);
+         Class supercl = cl.getSuperclass();
+         String modifiers = Modifier.toString(cl.getModifiers());
+         if (modifiers.length() > 0) System.out.print(modifiers + " ");
+         System.out.print("class " + name);
+         if (supercl != null && supercl != Object.class) System.out.print(" extends "
+               + supercl.getName());
+
+         System.out.print("\n{\n");
+         printConstructors(cl);
+         System.out.println();
+         printMethods(cl);
+         System.out.println();
+         printFields(cl);
+         System.out.println("}");
+      }
+      catch (ClassNotFoundException e)
+      {
+         e.printStackTrace();
+      }
+      System.exit(0);
+   }
+
+   /**
+    * Prints all constructors of a class
+    * @param cl a class
+    */
+   public static void printConstructors(Class cl)
+   {
+      Constructor[] constructors = cl.getDeclaredConstructors();
+
+      for (Constructor c : constructors)
+      {
+         String name = c.getName();
+         System.out.print("   ");
+         String modifiers = Modifier.toString(c.getModifiers());
+         if (modifiers.length() > 0) System.out.print(modifiers + " ");         
+         System.out.print(name + "(");
+
+         // print parameter types
+         Class[] paramTypes = c.getParameterTypes();
+         for (int j = 0; j < paramTypes.length; j++)
+         {
+            if (j > 0) System.out.print(", ");
+            System.out.print(paramTypes[j].getName());
+         }
+         System.out.println(");");
+      }
+   }
+
+   /**
+    * Prints all methods of a class
+    * @param cl a class
+    */
+   public static void printMethods(Class cl)
+   {
+      Method[] methods = cl.getDeclaredMethods();
+
+      for (Method m : methods)
+      {
+         Class retType = m.getReturnType();
+         String name = m.getName();
+
+         System.out.print("   ");
+         // print modifiers, return type and method name
+         String modifiers = Modifier.toString(m.getModifiers());
+         if (modifiers.length() > 0) System.out.print(modifiers + " ");         
+         System.out.print(retType.getName() + " " + name + "(");
+
+         // print parameter types
+         Class[] paramTypes = m.getParameterTypes();
+         for (int j = 0; j < paramTypes.length; j++)
+         {
+            if (j > 0) System.out.print(", ");
+            System.out.print(paramTypes[j].getName());
+         }
+         System.out.println(");");
+      }
+   }
+
+   /**
+    * Prints all fields of a class
+    * @param cl a class
+    */
+   public static void printFields(Class cl)
+   {
+      Field[] fields = cl.getDeclaredFields();
+
+      for (Field f : fields)
+      {
+         Class type = f.getType();
+         String name = f.getName();
+         System.out.print("   ");
+         String modifiers = Modifier.toString(f.getModifiers());
+         if (modifiers.length() > 0) System.out.print(modifiers + " ");         
+         System.out.println(type.getName() + " " + name + ";");
+      }
+   }
+}