java利用反射打印出類的結構

1 輸入一個類名：java.lang.String將打印出String類定義的結構，例如：

public final class java.lang.String
{
  public java.lang.String([B,int,int);
  public java.lang.String([B,java.nio.charset.Charset);
  public java.lang.String([B,java.lang.String);
  public java.lang.String([B,int,int,java.nio.charset.Charset);
  public java.lang.String([B,int,int,java.lang.String);
  java.lang.String([C,boolean);
  public java.lang.String(java.lang.StringBuilder);
  public java.lang.String(java.lang.StringBuffer);
  public java.lang.String([B);
  public java.lang.String([I,int,int);
  public java.lang.String();
  public java.lang.String([C);
  public java.lang.String(java.lang.String);
  public java.lang.String([C,int,int);
  public java.lang.String([B,int);
  public java.lang.String([B,int,int,int);

  public boolean equals(java.lang.Object);
  public java.lang.String toString();
  public int hashCode();
  public int compareTo(java.lang.String);
  public volatile int compareTo(java.lang.Object);
  public int indexOf(java.lang.String,int);
  public int indexOf(java.lang.String);
  public int indexOf(int,int);
  public int indexOf(int);
  static int indexOf([C,int,int,[C,int,int,int);
  static int indexOf([C,int,int,java.lang.String,int);
  public static java.lang.String valueOf(int);
  public static java.lang.String valueOf(long);
  public static java.lang.String valueOf(float);
  public static java.lang.String valueOf(boolean);
  public static java.lang.String valueOf([C);
  public static java.lang.String valueOf([C,int,int);
  public static java.lang.String valueOf(java.lang.Object);
  public static java.lang.String valueOf(char);
  public static java.lang.String valueOf(double);
  public char charAt(int);
  private static void checkBounds([B,int,int);
  public int codePointAt(int);
  public int codePointBefore(int);
  public int codePointCount(int,int);
  public int compareToIgnoreCase(java.lang.String);
  public java.lang.String concat(java.lang.String);
  public boolean contains(java.lang.CharSequence);
  public boolean contentEquals(java.lang.CharSequence);
  public boolean contentEquals(java.lang.StringBuffer);
  public static java.lang.String copyValueOf([C);
  public static java.lang.String copyValueOf([C,int,int);
  public boolean endsWith(java.lang.String);
  public boolean equalsIgnoreCase(java.lang.String);
  public static transient java.lang.String format(java.util.Locale,java.lang.String,[Ljava.lang.Object;);
  public static transient java.lang.String format(java.lang.String,[Ljava.lang.Object;);
  public void getBytes(int,int,[B,int);
  public [B getBytes(java.nio.charset.Charset);
  public [B getBytes(java.lang.String);
  public [B getBytes();
  public void getChars(int,int,[C,int);
void getChars([C,int);
  private int indexOfSupplementary(int,int);
  public native java.lang.String intern();
  public boolean isEmpty();
  public static transient java.lang.String join(java.lang.CharSequence,[Ljava.lang.CharSequence;);
  public static java.lang.String join(java.lang.CharSequence,java.lang.Iterable);
  public int lastIndexOf(int);
  public int lastIndexOf(java.lang.String);
  static int lastIndexOf([C,int,int,java.lang.String,int);
  public int lastIndexOf(java.lang.String,int);
  public int lastIndexOf(int,int);
  static int lastIndexOf([C,int,int,[C,int,int,int);
  private int lastIndexOfSupplementary(int,int);
  public int length();
  public boolean matches(java.lang.String);
  private boolean nonSyncContentEquals(java.lang.AbstractStringBuilder);
  public int offsetByCodePoints(int,int);
  public boolean regionMatches(int,java.lang.String,int,int);
  public boolean regionMatches(boolean,int,java.lang.String,int,int);
  public java.lang.String replace(char,char);
  public java.lang.String replace(java.lang.CharSequence,java.lang.CharSequence);
  public java.lang.String replaceAll(java.lang.String,java.lang.String);
  public java.lang.String replaceFirst(java.lang.String,java.lang.String);
  public [Ljava.lang.String; split(java.lang.String);
  public [Ljava.lang.String; split(java.lang.String,int);
  public boolean startsWith(java.lang.String,int);
  public boolean startsWith(java.lang.String);
  public java.lang.CharSequence subSequence(int,int);
  public java.lang.String substring(int);
  public java.lang.String substring(int,int);
  public [C toCharArray();
  public java.lang.String toLowerCase(java.util.Locale);
  public java.lang.String toLowerCase();
  public java.lang.String toUpperCase();
  public java.lang.String toUpperCase(java.util.Locale);
  public java.lang.String trim();

  private final [C value;
  private int hash;
  private static final long serialVersionUID;
  private static final [Ljava.io.ObjectStreamField; serialPersistentFields;
  public static final java.util.Comparator CASE_INSENSITIVE_ORDER;
}

主程序以下：

    public static void main(String[] args) throws ClassNotFoundException
    {
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 {
            Class c1=Class.forName(name);
            Class superClass=c1.getSuperclass();
            //獲取類的修飾符
            String modifiers=Modifier.toString(c1.getModifiers());
            if (modifiers.length()>0) {
                System.out.print(modifiers+" ");
            }
            System.out.print("class "+c1.getName());
            
            if (superClass!=null&&superClass!=Object.class) {
                System.out.print(" extends "+superClass.getName());
            }
            
            //\n表示換行
            System.out.print("\n{\n");
            //打印構造器
            printConstractors(c1);
            System.out.println();
            //打印類的方法
            printMethods(c1);
            
            System.out.println();
            //打印域
            printFields(c1);
            
            System.out.println("}");
            
        } catch (Exception e) {
            // TODO: handle exception
        }

        }

private static void printFields(Class c1) {
        // TODO Auto-generated method stub
        Field[] fields= c1.getDeclaredFields();
        for (Field field : fields) {
            Class type= field.getType();
            String name=field.getName();
            System.out.print("  ");
            String modifiers=Modifier.toString(field.getModifiers());
            if (modifiers.length()>0) {
                System.out.print(modifiers+" ");
            }
            System.out.println(type.getName()+" "+name+";");
        }
    }


    private static void printMethods(Class c1) {
        // TODO Auto-generated method stub
        //獲取當前類的全部方法
        Method[] methods= c1.getDeclaredMethods();
        for (Method m : methods) {
            Class returnType= m.getReturnType();
            String methodName=m.getName();
            String modifiers=Modifier.toString(m.getModifiers());
            if (modifiers.length()>0) {
                System.out.print("  "+modifiers+" ");
            }
            System.out.print(returnType.getName()+" "+methodName+"(");
            
            //打印方法參數
            Class[] paramTypes= m.getParameterTypes();
            for (int i = 0; i < paramTypes.length; i++) {
                if (i>0) {
                    System.out.print(",");
                }
                System.out.print(paramTypes[i].getName());
            }
            System.out.println(");");
        }
    }


    private static void printConstractors(Class c1) {
        // TODO Auto-generated method stub
        //獲得當前類的全部構造器，包括受保護的和私有的，不包含超類的
        Constructor[] constructors= c1.getDeclaredConstructors();
        for (Constructor constructor : constructors) {
            System.out.print("  ");
            String name=constructor.getName();
            String modifiers=Modifier.toString(constructor.getModifiers());
            if (modifiers.length()>0) {
                System.out.print(modifiers+" ");
            }
            System.out.print(name+"(");
            
            //打印構造器的參數
            Class[] paramsTypes= constructor.getParameterTypes();
            for (int i = 0; i < paramsTypes.length; i++) {
                if (i>0) {
                    System.out.print(",");
                }
                System.out.print(paramsTypes[i].getName());
            }
            System.out.println(");");
        }
    }