package com.sadhu;
import java.util.*;
import java.lang.reflect.*;
/**
反射---输入一个类，打印出类中所有元素
reflect包中有三个描述类元素的类：Field、Method、Constructor
*/
public class Sample
{
public static void main(String[] args)
{
String name;//收集用户输入的类
if(args.length > 0)
{
name = args[0];
}
else
{
Scanner in = new Scanner(System.in);
System.out.println("Enter class name!");
name = in.next();
}
try
{
Class cl = Class.forName(name);//获得用户输入类的Class类型
Class supercl = cl.getSuperclass();//获得用户输入类的超类
String modifiers = Modifier.toString(cl.getModifiers());//获得修饰符数值后用Modifier类解释出来。
if(modifiers.length() > 0)
{
System.out.print(modifiers + " ");
}
System.out.print("class " + name);
if(supercl != null)//如果想排除掉顶级根：&& supercl != Object.class
{
System.out.print(" extends "+supercl.getName());
}
System.out.print("\n{\n");
printConstructors(cl);//获得构造函数
System.out.println();
printMethods(cl);//获得方法
System.out.println();
printFields(cl);//获得字段
System.out.println("}");
}
catch (ClassNotFoundException e)
{
e.printStackTrace();
}
System.exit(0);
}
public static void printConstructors(Class cl)
{
Constructor[] constructors = cl.getDeclaredConstructors();//获得构造函数列表
for(Constructor c : constructors)
{
String name = c.getName();//获得名字
System.out.print(" ");
String modifiers = Modifier.toString(c.getModifiers());//获得修饰符
if(modifiers.length() > 0)
{
System.out.print(modifiers+" ");
}
System.out.print(name+"(");
Class[] paramTypes = c.getParameterTypes();//获得参数类型列表
for(int j = 0;j < paramTypes.length; j++)
{
System.out.print(paramTypes[j].getName());
if( j < paramTypes.length-1)
{
System.out.print(", ");
}
}
System.out.println(");");
}
}
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(" ");
String modifiers = Modifier.toString(m.getModifiers());
if(modifiers.length() > 0)
{
System.out.print(modifiers+" ");
}
System.out.print(retType.getName()+" "+name+"(");
Class[] paramTypes = m.getParameterTypes();
for(int j = 0;j < paramTypes.length; j++)
{
System.out.print(paramTypes[j].getName());
if( j < paramTypes.length-1)
{
System.out.print(", ");
}
}
System.out.println(");");
}
}
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+";");
}
}
}
/**
输出类似结果：
public final class java.util.Scanner extends java.lang.Object
{
private java.util.Scanner(java.nio.file.Path, java.nio.charset.Charset);
public java.util.Scanner(java.io.InputStream, java.lang.String);
public java.util.Scanner(java.io.InputStream);
public java.util.Scanner(java.nio.file.Path);
private java.util.Scanner(java.lang.Readable, java.util.regex.Pattern);
private java.util.Scanner(java.io.File, java.nio.charset.CharsetDecoder);
public java.util.Scanner(java.io.File, java.lang.String);
public java.util.Scanner(java.io.File);
public java.util.Scanner(java.nio.file.Path, java.lang.String);
public java.util.Scanner(java.nio.channels.ReadableByteChannel, java.lang.Stri
ng);
public java.util.Scanner(java.lang.Readable);
public java.util.Scanner(java.nio.channels.ReadableByteChannel);
public java.util.Scanner(java.lang.String);
public void remove();
public java.lang.String toString();
public boolean hasNext();
public boolean hasNext(java.lang.String);
public boolean hasNext(java.util.regex.Pattern);
public java.lang.String next();
public volatile java.lang.Object next();
public java.lang.String next(java.util.regex.Pattern);
public java.lang.String next(java.lang.String);
public void close();
public java.util.Scanner reset();
public double nextDouble();
public int nextInt(int);
public int nextInt();
public java.util.regex.MatchResult match();
public java.util.Scanner skip(java.util.regex.Pattern);
public java.util.Scanner skip(java.lang.String);
private void ensureOpen();
public java.util.Locale locale();
private static java.nio.charset.Charset toCharset(java.lang.String);
private static java.util.regex.Pattern boolPattern();
private void buildFloatAndDecimalPattern();
private java.lang.String buildIntegerPatternString();
private void cacheResult();
private void cacheResult(java.lang.String);
private void clearCaches();
private java.util.regex.Pattern decimalPattern();
public java.util.regex.Pattern delimiter();
public java.lang.String findInLine(java.util.regex.Pattern);
public java.lang.String findInLine(java.lang.String);
private java.lang.String findPatternInBuffer(java.util.regex.Pattern, int);
public java.lang.String findWithinHorizon(java.util.regex.Pattern, int);
public java.lang.String findWithinHorizon(java.lang.String, int);
private java.util.regex.Pattern floatPattern();
private java.lang.String getCachedResult();
private java.lang.String getCompleteTokenInBuffer(java.util.regex.Pattern);
public boolean hasNextBigDecimal();
public boolean hasNextBigInteger();
public boolean hasNextBigInteger(int);
public boolean hasNextBoolean();
public boolean hasNextByte(int);
public boolean hasNextByte();
public boolean hasNextDouble();
public boolean hasNextFloat();
public boolean hasNextInt(int);
public boolean hasNextInt();
public boolean hasNextLine();
public boolean hasNextLong(int);
public boolean hasNextLong();
public boolean hasNextShort();
public boolean hasNextShort(int);
private boolean hasTokenInBuffer();
private java.util.regex.Pattern integerPattern();
public java.io.IOException ioException();
private static java.util.regex.Pattern linePattern();
private static java.lang.Readable makeReadable(java.nio.channels.ReadableByteC
hannel, java.nio.charset.CharsetDecoder);
private static java.lang.Readable makeReadable(java.io.InputStream, java.nio.c
harset.Charset);
private static java.lang.Readable makeReadable(java.nio.channels.ReadableByteC
hannel);
private boolean makeSpace();
private java.lang.String matchPatternInBuffer(java.util.regex.Pattern);
public java.math.BigDecimal nextBigDecimal();
public java.math.BigInteger nextBigInteger();
public java.math.BigInteger nextBigInteger(int);
public boolean nextBoolean();
public byte nextByte();
public byte nextByte(int);
public float nextFloat();
public java.lang.String nextLine();
public long nextLong(int);
public long nextLong();
public short nextShort(int);
public short nextShort();
private java.lang.String processFloatToken(java.lang.String);
private java.lang.String processIntegerToken(java.lang.String);
public int radix();
private void readInput();
private boolean revertState(boolean);
private void revertState();
private void saveState();
private static java.util.regex.Pattern separatorPattern();
private void setRadix(int);
private void throwFor();
private static java.nio.charset.CharsetDecoder toDecoder(java.lang.String);
private void translateSavedIndexes(int);
public java.util.Scanner useDelimiter(java.lang.String);
public java.util.Scanner useDelimiter(java.util.regex.Pattern);
public java.util.Scanner useLocale(java.util.Locale);
public java.util.Scanner useRadix(int);
private void useTypeCache();
private java.nio.CharBuffer buf;
private static final int BUFFER_SIZE;
private int position;
private java.util.regex.Matcher matcher;
private java.util.regex.Pattern delimPattern;
private java.util.regex.Pattern hasNextPattern;
private int hasNextPosition;
private java.lang.String hasNextResult;
private java.lang.Readable source;
private boolean sourceClosed;
private boolean needInput;
private boolean skipped;
private int savedScannerPosition;
private java.lang.Object typeCache;
private boolean matchValid;
private boolean closed;
private int radix;
private int defaultRadix;
private java.util.Locale locale;
private sun.misc.LRUCache patternCache;
private java.io.IOException lastException;
private static java.util.regex.Pattern WHITESPACE_PATTERN;
private static java.util.regex.Pattern FIND_ANY_PATTERN;
private static java.util.regex.Pattern NON_ASCII_DIGIT;
private java.lang.String groupSeparator;
private java.lang.String decimalSeparator;
private java.lang.String nanString;
private java.lang.String infinityString;
private java.lang.String positivePrefix;
private java.lang.String negativePrefix;
private java.lang.String positiveSuffix;
private java.lang.String negativeSuffix;
private static volatile java.util.regex.Pattern boolPattern;
private static final java.lang.String BOOLEAN_PATTERN;
private java.util.regex.Pattern integerPattern;
private java.lang.String digits;
private java.lang.String non0Digit;
private int SIMPLE_GROUP_INDEX;
private static volatile java.util.regex.Pattern separatorPattern;
private static volatile java.util.regex.Pattern linePattern;
private static final java.lang.String LINE_SEPARATOR_PATTERN;
private static final java.lang.String LINE_PATTERN;
private java.util.regex.Pattern floatPattern;
private java.util.regex.Pattern decimalPattern;
static final boolean $assertionsDisabled;
}
*/
反射---输入一个类，打印出类中所有元素,布布扣,bubuko.com
原文地址：http://my.oschina.net/Sadhu/blog/294068
