java - Java 中的反射——意外的输出

Question

我正在编写一个类来使用反射获取有关指定类的信息。输出包括完全限定的方法名称，但我不希望输出中包含完全限定的名称。

这是一个例子。而不是:

public static java.lang.String java.lang.Integer.toString(int,int)

我希望它显示:

public static String toString(int, int);

这是我的类(class)的简化版本:

public class jr
{
    public static void main(String[] args) throws ClassNotFoundException
    {
        jr j = new jr();

        String str = java.lang.Integer;

        Class cls = Class.forName(str);
        j.print(cls);   
    }

   /*
    * Displays the Methods of the given class. The items displayed depends on 
    * the options entered.
    *
    * @param    cl    The class to be displayed
    */ 
    public void methods(Class cl)
    {
        // Get the Methods of the Class cl
        Method[] me = cl.getDeclaredMethods();

        for(Method x : me)
        {            
            System.out.println(x);
        }
    }

   /*
    * Displays the information about the class. Uses the options to filter which
    * information is printed.
    *
    * @param    cl    The class to be displayed
    */         
    public void print(Class cl)
    {
        System.out.println("\nMETHODS:");
        methods(cl);
    }
}

我总是可以解析字符串来清理它，但这看起来有点像黑客。但我没有看到更好的方法。

Answer 1

我建议你修改方法如下:

public void methods(Class cl) {
    // Get the Methods of the Class cl
    Method[] me = cl.getDeclaredMethods();

    for (Method x : me) {
        String parameterType = "";
        System.out.println(x);
        Class[] parameterTypes = x.getParameterTypes();
        for (Class c : parameterTypes)
        parameterType = parameterType + c.getSimpleName() + " ,";

        System.out.println(x.getModifiers() + " " + x.getReturnType().getSimpleName() + " " + x.getName() + " ( "
            + parameterType + " )");
    }
    }

输出方法:

public int java.lang.Integer.hashCode()
1 int hashCode (  )
public boolean java.lang.Integer.equals(java.lang.Object)
1 boolean equals ( Object , )
public static java.lang.String java.lang.Integer.toString(int)
9 String toString ( int , )
public static java.lang.String java.lang.Integer.toString(int,int)
9 String toString ( int ,int , )
public java.lang.String java.lang.Integer.toString()
1 String toString (  )
public static java.lang.String java.lang.Integer.toHexString(int)
9 String toHexString ( int , )
public static int java.lang.Integer.compare(int,int)
9 int compare ( int ,int , )
public int java.lang.Integer.compareTo(java.lang.Object)
4161 int compareTo ( Object , )
public int java.lang.Integer.compareTo(java.lang.Integer)
1 int compareTo ( Integer , )
public static java.lang.Integer java.lang.Integer.decode(java.lang.String) throws java.lang.NumberFormatException
9 Integer decode ( String , )
static void java.lang.Integer.getChars(int,int,char[])
8 void getChars ( int ,int ,char[] , )
public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String,int) throws java.lang.NumberFormatException
9 Integer valueOf ( String ,int , )
public static java.lang.Integer java.lang.Integer.valueOf(int)
9 Integer valueOf ( int , )
public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String) throws java.lang.NumberFormatException
9 Integer valueOf ( String , )
public int java.lang.Integer.intValue()
1 int intValue (  )
public static int java.lang.Integer.reverse(int)
9 int reverse ( int , )
static int java.lang.Integer.stringSize(int)
8 int stringSize ( int , )
public static int java.lang.Integer.reverseBytes(int)
9 int reverseBytes ( int , )
public byte java.lang.Integer.byteValue()
1 byte byteValue (  )
public double java.lang.Integer.doubleValue()
1 double doubleValue (  )
public float java.lang.Integer.floatValue()
1 float floatValue (  )
public long java.lang.Integer.longValue()
1 long longValue (  )
public short java.lang.Integer.shortValue()
1 short shortValue (  )
public static int java.lang.Integer.parseInt(java.lang.String) throws java.lang.NumberFormatException
9 int parseInt ( String , )
public static int java.lang.Integer.parseInt(java.lang.String,int) throws java.lang.NumberFormatException
9 int parseInt ( String ,int , )
public static int java.lang.Integer.bitCount(int)
9 int bitCount ( int , )
public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,java.lang.Integer)
9 Integer getInteger ( String ,Integer , )
public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,int)
9 Integer getInteger ( String ,int , )
public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String)
9 Integer getInteger ( String , )
public static int java.lang.Integer.highestOneBit(int)
9 int highestOneBit ( int , )
public static int java.lang.Integer.lowestOneBit(int)
9 int lowestOneBit ( int , )
public static int java.lang.Integer.numberOfLeadingZeros(int)
9 int numberOfLeadingZeros ( int , )
public static int java.lang.Integer.numberOfTrailingZeros(int)
9 int numberOfTrailingZeros ( int , )
public static int java.lang.Integer.rotateLeft(int,int)
9 int rotateLeft ( int ,int , )
public static int java.lang.Integer.rotateRight(int,int)
9 int rotateRight ( int ,int , )
public static int java.lang.Integer.signum(int)
9 int signum ( int , )
public static java.lang.String java.lang.Integer.toBinaryString(int)
9 String toBinaryString ( int , )
public static java.lang.String java.lang.Integer.toOctalString(int)
9 String toOctalString ( int , )
private static java.lang.String java.lang.Integer.toUnsignedString(int,int)
10 String toUnsignedString ( int ,int , )

我已经修改了内置的 toGenericString() 以满足您的需求:

package SO;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;

public class jr {
    // Modifiers that can be applied to a method in source code
    private static final int LANGUAGE_MODIFIERS = Modifier.PUBLIC | Modifier.PROTECTED | Modifier.PRIVATE
        | Modifier.ABSTRACT | Modifier.STATIC | Modifier.FINAL | Modifier.SYNCHRONIZED | Modifier.NATIVE;

    public static void main(String[] args) throws ClassNotFoundException {
    jr j = new jr();

    String str = "java.lang.Integer";

    Class<?> cls = Class.forName(str);
    j.print(cls);
    }

    /*
     * Displays the Methods of the given class. The items displayed depends on
     * the options entered.
     * 
     * @param cl The class to be displayed
     */
    public void methods(Class cl) {
    // Get the Methods of the Class cl
    Method[] me = cl.getDeclaredMethods();

    for (Method x : me) {
        String parameterType = "";
        System.out.println("simple   :" + x);
        System.out.println("generic  :" + x.toGenericString());
        System.out.println("modified :" + modifiedToGenericString(x));
        ;

    }
    }

    public String modifiedToGenericString(Method m) {
    try {
        StringBuilder sb = new StringBuilder();
        int mod = m.getModifiers() & LANGUAGE_MODIFIERS;
        if (mod != 0) {
        sb.append(Modifier.toString(mod) + " ");
        }
        Type[] typeparms = m.getTypeParameters();
        if (typeparms.length > 0) {
        boolean first = true;
        sb.append("<");
        for (Type typeparm : typeparms) {
            if (!first)
            sb.append(",");
            if (typeparm instanceof Class)
            sb.append(((Class) typeparm).getSimpleName());
            else
            sb.append(typeparm.toString());
            first = false;
        }
        sb.append("> ");
        }

        Type genRetType = m.getGenericReturnType();
        sb.append(((genRetType instanceof Class) ? ((Class) genRetType).getSimpleName() : genRetType.toString())
            + " ");

        // sb.append((m.getDeclaringClass()) + ".");
        sb.append(m.getName() + "(");
        Type[] params = m.getGenericParameterTypes();
        for (int j = 0; j < params.length; j++) {
        sb.append((params[j] instanceof Class) ? ((Class) params[j]) : (params[j].toString()));
        if (j < (params.length - 1))
            sb.append(",");
        }
        sb.append(")");
        Type[] exceptions = m.getGenericExceptionTypes();
        if (exceptions.length > 0) {
        sb.append(" throws ");
        for (int k = 0; k < exceptions.length; k++) {
            sb.append((exceptions[k] instanceof Class) ? ((Class) exceptions[k]).getSimpleName()
                : exceptions[k].toString());
            if (k < (exceptions.length - 1))
            sb.append(",");
        }
        }
        return sb.toString();
    } catch (Exception e) {
        return "<" + e + ">";
    }
    }

    /*
     * Displays the information about the class. Uses the options to filter
     * which information is printed.
     * 
     * @param cl The class to be displayed
     */
    public void print(Class cl) {
    System.out.println("\nMETHODS:");
    methods(cl);
    }
}

具有以下输出:

METHODS:
simple   :public int java.lang.Integer.hashCode()
generic  :public int java.lang.Integer.hashCode()
modified :public int hashCode()
simple   :public boolean java.lang.Integer.equals(java.lang.Object)
generic  :public boolean java.lang.Integer.equals(java.lang.Object)
modified :public boolean equals(class java.lang.Object)
simple   :public static java.lang.String java.lang.Integer.toString(int)
generic  :public static java.lang.String java.lang.Integer.toString(int)
modified :public static String toString(int)
simple   :public static java.lang.String java.lang.Integer.toString(int,int)
generic  :public static java.lang.String java.lang.Integer.toString(int,int)
modified :public static String toString(int,int)
simple   :public java.lang.String java.lang.Integer.toString()
generic  :public java.lang.String java.lang.Integer.toString()
modified :public String toString()
simple   :public static java.lang.String java.lang.Integer.toHexString(int)
generic  :public static java.lang.String java.lang.Integer.toHexString(int)
modified :public static String toHexString(int)
simple   :public static int java.lang.Integer.compare(int,int)
generic  :public static int java.lang.Integer.compare(int,int)
modified :public static int compare(int,int)
simple   :public int java.lang.Integer.compareTo(java.lang.Object)
generic  :public int java.lang.Integer.compareTo(java.lang.Object)
modified :public int compareTo(class java.lang.Object)
simple   :public int java.lang.Integer.compareTo(java.lang.Integer)
generic  :public int java.lang.Integer.compareTo(java.lang.Integer)
modified :public int compareTo(class java.lang.Integer)
simple   :public static java.lang.Integer java.lang.Integer.decode(java.lang.String) throws java.lang.NumberFormatException
generic  :public static java.lang.Integer java.lang.Integer.decode(java.lang.String) throws java.lang.NumberFormatException
modified :public static Integer decode(class java.lang.String) throws NumberFormatException
simple   :static void java.lang.Integer.getChars(int,int,char[])
generic  :static void java.lang.Integer.getChars(int,int,char[])
modified :static void getChars(int,int,class [C)
simple   :public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String,int) throws java.lang.NumberFormatException
generic  :public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String,int) throws java.lang.NumberFormatException
modified :public static Integer valueOf(class java.lang.String,int) throws NumberFormatException
simple   :public static java.lang.Integer java.lang.Integer.valueOf(int)
generic  :public static java.lang.Integer java.lang.Integer.valueOf(int)
modified :public static Integer valueOf(int)
simple   :public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String) throws java.lang.NumberFormatException
generic  :public static java.lang.Integer java.lang.Integer.valueOf(java.lang.String) throws java.lang.NumberFormatException
modified :public static Integer valueOf(class java.lang.String) throws NumberFormatException
simple   :public int java.lang.Integer.intValue()
generic  :public int java.lang.Integer.intValue()
modified :public int intValue()
simple   :public static int java.lang.Integer.reverse(int)
generic  :public static int java.lang.Integer.reverse(int)
modified :public static int reverse(int)
simple   :static int java.lang.Integer.stringSize(int)
generic  :static int java.lang.Integer.stringSize(int)
modified :static int stringSize(int)
simple   :public static int java.lang.Integer.reverseBytes(int)
generic  :public static int java.lang.Integer.reverseBytes(int)
modified :public static int reverseBytes(int)
simple   :public byte java.lang.Integer.byteValue()
generic  :public byte java.lang.Integer.byteValue()
modified :public byte byteValue()
simple   :public double java.lang.Integer.doubleValue()
generic  :public double java.lang.Integer.doubleValue()
modified :public double doubleValue()
simple   :public float java.lang.Integer.floatValue()
generic  :public float java.lang.Integer.floatValue()
modified :public float floatValue()
simple   :public long java.lang.Integer.longValue()
generic  :public long java.lang.Integer.longValue()
modified :public long longValue()
simple   :public short java.lang.Integer.shortValue()
generic  :public short java.lang.Integer.shortValue()
modified :public short shortValue()
simple   :public static int java.lang.Integer.parseInt(java.lang.String) throws java.lang.NumberFormatException
generic  :public static int java.lang.Integer.parseInt(java.lang.String) throws java.lang.NumberFormatException
modified :public static int parseInt(class java.lang.String) throws NumberFormatException
simple   :public static int java.lang.Integer.parseInt(java.lang.String,int) throws java.lang.NumberFormatException
generic  :public static int java.lang.Integer.parseInt(java.lang.String,int) throws java.lang.NumberFormatException
modified :public static int parseInt(class java.lang.String,int) throws NumberFormatException
simple   :public static int java.lang.Integer.bitCount(int)
generic  :public static int java.lang.Integer.bitCount(int)
modified :public static int bitCount(int)
simple   :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,java.lang.Integer)
generic  :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,java.lang.Integer)
modified :public static Integer getInteger(class java.lang.String,class java.lang.Integer)
simple   :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,int)
generic  :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String,int)
modified :public static Integer getInteger(class java.lang.String,int)
simple   :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String)
generic  :public static java.lang.Integer java.lang.Integer.getInteger(java.lang.String)
modified :public static Integer getInteger(class java.lang.String)
simple   :public static int java.lang.Integer.highestOneBit(int)
generic  :public static int java.lang.Integer.highestOneBit(int)
modified :public static int highestOneBit(int)
simple   :public static int java.lang.Integer.lowestOneBit(int)
generic  :public static int java.lang.Integer.lowestOneBit(int)
modified :public static int lowestOneBit(int)
simple   :public static int java.lang.Integer.numberOfLeadingZeros(int)
generic  :public static int java.lang.Integer.numberOfLeadingZeros(int)
modified :public static int numberOfLeadingZeros(int)
simple   :public static int java.lang.Integer.numberOfTrailingZeros(int)
generic  :public static int java.lang.Integer.numberOfTrailingZeros(int)
modified :public static int numberOfTrailingZeros(int)
simple   :public static int java.lang.Integer.rotateLeft(int,int)
generic  :public static int java.lang.Integer.rotateLeft(int,int)
modified :public static int rotateLeft(int,int)
simple   :public static int java.lang.Integer.rotateRight(int,int)
generic  :public static int java.lang.Integer.rotateRight(int,int)
modified :public static int rotateRight(int,int)
simple   :public static int java.lang.Integer.signum(int)
generic  :public static int java.lang.Integer.signum(int)
modified :public static int signum(int)
simple   :public static java.lang.String java.lang.Integer.toBinaryString(int)
generic  :public static java.lang.String java.lang.Integer.toBinaryString(int)
modified :public static String toBinaryString(int)
simple   :public static java.lang.String java.lang.Integer.toOctalString(int)
generic  :public static java.lang.String java.lang.Integer.toOctalString(int)
modified :public static String toOctalString(int)
simple   :private static java.lang.String java.lang.Integer.toUnsignedString(int,int)
generic  :private static java.lang.String java.lang.Integer.toUnsignedString(int,int)
modified :private static String toUnsignedString(int,int)