Java通过反射来打印类的方法实现

public class User {
    public int id;
    private String name;

    public User(String name, int id) {
        this.id = id;
        this.name = name;
    }

    private User(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

import java.lang.reflect.*;

public class Test {
    public static final String LINE = "\n";
    public static final String SPACE = "    ";

    public static void main(String[] args) throws Exception {
        Class<?> c = Class.forName("com.User");
        // Class<?> c = Test.class.getClassLoader().loadClass("com.User");
        StringBuilder sb = new StringBuilder();
        // 打印包，类名
        String packageName = c.getPackage().getName();
        sb.append("package " + packageName + ";" + LINE);
        sb.append(LINE);
        sb.append("public class " + c.getSimpleName() + "{" + LINE);
        // 打印成员变量
        Field[] declaredFields = c.getDeclaredFields();
        for (Field field : declaredFields) {
            // Field.getModifiers()返回一个int类型的数值，用于标识public、static等标识符
            String fieldModifier = Modifier.toString(field.getModifiers());
            // 获取属性类型的简要名称
            String typeName = field.getType().getSimpleName();
            // 属性的名称
            String fieldName = field.getName();
            sb.append(SPACE + fieldModifier + " " + typeName + " " + fieldName + ";" + LINE);
        }
        sb.append(LINE);
        // 打印构造
        Constructor<?>[] declaredConstructors = c.getDeclaredConstructors();
        for (Constructor<?> constructor : declaredConstructors) {
            // 构造函数的标识符
            String constructORModifier = Modifier.toString(constructor.getModifiers());
            sb.append(SPACE + constructorModifier + " " + c.getSimpleName() + " " + "(");
            // 打印构造函数的参数
            printParam(sb, constructor.getParameterTypes());
        }
        // 打印方法
        Method[] methods = c.getDeclaredMethods();
        for (Method method : methods) {
            // 方法的标识符
            String methodModifier = Modifier.toString(method.getModifiers());
            // 方法返回类型
            String returnTypeName = method.getReturnType().getSimpleName();
            // 方法名称
            String methodName = method.getName();
            sb.append(SPACE + methodModifier + " " + returnTypeName + " " + methodName + "(");
            printParam(sb, method.getParameterTypes());
        }

        sb.append("}");
        System.out.println(sb.toString());
    }

    private static void printParam(StringBuilder sb, Class<?>[] parameterTypes2) {
        Class<?>[] parameterTypes = parameterTypes2;
        for (int i = 0; i < parameterTypes.length; i++) {
            // 参数的类型
            String simpleName = parameterTypes[i].getSimpleName();
            if (i == 0) {
                sb.append(simpleName + " args");
            } else {
                sb.append(", " + simpleName + " args");
            }
        }
        sb.append(") {" + LINE);
        sb.append(SPACE + "}" + LINE);
        sb.append(LINE);
    }
}

String fieldModifier = Modifier.toString(field.getModifiers());

public static String toString(int mod) {
    StringBuilder sb = new StringBuilder();
    int len;

    if ((mod & PUBLIC) != 0)        sb.append("public ");
    if ((mod & PROTECTED) != 0)     sb.append("protected ");
    if ((mod & PRIVATE) != 0)       sb.append("private ");

    
    if ((mod & ABSTRACT) != 0)      sb.append("abstract ");
    if ((mod & STATIC) != 0)        sb.append("static ");
    if ((mod & FINAL) != 0)         sb.append("final ");
    if ((mod & TRANSIENT) != 0)     sb.append("transient ");
    if ((mod & VOLATILE) != 0)      sb.append("volatile ");
    if ((mod & SYNCHRONIZED) != 0)  sb.append("synchronized ");
    if ((mod & NATIVE) != 0)        sb.append("native ");
    if ((mod & STRICT) != 0)        sb.append("strictfp ");
    if ((mod & INTERFACE) != 0)     sb.append("interface ");

    if ((len = sb.length()) > 0)    
        return sb.toString().substring(0, len-1);
    return "";
}

Field[] declaredFields = c.getDeclaredFields();
Field[] fields = c.getFields();

public class Parent {
    public String parentAddress;
    private Integer Number;
}

String typeName = field.getType().getSimpleName();