java利用反射来调用一个类的私有方法和成员变量

public class BeanUtils {

public static void printMethods(String className)
throws ClassNotFoundException {
Class<?> classType = Class.forName(className);
Method[] methods = classType.getDeclaredMethods();
StringBuilder log = new StringBuilder();
for (Method method : methods) {

log.append(method.getReturnType().getName() + " " + method.getName());
Class<?>[] parameterTypes = method.getParameterTypes();
log.append("(");
if (parameterTypes != null && parameterTypes.length > 0) {
for (int i = 0; i < parameterTypes.length - 1; ++i) {
Class<?> clas = parameterTypes[i];
String parameterName = clas.getName();
log.append(parameterName + ", ");
}
Class<?> clas = parameterTypes[parameterTypes.length - 1];
String parameterName = clas.getName();
log.append(parameterName);
}
log.append(")\n");

}
log.append("*****************************");
System.out.println(log);
}

public static void printFields(String className)
throws ClassNotFoundException {
Class<?> classType = Class.forName(className);

Field[] fields = classType.getDeclaredFields();
StringBuilder log = new StringBuilder();
for (Field field : fields) {
// System.out.println(field);
log.append(field.getName()).append("\n");
}
log.append("*****************************");
System.out.println(log);
}
}

public class BeanUtilsTest {

@Test
public void testPrintMethods() {
String clsName = "java.lang.String";
try {
BeanUtils.printMethods(clsName);
assertTrue(true);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
assertTrue(false);
}
}

@Test
public void testPrintFields() {
String clsName = "java.lang.String";
try {
BeanUtils.printFields(clsName);
assertTrue(true);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
assertTrue(false);
}
}

}