每次实现Object的toString()方法很麻烦，所以通过反射写了个通用的toString()方法
public String toString() {
StringBuffer buffer = new StringBuffer();
Class clazz = getClass();
String fullName = clazz.getName();
int position = fullName.lastIndexOf(".");
String shortName = fullName.substring(position + 1);
buffer.append(shortName);
buffer.append(": [");
Field[] fields = clazz.getDeclaredFields();
Field.setAccessible(fields, true);
for (int i = 0; i < fields.length; i++) {
Field field = fields[i];
try {
buffer.append(field.getName());
buffer.append("=");
buffer.append(field.get(this));
buffer.append(", ");
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
}
buffer.setLength(buffer.length() - 2);
buffer.append("]");
return buffer.toString();
}