list頁面的字段要求可以根據用戶的喜好進行排序，所以每個用戶的字段都對應着不同的順序（字段順序存數據庫），我們從數據庫裏取出來的值是對象，但是前臺傳值是用的ajax和json array，所以就面臨着一個對象到json的轉換問題：1. 每個用戶的字段順序不固定，代碼不能寫死， 2. 根據用戶字段順序去取值，如果用if判斷每個值然後調用不同的方法，if條件語句太多。然後就看了下反射。
Model 類，跟正常model一樣
public class Person {
private String name;
private int age;
private String address;
private String phoneNumber;
private String sex;
public String getName() {
return name;
}
// 以下是get 和set方法，省略。
}
測試類
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
public class Test {
// init person object.
private Person initPerson() {
Person p = new Person();
p.setName("name");
p.setAge(21);
p.setAddress("this is my addrss");
p.setPhoneNumber("12312312312");
p.setSex("f");
return p;
}
public static void main(String[] args) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
Test test = new Test();
Person p = test.initPerson();
List<String> list = new ArrayList<String>();
// Add all get method.
// There is no ‘()’ of methods name.
list.add("getName");
list.add("getAge");
list.add("getAddress");
list.add("getPhoneNumber");
list.add("getSex");
for (String str : list) {
// Get method instance. first param is method name and second param is param type.
// Because Java exits the same method of different params, only method name and param type can confirm a method.
Method method = p.getClass().getMethod(str, new Class[0]);
// First param of invoke method is the object who calls this method.
// Second param is the param.
System.out.println(str + "(): Get Value is " + method.invoke(p, new Object[0]));
}
}
}
這樣就可以根據數據庫獲取的字段遍歷從對象去取相應的值了
上面那個方法是要給list添加get方法名，才能根據相應的get方法名去獲取值，如果前臺傳過來的只是一個屬性名，那我們還要轉換成相應的get方法，麻煩。
public static void getValueByProperty(Person p, String propertyName) throws IntrospectionException, IllegalArgumentException, IllegalAccessException, InvocationTargetException {
// get property by the argument propertyName.
PropertyDescriptor pd = new PropertyDescriptor(propertyName, p.getClass());
Method method = pd.getReadMethod();
Object o = method.invoke(p);
System.out.println("propertyName: " + propertyName + "\t value is: " + o);
}
public static void main(String[] args) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException, IntrospectionException {
Test test = new Test();
Person p = test.initPerson();
// get all properties.
Field[] fields = p.getClass().getDeclaredFields();
for (Field field : fields) {
getValueByProperty(p, field.getName());
}
}
這樣就能直接通過傳過來的propertyName獲取對應的value值了