如何从 Java 反射中获取 String 字段的值？

How to get value of String field from Java reflection?

提问by Paul Vargas

I have an object that has a String field. I can obtain this field by calling:

我有一个具有 String 字段的对象。我可以通过调用获取此字段：

Field field = someObj.getClass().getField("strField");

I sett a Field#set(Object)method, for setting the value of this instance's field, but the respective getter seems to be Field#get(Object), which is weird because I would have expected it to be Field#get().

我设置了一个Field#set(Object)方法，用于设置此实例字段的值，但相应的 getter 似乎是Field#get(Object)，这很奇怪，因为我原以为它是Field#get().

How do I obtain the value of the instance's strField?

如何获取实例的值strField？

回答by jtahlborn

if you are using java.lang.reflect.Field, the "setter" is Field.set(Object,Object)and the "getter" is Field.get(Object). in bothcases, the first parameter is the instance on which you want to access the field.

如果您使用的是java.lang.reflect.Field，则“setter”是Field.set(Object,Object)“getter” Field.get(Object)。在这两种情况下，第一个参数是您要访问该字段的实例。

回答by Paul Vargas

Even without the getter or the setter methods for a property, you can change or get the value using an object reference and Java Reflection.

即使没有属性的 getter 或 setter 方法，您也可以使用对象引用和 Java 反射来更改或获取值。

import java.lang.reflect.Field;

public class Bean {

    private String strField;

    public static void main(String[] args) throws Exception {
        Bean bean = new Bean();
        Field field = bean.getClass().getDeclaredField("strField");
        field.set(bean, "Hello");
        System.out.println(field.get(bean));
    }

}

回答by gerrytan

Easiest way is to use BeanUtils:

最简单的方法是使用BeanUtils：

String s = BeanUtils.getProperty(someObj, "strField");

Note that BeanUtils will attempt to convert your property into string. You need to have a getter and setter of the property

请注意 BeanUtils 将尝试将您的属性转换为字符串。你需要有一个属性的getter和setter