Java的反射工具很强大,有句著名的话:No reflection ,no frameworks.
反射工具类:
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
public class ReflectionUtil {
/***
* 获取私有成员变量的值
*
*/
public static Object getValue(Object instance, String fieldName)
throws IllegalAccessException, NoSuchFieldException {
Field field = instance.getClass().getDeclaredField(fieldName);
field.setAccessible(true); // 参数值为true,禁止访问控制检查
return field.get(instance);
}
/***
* 设置私有成员变量的值
*
*/
public static void setValue(Object instance, String fileName, Object value)
throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
Field field = instance.getClass().getDeclaredField(fileName);
field.setAccessible(true);
field.set(instance, value);
}
/***
* 访问私有方法
*
*/
public static Object callMethod(Object instance, String methodName, Class[] classes, Object[] objects)
throws NoSuchMethodException, SecurityException, IllegalAccessException, IllegalArgumentException,
InvocationTargetException {
Method method = instance.getClass().getDeclaredMethod(methodName, classes);
method.setAccessible(true);
return method.invoke(instance, objects);
}
}
测试实体:
public class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
private String getInfo(String str, int num) {
return str + num + " apples";
}
}
测试代码:
public class ReflectTest {
public static void main(String[] args) throws Exception {
Person person = new Person("jack", 25);
// test get private value
System.out.println("jack's name:" + ReflectionUtil.getValue(person, "name"));
System.out.println("jack's age:" + ReflectionUtil.getValue(person, "age"));
// test set private value
ReflectionUtil.setValue(person, "name", "jason");
ReflectionUtil.setValue(person, "age", 10);
System.out.println("jack's name:" + ReflectionUtil.getValue(person, "name"));
System.out.println("jack's age:" + ReflectionUtil.getValue(person, "age"));
// test call private method
String result = (String) ReflectionUtil.callMethod(person, "getInfo", new Class[] { String.class, int.class },
new Object[] { "I hava ", 4 });
System.out.println("result: " + result);
}
}