Get a Field object which backends data access to the given method name, from the supplied class - Java Reflection

Java examples for Reflection:Field Get

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Description

Get a Field object which backends data access to the given method name, from the supplied class

Demo Code


import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import sun.reflect.FieldAccessor;
import sun.reflect.ReflectionFactory;

public class Main{
    /**/*from  ww w. ja v  a2 s. c  o m*/
     * Get a Field object which backends data access to the given method name,
     * from the supplied class
     * @param m The name of the method
     * @param c The class to get the method from
     * @return a Field with an accessor that backends to the requested Method
     * @throws NoSuchMethodException 
     * @throws IllegalArgumentException 
     * @throws IllegalAccessException 
     */
    public static final Field getMethodField(String m, Class c)
            throws NoSuchMethodException, IllegalArgumentException,
            IllegalAccessException {
        // First, get ANY field at all to use as a base
        Field f = c.getDeclaredFields()[0];
        // Now set up the internal structures to 'look like' the given method
        // but chop up the name so that it is prettier for output
        if (m.startsWith("get") || m.startsWith("set"))
            m = m.substring(3, 4).toLowerCase() + m.substring(4);
        set("name", f, m);
        set("modifiers", f, Modifier.PUBLIC);
        // Finally, override the default FieldAccesors with our own
        FieldAccessor fa = new MethodPseudoAccessor(c, m);
        set("fieldAccessor", f, fa);
        set("overrideFieldAccessor", f, fa);
        return f;
    }
    /**
     * Find the requested Field declared in the target object's class, and set 
     * its value (irrespective of the field's modifiers)
     * @param fi The field name to seek
     * @param target The target object
     * @param v The value to set the field to
     * @throws java.lang.IllegalArgumentException
     * @throws java.lang.IllegalAccessException
     */
    public static final void set(String fi, Object target, Object v)
            throws IllegalArgumentException, IllegalAccessException {
        set(target.getClass(), fi, target, v);
    }
    /**
     * Find the requested Field declared in the given class, and set its value
     * (irrespective of the field's modifiers)
     * @param c The Class to look in
     * @param fi The field name to seek
     * @param target The target object
     * @param v The value to set the field to
     * @throws java.lang.IllegalArgumentException
     * @throws java.lang.IllegalAccessException
     */
    public static final void set(Class c, String fi, Object target, Object v)
            throws IllegalArgumentException, IllegalAccessException {
        for (Field f0 : c.getDeclaredFields())
            if (f0.getName().equals(fi))
                set(f0, target, v);
    }
    /**
     * Set the given field on target to value, irrespective of its modifiers
     * @param f The Field to set
     * @param target The object to set it on
     * @param v The value to set the field to
     * @throws java.lang.IllegalArgumentException
     * @throws java.lang.IllegalAccessException
     */
    public static final void set(Field f, Object target, Object v)
            throws IllegalArgumentException, IllegalAccessException {
        FieldAccessor fa = getReflectionFactory()
                .newFieldAccessor(f, false);
        fa.set(target, v);
    }
    /**
     * Get the Sun-JVM-specific ReflectionFactory object (in an unsafe manner). 
     * This allows us to assign values to and read from private Fields
     * @return the ReflectionFactory
     */
    public static final ReflectionFactory getReflectionFactory() {
        return (ReflectionFactory) AccessController
                .doPrivileged(new sun.reflect.ReflectionFactory.GetReflectionFactoryAction());
    }
}

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