package net.bytebuddy.implementation;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import lombok.EqualsAndHashCode;
import net.bytebuddy.utility.privilege.SetAccessibleAction;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.security.AccessController;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Implementations of this interface explicitly initialize a loaded type. Usually, such implementations inject runtime
* context into an instrumented type which cannot be defined by the means of the Java class file format.
*/
public interface LoadedTypeInitializer {
/**
* Callback that is invoked on the creation of an instrumented type. If the loaded type initializer is alive, this
* method should be implemented empty instead of throwing an exception.
*
* @param type The manifestation of the instrumented type.
*/
void onLoad(Class<?> type);
/**
* Indicates if this initializer is alive and needs to be invoked. This is only meant as a mark. A loaded type
* initializer that is not alive might still be called and must therefore not throw an exception but rather
* provide an empty implementation.
*
* @return {@code true} if this initializer is alive.
*/
boolean isAlive();
/**
* A loaded type initializer that does not do anything.
*/
enum NoOp implements LoadedTypeInitializer {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public void onLoad(Class<?> type) {
/* do nothing */
}
@Override
public boolean isAlive() {
return false;
}
}
/**
* A type initializer for setting a value for a static field.
*/
@EqualsAndHashCode
class ForStaticField implements LoadedTypeInitializer, Serializable {
/**
* This class's serial version UID.
*/
private static final long serialVersionUID = 1L;
/**
* A value for accessing a static field.
*/
private static final Object STATIC_FIELD = null;
/**
* The name of the field.
*/
private final String fieldName;
/**
* The value of the field.
*/
private final Object value;
/**
* Creates a new {@link LoadedTypeInitializer} for setting a static field.
*
* @param fieldName the name of the field.
* @param value The value to be set.
*/
protected ForStaticField(String fieldName, Object value) {
this.fieldName = fieldName;
this.value = value;
}
@Override
public void onLoad(Class<?> type) {
try {
Field field = type.getDeclaredField(fieldName);
if (!Modifier.isPublic(field.getModifiers()) || !Modifier.isPublic(field.getDeclaringClass().getModifiers())) {
AccessController.doPrivileged(new SetAccessibleAction<Field>(field));
}
field.set(STATIC_FIELD, value);
} catch (IllegalAccessException exception) {
throw new IllegalArgumentException("Cannot access " + fieldName + " from " + type, exception);
} catch (NoSuchFieldException exception) {
throw new IllegalStateException("There is no field " + fieldName + " defined on " + type, exception);
}
}
@Override
public boolean isAlive() {
return true;
}
}
/**
* A compound loaded type initializer that combines several type initializers.
*/
@SuppressFBWarnings(value = "SE_BAD_FIELD", justification = "Serialization is considered opt-in for a rare use case")
@EqualsAndHashCode
class Compound implements LoadedTypeInitializer, Serializable {
/**
* This class's serial version UID.
*/
private static final long serialVersionUID = 1L;
/**
* The loaded type initializers that are represented by this compound type initializer.
*/
private final List<LoadedTypeInitializer> loadedTypeInitializers;
/**
* Creates a new compound loaded type initializer.
*
* @param loadedTypeInitializer A number of loaded type initializers in their invocation order.
*/
public Compound(LoadedTypeInitializer... loadedTypeInitializer) {
this(Arrays.asList(loadedTypeInitializer));
}
/**
* Creates a new compound loaded type initializer.
*
* @param loadedTypeInitializers A number of loaded type initializers in their invocation order.
*/
public Compound(List<? extends LoadedTypeInitializer> loadedTypeInitializers) {
this.loadedTypeInitializers = new ArrayList<LoadedTypeInitializer>();
for (LoadedTypeInitializer loadedTypeInitializer : loadedTypeInitializers) {
if (loadedTypeInitializer instanceof Compound) {
this.loadedTypeInitializers.addAll(((Compound) loadedTypeInitializer).loadedTypeInitializers);
} else if (!(loadedTypeInitializer instanceof NoOp)) {
this.loadedTypeInitializers.add(loadedTypeInitializer);
}
}
}
@Override
public void onLoad(Class<?> type) {
for (LoadedTypeInitializer loadedTypeInitializer : loadedTypeInitializers) {
loadedTypeInitializer.onLoad(type);
}
}
@Override
public boolean isAlive() {
for (LoadedTypeInitializer loadedTypeInitializer : loadedTypeInitializers) {
if (loadedTypeInitializer.isAlive()) {
return true;
}
}
return false;
}
}
}