java.lang.invoke.SerializedLambda Maven / Gradle / Ivy
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package java.lang.invoke;
import java.io.Serializable;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Objects;
/**
* Serialized form of a lambda expression. The properties of this class
* represent the information that is present at the lambda factory site, including
* static metafactory arguments such as the identity of the primary functional
* interface method and the identity of the implementation method, as well as
* dynamic metafactory arguments such as values captured from the lexical scope
* at the time of lambda capture.
*
* Implementors of serializable lambdas, such as compilers or language
* runtime libraries, are expected to ensure that instances deserialize properly.
* One means to do so is to ensure that the {@code writeReplace} method returns
* an instance of {@code SerializedLambda}, rather than allowing default
* serialization to proceed.
*
*
{@code SerializedLambda} has a {@code readResolve} method that looks for
* a (possibly private) static method called
* {@code $deserializeLambda$(SerializedLambda)} in the capturing class, invokes
* that with itself as the first argument, and returns the result. Lambda classes
* implementing {@code $deserializeLambda$} are responsible for validating
* that the properties of the {@code SerializedLambda} are consistent with a
* lambda actually captured by that class.
*
* @see LambdaMetafactory
*/
public final class SerializedLambda implements Serializable {
private static final long serialVersionUID = 8025925345765570181L;
private final Class capturingClass;
private final String functionalInterfaceClass;
private final String functionalInterfaceMethodName;
private final String functionalInterfaceMethodSignature;
private final String implClass;
private final String implMethodName;
private final String implMethodSignature;
private final int implMethodKind;
private final String instantiatedMethodType;
private final Object[] capturedArgs;
/**
* Create a {@code SerializedLambda} from the low-level information present
* at the lambda factory site.
*
* @param capturingClass The class in which the lambda expression appears
* @param functionalInterfaceClass Name, in slash-delimited form, of static
* type of the returned lambda object
* @param functionalInterfaceMethodName Name of the functional interface
* method for the present at the
* lambda factory site
* @param functionalInterfaceMethodSignature Signature of the functional
* interface method present at
* the lambda factory site
* @param implMethodKind Method handle kind for the implementation method
* @param implClass Name, in slash-delimited form, for the class holding
* the implementation method
* @param implMethodName Name of the implementation method
* @param implMethodSignature Signature of the implementation method
* @param instantiatedMethodType The signature of the primary functional
* interface method after type variables
* are substituted with their instantiation
* from the capture site
* @param capturedArgs The dynamic arguments to the lambda factory site,
* which represent variables captured by
* the lambda
*/
public SerializedLambda(Class capturingClass,
String functionalInterfaceClass,
String functionalInterfaceMethodName,
String functionalInterfaceMethodSignature,
int implMethodKind,
String implClass,
String implMethodName,
String implMethodSignature,
String instantiatedMethodType,
Object[] capturedArgs) {
this.capturingClass = capturingClass;
this.functionalInterfaceClass = functionalInterfaceClass;
this.functionalInterfaceMethodName = functionalInterfaceMethodName;
this.functionalInterfaceMethodSignature = functionalInterfaceMethodSignature;
this.implMethodKind = implMethodKind;
this.implClass = implClass;
this.implMethodName = implMethodName;
this.implMethodSignature = implMethodSignature;
this.instantiatedMethodType = instantiatedMethodType;
this.capturedArgs = Objects.requireNonNull(capturedArgs).clone();
}
/**
* Get the name of the class that captured this lambda.
* @return the name of the class that captured this lambda
*/
public String getCapturingClass() {
return capturingClass.getName().replace('.', '/');
}
/**
* Get the name of the invoked type to which this
* lambda has been converted
* @return the name of the functional interface class to which
* this lambda has been converted
*/
public String getFunctionalInterfaceClass() {
return functionalInterfaceClass;
}
/**
* Get the name of the primary method for the functional interface
* to which this lambda has been converted.
* @return the name of the primary methods of the functional interface
*/
public String getFunctionalInterfaceMethodName() {
return functionalInterfaceMethodName;
}
/**
* Get the signature of the primary method for the functional
* interface to which this lambda has been converted.
* @return the signature of the primary method of the functional
* interface
*/
public String getFunctionalInterfaceMethodSignature() {
return functionalInterfaceMethodSignature;
}
/**
* Get the name of the class containing the implementation
* method.
* @return the name of the class containing the implementation
* method
*/
public String getImplClass() {
return implClass;
}
/**
* Get the name of the implementation method.
* @return the name of the implementation method
*/
public String getImplMethodName() {
return implMethodName;
}
/**
* Get the signature of the implementation method.
* @return the signature of the implementation method
*/
public String getImplMethodSignature() {
return implMethodSignature;
}
/**
* Get the method handle kind (see {@link MethodHandleInfo}) of
* the implementation method.
* @return the method handle kind of the implementation method
*/
public int getImplMethodKind() {
return implMethodKind;
}
/**
* Get the signature of the primary functional interface method
* after type variables are substituted with their instantiation
* from the capture site.
* @return the signature of the primary functional interface method
* after type variable processing
*/
public final String getInstantiatedMethodType() {
return instantiatedMethodType;
}
/**
* Get the count of dynamic arguments to the lambda capture site.
* @return the count of dynamic arguments to the lambda capture site
*/
public int getCapturedArgCount() {
return capturedArgs.length;
}
/**
* Get a dynamic argument to the lambda capture site.
* @param i the argument to capture
* @return a dynamic argument to the lambda capture site
*/
public Object getCapturedArg(int i) {
return capturedArgs[i];
}
private Object readResolve() throws ReflectiveOperationException {
try {
Method deserialize = AccessController.doPrivileged(new PrivilegedExceptionAction() {
@Override
public Method run() throws Exception {
Method m = capturingClass.getDeclaredMethod("$deserializeLambda$", SerializedLambda.class);
m.setAccessible(true);
return m;
}
});
return deserialize.invoke(null, this);
}
catch (PrivilegedActionException e) {
Exception cause = e.getException();
if (cause instanceof ReflectiveOperationException)
throw (ReflectiveOperationException) cause;
else if (cause instanceof RuntimeException)
throw (RuntimeException) cause;
else
throw new RuntimeException("Exception in SerializedLambda.readResolve", e);
}
}
@Override
public String toString() {
return String.format("SerializedLambda[%s=%s, %s=%s.%s:%s, " +
"%s=%s %s.%s:%s, %s=%s, %s=%d]",
"capturingClass", capturingClass,
"functionalInterfaceMethod", functionalInterfaceClass,
functionalInterfaceMethodName,
functionalInterfaceMethodSignature,
"implementation",
null,
implClass, implMethodName, implMethodSignature,
"instantiatedMethodType", instantiatedMethodType,
"numCaptured", capturedArgs.length);
}
}