com.facebook.presto.jdbc.internal.jol.info.FieldData Maven / Gradle / Ivy
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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.facebook.presto.jdbc.internal.jol.info;
import com.facebook.presto.jdbc.internal.jol.util.VMSupport;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
/**
* Holds the field information, without the layout.
*
* @author Aleksey Shipilev
*/
public class FieldData {
/**
* Creates the synthetic field data.
*
* @param hostKlass class name where the field is declared
* @param fieldName field name
* @param fieldType string representation of field type
* @return field data
*/
public static FieldData create(String hostKlass, String fieldName, String fieldType) {
return new FieldData(null, -1, hostKlass, fieldName, fieldType);
}
/**
* Parses the field data from the existing field.
*
* @param field field to parse
* @return field data
*/
public static FieldData parse(Field field) {
return new FieldData(field, computeOffset(field), field.getDeclaringClass().getSimpleName(), field.getName(), field.getType().getSimpleName());
}
private final String name;
private final String type;
private final String klass;
private final Field refField;
private final int vmOffset;
private FieldData(Field refField, int vmOffset, String hostKlass, String fieldName, String fieldType) {
this.klass = hostKlass;
this.name = fieldName;
this.type = fieldType;
this.refField = refField;
this.vmOffset = vmOffset;
}
private static int computeOffset(Field field) {
if (Modifier.isStatic(field.getModifiers())) {
return (int) VMSupport.U.staticFieldOffset(field);
} else {
return (int) VMSupport.U.objectFieldOffset(field);
}
}
/**
* Answers the class for the field type
*
* @return string representation of field type
*/
public String typeClass() {
return type;
}
/**
* Answers the class for the field holder.
*
* @return string representation of holder class
*/
public String hostClass() {
return klass;
}
/**
* Answers the field name.
*
* @return field name
*/
public String name() {
return name;
}
/**
* Gets the string representation of field value,
* if appropriate.
*
* @param object the object to read the contents from
* @return field value in given object
*/
public String safeValue(Object object) {
if (refField != null) {
try {
return VMSupport.safeToString(refField.get(object));
} catch (IllegalAccessException iae) {
// exception, try again
}
try {
refField.setAccessible(true);
return VMSupport.safeToString(refField.get(object));
} catch (Exception e) {
return "(access denied)";
}
} else {
return "N/A";
}
}
/**
* The VM offset for the field, as discovered.
* Some layouters need to know this.
*
* @return vm offset
*/
public int vmOffset() {
if (vmOffset != -1) {
return vmOffset;
} else {
throw new IllegalStateException("VM offset is not defined");
}
}
}
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