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package org.apache.qpid.tools.util;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Set;
public class ArgumentsParser
{
public ArgumentsParser()
{
}
public <T> T parse(String[] args, Class<T> pojoClass)
{
T object;
try
{
object = pojoClass.newInstance();
}
catch (Exception e)
{
throw new IllegalArgumentException("Cannot instantiate object of class " + pojoClass, e);
}
for (String arg: args)
{
int pos = arg.indexOf('=');
if (pos == -1)
{
throw new IllegalArgumentException("Invalid argument '" + arg + "' Argument should be specified in format <name>=<value>");
}
String name = arg.substring(0, pos);
String value = arg.substring(pos + 1);
Field field = findField(pojoClass, name);
if (field != null)
{
setField(object, field, value);
}
}
return object;
}
private Field findField(Class<?> objectClass, String name)
{
Field[] fields = objectClass.getDeclaredFields();
Field field = null;
for (int i = 0 ; i< fields.length ; i++)
{
if (fields[i].getName().equals(name) && !Modifier.isFinal(fields[i].getModifiers()))
{
field = fields[i];
break;
}
}
return field;
}
private void setField(Object object, Field field, String value)
{
Object convertedValue = convertStringToType(value, field.getType(), field.getName());
field.setAccessible(true);
try
{
field.set(object, convertedValue);
}
catch (IllegalAccessException e)
{
throw new RuntimeException("Cannot access field " + field.getName());
}
}
private Object convertStringToType(String value, Class<?> fieldType, String fieldName)
{
Object o;
if (fieldType == String.class)
{
o = value;
}
else if (fieldType == boolean.class)
{
try
{
o = Boolean.parseBoolean(value);
}
catch(Exception e)
{
throw new RuntimeException("Cannot convert to boolean argument " + fieldName);
}
}
else if (fieldType == int.class)
{
try
{
o = Integer.parseInt(value);
}
catch(Exception e)
{
throw new RuntimeException("Cannot convert to int argument " + fieldName);
}
}
else
{
throw new RuntimeException("Unsupported tye " + fieldType + " in " + fieldName);
}
return o;
}
public void usage(Class<?> objectClass, Set<String> requiredFields)
{
System.out.println("Supported arguments:");
Field[] fields = objectClass.getDeclaredFields();
Object object = null;
try
{
object = objectClass.newInstance();
}
catch(Exception e)
{
// ignore any
}
for (int i = 0 ; i< fields.length ; i++)
{
Field field = fields[i];
if (!Modifier.isFinal(field.getModifiers()))
{
Object defaultValue = null;
try
{
field.setAccessible(true);
defaultValue = field.get(object);
}
catch(Exception e)
{
// ignore any
}
System.out.println(" " + field.getName() + " ( type: "
+ field.getType().getSimpleName().toLowerCase()
+ (object != null ? ", default: " + defaultValue : "")
+ (requiredFields != null && requiredFields.contains(field.getName()) ? ", mandatory" : "")
+ ")");
}
}
}
}
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