Sample for use of schemata without location specification.

a.xsd

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="A"
           xmlns:xs="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">
    <xs:complexType name="AddressType">
        <xs:sequence>
            <xs:element name="Line1" type="xs:string" />
            <xs:element name="Line2" type="xs:string" />
        </xs:sequence>
    </xs:complexType>
</xs:schema>

b.xsd

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema targetNamespace="B"
           xmlns:a="A"
           xmlns:xs="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">
    <xs:import namespace="A" />
    <xs:complexType name="CustomerType">
        <xs:sequence>
            <xs:element name="name" type="xs:string" />
            <xs:element name="address" type="a:AddressType" />
        </xs:sequence>
    </xs:complexType>
</xs:schema>

XsdSample.java

import org.w3c.dom.ls.LSInput;

import javax.xml.XMLConstants;
import javax.xml.bind.util.JAXBSource;
import javax.xml.transform.dom.DOMSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.UncheckedIOException;

public class XsdSample {

    public static void main(String[] args) throws Exception {
        SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
        factory.setResourceResolver((type, namespaceURI, publicId, systemId, baseURI) -> {
            if (namespaceURI.equals("A")) {
                LSInput input = new SimpleLSInput();
                try {
                    input.setByteStream(XsdSample.class.getResource("/a.xsd").openStream());
                } catch (IOException e) {
                    throw new UncheckedIOException(e);
                }
                return input;
            }
            return null;
        });
        Schema schema = factory.newSchema(XsdSample.class.getResource("/b.xsd"));
    }

    private static class SimpleLSInput implements LSInput {

        private Reader characterStream;
        private InputStream byteStream;
        private String stringData;

        private String systemId, publicId, baseURI, encoding;

        private boolean certifiedText;

        @Override
        public Reader getCharacterStream() {
            return characterStream;
        }

        @Override
        public void setCharacterStream(Reader characterStream) {
            this.characterStream = characterStream;
        }

        @Override
        public InputStream getByteStream() {
            return byteStream;
        }

        @Override
        public void setByteStream(InputStream byteStream) {
            this.byteStream = byteStream;
        }

        @Override
        public String getStringData() {
            return stringData;
        }

        @Override
        public void setStringData(String stringData) {
            this.stringData = stringData;
        }

        @Override
        public String getSystemId() {
            return systemId;
        }

        @Override
        public void setSystemId(String systemId) {
            this.systemId = systemId;
        }

        @Override
        public String getPublicId() {
            return publicId;
        }

        @Override
        public void setPublicId(String publicId) {
            this.publicId = publicId;
        }

        @Override
        public String getBaseURI() {
            return baseURI;
        }

        @Override
        public void setBaseURI(String baseURI) {
            this.baseURI = baseURI;
        }

        @Override
        public String getEncoding() {
            return encoding;
        }

        @Override
        public void setEncoding(String encoding) {
            this.encoding = encoding;
        }

        @Override
        public boolean getCertifiedText() {
            return certifiedText;
        }

        @Override
        public void setCertifiedText(boolean certifiedText) {
            this.certifiedText = certifiedText;
        }
    }
}