将字符串转换为输入流，然后将其读入SOAP消息工厂。

InputStream is = new ByteArrayInputStream(send.getBytes());
SOAPMessage request = MessageFactory.newInstance().createMessage(null, is);

你可以在这里阅读如何做到这一点。

这对我有用：

SOAPMessage sm = MessageFactory.newInstance(SOAPConstants.SOAP_1_2_PROTOCOL).createMessage(new MimeHeaders(), is);

我测量了使用SAXSource提供SOAPMessage比公认答案中使用的内部SAAJ解析实现快50%左右：

SOAPMessage message = messageFactory.createMessage();
message.getSOAPPart().setContent(new SAXSource(new InputSource(new StringReader(send))));

以下是测试各种XML解析源和工厂缓存影响的基准测试：

/*
Benchmark (jdk1.8.0_202 32-bit)                                       Mode  Cnt     Score     Error  Units
SoapMessageBenchmark.testCreateMessage                               thrpt  100  4156,685 ? 215,571  ops/s
SoapMessageBenchmark.testCreateMessageWithMessageFactoryNotCached    thrpt  100  3709,299 ? 115,495  ops/s
SoapMessageBenchmark.testSetContentDom                               thrpt  100  5935,972 ? 215,389  ops/s
SoapMessageBenchmark.testSetContentDomWithDocumentBuilderNotCached   thrpt  100  3433,539 ? 218,889  ops/s
SoapMessageBenchmark.testSetContentSax                               thrpt  100  6693,179 ? 319,581  ops/s
SoapMessageBenchmark.testSetContentSaxAndExtractContentAsDocument    thrpt  100  4109,924 ? 229,987  ops/s
SoapMessageBenchmark.testSetContentStax                              thrpt  100  5126,822 ? 249,648  ops/s
SoapMessageBenchmark.testSetContentStaxWithXmlInputFactoryNotCached  thrpt  100  4630,860 ? 235,773  ops/s
*/

package org.sample;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Timeout;
import org.openjdk.jmh.annotations.Warmup;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.soap.MessageFactory;
import javax.xml.soap.SOAPBody;
import javax.xml.soap.SOAPConstants;
import javax.xml.soap.SOAPException;
import javax.xml.soap.SOAPMessage;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stax.StAXSource;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.Throughput)
@Warmup(iterations = 10, time = 100, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 10, time = 100, timeUnit = TimeUnit.MILLISECONDS)
@Timeout(time = 10)
public class SoapMessageBenchmark {

    private static MessageFactory messageFactory;
    private static DocumentBuilder documentBuilder;
    private static XMLInputFactory xmlInputFactory;

    static {
        try {
            documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            messageFactory = MessageFactory.newInstance(SOAPConstants.SOAP_1_1_PROTOCOL);
            xmlInputFactory = XMLInputFactory.newInstance();
        } catch (SOAPException | ParserConfigurationException e) {
            throw new IllegalStateException(e);
        }
    }

    @State(Scope.Benchmark)
    public static class S {
        byte[] bytes = ("<soap:Envelope xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\n" +
                                "  <soap:Header>\n" +
                                "    <ResponseHeader xmlns=\"https://www.google.com/apis/ads/publisher/v201905\">\n" +
                                "      <requestId>xxxxxxxxxxxxxxxxxxxx</requestId>\n" +
                                "      <responseTime>1063</responseTime>\n" +
                                "    </ResponseHeader>\n" +
                                "  </soap:Header>\n" +
                                "  <soap:Body>\n" +
                                "    <getAdUnitsByStatementResponse xmlns=\"https://www.google.com/apis/ads/publisher/v201905\">\n" +
                                "      <rval>\n" +
                                "        <totalResultSetSize>1</totalResultSetSize>\n" +
                                "        <startIndex>0</startIndex>\n" +
                                "        <results>\n" +
                                "          <id>2372</id>\n" +
                                "          <name>RootAdUnit</name>\n" +
                                "          <description></description>\n" +
                                "          <targetWindow>TOP</targetWindow>\n" +
                                "          <status>ACTIVE</status>\n" +
                                "          <adUnitCode>1002372</adUnitCode>\n" +
                                "          <inheritedAdSenseSettings>\n" +
                                "            <value>\n" +
                                "              <adSenseEnabled>true</adSenseEnabled>\n" +
                                "              <borderColor>FFFFFF</borderColor>\n" +
                                "              <titleColor>0000FF</titleColor>\n" +
                                "              <backgroundColor>FFFFFF</backgroundColor>\n" +
                                "              <textColor>000000</textColor>\n" +
                                "              <urlColor>008000</urlColor>\n" +
                                "              <adType>TEXT_AND_IMAGE</adType>\n" +
                                "              <borderStyle>DEFAULT</borderStyle>\n" +
                                "              <fontFamily>DEFAULT</fontFamily>\n" +
                                "              <fontSize>DEFAULT</fontSize>\n" +
                                "            </value>\n" +
                                "          </inheritedAdSenseSettings>\n" +
                                "        </results>\n" +
                                "      </rval>\n" +
                                "    </getAdUnitsByStatementResponse>\n" +
                                "  </soap:Body>\n" +
                                "</soap:Envelope>").getBytes();
    }

    @Benchmark
    public SOAPBody testCreateMessage(S s) throws SOAPException, IOException {
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            SOAPMessage message = messageFactory.createMessage(null, inputStream);
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public SOAPBody testCreateMessageWithMessageFactoryNotCached(S s) throws SOAPException, IOException {
        MessageFactory messageFactory = MessageFactory.newInstance(SOAPConstants.SOAP_1_1_PROTOCOL);
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            SOAPMessage message = messageFactory.createMessage(null, inputStream);
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public SOAPBody testSetContentDom(S s) throws SOAPException, IOException, SAXException {
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            Document document = documentBuilder.parse(inputStream);
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new DOMSource(document));
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public SOAPBody testSetContentDomWithDocumentBuilderNotCached(S s) throws SOAPException, IOException, SAXException, ParserConfigurationException {
        DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            Document document = documentBuilder.parse(inputStream);
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new DOMSource(document));
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public SOAPBody testSetContentSax(S s) throws SOAPException, IOException {
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new SAXSource(new InputSource(inputStream)));
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public Document testSetContentSaxAndExtractContentAsDocument(S s) throws SOAPException, IOException {
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new SAXSource(new InputSource(inputStream)));
            return message.getSOAPBody().extractContentAsDocument();
        }
    }

    @Benchmark
    public SOAPBody testSetContentStax(S s) throws SOAPException, IOException, XMLStreamException {
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            XMLStreamReader xmlStreamReader = new StreamReaderDelegate(xmlInputFactory.createXMLStreamReader(inputStream)) {
                @Override
                public String getVersion() {
                    return "1.1";
                }
            };
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new StAXSource(xmlStreamReader));
            return message.getSOAPBody();
        }
    }

    @Benchmark
    public SOAPBody testSetContentStaxWithXmlInputFactoryNotCached(S s) throws SOAPException, IOException, XMLStreamException {
        XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
        try (InputStream inputStream = new ByteArrayInputStream(s.bytes)) {
            XMLStreamReader xmlStreamReader = new StreamReaderDelegate(xmlInputFactory.createXMLStreamReader(inputStream)) {
                @Override
                public String getVersion() {
                    return "1.1";
                }
            };
            SOAPMessage message = messageFactory.createMessage();
            message.getSOAPPart().setContent(new StAXSource(xmlStreamReader));
            return message.getSOAPBody();
        }
    }

}