001/* 002 * Copyright 2002-2020 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.messaging.converter; 018 019import java.io.ByteArrayInputStream; 020import java.io.ByteArrayOutputStream; 021import java.io.StringReader; 022import java.io.StringWriter; 023import java.io.Writer; 024 025import javax.xml.transform.Result; 026import javax.xml.transform.Source; 027import javax.xml.transform.stream.StreamResult; 028import javax.xml.transform.stream.StreamSource; 029 030import org.springframework.beans.TypeMismatchException; 031import org.springframework.lang.Nullable; 032import org.springframework.messaging.Message; 033import org.springframework.messaging.MessageHeaders; 034import org.springframework.oxm.Marshaller; 035import org.springframework.oxm.Unmarshaller; 036import org.springframework.util.Assert; 037import org.springframework.util.MimeType; 038 039/** 040 * Implementation of {@link MessageConverter} that can read and write XML using Spring's 041 * {@link Marshaller} and {@link Unmarshaller} abstractions. 042 * 043 * <p>This converter requires a {@code Marshaller} and {@code Unmarshaller} before it can 044 * be used. These can be injected by the {@linkplain #MarshallingMessageConverter(Marshaller) 045 * constructor} or {@linkplain #setMarshaller(Marshaller) bean properties}. 046 * 047 * @author Arjen Poutsma 048 * @since 4.2 049 * @see Marshaller 050 * @see Unmarshaller 051 */ 052public class MarshallingMessageConverter extends AbstractMessageConverter { 053 054 @Nullable 055 private Marshaller marshaller; 056 057 @Nullable 058 private Unmarshaller unmarshaller; 059 060 061 /** 062 * Default construct allowing for {@link #setMarshaller(Marshaller)} and/or 063 * {@link #setUnmarshaller(Unmarshaller)} to be invoked separately. 064 */ 065 public MarshallingMessageConverter() { 066 this(new MimeType("application", "xml"), new MimeType("text", "xml"), 067 new MimeType("application", "*+xml")); 068 } 069 070 /** 071 * Constructor with a given list of MIME types to support. 072 * @param supportedMimeTypes the MIME types 073 */ 074 public MarshallingMessageConverter(MimeType... supportedMimeTypes) { 075 super(supportedMimeTypes); 076 } 077 078 /** 079 * Constructor with {@link Marshaller}. If the given {@link Marshaller} also 080 * implements {@link Unmarshaller}, it is also used for unmarshalling. 081 * <p>Note that all {@code Marshaller} implementations in Spring also implement 082 * {@code Unmarshaller} so that you can safely use this constructor. 083 * @param marshaller object used as marshaller and unmarshaller 084 */ 085 public MarshallingMessageConverter(Marshaller marshaller) { 086 this(); 087 Assert.notNull(marshaller, "Marshaller must not be null"); 088 this.marshaller = marshaller; 089 if (marshaller instanceof Unmarshaller) { 090 this.unmarshaller = (Unmarshaller) marshaller; 091 } 092 } 093 094 095 /** 096 * Set the {@link Marshaller} to be used by this message converter. 097 */ 098 public void setMarshaller(@Nullable Marshaller marshaller) { 099 this.marshaller = marshaller; 100 } 101 102 /** 103 * Return the configured Marshaller. 104 */ 105 @Nullable 106 public Marshaller getMarshaller() { 107 return this.marshaller; 108 } 109 110 /** 111 * Set the {@link Unmarshaller} to be used by this message converter. 112 */ 113 public void setUnmarshaller(@Nullable Unmarshaller unmarshaller) { 114 this.unmarshaller = unmarshaller; 115 } 116 117 /** 118 * Return the configured unmarshaller. 119 */ 120 @Nullable 121 public Unmarshaller getUnmarshaller() { 122 return this.unmarshaller; 123 } 124 125 126 @Override 127 protected boolean canConvertFrom(Message<?> message, Class<?> targetClass) { 128 return (supportsMimeType(message.getHeaders()) && this.unmarshaller != null && 129 this.unmarshaller.supports(targetClass)); 130 } 131 132 @Override 133 protected boolean canConvertTo(Object payload, @Nullable MessageHeaders headers) { 134 return (supportsMimeType(headers) && this.marshaller != null && 135 this.marshaller.supports(payload.getClass())); 136 } 137 138 @Override 139 protected boolean supports(Class<?> clazz) { 140 // should not be called, since we override canConvertFrom/canConvertTo instead 141 throw new UnsupportedOperationException(); 142 } 143 144 @Override 145 @Nullable 146 protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) { 147 Assert.notNull(this.unmarshaller, "Property 'unmarshaller' is required"); 148 try { 149 Source source = getSource(message.getPayload()); 150 Object result = this.unmarshaller.unmarshal(source); 151 if (!targetClass.isInstance(result)) { 152 throw new TypeMismatchException(result, targetClass); 153 } 154 return result; 155 } 156 catch (Exception ex) { 157 throw new MessageConversionException(message, "Could not unmarshal XML: " + ex.getMessage(), ex); 158 } 159 } 160 161 private Source getSource(Object payload) { 162 if (payload instanceof byte[]) { 163 return new StreamSource(new ByteArrayInputStream((byte[]) payload)); 164 } 165 else { 166 return new StreamSource(new StringReader(payload.toString())); 167 } 168 } 169 170 @Override 171 @Nullable 172 protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers, 173 @Nullable Object conversionHint) { 174 175 Assert.notNull(this.marshaller, "Property 'marshaller' is required"); 176 try { 177 if (byte[].class == getSerializedPayloadClass()) { 178 ByteArrayOutputStream out = new ByteArrayOutputStream(1024); 179 Result result = new StreamResult(out); 180 this.marshaller.marshal(payload, result); 181 payload = out.toByteArray(); 182 } 183 else { 184 Writer writer = new StringWriter(1024); 185 Result result = new StreamResult(writer); 186 this.marshaller.marshal(payload, result); 187 payload = writer.toString(); 188 } 189 } 190 catch (Throwable ex) { 191 throw new MessageConversionException("Could not marshal XML: " + ex.getMessage(), ex); 192 } 193 return payload; 194 } 195 196}