package com.googlecode.jsonrpc4j.spring.rest;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.Assert;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
/**
* JSON-RPC Message converter for Spring RestTemplate
*/
@SuppressWarnings({"WeakerAccess", "unused"})
class MappingJacksonRPC2HttpMessageConverter extends AbstractHttpMessageConverter<Object> {
private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
public static final MediaType APPLICATION_JSON_RPC = new MediaType("application", "json-rpc", DEFAULT_CHARSET);
private ObjectMapper objectMapper;
private boolean prefixJson = false;
/**
* Construct a new {@code BindingJacksonHttpMessageConverter}.
*/
public MappingJacksonRPC2HttpMessageConverter() {
super(APPLICATION_JSON_RPC);
objectMapper = new ObjectMapper();
}
/**
* Construct a new {@code BindingJacksonHttpMessageConverter}.
*
* @param objectMapper the object mapper for this view
*/
public MappingJacksonRPC2HttpMessageConverter(ObjectMapper objectMapper) {
super(APPLICATION_JSON_RPC);
Assert.notNull(objectMapper, "ObjectMapper must not be null");
this.objectMapper = objectMapper;
}
/**
* Return the underlying {@code ObjectMapper} for this view.
*
* @return the object mapper for this view
*/
public ObjectMapper getObjectMapper() {
return this.objectMapper;
}
/**
* Set the {@code ObjectMapper} for this view. If not set, a default
* {@link ObjectMapper#ObjectMapper() ObjectMapper} is used.
* <p>
* Setting a custom-configured {@code ObjectMapper} is one way to take further control of the JSON serialization
* process. For example, an extended {@code org.codehaus.jackson.map.SerializerFactory} can be configured that
* provides custom serializers for specific types. The other option for refining the serialization process is to use
* Jackson's provided annotations on the types to be serialized, in which case a custom-configured ObjectMapper is
* unnecessary.
*
* @param objectMapper the object mapper for this view
*/
public void setObjectMapper(ObjectMapper objectMapper) {
Assert.notNull(objectMapper, "ObjectMapper must not be null");
this.objectMapper = objectMapper;
}
/**
* Indicate whether the JSON output by this view should be prefixed with "{} &&". Default is false.
* <p>
* Prefixing the JSON string in this manner is used to help prevent JSON Hijacking. The prefix renders the string
* syntactically invalid as a script so that it cannot be hijacked. This prefix does not affect the evaluation of
* JSON, but if JSON validation is performed on the string, the prefix would need to be ignored.
*
* @param prefixJson whether the JSON should be prefixed
*/
public void setPrefixJson(boolean prefixJson) {
this.prefixJson = prefixJson;
}
@Override
public boolean canRead(Class<?> clazz, MediaType mediaType) {
if (!JsonNode.class.isAssignableFrom(clazz)) {
return false;
}
if (mediaType == null) {
return true;
}
for (MediaType supportedMediaType : getSupportedMediaTypes()) {
// we can't read multipart
if (supportedMediaType.includes(mediaType)) {
return true;
}
}
return false;
}
@Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
if (!ObjectNode.class.isAssignableFrom(clazz)) {
return false;
}
if (mediaType == null || MediaType.ALL.equals(mediaType)) {
return true;
}
for (MediaType supportedMediaType : getSupportedMediaTypes()) {
if (supportedMediaType.isCompatibleWith(mediaType)) {
return true;
}
}
return false;
}
@Override
protected boolean supports(Class<?> clazz) {
// should not be called, since we override canRead/Write instead
throw new UnsupportedOperationException();
}
@Override
protected Object readInternal(Class<?> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
JavaType javaType = getJavaType(clazz);
try {
return this.objectMapper.readValue(inputMessage.getBody(), javaType);
} catch (IOException ex) {
throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
}
}
@Override
protected void writeInternal(Object object, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
final JsonEncoding encoding = getJsonEncoding(outputMessage.getHeaders().getContentType());
final JsonGenerator jsonGenerator = this.objectMapper.getFactory().createGenerator(outputMessage.getBody(), encoding);
try {
if (this.prefixJson) {
jsonGenerator.writeRaw("{} && ");
}
this.objectMapper.writeValue(jsonGenerator, object);
} catch (IOException ex) {
throw new HttpMessageNotWritableException("Could not write JSON: " + ex.getMessage(), ex);
}
}
/**
* Determine the JSON encoding to use for the given content type.
*
* @param contentType the media type as requested by the caller
* @return the JSON encoding to use (never <code>null</code>)
*/
private JsonEncoding getJsonEncoding(MediaType contentType) {
if (contentType != null && contentType.getCharset() != null) {
Charset charset = contentType.getCharset();
for (JsonEncoding encoding : JsonEncoding.values()) {
if (charset.name().equals(encoding.getJavaName())) {
return encoding;
}
}
}
return JsonEncoding.UTF8;
}
/**
* Return the Jackson {@link JavaType} for the specified class.
* <p>
* The default implementation returns {@link ObjectMapper#constructType(java.lang.reflect.Type)}, but this can be
* overridden in subclasses, to allow for custom generic collection handling. For instance:
* <pre class="code">
* protected JavaType getJavaType(Class<?> clazz) { if (List.class.isAssignableFrom(clazz)) { return
* objectMapper.getTypeFactory().constructCollectionType(ArrayList.class, MyBean.class); } else { return
* super.getJavaType(clazz); } }
* </pre>
*
* @param javaClass the class to return the java type for
* @return the java type
*/
private JavaType getJavaType(Class<?> javaClass) {
return objectMapper.constructType(javaClass);
}
}