package com.springone.myrestaurants.web;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.codehaus.jackson.JsonEncoding;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.JsonProcessingException;
import org.codehaus.jackson.JsonToken;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.type.TypeFactory;
import org.codehaus.jackson.type.JavaType;
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;
public class CouchDbMappingJacksonHttpMessageConverter extends
AbstractHttpMessageConverter<Object> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private static final String ROWS_FIELD_NAME = "rows";
private static final String VALUE_FIELD_NAME = "value";
private static final String INCLUDED_DOC_FIELD_NAME = "doc";
private static final String TOTAL_ROWS_FIELD_NAME = "total_rows";
private ObjectMapper objectMapper = new ObjectMapper();
private boolean prefixJson = false;
/**
* Construct a new {@code BindingJacksonHttpMessageConverter}.
*/
public CouchDbMappingJacksonHttpMessageConverter() {
super(new MediaType("application", "json", DEFAULT_CHARSET));
}
/**
* Sets 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 {@link 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.
*/
public void setObjectMapper(ObjectMapper objectMapper) {
Assert.notNull(objectMapper, "'objectMapper' must not be null");
this.objectMapper = objectMapper;
}
/**
* Indicates 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.
*/
public void setPrefixJson(boolean prefixJson) {
this.prefixJson = prefixJson;
}
@Override
public boolean canRead(Class<?> clazz, MediaType mediaType) {
JavaType javaType = getJavaType(clazz);
return this.objectMapper.canDeserialize(javaType) && canRead(mediaType);
}
/**
* Returns the Jackson {@link JavaType} for the specific class.
*
* <p>
* Default implementation returns
* {@link TypeFactory#type(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 TypeFactory.collectionType(ArrayList.class, MyBean.class);
* } else {
* return super.getJavaType(clazz);
* }
* }
* </pre>
*
* @param clazz
* the class to return the java type for
* @return the java type
*/
protected JavaType getJavaType(Class<?> clazz) {
return TypeFactory.type(clazz);
}
@Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
return this.objectMapper.canSerialize(clazz) && canWrite(mediaType);
}
@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 success(clazz, inputMessage);
// return this.objectMapper.readValue(inputMessage.getBody(),
// javaType);
} catch (Exception ex) {
throw new HttpMessageNotReadableException("Could not read JSON: "
+ ex.getMessage(), ex);
}
}
private Object success(Class<?> clazz, HttpInputMessage inputMessage)
throws JsonParseException, IOException {
//Note, parsing code used from ektorp project
JsonParser jp = objectMapper.getJsonFactory().createJsonParser(
inputMessage.getBody());
if (jp.nextToken() != JsonToken.START_OBJECT) {
throw new RuntimeException("Expected data to start with an Object");
}
Map<String, Integer> fields = readHeaderFields(jp);
List result;
if (fields.containsKey(TOTAL_ROWS_FIELD_NAME)) {
int totalRows = fields.get(TOTAL_ROWS_FIELD_NAME);
if (totalRows == 0) {
return Collections.emptyList();
}
result = new ArrayList(totalRows);
} else {
result = new ArrayList();
}
ParseState state = new ParseState();
Object first = parseFirstRow(jp, state, clazz);
if (first == null) {
return Collections.emptyList();
} else {
result.add(first);
}
while (jp.getCurrentToken() != null) {
skipToField(jp, state.docFieldName, state);
if (atEndOfRows(jp)) {
return result;
}
result.add(jp.readValueAs(clazz));
endRow(jp, state);
}
return result;
}
private Object parseFirstRow(JsonParser jp, ParseState state, Class clazz)
throws JsonParseException, IOException, JsonProcessingException,
JsonMappingException {
skipToField(jp, VALUE_FIELD_NAME, state);
JsonNode value = null;
if (atObjectStart(jp)) {
value = jp.readValueAsTree();
jp.nextToken();
if (isEndOfRow(jp)) {
state.docFieldName = VALUE_FIELD_NAME;
Object doc = objectMapper.readValue(value, clazz);
endRow(jp, state);
return doc;
}
}
skipToField(jp, INCLUDED_DOC_FIELD_NAME, state);
if (atObjectStart(jp)) {
state.docFieldName = INCLUDED_DOC_FIELD_NAME;
Object doc = jp.readValueAs(clazz);
endRow(jp, state);
return doc;
}
return null;
}
private boolean isEndOfRow(JsonParser jp) {
return jp.getCurrentToken() == JsonToken.END_OBJECT;
}
private void endRow(JsonParser jp, ParseState state) throws IOException, JsonParseException {
state.inRow = false;
jp.nextToken();
}
private boolean atObjectStart(JsonParser jp) {
return jp.getCurrentToken() == JsonToken.START_OBJECT;
}
private boolean atEndOfRows(JsonParser jp) {
return jp.getCurrentToken() != JsonToken.START_OBJECT;
}
private void skipToField(JsonParser jp, String fieldName, ParseState state) throws JsonParseException, IOException {
String lastFieldName = null;
while (jp.getCurrentToken() != null) {
switch (jp.getCurrentToken()) {
case FIELD_NAME:
lastFieldName = jp.getCurrentName();
jp.nextToken();
break;
case START_OBJECT:
if (!state.inRow) {
state.inRow = true;
jp.nextToken();
} else {
if (isInField(fieldName, lastFieldName)) {
return;
} else {
jp.skipChildren();
}
}
break;
default:
if (isInField(fieldName, lastFieldName)) {
jp.nextToken();
return;
}
jp.nextToken();
break;
}
}
}
private boolean isInField(String fieldName, String lastFieldName) {
return lastFieldName != null && lastFieldName.equals(fieldName);
}
private Map<String, Integer> readHeaderFields(JsonParser jp)
throws JsonParseException, IOException {
Map<String, Integer> map = new HashMap<String, Integer>();
jp.nextToken();
String nextFieldName = jp.getCurrentName();
while (!nextFieldName.equals(ROWS_FIELD_NAME)) {
jp.nextToken();
map.put(nextFieldName, Integer.valueOf(jp.getIntValue()));
jp.nextToken();
nextFieldName = jp.getCurrentName();
}
return map;
}
@Override
protected void writeInternal(Object o, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
JsonEncoding encoding = getEncoding(outputMessage.getHeaders()
.getContentType());
JsonGenerator jsonGenerator = this.objectMapper.getJsonFactory()
.createJsonGenerator(outputMessage.getBody(), encoding);
try {
if (this.prefixJson) {
jsonGenerator.writeRaw("{} && ");
}
this.objectMapper.writeValue(jsonGenerator, o);
} catch (JsonGenerationException ex) {
throw new HttpMessageNotWritableException("Could not write JSON: "
+ ex.getMessage(), ex);
}
}
private JsonEncoding getEncoding(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;
}
private static class ParseState {
boolean inRow;
String docFieldName = "";
}
}