Instantly share code, notes, and snippets.

Embed
What would you like to do?
/*
* Copyright 2002-2014 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package info.xudshen.basic.util.gson;
import com.google.gson.Gson;
import com.google.gson.JsonIOException;
import com.google.gson.JsonParseException;
import com.google.gson.JsonSyntaxException;
import org.springframework.http.HttpHeaders;
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.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
/**
* Created by xudshen on 14/8/1.
*/
public class GsonHttpMessageConverter extends AbstractHttpMessageConverter<Object> {
public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");
private Gson gson;
private Type type = null;
private boolean prefixJson = false;
private Class[] excludeClazz = {};
/**
* Construct a new {@code GsonHttpMessageConverter} with a default {@link Gson#Gson() Gson}.
*/
public GsonHttpMessageConverter() {
this(GsonSingleton.getInstance().getGson());
}
public GsonHttpMessageConverter(Class[] excludeClazz) {
this(GsonSingleton.getInstance().getGson());
this.excludeClazz = excludeClazz;
}
/**
* Construct a new {@code GsonHttpMessageConverter}.
*
* @param gson a customized {@link Gson#Gson() Gson}
*/
public GsonHttpMessageConverter(Gson gson) {
super(new MediaType("application", "json", DEFAULT_CHARSET));
setGson(gson);
}
/**
* Sets the {@code Gson} for this view. If not set, a default
* {@link Gson#Gson() Gson} is used.
* <p>Setting a custom-configured {@code Gson} is one way to take further control of the JSON serialization
* process.
*
* @throws IllegalArgumentException if gson is null
*/
public void setGson(Gson gson) {
Assert.notNull(gson, "'gson' must not be null");
this.gson = gson;
}
public Type getType() {
return type;
}
public void setType(Type type) {
this.type = type;
}
/**
* 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) {
return canRead(mediaType);
}
@Override
public boolean canWrite(Class<?> clazz, MediaType mediaType) {
for (Class exclude : excludeClazz) {
if (exclude.equals(clazz))
return false;
}
return 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 {
Reader json = new InputStreamReader(inputMessage.getBody(), getCharset(inputMessage.getHeaders()));
Object ret = null;
try {
Type typeOfT = getType();
if (typeOfT != null) {
ret = this.gson.fromJson(json, typeOfT);
} else {
ret = this.gson.fromJson(json, clazz);
}
if (ret == null) {
throw new HttpMessageNotReadableException("Could not read JSON: null json");
} else {
return ret;
}
} catch (JsonSyntaxException ex) {
throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
} catch (JsonIOException ex) {
throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
} catch (JsonParseException ex) {
throw new HttpMessageNotReadableException("Could not read JSON: " + ex.getMessage(), ex);
}
}
@Override
protected void writeInternal(Object o, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
OutputStreamWriter writer = new OutputStreamWriter(outputMessage.getBody(), getCharset(outputMessage.getHeaders()));
try {
if (this.prefixJson) {
writer.append("{} && ");
}
Type typeOfSrc = getType();
if (typeOfSrc != null) {
this.gson.toJson(o, typeOfSrc, writer);
} else {
this.gson.toJson(o, writer);
}
writer.close();
} catch (JsonIOException ex) {
throw new HttpMessageNotWritableException("Could not write JSON: " + ex.getMessage(), ex);
}
}
// helpers
private Charset getCharset(HttpHeaders headers) {
if (headers != null && headers.getContentType() != null
&& headers.getContentType().getCharSet() != null) {
return headers.getContentType().getCharSet();
}
return DEFAULT_CHARSET;
}
}
@razvanbalan

This comment has been minimized.

Copy link

razvanbalan commented Nov 6, 2017

Why we have this writer.close() here and not having it on a finally block?

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment