cn.fintecher.print.web.util.JacksonDecoder.java Source code

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Here is the source code for cn.fintecher.print.web.util.JacksonDecoder.java

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/*
 * Copyright 2013 Netflix, Inc.
 *
 * 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 cn.fintecher.print.web.util;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.Module;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.RuntimeJsonMappingException;
import feign.Response;
import feign.Util;
import feign.codec.Decoder;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.lang.reflect.Type;
import java.util.Collections;

public class JacksonDecoder implements Decoder {

    private final ObjectMapper mapper;

    public JacksonDecoder() {
        this(Collections.<Module>emptyList());
    }

    public JacksonDecoder(Iterable<Module> modules) {
        this(new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
                .registerModules(modules));
    }

    public JacksonDecoder(ObjectMapper mapper) {
        this.mapper = mapper;
    }

    @Override
    public Object decode(Response response, Type type) throws IOException {
        if (response.status() == 404)
            return Util.emptyValueOf(type);
        if (response.body() == null)
            return null;
        Reader reader = response.body().asReader();
        if (!reader.markSupported()) {
            reader = new BufferedReader(reader, 1);
        }
        try {
            // Read the first byte to see if we have any data
            reader.mark(1);
            if (reader.read() == -1) {
                return null; // Eagerly returning null avoids "No content to map due to end-of-input"
            }
            reader.reset();
            return mapper.readValue(reader, mapper.constructType(type));
        } catch (RuntimeJsonMappingException e) {
            if (e.getCause() != null && e.getCause() instanceof IOException) {
                throw IOException.class.cast(e.getCause());
            }
            throw e;
        }
    }
}