com.effektif.workflow.impl.json.JsonStreamMapper.java Source code

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Here is the source code for com.effektif.workflow.impl.json.JsonStreamMapper.java

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/* Copyright (c) 2014, Effektif GmbH.
 * 
 * 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 com.effektif.workflow.impl.json;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.Type;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * An API that implements logic for mapping model classes to and from JSON.
 *
 * @author Tom Baeyens
 */
public class JsonStreamMapper {

    ObjectMapper objectMapper;
    Mappings mappings;
    boolean pretty;

    public JsonStreamMapper() {
        this.objectMapper = new ObjectMapper();
    }

    public JsonStreamMapper pretty() {
        this.pretty = true;
        return this;
    }

    public <T> T readString(String jsonString, Class<T> clazz) {
        return readString(jsonString, (Type) clazz);
    }

    public <T> T readString(String jsonString, Type type) {
        if (jsonString == null || "".equals(jsonString.trim())) {
            return null;
        }
        Reader reader = new StringReader(jsonString);
        return read(reader, type);
    }

    public <T> T read(Reader reader, Class<T> clazz) {
        return read(reader, (Type) clazz);
    }

    public <T> T read(Reader reader, Type type) {
        try {
            Object beanJsonObject = parseJson(reader);
            if (beanJsonObject == null) {
                return null;
            }
            return readJsonObject(beanJsonObject, type);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public Object parseJson(Reader reader) {
        try {
            return objectMapper.readValue(reader, Object.class);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public <T> T readJsonObject(Object jsonObject, Type type) {
        if (jsonObject == null) {
            return null;
        }
        JsonStreamReader jsonStreamReader = new JsonStreamReader(mappings);
        return (T) jsonStreamReader.readObject(jsonObject, type);
    }

    public <T> String write(T o) {
        StringWriter stringWriter = new StringWriter();
        write(o, stringWriter);
        return stringWriter.toString();
    }

    public <T> void write(T bean, Writer writer) {
        try {
            JsonGenerator jgen = new JsonFactory().createGenerator(writer);
            if (pretty) {
                jgen.setPrettyPrinter(new DefaultPrettyPrinter());
            }
            JsonStreamWriter jsonStreamWriter = new JsonStreamWriter(mappings, jgen);
            jsonStreamWriter.writeObject(bean);
            jgen.flush();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public Mappings getMappings() {
        return mappings;
    }

    public void setMappings(Mappings mappings) {
        this.mappings = mappings;
    }
}