JsonWriter.java

package org.eluder.logback.ext.jackson;

/*
 * #[license]
 * logback-ext-jackson
 * %%
 * Copyright (C) 2014 - 2015 Tapio Rautonen
 * %%
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * %[license]
 */

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.util.MinimalPrettyPrinter;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.Closeable;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.nio.charset.Charset;

public class JsonWriter implements Closeable {

    private final JsonGenerator generator;

    public JsonWriter(OutputStream os, Charset charset, ObjectMapper mapper) throws IOException {
        generator = mapper.getFactory()
                .createGenerator(new OutputStreamWriter(os, charset))
                .configure(JsonGenerator.Feature.AUTO_CLOSE_TARGET, false)
                .setPrettyPrinter(new MinimalPrettyPrinter(""));
    }

    @Override
    public void close() throws IOException {
        generator.close();
    }

    public JsonWriter flush() throws IOException {
        generator.flush();
        return this;
    }

    public JsonWriter newline() throws IOException {
        generator.writeRaw('\n');
        return this;
    }

    public ObjectWriter<JsonWriter> writeObject() throws IOException {
        return new ObjectWriter<JsonWriter>(this, true);
    }

    public ArrayWriter<JsonWriter> writeArray() throws IOException {
        return new ArrayWriter<JsonWriter>(this, true);
    }

    public class ObjectWriter<T> {
        private final T parent;
        private final boolean enabled;

        ObjectWriter(T parent, boolean parentEnabled) throws IOException {
            this.parent = parent;
            this.enabled = parentEnabled;
            if (enabled) {
                generator.writeStartObject();
            }
        }

        ObjectWriter(T parent, boolean parentEnabled, String name, boolean active) throws IOException {
            this.parent = parent;
            this.enabled = parentEnabled && active;
            if (enabled) {
                generator.writeObjectFieldStart(name);
            }
        }

        public ObjectWriter<T> writeStringField(String name, String value, boolean active) throws IOException {
            if (enabled && active) {
                generator.writeStringField(name, value);
            }
            return this;
        }

        public ObjectWriter<T> writeNumberField(String name, int value, boolean active) throws IOException {
            if (enabled && active) {
                generator.writeNumberField(name, value);
            }
            return this;
        }

        public ObjectWriter<T> writeNumberField(String name, long value, boolean active) throws IOException {
            if (enabled && active) {
                generator.writeNumberField(name, value);
            }
            return this;
        }

        public ArrayWriter<ObjectWriter<T>> writeArray(String name, boolean active) throws IOException {
            return new ArrayWriter<ObjectWriter<T>>(this, enabled, name, active);
        }

        public ObjectWriter<ObjectWriter<T>> writeObject(String name, boolean active) throws IOException {
            return new ObjectWriter<ObjectWriter<T>>(this, enabled, name, active);
        }

        public T done() throws IOException {
            if (enabled) {
                generator.writeEndObject();
            }
            return parent;
        }
    }

    public class ArrayWriter<T> {
        private final T parent;
        private final boolean enabled;

        ArrayWriter(T parent, boolean parentEnabled) throws IOException {
            this.parent = parent;
            this.enabled = parentEnabled;
            if (enabled) {
                generator.writeStartArray();
            }
        }

        ArrayWriter(T parent, boolean parentEnabled, String name, boolean active) throws IOException {
            this.parent = parent;
            this.enabled = parentEnabled && active;
            if (enabled) {
                generator.writeArrayFieldStart(name);
            }
        }

        public ArrayWriter<T> writeString(String value, boolean active) throws IOException {
            if (enabled && active) {
                generator.writeString(value);
            }
            return this;
        }

        public ArrayWriter<ArrayWriter<T>> writeArray() throws IOException {
            return new ArrayWriter<ArrayWriter<T>>(this, enabled);
        }

        public ObjectWriter<ArrayWriter<T>> writeObject() throws IOException {
            return new ObjectWriter<ArrayWriter<T>>(this, enabled);
        }

        public T done() throws IOException {
            if (enabled) {
                generator.writeEndArray();
            }
            return parent;
        }
    }

}