onl.area51.httpd.rest.JsonEntity.java Source code

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Here is the source code for onl.area51.httpd.rest.JsonEntity.java

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/*
 * Copyright 2016 peter.
 *
 * 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 onl.area51.httpd.rest;

import java.io.StringWriter;
import java.util.function.Supplier;
import javax.json.Json;
import javax.json.JsonArrayBuilder;
import javax.json.JsonObjectBuilder;
import javax.json.JsonStructure;
import javax.json.JsonWriter;
import onl.area51.httpd.action.Actions;
import onl.area51.httpd.action.Request;
import org.apache.http.HttpEntity;
import org.apache.http.HttpStatus;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;

/**
 * Entity for returning Json objects
 *
 * @author peter
 */
public class JsonEntity extends StringEntity implements Cloneable {

    public static HttpEntity createFromAttribute(String n, Request r) {
        Object o = r.getAttribute(n);
        if (o instanceof JsonStructure) {
            return new JsonEntity((JsonStructure) o);
        }
        if (o instanceof JsonObjectBuilder) {
            return new JsonEntity((JsonObjectBuilder) o);
        }
        if (o instanceof JsonArrayBuilder) {
            return new JsonEntity((JsonArrayBuilder) o);
        }
        return Actions.errorEntity(r, HttpStatus.SC_INTERNAL_SERVER_ERROR, "Unsupported Json " + o);
    }

    public JsonEntity(JsonStructure json) {
        super(encode(json), ContentType.APPLICATION_JSON);
    }

    public JsonEntity(JsonObjectBuilder b) {
        this(b.build());
    }

    public JsonEntity(JsonArrayBuilder b) {
        this(b.build());
    }

    /**
     * Convert a {@link JsonStructure} to a String
     * <p>
     * @param s <p>
     * @return
     */
    public static String encode(JsonStructure s) {
        final StringWriter w = new StringWriter();
        try (JsonWriter jw = Json.createWriter(w)) {
            jw.write(s);
            return w.toString();
        }
    }

    public static Supplier<HttpEntity> encodeArray(Supplier<JsonArrayBuilder> s) {
        return () -> new JsonEntity(s.get().build());
    }

    public static Supplier<HttpEntity> encodeObject(Supplier<JsonObjectBuilder> s) {
        return () -> new JsonEntity(s.get().build());
    }

}