org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer.java Source code

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Here is the source code for org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer.java

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/*
 * Copyright 2011-2019 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
 *
 *      https://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 org.springframework.data.redis.serializer;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ser.SerializerFactory;
import com.fasterxml.jackson.databind.type.TypeFactory;

/**
 * {@link RedisSerializer} that can read and write JSON using
 * <a href="https://github.com/FasterXML/jackson-core">Jackson's</a> and
 * <a href="https://github.com/FasterXML/jackson-databind">Jackson Databind</a> {@link ObjectMapper}.
 * <p>
 * This converter can be used to bind to typed beans, or untyped {@link java.util.HashMap HashMap} instances.
 * <b>Note:</b>Null objects are serialized as empty arrays and vice versa.
 *
 * @author Thomas Darimont
 * @since 1.2
 */
public class Jackson2JsonRedisSerializer<T> implements RedisSerializer<T> {

    public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;

    private final JavaType javaType;

    private ObjectMapper objectMapper = new ObjectMapper();

    /**
     * Creates a new {@link Jackson2JsonRedisSerializer} for the given target {@link Class}.
     *
     * @param type
     */
    public Jackson2JsonRedisSerializer(Class<T> type) {
        this.javaType = getJavaType(type);
    }

    /**
     * Creates a new {@link Jackson2JsonRedisSerializer} for the given target {@link JavaType}.
     *
     * @param javaType
     */
    public Jackson2JsonRedisSerializer(JavaType javaType) {
        this.javaType = javaType;
    }

    @SuppressWarnings("unchecked")
    public T deserialize(@Nullable byte[] bytes) throws SerializationException {

        if (SerializationUtils.isEmpty(bytes)) {
            return null;
        }
        try {
            return (T) this.objectMapper.readValue(bytes, 0, bytes.length, javaType);
        } catch (Exception ex) {
            throw new SerializationException("Could not read JSON: " + ex.getMessage(), ex);
        }
    }

    @Override
    public byte[] serialize(@Nullable Object t) throws SerializationException {

        if (t == null) {
            return SerializationUtils.EMPTY_ARRAY;
        }
        try {
            return this.objectMapper.writeValueAsBytes(t);
        } catch (Exception ex) {
            throw new SerializationException("Could not write JSON: " + ex.getMessage(), ex);
        }
    }

    /**
     * Sets the {@code ObjectMapper} for this view. If not set, a default {@link ObjectMapper#ObjectMapper() ObjectMapper}
     * is used.
     * <p>
     * Setting a custom-configured {@code ObjectMapper} is one way to take further control of the JSON serialization
     * process. For example, an extended {@link SerializerFactory} can be configured that provides custom serializers for
     * specific types. The other option for refining the serialization process is to use Jackson's provided annotations on
     * the types to be serialized, in which case a custom-configured ObjectMapper is unnecessary.
     */
    public void setObjectMapper(ObjectMapper objectMapper) {

        Assert.notNull(objectMapper, "'objectMapper' must not be null");
        this.objectMapper = objectMapper;
    }

    /**
     * Returns the Jackson {@link JavaType} for the specific class.
     * <p>
     * Default implementation returns {@link TypeFactory#constructType(java.lang.reflect.Type)}, but this can be
     * overridden in subclasses, to allow for custom generic collection handling. For instance:
     *
     * <pre class="code">
     * protected JavaType getJavaType(Class&lt;?&gt; clazz) {
     *    if (List.class.isAssignableFrom(clazz)) {
     *       return TypeFactory.defaultInstance().constructCollectionType(ArrayList.class, MyBean.class);
     *    } else {
     *       return super.getJavaType(clazz);
     *    }
     * }
     * </pre>
     *
     * @param clazz the class to return the java type for
     * @return the java type
     */
    protected JavaType getJavaType(Class<?> clazz) {
        return TypeFactory.defaultInstance().constructType(clazz);
    }
}