com.coul.common.mapper.JsonMapper.java Source code

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Here is the source code for com.coul.common.mapper.JsonMapper.java

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/**
 * Copyright (c) 2005-2012 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 */
/**
 * Copyright (c) 2005-2012 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 */
package com.coul.common.mapper;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonParser.Feature;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.util.JSONPObject;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

/**
 * ??JacksonJSON String<->Java ObjectMapper.
 * 
 * ???, ??builder.
 * 
 * @author calvin
 * @version 2013-01-15
 */
public class JsonMapper extends ObjectMapper {

    private static final long serialVersionUID = 1L;

    private static Logger logger = LoggerFactory.getLogger(JsonMapper.class);

    private static JsonMapper mapper;

    public JsonMapper() {
        this(Include.NON_EMPTY);
    }

    public JsonMapper(Include include) {
        // ?
        if (include != null) {
            this.setSerializationInclusion(include);
        }
        // ?????????
        this.enableSimple();
        // JSONJava
        this.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        // ?
        this.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
            @Override
            public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider)
                    throws IOException, JsonProcessingException {
                jgen.writeString("");
            }
        });
    }

    /**
     * ??Null?Empty(List.isEmpty)JsonMapper,?.
     */
    public static JsonMapper getInstance() {
        if (mapper == null) {
            mapper = new JsonMapper().enableSimple();
        }
        return mapper;
    }

    /**
     * ???JsonMapper, ??
     */
    public static JsonMapper nonDefaultMapper() {
        if (mapper == null) {
            mapper = new JsonMapper(Include.NON_DEFAULT);
        }
        return mapper;
    }

    /**
     * Object?POJO?Collection
     * Null, "null".
     * ??, "[]".
     */
    public String toJson(Object object) {

        try {
            return this.writeValueAsString(object);
        } catch (IOException e) {
            logger.warn("write to json string error:" + object, e);
            return null;
        }
    }

    /**
     * ???POJO?CollectionList<String>.
     * 
     * JSONNull"null", Null.
     * JSON"[]", ?.
     * 
     * ?????CollectionList<MyBean>, fromJson(String,JavaType)
     * @see #fromJson(String, JavaType)
     */
    public <T> T fromJson(String jsonString, Class<T> clazz) {
        if (StringUtils.isEmpty(jsonString)) {
            return null;
        }
        try {
            return this.readValue(jsonString, clazz);
        } catch (IOException e) {
            logger.warn("parse json string error:" + jsonString, e);
            return null;
        }
    }

    /**
     * ?????CollectionList<Bean>, createCollectionType,?.
     * @see #createCollectionType(Class, Class...)
     */
    @SuppressWarnings("unchecked")
    public <T> T fromJson(String jsonString, JavaType javaType) {
        if (StringUtils.isEmpty(jsonString)) {
            return null;
        }
        try {
            return (T) this.readValue(jsonString, javaType);
        } catch (IOException e) {
            logger.warn("parse json string error:" + jsonString, e);
            return null;
        }
    }

    /**
     * Collection Type:
     * ArrayList<MyBean>, constructCollectionType(ArrayList.class,MyBean.class)
     * HashMap<String,MyBean>, (HashMap.class,String.class, MyBean.class)
     */
    public JavaType createCollectionType(Class<?> collectionClass, Class<?>... elementClasses) {
        return this.getTypeFactory().constructParametricType(collectionClass, elementClasses);
    }

    /**
     * JSON??BeanBean?.
     */
    @SuppressWarnings("unchecked")
    public <T> T update(String jsonString, T object) {
        try {
            return (T) this.readerForUpdating(object).readValue(jsonString);
        } catch (JsonProcessingException e) {
            logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e);
        } catch (IOException e) {
            logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e);
        }
        return null;
    }

    /**
     * JSONP?.
     */
    public String toJsonP(String functionName, Object object) {
        return toJson(new JSONPObject(functionName, object));
    }

    /**
     * ?EnumtoStringEnum,
     * FalseEnumname()Enum, ?False.
     * ??Mapper, ?.
     */
    public JsonMapper enableEnumUseToString() {
        this.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
        this.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
        return this;
    }

    //   /**
    //    * ?JaxbAnnotationPOJOannotation?Jackson?
    //    * jaxbannotation??jackson
    //    */
    //   public JsonMapper enableJaxbAnnotation() {
    //      JaxbAnnotationModule module = new JaxbAnnotationModule();
    //      this.registerModule(module);
    //      return this;
    //   }

    /**
     * ???
     * ?????
     */
    public JsonMapper enableSimple() {
        this.configure(Feature.ALLOW_SINGLE_QUOTES, true);
        this.configure(Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
        return this;
    }

    /**
     * ?Mapper??API.
     */
    public ObjectMapper getMapper() {
        return this;
    }

    /**
     * ?JSON
     * @param object
     * @return
     */
    public static String toJsonString(Object object) {
        return JsonMapper.getInstance().toJson(object);
    }

    /**
     * 
     */
    public static void main(String[] args) {
        List<Map<String, Object>> list = Lists.newArrayList();
        Map<String, Object> map = Maps.newHashMap();
        map.put("id", 1);
        map.put("pId", -1);
        map.put("name", "");
        list.add(map);
        map = Maps.newHashMap();
        map.put("id", 2);
        map.put("pId", 1);
        map.put("name", "");
        map.put("open", true);
        list.add(map);
        String json = JsonMapper.getInstance().toJson(list);
        System.out.println(json);
    }

}