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package com.github.ibole.infrastructure.web.spring;

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.module.SimpleModule;
import com.fasterxml.jackson.databind.util.JSONPObject;

import com.fasterxml.jackson.module.jaxb.JaxbAnnotationModule;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;

import org.apache.commons.lang3.StringEscapeUtils;
import org.apache.commons.lang3.StringUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * 
 * 简单封装Jackson,实现JSON String <->Java Object的Mapper. 封装不同的输出风格, 使用不同的builder函数创建实例.
 * 
 */
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);
  }

  /**
   * JsonMapper constructor.
   * 
   * @param include Include
   */
  public JsonMapper(Include include) {
    // 设置输出时包含属性的风格
    if (include != null) {
      this.setSerializationInclusion(include);
    }
    // 允许单引号、允许不带引号的字段名称
    this.enableSimple();
    // 设置输入时忽略在JSON字符串中存在但Java对象实际没有的属性
    this.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
    // 空值处理为空串
    this.getSerializerProvider().setNullValueSerializer(new JsonSerializer() {
      @Override
      public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider)
          throws IOException, JsonProcessingException {
        jgen.writeString("");
      }
    });  
    // 进行HTML解码。
    this.registerModule(new SimpleModule().addSerializer(String.class,
        new JsonSerializer() {
          @Override
          public void serialize(String value, JsonGenerator jgen, SerializerProvider provider)
              throws IOException, JsonProcessingException {
            jgen.writeString(StringEscapeUtils.unescapeHtml4(value));
          }
        }));
    // 设置时区
    this.setTimeZone(TimeZone.getDefault());// getTimeZone("GMT+8:00")
  }

  /**
   * 创建只输出非Null且非Empty(如List.isEmpty)的属性到Json字符串的Mapper,建议在外部接口中使用.
   * @return JsonMapper instance
   */
  public static JsonMapper getInstance() {
    if (mapper == null) {
      mapper = new JsonMapper().enableSimple();
    }
    return mapper;
  }

  /**
   * 创建只输出初始值被改变的属性到Json字符串的Mapper, 最节约的存储方式,建议在内部接口中使用。
   * @return JsonMapper instance
   */
  public static JsonMapper nonDefaultMapper() {
    if (mapper == null) {
      mapper = new JsonMapper(Include.NON_DEFAULT);
    }
    return mapper;
  }

  /**
   * Object可以是POJO,也可以是Collection或数组。 如果对象为Null, 返回"null". 如果集合为空集合, 返回"[]".
   * @param object Object
   * @return json string
   */
  public String toJson(Object object) {
    try {
      return this.writeValueAsString(object);
    } catch (IOException e) {
      logger.warn("write to json string error:" + object, e);
      return null;
    }
  }

  /**
   * 反序列化POJO或简单Collection如List <String>.
   * 
   * 如果JSON字符串为Null或"null"字符串, 返回Null. 如果JSON字符串为"[]", 返回空集合.
   * 
   * 如需反序列化复杂Collection如List<MyBean>, 请使用fromJson(String,JavaType)
   * 
   * @see #fromJson(String, JavaType)
   * @param  T
   * @param jsonString String
   * @param clazz Class
   * @return object converted from json string
   */
  public  T fromJson(String jsonString, Class 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;
    }
  }

  /**
   * 反序列化复杂Collection如List<Bean>, 先使用函數createCollectionType构造类型,然后调用本函数.
   * 
   * @see #createCollectionType(Class, Class...)
   * @param  T
   * @param jsonString String
   * @param javaType JavaType
   * @return object converted from json string
   */
  @SuppressWarnings("unchecked")
  public  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;
    }
  }

  /**
   * 構造泛型的Collection Type如: ArrayList<MyBean>,
   * 则调用constructCollectionType(ArrayList.class,MyBean.class) HashMap<String,MyBean>
   * 则调用(HashMap.class,String.class, MyBean.class).
   * @param collectionClass Class
   * @param elementClasses Class
   * @return JavaType JavaType
   */
  public JavaType createCollectionType(Class collectionClass, Class... elementClasses) {
    return this.getTypeFactory().constructParametricType(collectionClass, elementClasses);
  }

  /**
   * 當JSON裡只含有Bean的部分屬性時,更新一個已存在Bean,只覆蓋該部分的屬性.
   * @param jsonString String
   * @param object T
   * @param  T 
   * @return Object updated from json string
   */
  @SuppressWarnings("unchecked")
  public  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;
  }

  /**
   * 輸出JSONP格式數據.
   * @param functionName String
   * @param object Object
   * @return json string
   */
  public String toJsonP(String functionName, Object object) {
    return toJson(new JSONPObject(functionName, object));
  }

  /**
   * 設定是否使用Enum的toString函數來讀寫Enum, 為False時時使用Enum的name()函數來讀寫Enum, 默認為False. 注意本函數一定要在Mapper創建後,
   * 所有的讀寫動作之前調用.
   * @return JsonMapper JsonMapper
   */
  public JsonMapper enableEnumUseToString() {
    this.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
    this.enable(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
    return this;
  }

  /**
   * 支持使用Jaxb的Annotation,使得POJO上的annotation不用与Jackson耦合。 默认会先查找jaxb的annotation,如果找不到再找jackson的.
   * @return JsonMapper JsonMapper
   */
  public JsonMapper enableJaxbAnnotation() {
    JaxbAnnotationModule module = new JaxbAnnotationModule();
    this.registerModule(module);
    return this;
  }

  /**
   * 允许单引号 允许不带引号的字段名称.
   * @return JsonMapper JsonMapper
   */
  public JsonMapper enableSimple() {
    this.configure(Feature.ALLOW_SINGLE_QUOTES, true);
    this.configure(Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
    return this;
  }

  /**
   * 取出Mapper做进一步的设置或使用其他序列化API.
   * @return ObjectMapper ObjectMapper
   */
  public ObjectMapper getMapper() {
    return this;
  }

  /**
   * 对象转换为JSON字符串.
   * 
   * @param object Object
   * @return json string
   */
  public static String toJsonString(Object object) {
    return JsonMapper.getInstance().toJson(object);
  }

  /**
   * JSON字符串转换为对象.
   * 
   * @param jsonString String
   * @param clazz Class
   * @return Object Object
   */
  public static Object fromJsonString(String jsonString, Class clazz) {
    return JsonMapper.getInstance().fromJson(jsonString, clazz);
  }

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

}