@JsonIgnore注解的功能及示例说明

@JsonIgnore注解的功能说明

@JsonIgnore注解:
   用来忽略某些字段
   可用在Field或Getter方法上
   用在Setter方法时和Filed效果一样
   这个注解只能用在POJO存在的字段要忽略的情况
    不能满足现在需要的情况

@JsonIgnoreProperties(ignoreUnknown = true)
    将此注解写在类上之后
    就会忽略类中不存在的字段
    可以满足当前的需要
   这个注解还可以指定要忽略的字段
   
如：
 @JsonIgnoreProperties({ "internalId", "secretKey" })
 指定的字段不会被序列化和反序列化

工具类

package com.java265.util;

import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
 
import lombok.extern.slf4j.Slf4j;

@Slf4j
public class JacksonUtil {
    private final static ObjectMapper objectMapper = new ObjectMapper();
 
    static {
        objectMapper.configure(JsonParser.Feature.ALLOW_COMMENTS, true);
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
        objectMapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        objectMapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
        objectMapper.configure(JsonParser.Feature.INTERN_FIELD_NAMES, true);
        objectMapper.configure(JsonParser.Feature.CANONICALIZE_FIELD_NAMES, true);
        objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    }
 
    public static String encode(Object obj) {
        try {
            return objectMapper.writeValueAsString(obj);
        } catch (JsonGenerationException e) {
            log.error("encode(Object)", e); //$NON-NLS-1$
        } catch (JsonMappingException e) {
            log.error("encode(Object)", e); //$NON-NLS-1$
        } catch (IOException e) {
            log.error("encode(Object)", e); //$NON-NLS-1$
        }
        return null;
    }
 
    /**
     * 将json string反序列化成对象
     *
     * @param json
     * @param valueType
     * @return
     */
    public static <T> T decode(String json, Class<T> valueType) {
        try {
            return objectMapper.readValue(json, valueType);
        } catch (JsonParseException e) {
            log.error("decode(String, Class<T>)", e);
        } catch (JsonMappingException e) {
            log.error("decode(String, Class<T>)", e);
        } catch (IOException e) {
            log.error("decode(String, Class<T>)", e);
        }
        return null;
    }
}