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Jackson快速替换Fastjson之道

一· 概述

Fastjson已经连续几次爆出高危漏洞，和Structs一样，每次影响范围都比较广，殃及几乎所有的JAVA后台系统。为避免以后频繁地应急处理Fastjson的安全漏洞，痛定思痛，决定放弃Fastjson转投jackson的怀抱了。

二· 快速替换

2.1 加入依赖

在pom文件中添加jackson的依赖包，如下：

<properties>
        <jackson-version>2.9.9</jackson-version>
    </properties>
    ...

    <dependencyManagement>
        <dependencies>
            <!--jackson-->
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-core</artifactId>
                <version>${jackson-version}</version>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-databind</artifactId>
                <version>${jackson-version}</version>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-annotations</artifactId>
                <version>${jackson-version}</version>
            </dependency>
            ...

2.2 适配接口

在FastJson中序列化和发序列化用的最多的两个函数就是 toJSONString 和 toJavaObject ，部分场景也会用到数据组的序列化相关函数，以及利用json进行复制对象（类似Cloneable)，因此，我们需要适配基本所需的功能，以下的接口基本能涵盖大部分的场景。

public static String toJSONString(Object obj);
public static String toJSONString(Object obj, Supplier<String> defaultSupplier);

public static <T> T toJavaObject(String value, Class<T> tClass);
public static <T> T toJavaObject(Object obj, Class<T> tClass);
public static <T> T toJavaObject(String value, Class<T> tClass, Supplier<T> defaultSupplier)

public static <T> T jsonCopy(Object obj, Class<T> tClass)

数组相关的接口定义如下：

public static List<Object> toList(String value);
public static List<Object> toList(Object value);
public static List<Object> toList(String value, Supplier<List<Object>> defaultSuppler);
public static List<Object> toList(Object value, Supplier<List<Object>> defaultSuppler);

public static <T> List<T> toJavaObjectList(String value, Class<T> tClass)
public static <T> List<T> toJavaObjectList(Object obj, Class<T> tClass)
public static <T> List<T> toJavaObjectList(String value, Class<T> tClass, Supplier<List<T>> defaultSupplier)

2.3 适配JsonObject

如果变量定义为JsonObject类型，可以将其修改为Map<String, Object>。为此，需定义相关的函数进行辅助变换：

public static Map<String, Object> toMap(String value);
public static Map<String, Object> toMap(Object value);
public static Map<String, Object> toMap(Object value, Supplier<Map<String, Object>> defaultSupplier);
public static Map<String, Object> toMap(String value, Supplier<Map<String, Object>> defaultSupplier);

三· 工具类封装代码

为了统一替换fastjson，我封装了一个Java(要求JDK8+)工具类JsonUtils，方便大家扩展。

package com.netease.is.nm.base.util;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;

import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Supplier;


@Slf4j
public class JsonUtils {
    // 加载速度太慢了，放在静态代码块中
    // private static final ObjectMapper mapper = new ObjectMapper();
    private static ObjectMapper mapper;

    /**
     * 设置一些通用的属性
     */
    static {
        mapper = new ObjectMapper();
        // 如果json中有新增的字段并且是实体类类中不存在的，不报错
        // mapper.configure(DeserializationFeature.FAIL_ON_IGNORED_PROPERTIES, false);
        // 如果存在未知属性，则忽略不报错
        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        // 允许key没有双引号
        mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
        // 允许key有单引号
        mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
        // 允许整数以0开头
        mapper.configure(JsonParser.Feature.ALLOW_NUMERIC_LEADING_ZEROS, true);
        // 允许字符串中存在回车换行控制符
        mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
    }

    public static String toJSONString(Object obj) {
        return obj != null ? toJSONString(obj, () -> "") : "";
    }

    public static String toJSONString(Object obj, Supplier<String> defaultSupplier) {
        try {
            return obj != null ? mapper.writeValueAsString(obj) : defaultSupplier.get();
        } catch (Throwable e) {
            log.error(String.format("toJSONString %s", obj != null ? obj.toString() : "null"), e);
        }
        return defaultSupplier.get();
    }

    public static <T> T toJavaObject(String value, Class<T> tClass) {
        return StringUtils.isNotBlank(value) ? toJavaObject(value, tClass, () -> null) : null;
    }

    public static <T> T toJavaObject(Object obj, Class<T> tClass) {
        return obj != null ? toJavaObject(toJSONString(obj), tClass, () -> null) : null;
    }

    public static <T> T toJavaObject(String value, Class<T> tClass, Supplier<T> defaultSupplier) {
        try {
            if (StringUtils.isBlank(value)) {
                return defaultSupplier.get();
            }
            return mapper.readValue(value, tClass);
        } catch (Throwable e) {
            log.error(String.format("toJavaObject exception: /n %s/n %s", value, tClass), e);
        }
        return defaultSupplier.get();
    }

    public static <T> List<T> toJavaObjectList(String value, Class<T> tClass) {
        return StringUtils.isNotBlank(value) ? toJavaObjectList(value, tClass, () -> null) : null;
    }

    public static <T> List<T> toJavaObjectList(Object obj, Class<T> tClass) {
        return obj != null ? toJavaObjectList(toJSONString(obj), tClass, () -> null) : null;
    }

    public static <T> List<T> toJavaObjectList(String value, Class<T> tClass, Supplier<List<T>> defaultSupplier) {
        try {
            if (StringUtils.isBlank(value)) {
                return defaultSupplier.get();
            }
            JavaType javaType = mapper.getTypeFactory().constructParametricType(List.class, tClass);
            return mapper.readValue(value, javaType);
        } catch (Throwable e) {
            log.error(String.format("toJavaObjectList exception /n%s/n%s", value, tClass), e);
        }
        return defaultSupplier.get();
    }

    // 简单地直接用json复制或者转换(Cloneable)
    public static <T> T jsonCopy(Object obj, Class<T> tClass) {
        return obj != null ? toJavaObject(toJSONString(obj), tClass) : null;
    }

    public static Map<String, Object> toMap(String value) {
        return StringUtils.isNotBlank(value) ? toMap(value, () -> null) : null;
    }

    public static Map<String, Object> toMap(Object value) {
        return value != null ? toMap(value, () -> null) : null;
    }

    public static Map<String, Object> toMap(Object value, Supplier<Map<String, Object>> defaultSupplier) {
        if (value == null) {
            return defaultSupplier.get();
        }
        try {
            if (value instanceof Map) {
                return (Map<String, Object>) value;
            }
        } catch (Exception e) {
            log.info("fail to convert" + toJSONString(value), e);
        }
        return toMap(toJSONString(value), defaultSupplier);
    }

    public static Map<String, Object> toMap(String value, Supplier<Map<String, Object>> defaultSupplier) {
        if (StringUtils.isBlank(value)) {
            return defaultSupplier.get();
        }
        try {
            return toJavaObject(value, LinkedHashMap.class);
        } catch (Exception e) {
            log.error(String.format("toMap exception/n%s", value), e);
        }
        return defaultSupplier.get();
    }


    public static List<Object> toList(String value) {
        return StringUtils.isNotBlank(value) ? toList(value, () -> null) : null;
    }

    public static List<Object> toList(Object value) {
        return value != null ? toList(value, () -> null) : null;
    }

    public static List<Object> toList(String value, Supplier<List<Object>> defaultSuppler) {
        if (StringUtils.isBlank(value)) {
            return defaultSuppler.get();
        }
        try {
            return toJavaObject(value, List.class);
        } catch (Exception e) {
            log.error("toList exception/n" + value, e);
        }
        return defaultSuppler.get();
    }

    public static List<Object> toList(Object value, Supplier<List<Object>> defaultSuppler) {
        if (value == null) {
            return defaultSuppler.get();
        }
        if (value instanceof List) {
            return (List<Object>) value;
        }
        return toList(toJSONString(value), defaultSuppler);
    }
}