Fastjson

这玩意儿不多说，Alibaba出品，出过几次重大的安全漏洞，然而仍然很风行。这里写一下它怎么解决枚举。

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson --><dependency>    <groupId>com.alibaba</groupId>    <artifactId>fastjson</artifactId>    <version>1.2.76</version></dependency>

序列化为name()值

默认就是，啥也不必动

import com.alibaba.fastjson.JSON;enum Gender {    BOY, GIRL, UNKNOW}class User {    private Integer id;    private Gender gender;    public User() {    }    public User(Integer id, Gender gender) {        super();        this.id = id;        this.gender = gender;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public Gender getGender() {        return gender;    }    public void setGender(Gender gender) {        this.gender = gender;    }}public class MainTest {    public static void main(String[] args) throws Exception {                // 序列化为JSON输入        User user = new User(1, Gender.BOY);        String jsonString = JSON.toJSONString(user);         System.out.println(jsonString);    // {"gender":"BOY","id":1}                        // 反序列化为对象        user = JSON.parseObject(jsonString, User.class);        System.out.println(user.getGender());        // BOY    }}

序列化为ordinal()值

全局设置

代码跟下面没有变动，就须要在结尾增加一句代码，任何枚举，都会被序列化为ordinal()值

JSON.DEFAULT_GENERATE_FEATURE &= ~SerializerFeature.WriteEnumUsingName.mask;
        // 全局设置，枚举的序列化应用 ordinal()        JSON.DEFAULT_GENERATE_FEATURE &= ~SerializerFeature.WriteEnumUsingName.mask;                // 序列化为JSON输入，枚举值为 ordinal()        User user = new User(1, Gender.BOY);        String jsonString = JSON.toJSONString(user);         System.out.println(jsonString);    // {"gender":0,"id":1}                        // 反序列化为对象        user = JSON.parseObject(jsonString, User.class);        System.out.println(user.getGender());        // BOY

非凡设置

只想针对某一次序列化失效。只须要调用JSON.toJSONString的重载办法，增加配置就行。

public static String toJSONString(Object object, int defaultFeatures, SerializerFeature... features)
        // 序列化为JSON输入，本次把枚举值序列化为 ordinal()        User user = new User(1, Gender.BOY);        String jsonString = JSON.toJSONString(user, JSON.DEFAULT_GENERATE_FEATURE & ~SerializerFeature.WriteEnumUsingName.mask);         System.out.println(jsonString);    // {"gender":0,"id":1}                        // 反序列化为对象        user = JSON.parseObject(jsonString, User.class);        System.out.println(user.getGender());        // BOY

序列化为自定义属性

很多人也喜爱给枚举定义一个公有的属性，序列化为JSON时，心愿以这个属性值作为value，这个时候就须要本人定义JSON的序列化和反序列化实现了。Fastjson提供了2个接口。用户管制序列化和反序列化行为，这个切实是太简略，这里不多说。看代码

  • ObjectSerializer
  • ObjectDeserializer

序列化器的定义

import java.io.IOException;import java.lang.reflect.Type;import com.alibaba.fastjson.serializer.JSONSerializer;import com.alibaba.fastjson.serializer.ObjectSerializer;public class GenderEnumSerializer implements ObjectSerializer {    @Override    public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType, int features) throws IOException {        // 强制把值转换为Gender        Gender gender = (Gender) object;        // 序列化为自定义的name属性，输入就行        serializer.out.writeString(gender.getName());    }}

反序列化器的定义

import java.lang.reflect.Type;import com.alibaba.fastjson.parser.DefaultJSONParser;import com.alibaba.fastjson.parser.JSONToken;import com.alibaba.fastjson.parser.deserializer.ObjectDeserializer;public class GenderEnumDeserializer implements ObjectDeserializer {    @SuppressWarnings("unchecked")    @Override    public <T> T deserialze(DefaultJSONParser parser, Type type, Object fieldName) {        // 解析值为字符串        String value = parser.parseObject(String.class);        // 遍历所有的枚举实例        for (Gender gender : Gender.values()) {            if (gender.getName().equals(value)) {                // 胜利匹配，返回实例                return (T) gender;            }        }        // 没有匹配到，能够抛出异样或者返回null        return null;    }    @Override    public int getFastMatchToken() {        // 仅仅匹配字符串类型的值        return JSONToken.LITERAL_STRING;    }}

对象 & 枚举的定义

enum Gender {        BOY("男"), GIRL("女"), UNKNOW("不晓得");        public final String name;        Gender(String name) {        this.name = name;    }    public String getName() {        return name;    }}class User {        private Integer id;        // 标识注解，指定枚举的序列化。反序列化实现类    @JSONField(serializeUsing = GenderEnumSerializer.class, deserializeUsing = GenderEnumDeserializer.class)    private Gender gender;    public User() {    }    public User(Integer id, Gender gender) {        super();        this.id = id;        this.gender = gender;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public Gender getGender() {        return gender;    }    public void setGender(Gender gender) {        this.gender = gender;    }}

测试

public class MainTest {    public static void main(String[] args) throws Exception {        // 序列化为JSON输入，枚举值为 getName()        User user = new User(1, Gender.UNKNOW);        String jsonString = JSON.toJSONString(user);        System.out.println(jsonString); // {"gender":"不晓得","id":1}        // 反序列化为对象        user = JSON.parseObject(jsonString, User.class);        System.out.println(user.getGender()); // UNKNOW    }}

最初

很显然，自定义 ObjectSerializer /ObjectDeserializer 的形式最为灵便，能够思考形象一个接口进去，让所有的枚举都实现接口。这样针对接口编写ObjectSerializer /ObjectDeserializer实现，就能够很好的复用了。

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