2019年/11月/04日

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常用json lib对比

我们常用来处理的json库有gson,jackson,fastjson,simple json，他们各自在处理json的反序列化的时候有重大的差异

       <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.6</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.10.0</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.62</version>
        </dependency>

        <dependency>
            <groupId>com.googlecode.json-simple</groupId>
            <artifactId>json-simple</artifactId>
            <version>1.1.1</version>
        </dependency>

对于json-simple因为api太简单了，实用性不好

            String json = JSONValue.toJSONString(obj);
            Object obj = JSONValue.parse(JSON.toJSONString(obj));

对于对象序列化到json完全不支持java的自定义类型

我们主要看gson,jackson,fastjson

基础数据

public class User {

    private String name = "hello";

    private Date date = new Date();

    private byte[] bytes = "hello".getBytes();

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public byte[] getBytes() {
        return bytes;
    }

    public void setBytes(byte[] bytes) {
        this.bytes = bytes;
    }
}

User user = new User();

List<User> users = Arrays.asList(user);

List list = new ArrayList();
list.add(1);
list.add(new BigInteger("13323234242444444444444"));
list.add(1.0);
list.add(new BigDecimal("22355555555555555555555555555555555555555.3255555555555550005"));
list.add("hello");
list.add(null);
list.add(true);
list.add(false);
list.add(user);
list.add(users);

fast json

for (Object obj : list) {
            System.out.print(JSON.toJSONString(obj));
            System.out.print(" => ");
            Object parse = JSON.parse(JSON.toJSONString(obj));
            if (parse != null) {
                System.out.println(parse.getClass());
            } else {
                System.out.println();
            }
        }
1 => class java.lang.Integer
13323234242444444444444 => class java.math.BigInteger
1.0 => class java.math.BigDecimal
22355555555555555555555555555555555555555.3255555555555550005 => class java.math.BigDecimal
"hello" => class java.lang.String
null => 
true => class java.lang.Boolean
false => class java.lang.Boolean
{"bytes":"aGVsbG8=","date":1573560286315,"name":"hello"} => class com.alibaba.fastjson.JSONObject
[{"bytes":"aGVsbG8=","date":1573560286315,"name":"hello"}] => class com.alibaba.fastjson.JSONArray

Gson

Gson gson = new Gson();
        for (Object obj : list) {
            System.out.print(gson.toJson(obj));
            System.out.print(" => ");
            Object o = gson.fromJson(gson.toJson(obj), Object.class);
            if (o != null) {
                System.out.println(o.getClass());
            } else {
                System.out.println();
            }
        }
1 => class java.lang.Double
13323234242444444444444 => class java.lang.Double
1.0 => class java.lang.Double
22355555555555555555555555555555555555555.3255555555555550005 => class java.lang.Double
"hello" => class java.lang.String
null => 
true => class java.lang.Boolean
false => class java.lang.Boolean
{"name":"hello","date":"Nov 12, 2019 8:04:46 PM","bytes":[104,101,108,108,111]} => class com.google.gson.internal.LinkedTreeMap
[{"name":"hello","date":"Nov 12, 2019 8:04:46 PM","bytes":[104,101,108,108,111]}] => class java.util.ArrayList

Jackson

ObjectMapper mapper = new ObjectMapper();
        for (Object obj : list) {
            System.out.print(mapper.writeValueAsString(obj));
            System.out.print(" => ");

            Object o = mapper.readValue(mapper.writeValueAsString(obj), Object.class);
            if (o != null) {
                System.out.println(o.getClass());
            } else {
                System.out.println();
            }
        }
1 => class java.lang.Integer
13323234242444444444444 => class java.math.BigInteger
1.0 => class java.lang.Double
22355555555555555555555555555555555555555.3255555555555550005 => class java.lang.Double
"hello" => class java.lang.String
null => 
true => class java.lang.Boolean
false => class java.lang.Boolean
{"name":"hello","date":1573560286315,"bytes":"aGVsbG8="} => class java.util.LinkedHashMap
[{"name":"hello","date":1573560286315,"bytes":"aGVsbG8="}] => class java.util.ArrayList

总结