使用FastJson处理JSON数据

Json 数据处理技术 之 FastJson

• Maven依赖

    com.alibaba
    fastjson
    1.2.62

测试代码实体类：

public class Dept {
    private Integer deptno;
    private String dname;
    private String loc;

    public Dept() {
    }

    public Dept(Integer deptno, String dname, String loc) {
        this.deptno = deptno;
        this.dname = dname;
        this.loc = loc;
    }

    public Integer getDeptno() {
        return deptno;
    }

    public void setDeptno(Integer deptno) {
        this.deptno = deptno;
    }

    public String getDname() {
        return dname;
    }

    public void setDname(String dname) {
        this.dname = dname;
    }

    public String getLoc() {
        return loc;
    }

    public void setLoc(String loc) {
        this.loc = loc;
    }

    @Override
    public String toString() {
        return "Dept{" +
                "deptno=" + deptno +
                ", dname='" + dname + '\'' +
                ", loc='" + loc + '\'' +
                '}';
    }
}

注：采用FastJSON的实体类必须得实现getter/setter方法，否则序列化时会得不到数据，只会得到一个空的JSON对象

示例：实体类序列化和反序列化

public static void main(String[] args) {
    Dept dept = new Dept(10, "RESEARCH", "NEWYORK");
    //序列化
    String json = JSON.toJSONString(dept);
    System.out.println(json);

    //反序列化
    Dept res =  JSON.parseObject(json,Dept.class);
    System.out.println(res.getDname());
}

示例：List/Set序列化和反序列化

public static void main(String[] args) {
    Set depts = new HashSet();
    depts.add(new Dept(10,"ACCOUNTING","CHICAGO"));
    depts.add(new Dept(20,"RESEARCH","DALLAS"));
    depts.add(new Dept(30,"SALES","CHICAGO"));
    depts.add(new Dept(40,"OPERATIONS","BOSTON"));

    //序列化
    String json = JSON.toJSONString(depts);
    System.out.println(json);

    //反序列化
    List res = JSON.parseArray(json, Dept.class);
    res.forEach(System.out::println);
}

示例：Map序列化和反序列化

public static void main(String[] args) {
    Map map = new HashMap();

    map.put("ACCOUNTING",new Dept(10,"ACCOUNTING","CHICAGO"));
    map.put("RESEARCH",new Dept(20,"RESEARCH","DALLAS"));
    map.put("SALES",new Dept(30,"SALES","CHICAGO"));
    map.put("OPERATIONS",new Dept(40,"OPERATIONS","BOSTON"));

    //序列化
    String json = JSON.toJSONString(map);
    System.out.println(json);

    //反序列化
    Map res = JSONObject.parseObject(json, new TypeReference() {});
    res.forEach((k,v)-> System.out.println(k+" : "+v));
}

常用注解

• @JSONField(ordinal =0)：指定序列化字段的顺序，默认是0
• @JSONField(name = “”)：指定序列化字段的别名
• @JSONField(format = “”)：指定日期格式
• @JSONField(serialize = 布尔类型)：是否要把这个字段序列化成JSON字符串，默认是true
• @JSONField(deserialize = 布尔类型)：是否需要进行反序列化，默认是true

示例：FastJson中常用注解

• 实体类：

public class Stu {
    @JSONField(ordinal = 0) //指定序列化的顺序
    private int id;
    @JSONField(ordinal = 1,name = "stuName")//指定序列化后的字段名
    private String name;
    @JSONField(ordinal = 2,format = "yyyy-MM-DD")//日期格式化
    private Date birth;
    @JSONField(ordinal = 3,serialize = false,deserialize = false)//指定字段不序列化,不反序列化
    private float score;

    public Stu() {
    }

    public Stu(int id, String name, Date birth, float score) {
        this.id = id;
        this.name = name;
        this.birth = birth;
        this.score = score;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Date getBirth() {
        return birth;
    }

    public void setBirth(Date birth) {
        this.birth = birth;
    }

    public float getScore() {
        return score;
    }

    public void setScore(float score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "Stu{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", birth=" + birth +
                ", score=" + score +
                '}';
    }
}

• 测试代码：

public static void main(String[] args) {
    Stu stu = new Stu(1111, "zhangsan", new Date(), 88);
    String json = JSON.toJSONString(stu);//序列化
    System.out.println(json);
    
    String data = "{'id':1111,'stuName':'zhangsan','birth':'2019-10-290','score':98}";
    Stu res = JSON.parseObject(data, Stu.class);//反序列化
    System.out.println(res);
}