FastJson序列号和反序列化范例(Java、Scala版)

港控/mmm° 2022-05-17 00:16 285阅读 0赞

**目录**

1. Java版

1.1 序列化

1.1.1 序列化一个普通对象

1.1.2 序列化和反序列化日期

1.2 反序列化

1.3 一些其他常用函数

2. Scala版

2.1 序列化

2.2 反序列化

--------------------

#  #

# 1. Java版 #

## 1.1 序列化 ##

### 1.1.1 序列化一个普通对象 ###

存在空值时，有两种处理方法。

// 正常对象
    User u = new User();
    u.setName("王五");
    u.setAge(30);
    
    System.out.println(JSON.toJSONString(u));
    // 输出结果 {"age":30,"name":"王五"}
     
    
    // 存在空值的对象
    User u1 = new User();
    u1.setAge(30);
    
    System.out.println(JSON.toJSONString(u1,SerializerFeature.WriteMapNullValue)); 
    // 输出null，输出结果 {"age":30,"name":null}
    
    System.out.println(JSON.toJSONString(u1,SerializerFeature.WriteNullStringAsEmpty)); 
    // 输出""，输出结果 {"age":30,"name":""}

## 1.1.2 序列化和反序列化日期 ##

Date date = new Date();
     
    String dateString = JSON.toJSONStringWithDateFormat(date, "yyyy-MM-dd HH:mm:ss");
    System.out.println(dateString);
     
    // 输出结果 "2018-08-03 09:44:21"
     
    String dateString1 = "{\"time\":\"2018-08-01 22:22:22\"}";
    System.out.println(JSON.parseObject(dateString1));
     
    // 输出结果 {"time":"2018-08-01 22:22:22"}

## 1.2 反序列化 ##

反序列化一个复杂的JSON字符串。得到一个成员变量包括 string int Object List<Object> 等多种类型的复杂类的对象。

下面是类的声明：

// 课程类
        public class Course {
    	    private String courseName;
    	    private String code;
     
    	    public Course (String courseName, String code){
    	        this.setCourseName(courseName);
    	        this.setCode(code);
    	    }
     
    	    public String getCourseName() {
    	        return courseName;
    	    }
     
    	    public void setCourseName(String courseName) {
    	        this.courseName = courseName;
    	    }
     
    	    public String getCode() {
    	        return code;
    	    }
     
    	    public void setCode(String code) {
    	        this.code = code;
    	    }
    	}
    
    // 学生类 
    	public class Student {
    	    private int id;
    	    private String studentName;
    	    private int age;
     
    	    public Student(int id, String studentName, int age) {
    	        this.setId(id);
    	        this.setStudentName(studentName);
    	        this.setAge(age);
    	    }
     
    	    public int getId() {
    	        return id;
    	    }
     
    	    public void setId(int id) {
    	        this.id = id;
    	    }
     
    	    public String getStudentName() {
    	        return studentName;
    	    }
     
    	    public void setStudentName(String studentName) {
    	        this.studentName = studentName;
    	    }
     
    	    public int getAge() {
    	        return age;
    	    }
     
    	    public void setAge(int age) {
    	        this.age = age;
    	    }
    	}
     
    // 将要序列化的 老师类
    // 成员变量包括 string int Object List<Object> 等多种类型。
    	public class Teacher {
    	    private String teacherName;
    	    private int age;
    	    private Course course;
    	    private List<Student> students;
     
    	    public Teacher(String teacherName, int age, Course course, List<Student> students) {
    	        this.setTeacherName(teacherName);
    	        this.setAge(age);
    	        this.setCourse(course);
    	        this.setStudents(students);
    	    }
     
    	    public String getTeacherName() {
    	        return teacherName;
    	    }
     
    	    public void setTeacherName(String teacherName) {
    	        this.teacherName = teacherName;
    	    }
     
    	    public int getAge() {
    	        return age;
    	    }
     
    	    public void setAge(int age) {
    	        this.age = age;
    	    }
     
    	    public Course getCourse() {
    	        return course;
    	    }
     
    	    public void setCourse(Course course) {
    	        this.course = course;
    	    }
     
    	    public List<Student> getStudents() {
    	        return students;
    	    }
     
    	    public void setStudents(List<Student> students) {
    	        this.students = students;
    	    }
    	}

反序列化结果：

String complexJsonString = "{\"teacherName\":\"crystall\",\"age\":27,\"course\":{\"courseName\":\"english\",\"code\":1270},\"students\":[{\"id\":1,\"studentName\":\"lily\",\"age\":12},{\"id\":2,\"studentName\":\"lucy\",\"age\":15}]}";
    Teacher teacher = JSON.parseObject(complexJsonString,Teacher.class);

## 1.3 一些其他常用函数 ##

String jsonString1 = "{\"name\":\"张三\",\"age\":50}";
    JSONObject jsonObject = JSON.parseObject(jsonString1);
     
    System.out.println(jsonObject.keySet()); // 输出key集合，输出结果 [name, age]
     
    if(jsonObject.containsKey("sex")) { // 判断key是否存在，输出结果 false
        System.out.println(true);
    } else {
        System.out.println(false);
    }
     
    jsonObject.put("sex","man"); // 添加k/v键值对，输出结果 {"sex":"man","name":"张三","age":50}
    System.out.println(jsonObject);
     
    if (jsonObject.containsValue("man")) { // 判断value是否存在，输出结果 false
        System.out.println(true);
    } else {
        System.out.println(false);
    }
    
    String jsonArrayString1 = "[{\"id\":1,\"studentName\":\"lily\",\"age\":12},{\"id\":2,\"studentName\":\"lucy\",\"age\":15}]";
    JSONArray jsonArray = JSON.parseArray(jsonArrayString1);
     
    for (int i = 0; i < jsonArray.size(); i++) { // 遍历输出
        JSONObject jsonObj= jsonArray.getJSONObject(i);
        System.out.println(jsonObj.get("id"));
    }
     
    Student s3 = new Student(3,"学生乙",15);
    jsonArray.add(s3); // 添加新jsonobject对象，输出结果 3
    System.out.println(jsonArray.size());
     
    if(jsonArray.contains(s3)) { // 判断是否存在，输出结果 true
        System.out.println(true);
    } else {
        System.out.println(false);
    }

# 2. Scala版 #

## 2.1 序列化 ##

val arr = Seq("tom:10", "bob:14", "hurry:9")
    val dataRdd = spark.sparkContext.parallelize(arr)
     
    val dataString = dataRdd.map(x => {
      val arr = x.split(":")
      val name = arr(0)
      val age = arr(1).toInt
      val u = new User(name,age)
      u
    }).map(x => {
      JSON.toJSONString(x,SerializerFeature.WriteMapNullValue)  // 这里需要显示SerializerFeature中的某一个，否则会报同时匹配两个方法的错误
    })
     
    dataString.foreach(println)
     
    // 输出结果
    {"age":10,"name":"tom"}
    {"age":14,"name":"bob"}
    {"age":9,"name":"hurry"}

## 2.2 反序列化 ##

...待续...