JSON数组格式

  1. var josnArray=["k1","k2",100,9.9,true];
  3. console.log(jsonArray[1]);   //输出k2
  5. for(var i=2;;i<jsonArray.length;i++){
  6.       console.log(jsonArray[i]);
  7. }

JOSN对象格式

  1. var  jsonObject={"k1":"v1","k2":"v2","k3":100,"k4":9.9,"k5":true}
  3. console.log(jsonObject.k1);
  4. console.log(jsonObject.k2);
  5. console.log(jsonObject.k3);
  6. console.log(jsonObject.k4);
  7. console.log(jsonObject.k5);

JSON一层相互嵌套

数组中嵌套对象

  1. var jsonArray=[
  2.   {"name":"张三","age":20},
  3.   {"name":"李四","age":22},
  4. ];
  6. //取出第一个对象中的属性值
  7. console.log(jsonArray[0].name+"======"+josnArray[0].age);
  9. //遍历数组输出对象属性
  10. for(var i=0;i<jsonArray.length;i++){
  11.     console.log(jsonArray[i].name+"======"+jsonArray[i].age);
  12. }

对象中嵌套数组

  1. var josnObject={
  2.     "k1":["北京","天津","上海"],
  3.     "k2":["中国","美国","英国"]
  4. };
  6. //取出数组中的单个元素
  7. console.log(jsonObject.k1[2]);
  9. //取出k1，k2数组进行遍历
  10. for(var i=0;i<jsonObject.k1.length;i++){
  11.     console.log(josnObject.k1[i]);
  12. }
  14. console.log("==============");
  16. for(var i=0;i<jsonObject.k2.length;i++){
  17.     console.log(josnObject.k2[i]);
  18. }

JSON多层相互嵌套

  1. var jsonObject{
  2.     "k1":[
  3.       {"name":"张三","age":"20"},
  4.       {"name":"李四","age":"22"},
  5.     ];
  6.      "k1":[
  7.       {"name":"王五","age":"24"},
  8.       {"name":"赵六","age":"28"},
  9.     ];
  10. };
  13. //取出数组中的单个属性
  14. console.log(jsonObject.k1[1].name+"==="+jsonObject.k1[1].age);
  16. //遍历k2对应的数组
  17. for(var i=0;i<jsonBoject.k2.length;i++){
  18.     console.log(jsonObject.k2[i].name+"==="+jsonObject.k2[i].age);
  19. }

FastJson

FatsJson是阿里巴巴的开源JSON解析库，它可以解析JSON格式的字符串，支持将Java Bean 序列化未JSON字符串，也可以将Json字符串反序列化到Java Bean。
FastJson的优点

  • 速度快
  • 使用广泛
  • 测试完备
  • 使用简单

  • 功能完备

    FastJson的序列化操作

    JSON.toJSONString
    1、创建项目导入FastJson依赖，单元测试依赖，Lombok依赖
    2、创建实体类Student

    1. @Data
    2. public class Student {
    3.   private int id;
    4.   private String name;
    5.   private int age;
    6.   private String email;
    7.   private Date birthday;
    8. }

    对象转JSON -对象-toJSONString

    结果为对象

  • 单元测试 ```java public class StudentTest { @Test public void testJosn(){

    1.   Student student = new Student();
    2.   student.setId(1);
    3.   student.setName("张三");
    4.   student.setAge(20);
    5.   student.setEmail("zs@sina.com");
    6.   student.setBirthday(new Date());
    8.   String result = JSON.toJSONString(student);
    9.   System.out.println(result);

    } }

  2. - 测试结果
  3. ```java
  4. {"age":20,"birthday":1656753454318,"email":"zs@sina.com","id":1,"name":"张三"}

List转JSON -数组-toJSONString

结果为数组，数组的元素为对象。

  • 单元测试

    1. @Test
    2.   public void testJosnList(){
    3.       Student student = new Student();
    4.       student.setId(1);
    5.       student.setName("张三");
    6.       student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       Student student1 = new Student();
    11.       student1.setId(2);
    12.       student1.setName("李四");
    13.       student1.setAge(24);
    14.       student1.setEmail("ls@126.com");
    15.       student1.setBirthday(new Date());
    17.       ArrayList<Student> list = new ArrayList<>();
    18.       list.add(student);
    19.       list.add(student1);
    21.       String result = JSON.toJSONString(list);
    22.       System.out.println(result);
    23.   }

  • 结果

    1. [{"age":20,"birthday":1656754123105,"email":"zs@sina.com","id":1,"name":"张三"},{"age":24,"birthday":1656754123105,"email":"ls@126.com","id":2,"name":"李四"}]

    Map转JSON -对象-toJSONString

  • 单元测试

    1. @Test
    2.   public void testJosnMap(){
    3.       Student student = new Student();
    4.       student.setId(1);
    5.       student.setName("张三");
    6.       student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       Student student1 = new Student();
    11.       student1.setId(2);
    12.       student1.setName("李四");
    13.       student1.setAge(24);
    14.       student1.setEmail("ls@126.com");
    15.       student1.setBirthday(new Date());
    17.       Map<String,Student> map = new HashMap<>();
    18.       map.put("student",student);
    19.       map.put("student1",student1);
    21.       String result = JSON.toJSONString(map);
    22.       System.out.println(result);
    23.   }

  • 结果

    1. {"student":{"age":20,"birthday":1656754579419,"email":"zs@sina.com","id":1,"name":"张三"},"student1":{"age":24,"birthday":1656754579419,"email":"ls@126.com","id":2,"name":"李四"}}

    FastJson的反序列化操作

    JSON对象转Java对象-parseObject

    JSON.parseObject(jsonString, Student.class);

  • 单元测试

    1.   @Test
    2.   public void tsetJsonToJavaObject(){
    3.       String jsonString="{\"age\":20,\"birthday\":1656753454318,"+
    4.           "\"email\":\"zs@sina.com\",\"id\":1,\"name\":\"张三\"}";
    6.       Student student = JSON.parseObject(jsonString, Student.class);
    7.       System.out.println(student);
    8.   }

  • 结果

    1. Student(id=1, name=张三, age=20, email=zs@sina.com, birthday=Sat Jul 02 17:17:34 CST 2022)

    JSON的List转Java-parseArray

    JSON.parseArray(jsonString, Student.class);

  • 单元测试

    1. @Test
    2.   public void tsetJsonToJavaArray(){
    3.       String jsonString="[{\"age\":20,\"birthday\":1656754123105,\"email\":\"zs@sina.com\"," +
    4.               "\"id\":1,\"name\":\"张三\"},{\"age\":24,\"birthday\":1656754123105,\"email\":" +
    5.               "\"ls@126.com\",\"id\":2,\"name\":\"李四\"}]";
    7.       List<Student> list = JSON.parseArray(jsonString, Student.class);
    8.       for(Student student:list){
    9.           System.out.println(student);
    10.       }
    11.   }

  • 结果

    1. Student(id=1, name=张三, age=20, email=zs@sina.com, birthday=Sat Jul 02 17:28:43 CST 2022)
    2. Student(id=2, name=李四, age=24, email=ls@126.com, birthday=Sat Jul 02 17:28:43 CST 2022)

    JSON的Map转Java -parseObject

    JSON.parseObject(jsonString,new TypeReference>() {});

  • 单元测试

    1. @Test
    2.   public void tsetJsonToJavaMap(){
    3.       String jsonString="{\"student\":{\"age\":20,\"birthday\":1656754579419," +
    4.               "\"email\":\"zs@sina.com\",\"id\":1,\"name\":\"张三\"},\"student1\"" +
    5.               ":{\"age\":24,\"birthday\":1656754579419,\"email\":\"ls@126.com\"," +
    6.               "\"id\":2,\"name\":\"李四\"}}";
    8.       Map<String, Student> map = JSON.parseObject(jsonString,
    9.               new TypeReference<Map<String, Student>>() {});
    11.       for (String key:map.keySet()){
    12.           System.out.println(key+"::"+map.get(key));
    13.       }
    14.   }

  • 结果

    1. student::Student(id=1, name=张三, age=20, email=zs@sina.com, birthday=Sat Jul 02 17:36:19 CST 2022)
    2. student1::Student(id=2, name=李四, age=24, email=ls@126.com, birthday=Sat Jul 02 17:36:19 CST 2022)

    SerializerFeature序列化对象

    WriteMapNullValue

    没有赋值的字符串属性，序列化时不会显示该属性，在序列化时加上该参数，序列化时该属性会显示为null

  • 单元测试

    1.   @Test
    2.   public void testNull(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.WriteMapNullValue);
    11. //        String result = JSON.toJSONString(student);
    12.       System.out.println(result);
    13.   }

  • 结果

    1. {"age":0,"birthday":1657007508874,"email":"zs@sina.com","id":1,"name":null}

    WriteNullStringAsEmpty

    将没有赋值的属性，显示为空字符串。

  • 单元测试

    1. @Test
    2.   public void testNullToEmpty(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.WriteNullStringAsEmpty);
    11.       System.out.println(result);
    12.   }

  • 结果

    1. {"age":0,"birthday":1657007677593,"email":"zs@sina.com","id":1,"name":""}

    WriteNullNumberAsZero

    将没有赋值的数值型的属性显示为0（注：版本默认将不赋值的数值型属性显示为0），该属性不会影响不赋值的字符串属性是否显示。

  • 单元测试

    1. @Test
    2.   public void testNullToZero(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.WriteNullNumberAsZero);
    11.       System.out.println(result);
    12.   }

  • 结果

    1. @Test
    2.   public void testNullToZero(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.WriteNullNumberAsZero);
    11.       System.out.println(result);
    12.   }

    WriteNullBooleanAsFalse

    将未赋值的Boolean值序列化为false。

  • 单元测试

    1. @Test
    2.   public void testBooleanToFalse(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    9. //        student.setFlag(true);
    11.       String result = JSON.toJSONString(student, SerializerFeature.WriteNullBooleanAsFalse);
    12.       System.out.println(result);
    13.   }

  • 结果

    1. {"age":0,"birthday":1657008348277,"email":"zs@sina.com","flag":false,"id":1}

    WriteDateUseDateFormat

    将时间日期序列化为标准的格式。

  • 单元测试

    1. @Test
    2.   public void testDateToFormat(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.WriteDateUseDateFormat);
    11.       System.out.println(result);
    12.   }

  • 结果

    1. {"age":0,"birthday":"2022-07-05 16:09:20","email":"zs@sina.com","id":1}

    PrettyFormat

    将输出的格式转化为纵向输出。

  • 单元测试

    1. @Test
    2.   public void testDateToPrettyFormat(){
    3.       Student student=new Student();
    4.       student.setId(1);
    5. //        student.setName("张三");
    6. //        student.setAge(20);
    7.       student.setEmail("zs@sina.com");
    8.       student.setBirthday(new Date());
    10.       String result = JSON.toJSONString(student, SerializerFeature.PrettyFormat);
    11.       System.out.println(result);
    12.   }

  • 结果

    1. {
    2.   "age":0,
    3.   "birthday":1657008638537,
    4.   "email":"zs@sina.com",
    5.   "id":1
    6. }

    JSonFields注解

    该注解可以使用在类上，方法上和参数上。

  • name属性，可以表明序列化后的字段名

  • ordinal属性，表明系列化后的字段的顺序，默认值为0，值越大越往后
  • format属性，表明序列化后的格式
  • serialize属性，是否序列化
  • disserialize属性，是否反序列化（注：未序列化的不可反序列化）

  • serialzeFeatures序列化时的特性定义。与SerializerFeature类似。

    1. @JSonFields(name="studentName",ordinal=1)
    2. @JSonFields(format="YYYY-MM-dd")
    3. @JSonFields(serialize="false")

    JSonType注解

    该注解作用在类上

  • includes属性，指明需要进行序列化的属性（注：与JSonFields注解冲突时，JSonType优先）

  • orders属性，指明序列化后的顺序。
  • serialzeFeatures属性，与SerializerFeature类似
    1. @JSonType(includes={"id","name","address"},orders={"name","address","age"})