FastJson基本使用_fastjson maven_兮动人

大大的周 02-07 1558

文章目录 1. FastJson序列化API1.1 序列化Java对象1.2 序列化List集合1.3 序列化Map集合 2. FashJson反序列化API2.1 反序列化Java对象2.2 反序列化List集合2.3 反序列化Map集合 3. SerializerFeature枚举3.1 WriteMapNullValue3.2 WriteNullStringAsEmpty3.3 WriteNullNumberAsZero3.4 WriteNullBooleanAsFalse3.5 WriteDateUseDateFormat3.6 PrettyFormat 4. JSonField 注解5. JSonType 注解

1. FastJson序列化API 方法：JSON.toJSONString序列化 : 是指将Java对象转成json格式字符串的过程。JavaBean对象、List集合对象、Map集合为应用最广泛的。 1.1 序列化Java对象 Java 中的 Student 对象序列化为 JSON 格式字符串 @Test public void objectToJson(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); String jsonString = JSON.toJSONString(student); System.out.println(jsonString); }

{ "address":"深圳市", "age":24, "flag":true, "id":1, "name":"兮动人" } 1.2 序列化List集合 @Test public void listToJson(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); Student student2 = new Student(); student2.setId(2); student2.setName("Mike"); student2.setAge(25); student2.setAddress("北京市"); student2.setFlag(false); List<Student> list = new ArrayList<Student>(); list.add(student); list.add(student2); String jsonString = JSON.toJSONString(list); System.out.println(jsonString); }

[{ "address":"深圳市","age":24,"flag":true, "id":1,"name":"兮动人"},{"address":"北京市","age":25,"flag":false,"id":2,"name":"Mike"}] 可以观察到 JSON 默认排序是按a-z字母顺序排的 [ { "address":"深圳市", "age":24, "flag":true, "id":1, "name":"兮动人" }, { "address":"北京市", "age":25, "flag":false, "id":2, "name":"Mike" } ] 1.3 序列化Map集合 @Test public void mapToJson(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); Student student2 = new Student(); student2.setId(2); student2.setName("Mike"); student2.setAge(25); student2.setAddress("北京市"); student2.setFlag(false); Map<String,Student> map = new HashMap<String, Student>(); map.put("s1",student); map.put("s2",student2); String jsonString = JSON.toJSONString(map); System.out.println(jsonString); }

{ "s1":{ "address":"深圳市", "age":24, "flag":true, "id":1, "name":"兮动人" }, "s2":{ "address":"北京市", "age":25, "flag":false, "id":2, "name":"Mike" } } 2. FashJson反序列化API 反序列化：JSON 格式字符串，反序列化为 Java 对象 2.1 反序列化Java对象方法：JSON.parseObject @Test public void jsonToObject(){ String jsonString = "{\"address\":\"深圳市\",\"age\":24,\"flag\":true,\"id\":1,\"name\":\"兮动人\"}"; Student student = JSON.parseObject(jsonString, Student.class); System.out.println(student); } Student(id=1, name=兮动人, age=24, address=深圳市, flag=true) 2.2 反序列化List集合方法：JSON.parseArray @Test public void jsonToList(){ String jsonString = "[{\"address\":\"深圳市\",\"age\":24,\"flag\":true,\"id\":1,\"name\":\"兮动人\"}," + "{\"address\":\"北京市\",\"age\":25,\"flag\":false,\"id\":2,\"name\":\"Mike\"}]"; List<Student> list = JSON.parseArray(jsonString,Student.class); for (int i = 0; i < list.size(); i++) { Student student = list.get(i); System.out.println(student); } } Student(id=1, name=兮动人, age=24, address=深圳市, flag=true) Student(id=2, name=Mike, age=25, address=北京市, flag=false) 2.3 反序列化Map集合方法：JSON.parseObject @Test public void jsonToMap(){ String jsonString = "{\"s1\":{\"address\":\"深圳市\",\"age\":24,\"flag\":true,\"id\":1,\"name\":\"兮动人\"}," + "\"s2\":{\"address\":\"北京市\",\"age\":25,\"flag\":false,\"id\":2,\"name\":\"Mike\"}}"; Map<String,Student> parse = JSON.parseObject(jsonString,new TypeReference<Map<String,Student>>(){}); for(String s : parse.keySet()){ System.out.println(s + ":"+parse.get(s)); } } s1:Student(id=1, name=兮动人, age=24, address=深圳市, flag=true) s2:Student(id=2, name=Mike, age=25, address=北京市, flag=false) 3. SerializerFeature枚举该枚举支持序列化的一些特性数据定义 3.1 WriteMapNullValue 枚举常量 WriteMapNullValue 序列化为 null 的字段 @Test public void testSerializerFeature(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); // student.setAddress("深圳市"); student.setFlag(true); String jsonString = JSON.toJSONString(student, SerializerFeature.WriteMapNullValue); System.out.println(jsonString); } {"address":null,"age":24,"flag":true,"id":1,"name":"兮动人"} 3.2 WriteNullStringAsEmpty 枚举常量 WriteNullStringAsEmpty 字段为null，序列化为"" String jsonString = JSON.toJSONString(student, SerializerFeature.WriteNullStringAsEmpty); {"address":"","age":24,"flag":true,"id":1,"name":"兮动人"} 3.3 WriteNullNumberAsZero 枚举常量 WriteNullNumberAsZero 字段为null，序列化为0 @Test public void testAsZero(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); // student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); String jsonString = JSON.toJSONString(student, SerializerFeature.WriteNullNumberAsZero); System.out.println(jsonString); } {"address":"深圳市","age":0,"flag":true,"id":1,"name":"兮动人"} 3.4 WriteNullBooleanAsFalse 枚举常量 WriteNullBooleanAsFalse 字段值为null 输出false @Test public void testAsFalse(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); // student.setFlag(true); String jsonString = JSON.toJSONString(student, SerializerFeature.WriteNullBooleanAsFalse); System.out.println(jsonString); }

3.5 WriteDateUseDateFormat

枚举常量 WriteDateUseDateFormat 格式化日期格式

没有加属性的情况下，序列化话，日期显示的是毫秒值 @Test public void testDateFormat(){ Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); student.setBirthDate(new Date()); String jsonString = JSON.toJSONString(student); System.out.println(jsonString); }

加上格式化日期后： String jsonString = JSON.toJSONString(student, SerializerFeature.WriteDateUseDateFormat);

3.6 PrettyFormat 也可以在后面都加上枚举常量 PrettyFormat格式化输出，一目了然 String jsonString = JSON.toJSONString(student,SerializerFeature.WriteDateUseDateFormat, SerializerFeature.PrettyFormat);

4. JSonField 注解

该注解作用于方法上,字段上和参数上，可在序列化和反序列化时进行特性功能定制。

1、注解属性 : name 序列化后的名字

@Data public class Student { private Integer id; @JSONField(name = "studentName") private String name; private Integer age; private String address; private boolean flag; private Date birthDate; } @Test public void testName() { Student student = new Student(); student.setId(1); student.setName("兮动人"); student.setAge(24); student.setAddress("深圳市"); student.setFlag(true); student.setBirthDate(new Date()); String jsonString = JSON.toJSONString(student); System.out.println(jsonString); }

2、注解属性 : ordinal序列化后字段的顺序，属性值越小，顺序越靠前

可以看到上面序列化话默认的顺序是按照 a-z 字幕顺序来排序的给字段设置顺序的属性值 @JSONField(name = "studentName", ordinal = 1) private String name; @JSONField(ordinal = 2) private Integer age; 发现值越小，就越靠前

3、注解属性 : format 指定序列化后的格式

@JSONField(format = "YYYY-MM-dd") private Date birthDate;

4、注解属性 : serialize 指定是否序列化该字段，默认为 true

@JSONField(serialize = false) private String address; 可以发现并没有序列化 address 字段

5、注解属性 : deserialize 指定是否反序列化该字段，默认为 true

6、注解属性 : serialzeFeatures 指定序列化时的特性定义

这个属性的用法和上面的 SerializerFeature枚举用法是一致的 5. JSonType 注解

该注解作用于类上，对该类的字段进行序列化和反序列化时的特性功能定制。

1、注解属性 : includes 要被序列化的字段

@Data @JSONType(includes = {"id", "name", "age"}) public class Person { private int id; private String name; private int age; private String address; } @Test public void test() { Person person = new Person(); person.setId(1); person.setName("兮动人"); person.setAge(23); person.setAddress("北京市"); String s = JSON.toJSONString(person); System.out.println(s); } 可以看到并没有序列化 address 字段、

2、注解属性 : orders 序列化后的顺序

@Data @JSONType(includes = {"id", "name", "age", "address"}, orders = {"name", "age", "address", "id"}) public class Person { private int id; private String name; private int age; private String address; } @Test public void test() { Person person = new Person(); person.setId(1); person.setName("兮动人"); person.setAge(23); person.setAddress("北京市"); String s = JSON.toJSONString(person); System.out.println(s); }

3、注解属性 : serialzeFeatures 序列化时的特性定义

serialzeFeatures 实现和上面案例上的枚举效果是一样的