TOC
[[TOC]]
依赖
fastxml
Jackson JSON Tutorial
Do-JSON-with-Jackson.pdf-很详细
Creating Java List from JSON Array String
String jsonCarArray =
"[{ \"color\" : \"Black\", \"type\" : \"BMW\" }, { \"color\" : \"Red\", \"type\" : \"FIAT\" }]";
List<Car> listCar = objectMapper.readValue(jsonCarArray, new TypeReference<List<Car>>(){});
Creating Java Map from JSON String
String json = "{ \"color\" : \"Black\", \"type\" : \"BMW\" }";
Map<String, Object> map = objectMapper.readValue(json, new TypeReference<Map<String,Object>>(){});
Handling Collections
数组
String jsonCarArray =
"[{ \"color\" : \"Black\", \"type\" : \"BMW\" }, { \"color\" : \"Red\", \"type\" : \"FIAT\" }]";
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(DeserializationFeature.USE_JAVA_ARRAY_FOR_JSON_ARRAY, true);
Car[] cars = objectMapper.readValue(jsonCarArray, Car[].class);
// print cars
List
String jsonCarArray =
"[{ \"color\" : \"Black\", \"type\" : \"BMW\" }, { \"color\" : \"Red\", \"type\" : \"FIAT\" }]";
ObjectMapper objectMapper = new ObjectMapper();
List<Car> listCar = objectMapper.readValue(jsonCarArray, new TypeReference<List<Car>>(){});
// print cars
Dealing with Unknown Fields on the Class
@JsonIgnoreProperties(ignoreUnknown = true)
public class MyDtoIgnoreUnknown { ... }
Ignore Null Fields on the Class
@JsonInclude(Include.NON_NULL)
public class MyDto { ... }
属性上
public class MyDto {
@JsonInclude(Include.NON_NULL)
private String stringValue;
private int intValue;
// standard getters and setters
}
Ignore Null Fields Globally
mapper.setSerializationInclusion(Include.NON_NULL);
Change Name of Field for Serialization
@JsonProperty("strVal")
public String getStringValue() {
return stringValue;
}
Enum as Json Object
@JsonFormat(shape = JsonFormat.Shape.OBJECT)
public enum Distance { ... }
Enums and @JsonValue
public enum Distance {
...
@JsonValue
public String getMeters() {
return meters;
}
}
Use @JsonFormat to format Date
public class Event {
public String name;
@JsonFormat
(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy hh:mm:ss")
public Date eventDate;
}
@Test
public void whenUsingJsonFormatAnnotationToFormatDate_thenCorrect()
throws JsonProcessingException, ParseException {
SimpleDateFormat df = new SimpleDateFormat("dd-MM-yyyy hh:mm:ss");
df.setTimeZone(TimeZone.getTimeZone("UTC"));
String toParse = "20-12-2014 02:30:00";
Date date = df.parse(toParse);
Event event = new Event("party", date);
ObjectMapper mapper = new ObjectMapper();
String result = mapper.writeValueAsString(event);
assertThat(result, containsString(toParse));
}
Serialize Joda-Time with Jackson
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-joda</artifactId>
<version>2.4.0</version>
</dependency>
@Test
public void whenSerializingJodaTime_thenCorrect()
throws JsonProcessingException {
DateTime date = new DateTime(2014, 12, 20, 2, 30,
DateTimeZone.forID("Europe/London"));
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JodaModule());
mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
String result = mapper.writeValueAsString(date);
assertThat(result, containsString("2014-12-20T02:30:00.000Z"));
}
Serialize Java 8 Date with Jackson
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-jsr310</artifactId>
<version>2.4.0</version>
</dependency>
@Test
public void whenSerializingJava8Date_thenCorrect()
throws JsonProcessingException {
LocalDateTime date = LocalDateTime.of(2014, 12, 20, 2, 30);
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new JSR310Module());
mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
String result = mapper.writeValueAsString(date);
assertThat(result, containsString("2014-12-20T02:30"));
}
Deserialize Date
@Test
public void whenDeserializingDateWithJackson_thenCorrect()
throws JsonProcessingException, IOException {
String json = "{"name":"party","eventDate":"20-12-2014 02:30:00"}";
SimpleDateFormat df = new SimpleDateFormat("dd-MM-yyyy hh:mm:ss");
ObjectMapper mapper = new ObjectMapper();
mapper.setDateFormat(df);
Event event = mapper.readerFor(Event.class).readValue(json);
assertEquals("20-12-2014 02:30:00", df.format(event.eventDate));
}
Serialize Using JSON Views
public class Views {
public static class Public {
}
public static class Internal extends Public {
}
}
public class Item {
@JsonView(Views.Public.class)
public int id;
@JsonView(Views.Public.class)
public String itemName;
@JsonView(Views.Internal.class)
public String ownerName;
}
@Test
public void whenUsePublicView_thenOnlyPublicSerialized()
throws JsonProcessingException {
Item item = new Item(2, "book", "John");
ObjectMapper mapper = new ObjectMapper();
String result = mapper
.writerWithView(Views.Public.class)
.writeValueAsString(item);
assertThat(result, containsString("book"));
assertThat(result, containsString("2"));
assertThat(result, not(containsString("John")));
}
@Test
public void whenUseInternalView_thenAllSerialized()
throws JsonProcessingException {
Item item = new Item(2, "book", "John");
ObjectMapper mapper = new ObjectMapper();
String result = mapper
.writerWithView(Views.Internal.class)
.writeValueAsString(item);
assertThat(result, containsString("book"));
assertThat(result, containsString("2"));
assertThat(result, containsString("John"));
}
Deserialize Using JSON Views
@Test
public void whenUseJsonViewToDeserialize_thenCorrect()
throws IOException {
String json = "{"id":1,"name":"John"}";
ObjectMapper mapper = new ObjectMapper();
User user = mapper
.readerWithView(Views.Public.class)
.forType(User.class)
.readValue(json);
assertEquals(1, user.getId());
assertEquals("John", user.getName());
}
Using JSON Views with Spring
@JsonView(Views.Public.class)
@RequestMapping("/items/{id}")
public Item getItemPublic(@PathVariable int id) {
return ItemManager.getById(id);
}
{"id":2,"itemName":"book"}
@JsonView(Views.Internal.class)
@RequestMapping("/items/internal/{id}")
public Item getItemInternal(@PathVariable int id) {
return ItemManager.getById(id);
}
{"id":2,"itemName":"book","ownerName":"John"}
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