java-json

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http://dreamhead.blogbus.com/logs/230244031.html

jackson 是 java 最常用的json 序列化 和反序列化工具。

pom.xml 引入

<dependency>
			<!-- note: typically only ".0" patch version exists for core annotations -->
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-annotations</artifactId>
			<version>2.3.0</version>
		</dependency>
		
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-core</artifactId>
			<version>2.3.1</version>
		</dependency>


		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
			<version>2.3.3</version>
		</dependency>

1、同一个model中，基于注解的序列化其中部分字段的方式

class Views {
    static class Public {}
    static class ExtendedPublic extends Public{}
}
 class Thing {
    @JsonView(Views.Public.class) Integer id = 100;
    @JsonView(Views.Public.class) String email = "[email protected]";
    @JsonView(Views.ExtendedPublic.class) String name = "admin";
}

 /**
  * 同一个model 序列化其中部分字段的方式
  * @author wangxinchun
  */
public class JsonViewUseage {
	@Test
	public void testExtendedPublic() throws JsonGenerationException, JsonMappingException, IOException {
		ObjectMapper mapper = new ObjectMapper();
		mapper.writerWithView(Views.ExtendedPublic.class).writeValue(System.out, new Thing());
		//{"id":100,"email":"[email protected]","name":"admin"}
	}
	
	@Test
	public void testPublic() throws JsonGenerationException, JsonMappingException, IOException {
		ObjectMapper mapper = new ObjectMapper();
		mapper.writerWithView(Views.Public.class).writeValue(System.out, new Thing());
		//{"id":100,"email":"[email protected]"}
	}
	
	@Test
	public void testObject() throws JsonGenerationException, JsonMappingException, IOException {
		ObjectMapper mapper = new ObjectMapper();
		mapper.writerWithView(Object.class).writeValue(System.out, new Thing());
		//{}
	}
}

2、基于泛型的序列化处理。

class User {
	private String username = "admin";
	private String password = "password";
	public String getUsername() {return username;}
	public void setUsername(String username) {this.username = username;}
	public String getPassword() {return password;}
	public void setPassword(String password) {this.password = password;}
}

public class TypeReferenceUseage {
	public static void main(String[] args) throws Exception {
		Map<String, User> map = new LinkedHashMap<String, User>();
		map.put("532002108", new User());
		StringWriter sw = new StringWriter();
		ObjectMapper mapper = new ObjectMapper();
		JsonGenerator jg = new JsonFactory().createGenerator(sw);
		mapper.writeValue(jg, map);
		System.out.println(sw.toString());
		//{"532002108":{"username":"admin","password":"password"}}
		Map<String,User> newMap = mapper.readValue(sw.toString(), new TypeReference<Map<String,User>>(){});
		//password
		System.out.println(newMap.get("532002108").getPassword());
	}
}

public class PayCenterResponse<T> {
	@SuppressWarnings("rawtypes")
	public static PayCenterResponse EMPTY_RESPONSE = new PayCenterResponse(false,"","");

	protected boolean ret;
	protected String errcode;
	protected String errmsg;

	private List<T> data;
  /***略***/
}


private PayCenterResponse<DaiKouResponseData>  wrapDaiKouResponse(String responseText){
		if(StringUtils.isEmpty(responseText)){
			return PayCenterResponse.EMPTY_RESPONSE;
		}
		PayCenterResponse<DaiKouResponseData> result = JsonUtils.readJsonToObject(responseText, new TypeReference<PayCenterResponse<DaiKouResponseData>>(){});
		return result;
	}

 public static <T>  T readJsonToObject(String data,TypeReference<T> reference) {
    	T t = null;
		try {
			t = mapper.readValue(data, reference);
		}catch (IOException e) {
			logger.error("data {}",data, e);
		}
    	return t;
    }

3、字段名字替换。 jackson 注解实现。

class Job{
	@JsonProperty("jName")
	private String jobName = "java工程师";
	@JsonProperty("jId")
	private int jobId = 1;
	@JsonIgnore
	private String jobNo = "hr177739477894";
	@JsonFormat(pattern = "yyyy-MM-dd")
	private Date createDate = new Date();
	
}
@Test
   public void testJacksonAnnotation() throws Exception{
	   ObjectMapper maper = new ObjectMapper();
	   maper.setAnnotationIntrospector(new JacksonAnnotationIntrospector());
	   maper.writeValue(System.out, new Job());
   }

4、字段重命名。jaxb注解。

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
class Job2{
	@XmlElement(name = "jName")
	private String jobName = "java工程师";
	@XmlElement(name = "jid")
	private int jobId = 2;
	@XmlTransient
	private String jobNo = "hr177739477894";

	@XmlJavaTypeAdapter(value = LocalDateAdapter.class)
	private Date createDate = new Date();
}

class LocalDateAdapter extends XmlAdapter<String,Date>{

	@Override
	public Date unmarshal(String v) throws Exception {
		return new SimpleDateFormat("yyyy-MM-dd").parse(v);
	}

	@Override
	public String marshal(Date v) throws Exception {
		return new SimpleDateFormat("yyyy-MM-dd").format(v);
	}
} 

@Test
	public void testJaxbAnnotation() throws Exception{
		   ObjectMapper maper = new ObjectMapper();
		   maper.setAnnotationIntrospector(new JaxbAnnotationIntrospector());
		   maper.writeValue(System.out, new Job2());
	}