fastxml 简单常用注解学习笔记

fastxml 简单常用注解学习笔记

@JsonNaming

@JsonIgnoreProperties

@JsonIgnore

@JsonFormat

@JsonDeserialize

@JsonSerialize

@JsonProperty

如下User类

package com.usoft;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.PropertyNamingStrategy; import com.fasterxml.jackson.databind.annotation.JsonDeserialize; import com.fasterxml.jackson.databind.annotation.JsonNaming; import com.fasterxml.jackson.databind.annotation.JsonSerialize; import java.math.BigDecimal; import java.util.Date; /** * Created by xinxingegeya on 2015/3/7. */ @JsonNaming(PropertyNamingStrategy.LowerCaseWithUnderscoresStrategy.class) @JsonIgnoreProperties(value = {"enabled", "age", "bigDecimal"}, ignoreUnknown = true) public class User { private String username; @JsonIgnore private String passwd; @JsonFormat(pattern = "yyyy-MM-dd") @JsonDeserialize(using = CustomDateDeserialize.class) private Date createDate; private boolean enabled; private int age; private BigDecimal bigDecimal; @JsonSerialize(using = CustomDoubleSerialize.class) private double helloDouble; // 该属性没有setter和getter方法，如果想要序列化必须标注该注解 @JsonProperty(value = "belong_to_role") private boolean belongToRole = false; public double getHelloDouble() { return helloDouble; } public void setHelloDouble(double helloDouble) { this.helloDouble = helloDouble; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPasswd() { return passwd; } public void setPasswd(String passwd) { this.passwd = passwd; } public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } public boolean isEnabled() { return enabled; } public void setEnabled(boolean enabled) { this.enabled = enabled; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public BigDecimal getBigDecimal() { return bigDecimal; } public void setBigDecimal(BigDecimal bigDecimal) { this.bigDecimal = bigDecimal; } } 

相关的类

package com.usoft;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;

import java.io.IOException;
import java.text.ParseException;
import java.text.SimpleDateFormat; import java.util.Date; public class CustomDateDeserialize extends JsonDeserializer<Date> { private SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); @Override public Date deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException { Date date = null; try { date = sdf.parse(jp.getText()); } catch (ParseException e) { e.printStackTrace(); } return date; } } 

package com.usoft;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.SerializerProvider;

import java.io.IOException;
import java.text.DecimalFormat; public class CustomDoubleSerialize extends JsonSerializer<Double> { private DecimalFormat df = new DecimalFormat("##.00"); @Override public void serialize(Double value, JsonGenerator jgen, SerializerProvider provider) throws IOException { jgen.writeString(df.format(value)); } } 

测试类，

package com.usoft;

import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.math.BigDecimal;
import java.util.Date; /** * Created by xinxingegeya on 2015/3/7. */ public class TestJson { private static final JsonMapper mapper = new JsonMapper(); private static Logger logger = LoggerFactory.getLogger(TestJson.class); /** * fastxml序列化json */ @Test public void test76() { User user = new User(); user.setAge(19); user.setBigDecimal(new BigDecimal(12)); user.setCreateDate(new Date()); user.setEnabled(true); user.setPasswd("122"); user.setUsername("admin"); user.setHelloDouble(3.1); String json = mapper.toJson(user); logger.info(json); } @Test public void testu68() { String helloJson = "{\"username\":\"admin\",\"passwd\":\"122\",\"createDate\":\"2015-03-07 13:25:47\",\"birthday\":\"2015-03-07 13:25:47\"}"; User user = mapper.fromJson(helloJson, User.class); logger.info(user.toString()); logger.info(user.getCreateDate().toString()); } } 

更多详见：http://blog.csdn.net/sdyy321/article/details/40298081

最后附上一个Json序列化的工具类，该工具类是从springside项目中拿来的。

package com.usoft;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.util.JSONPObject; import org.apache.commons.lang3.StringUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.text.SimpleDateFormat; public class JsonMapper { private static Logger logger = LoggerFactory.getLogger(JsonMapper.class); private ObjectMapper mapper; public JsonMapper() { this(null); } public JsonMapper(JsonInclude.Include include) { this.mapper = new ObjectMapper(); //设置日期格式当使用jackson在处理时间时，默认是将时间输出为timestamps格式 SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); this.mapper.setDateFormat(fmt); //设置输出时包含属性的风格 if (include != null) { this.mapper.setSerializationInclusion(include); } //设置输入时忽略在JSON字符串中存在但Java对象实际没有的属性 this.mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); } //Include.Include.ALWAYS 默认 //Include.NON_DEFAULT 属性为默认值不序列化 //Include.NON_EMPTY 属性为 空（“”） 或者为 NULL 都不序列化 //Include.NON_NULL 属性为NULL 不序列化 /** * 属性为 空（“”） 或者为 NULL 都不序列化 * * @return */ public static JsonMapper nonEmptyMapper() { return new JsonMapper(JsonInclude.Include.NON_EMPTY); } /** * 属性为默认值不序列化 * * @return */ public static JsonMapper nonDefaultMapper() { return new JsonMapper(JsonInclude.Include.NON_DEFAULT); } /** * 属性为NULL不序列化 * * @return */ public static JsonMapper nonNullMapper() { return new JsonMapper(JsonInclude.Include.NON_NULL); } /** * Object可以是POJO，也可以是Collection或数组。 * 如果对象为Null, 返回"null". * 如果集合为空集合, 返回"[]". * * @param object * @return */ public String toJson(Object object) { try { return this.mapper.writeValueAsString(object); } catch (IOException e) { JsonMapper.logger.warn("write to json string error:" + object, e); System.out.println(e.getMessage()); return null; } } /** * 反序列化POJO或简单Collection如List. * 
 * 如果JSON字符串为Null或"null"字符串, 返回Null. 如果JSON字符串为"[]", 返回空集合. * 
 * 如需反序列化复杂Collection如List, 请使用fromJson(String,JavaType) * * @param jsonString * @param clazz * @return * @see #fromJson(String, com.fasterxml.jackson.databind.JavaType) */ public  T fromJson(String jsonString, Class clazz) { if (StringUtils.isEmpty(jsonString)) { return null; } try { return this.mapper.readValue(jsonString, clazz); } catch (IOException e) { JsonMapper.logger.warn("parse json string error:" + jsonString, e); return null; } } /** * 反序列化复杂Collection如List, 先使用函數createCollectionType构造类型,然后调用本函数. * * @param jsonString * @param javaType * @return * @see #createCollectionType(Class, Class...) */ public  T fromJson(String jsonString, JavaType javaType) { if (StringUtils.isEmpty(jsonString)) { return null; } try { return (T) this.mapper.readValue(jsonString, javaType); } catch (IOException e) { JsonMapper.logger.warn("parse json string error:" + jsonString, e); return null; } } /** * 構造泛型的Collection Type如: * ArrayList, * 则调用constructCollectionType(ArrayList.class,MyBean.class) * HashMap, 则调用(HashMap.class,String.class, MyBean.class) * * @param collectionClass * @param elementClasses * @return */ public JavaType createCollectionType(Class collectionClass, Class... elementClasses) { return this.mapper.getTypeFactory().constructParametricType( collectionClass, elementClasses); } /** * @param jsonString * @param object * @return */ public  T update(String jsonString, T object) { try { return (T) this.mapper.readerForUpdating(object).readValue( jsonString); } catch (JsonProcessingException e) { JsonMapper.logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e); } catch (IOException e) { JsonMapper.logger.warn("update json string:" + jsonString + " to object:" + object + " error.", e); } return null; } /** * @param functionName * @param object * @return */ public String toJsonP(String functionName, Object object) { return this.toJson(new JSONPObject(functionName, object)); } } 

====================================END====================================