Fastxml 简单常用注解学习笔记

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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<String>.     * <p/>     * 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.     * <p/>     * 如需反序列化复杂Collection如List<MyBean>, 请使用fromJson(String,JavaType)     *     * @param jsonString     * @param clazz     * @return     * @see #fromJson(String, com.fasterxml.jackson.databind.JavaType)     */    public <T> T fromJson(String jsonString, Class<T> 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<Bean>, 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> 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<MyBean>,     * 则调用constructCollectionType(ArrayList.class,MyBean.class)     * HashMap<String,MyBean>, 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> 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));    }}

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