json字符串忽略null，忽略字段，首字母大写等gson,jackson,fastJson实现demo,T data JSON.parseObject json转换

json字符串忽略null，忽略字段，首字母大写等gson,jackson,fastJson实现demo

package com.example.core.mydemo.json.vo;

import com.alibaba.fastjson.annotation.JSONField;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

import java.util.List;

@JsonAutoDetect(fieldVisibility= JsonAutoDetect.Visibility.ANY, getterVisibility=JsonAutoDetect.Visibility.NONE)
public class JsonReqVo {

    @Expose
    @SerializedName("Username")  //gson
    @JSONField(name= "Username")  //fastjson
    private String username;

    @Expose
    @JsonProperty("Status")
    private String status; //jackson

    @Expose
    private String school;
    @Expose
    private String password;
    @Expose
    private String address;

    @JsonIgnore   //可以直接放在field上面表示要忽略的filed   //jackson
    @Expose(serialize = false)  //gson
    @JSONField(serialize = false)  //fastjson
    private String apikey;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getSchool() {
        return school;
    }

    public void setSchool(String school) {
        this.school = school;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String getApikey() {
        return apikey;
    }

    public void setApikey(String apikey) {
        this.apikey = apikey;
    }
}

package com.example.core.mydemo.json;

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.List;

public class JsonUtils {
    // 定义jackson对象
    private static final ObjectMapper MAPPER = new ObjectMapper();

    /**
     * 将对象转换成json字符串。
     * <p>Title: pojoToJson</p>
     * <p>Description: </p>
     * @param data
     * @return
     */
    public static String objectToJson(Object data) {
        try {
            MAPPER.setSerializationInclusion(JsonInclude.Include.NON_NULL);
            //通过该方法对mapper对象进行设置，所有序列化的对象都将按改规则进行系列化  Include.NON_NULL 属性为NULL 不序列化
            //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

            String string = MAPPER.writeValueAsString(data);
            return string;
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 将json结果集转化为对象
     *
     * @param jsonData json数据
     * @param beanType 对象中的object类型
     * @return
     */
    public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {
        try {
            MAPPER.setSerializationInclusion(JsonInclude.Include.NON_NULL);
            T t = MAPPER.readValue(jsonData, beanType);
            return t;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 将json数据转换成pojo对象list
     * <p>Title: jsonToList</p>
     * <p>Description: </p>
     * @param jsonData
     * @param beanType
     * @return
     */
    public static <T> List<T> jsonToList(String jsonData, Class<T> beanType) {
        MAPPER.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);
        try {
            List<T> list = MAPPER.readValue(jsonData, javaType);
            return list;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

}

package com.example.core.mydemo.json;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.PascalNameFilter;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.example.core.mydemo.json.vo.JsonReqVo;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;

/**
 * last print:
 * gson={"Username":"刘天王","status":"1","password":"","apikey":"1111111111111"}
 * gson2={"Username":"刘天王","status":"1","school":null,"password":"","address":null,"apikey":"1111111111111"}
 * gson3={"Username":"刘天王","status":"1","password":""}
 * json={"username":"刘天王","password":"","Status":"1"}
 * json2={"Username":"刘天王","password":"","status":"1"}
 * jsonStr3={"Username":"刘天王","Password":"","Status":"1"}
 * jsonStr4={"Username":"刘天王","password":"","status":"1"}
 * jsonStr5={"Username":"刘天王","address":null,"password":"","school":null,"status":"1"}
 * jsonStr6={"Username":"刘天王","password":"","status":"1"}
 * jsonStr7={"Username":"刘天王","password":"","status":"1"}
 * jsonStr8={"Username":"刘天王","address":"","password":"","school":"","status":"1"}
 * jsonStr9={"Username":"刘天王","password":"","status":"1"}
 *
 */
//@RunWith(SpringRunner.class)
//@SpringBootTest()
public class JsonUtilsTest {
    @Test
    public void test(){
        JsonReqVo reqVo = new JsonReqVo();
        reqVo.setApikey("1111111111111");
        reqVo.setStatus("1");
        reqVo.setUsername("刘天王");
        reqVo.setPassword("");
        reqVo.setSchool(null);

        //Gson
        String g1 = new Gson().toJson(reqVo);
        //首字母大写 @SerializedName("Username")
        //gson默认忽略null
        //gson={"Username":"刘天王","status":"1","password":"","apikey":"1111111111111"}
        System.out.println("gson=" + g1);

        // Both Gson instances must have serializeNulls()
        final Gson gson = new GsonBuilder().serializeNulls().create();
        //gson2={"Username":"刘天王","status":"1","school":null,"password":"","address":null,"apikey":"1111111111111"}
        System.out.println("gson2=" + gson.toJson(reqVo));

        GsonBuilder builder = new GsonBuilder();
        builder.excludeFieldsWithoutExposeAnnotation();
        Gson gson3 = builder.create();
        //@Expose(serialize = false)  其他的字段也需要加上
        //gson3={"Username":"刘天王","status":"1","password":""}
        System.out.println("gson3=" + gson3.toJson(reqVo));

        // jackson
        String json = JsonUtils.objectToJson(reqVo);
        //通过该方法对mapper对象进行设置，所有序列化的对象都将按改规则进行系列化  Include.NON_NULL 属性为NULL 不序列化

        //加上 @JsonAutoDetect(fieldVisibility= JsonAutoDetect.Visibility.ANY, getterVisibility=JsonAutoDetect.Visibility.NONE)
        /**
         * JsonAutoDetect.Visibility.ANY : 表示所有字段都可以被发现, 包括private修饰的字段, 解决大小写问题
         * JsonAutoDetect.Visibility.NONE : 表示get方法不可见,解决字段重复问题
         */
        //需要将字段设置为首字母大写
        //json={"username":"刘天王","password":"","Status":"1"}
        System.out.println("json=" + json);

        // fastJson
        //@JSONField(name= "SjAreasNum")  单个字段  默认过滤空值
        String ss = JSON.toJSONString(reqVo);
        //json2={"Username":"刘天王","apikey":"1111111111111","password":"","status":"1"}
        System.out.println("json2=" + ss);

        //全部的首字母大写 null忽略，空字符串保留
        String jsonStr3= JSON.toJSONString(reqVo ,new PascalNameFilter());
        //jsonStr3={"Username":"刘天王","Apikey":"1111111111111","Password":"","Status":"1"}
        System.out.println("jsonStr3=" + jsonStr3);

        //QuoteFieldNames：输出key时是否使用双引号,默认为true
        String jsonStr4= JSONObject.toJSONString(reqVo, SerializerFeature.QuoteFieldNames);
        //jsonStr4={"Username":"刘天王","apikey":"1111111111111","password":"","status":"1"}
        System.out.println("jsonStr4=" + jsonStr4);

        //WriteMapNullValue:是否输出值为null的字段,默认为false
        String jsonStr5= JSONObject.toJSONString(reqVo, SerializerFeature.WriteMapNullValue);
        //有效
        //jsonStr5={"Username":"刘天王","address":null,"apikey":"1111111111111","password":"","school":null,"status":"1"}
        System.out.println("jsonStr5=" + jsonStr5);

        //WriteNullNumberAsZero：数值字段如果为null,输出为0,而非null
        String jsonStr6= JSONObject.toJSONString(reqVo, SerializerFeature.WriteNullNumberAsZero);
        //jsonStr6={"Username":"刘天王","apikey":"1111111111111","password":"","status":"1"}
        System.out.println("jsonStr6=" + jsonStr6);

        //WriteNullListAsEmpty：List字段如果为null,输出为[],而非null
        String jsonStr7= JSONObject.toJSONString(reqVo, SerializerFeature.WriteNullListAsEmpty);
        //jsonStr7={"Username":"刘天王","apikey":"1111111111111","password":"","status":"1"}
        System.out.println("jsonStr7=" + jsonStr7);

        //WriteNullStringAsEmpty：字符类型字段如果为null,输出为”“,而非null
        String jsonStr8= JSONObject.toJSONString(reqVo, SerializerFeature.WriteNullStringAsEmpty);
        //有效
        //jsonStr8={"Username":"刘天王","address":"","apikey":"1111111111111","password":"","school":"","status":"1"}
        System.out.println("jsonStr8=" + jsonStr8);

        //WriteNullBooleanAsFalse：Boolean字段如果为null,输出为false,而非null
        String jsonStr9= JSONObject.toJSONString(reqVo, SerializerFeature.WriteNullBooleanAsFalse);
        //jsonStr9={"Username":"刘天王","apikey":"1111111111111","password":"","status":"1"}
        System.out.println("jsonStr9=" + jsonStr9);

    }
}