FastJson-简单使用

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.annotation.JSONField;
import com.alibaba.fastjson.serializer.*;
import org.junit.Before;
import org.junit.Test;

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

import static junit.framework.TestCase.assertEquals;

public class fastjson {

    private List<Person> listOfPersons = new ArrayList<Person>();
    private List<Person2> listOfPersons2 = new ArrayList<Person2>();

    @Before
    public void setUp() {
        listOfPersons.add(
                new Person(15, "John Doe", new Date()));
        listOfPersons.add(
                new Person(20, "Janette Doe", new Date()));
    }

    @Test
    public void whenJavaList_thanConvertToJsonCorrect() {
        String jsonOutput= JSON.toJSONString(listOfPersons);
        System.out.println(jsonOutput);
    }

    @Before
    public void setUp2() {
        listOfPersons2.add(
                new Person2(15, "John", "Doe", new Date()));
        listOfPersons2.add(
                new Person2(20, "Janette", "Doe", new Date()));
    }

    @Test
    public void whenJavaList_thanConvertToJsonCorrect2() {
        String jsonOutput= JSON.toJSONString(listOfPersons2);
        System.out.println(jsonOutput);
        String jsonOutput2= JSON.toJSONString(listOfPersons2,
                SerializerFeature.BeanToArray);
        System.out.println(jsonOutput2);
    }

创建JSON对象

    @Test
    public void whenGenerateJson_thanGenerationCorrect() {
        JSONArray jsonArray = new JSONArray();
        for (int i = 0; i < 2; i++) {
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("AGE", 10);
            jsonObject.put("FULL NAME", "Doe " + i);
            jsonObject.put("DATE OF BIRTH", "2016/12/12 12:12:12");
            jsonArray.add(jsonObject);
        }
        String jsonOutput = jsonArray.toJSONString();
        System.out.println(jsonOutput);
    }

JSON字符串转换为java对象
ATTENTION: class need default constructor

    @Test
    public void whenJson_thanConvertToObjectCorrect() {
        Person2 person = new Person2(20, "John", "Doe", new Date());
        String jsonObject = JSON.toJSONString(person);
        System.out.println(jsonObject);
        Person2 newPerson = JSON.parseObject(jsonObject, Person2.class);
        System.out.println(newPerson);

        assertEquals(newPerson.getAge(), 0); // 如果我们设置序列化为 false
        assertEquals(newPerson.getLastName(),
                listOfPersons2.get(0).getLastName());
    }

使用 ContextValueFilter 配置 JSON 转换

    @Test
    public void givenContextFilter_whenJavaObject_thanJsonCorrect() {
        ContextValueFilter valueFilter = new ContextValueFilter () {
            public Object process(
                    BeanContext context, Object object, String name, Object value) {
                if (name.equals("DATE OF BIRTH")) {
                    return "NOT TO DISCLOSE";
                }
                if (value.equals("John")) {
                    return ((String) value).toUpperCase();
                } else {
                    //return null;//过滤其余
                    return value;//返回其余
                }
            }
        };
        String jsonOutput = JSON.toJSONString(listOfPersons2, valueFilter);
        System.out.println(jsonOutput);
        String jsonOutput2 = JSON.toJSONString(listOfPersons2);
        System.out.println(jsonOutput2);
    }

使用 NameFilter 和 SerializeConfig
NameFilter: 序列化时修改 Key。
SerializeConfig：内部是个map容器主要功能是配置并记录每种Java类型对应的序列化类。
toJSONStringWithDateFormat()可以更快速的格式化日期

    @Test
    public void givenSerializeConfig_whenJavaObject_thanJsonCorrect() {
        NameFilter formatName = new NameFilter() {
            public String process(Object object, String name, Object value) {
                return name.toLowerCase().replace(" ", "_");
            }
        };

        SerializeConfig.getGlobalInstance().addFilter(Person.class,  formatName);
        String jsonOutput =
                JSON.toJSONStringWithDateFormat(listOfPersons, "yyyy-MM-dd");
        System.out.println(jsonOutput);
    }

}

Person.class

/**
 * {"AGE":15,"DATE OF BIRTH":1545900124680,"FULL NAME":"John Doe"}
 */
class Person {

    @JSONField(name = "AGE")
    private int age;

    @JSONField(name = "FULL NAME")
    private String fullName;

    @JSONField(name = "DATE OF BIRTH")
    private Date dateOfBirth;

     Person(int age, String fullName, Date dateOfBirth) {
        this.age = age;
        this.fullName= fullName;
        this.dateOfBirth = dateOfBirth;
    }

    public int getAge() {
        return age;
    }

    public String getFullName() {
        return fullName;
    }

    public Date getDateOfBirth() {
        return dateOfBirth;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setFullName(String fullName) {
        this.fullName = fullName;
    }

    public void setDateOfBirth(Date dateOfBirth) {
        this.dateOfBirth = dateOfBirth;
    }
}

Person2.class
format 参数用于格式化 date 属性。
默认情况下， FastJson 库可以序列化 Java bean 实体， 但我们可以使用 serialize 指定字段不序列化。
使用 ordinal 参数指定字段的顺序

/**
 *  {"FIRST NAME":"Doe","LAST NAME":"John","DATE OF BIRTH":"27/12/2018"}
 */
class Person2{
    @JSONField(name="AGE", serialize=false, deserialize = false)
    private int age;

    @JSONField(name="LAST NAME", ordinal = 2)
    private String lastName;

    @JSONField(name="FIRST NAME", ordinal = 1)
    private String firstName;

    @JSONField(name="DATE OF BIRTH", format="HH:mm:ss", ordinal = 3)
    private Date dateOfBirth;


    public Person2() {
    }

    Person2(int age, String lastName, String firstName, Date dateOfBirth) {
        this.age = age;
        this.lastName = lastName;
        this.firstName = firstName;
        this.dateOfBirth = dateOfBirth;
    }

    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public Date getDateOfBirth() {
        return dateOfBirth;
    }

    public void setDateOfBirth(Date dateOfBirth) {
        this.dateOfBirth = dateOfBirth;
    }

    @Override
    public String toString() {
        return "Person2{" +
                "age=" + age +
                ", lastName='" + lastName + '\'' +
                ", firstName='" + firstName + '\'' +
                ", dateOfBirth=" + dateOfBirth +
                '}';
    }
}

dependencies

<dependencies>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.54</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>RELEASE</version>
        </dependency>
    </dependencies>