举例讲解Java的JSON类库GSON的基本用法

Logger logger = Logger.getLogger(CommonAction.class);
Gson g = new Gson();
logger.info(“return:”+g.toJson(map)); 

Gson gson = new Gson();
List persons = new ArrayList();
String str = gson.toJson(persons); 

[{“name”:”name0”,”age”:0}]

Person person = gson.fromJson(str, Person.class); 

GsonBuilder().disableHtmlEscaping().create(); 

Gson g = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create(); 

import java.lang.reflect.Type;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonParseException;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import com.google.gson.reflect.TypeToken;


public class GSonDemo {
 public static void main(String[] args) {
// Gson gson = new Gson();
 //设置将类型的属性进行格式转换
 Gson gson = new GsonBuilder().registerTypeAdapter(Timestamp.class, new TimestampTypeAdapter()).setDateFormat("yyyy-MM-dd HH:mm:ss").create();
 List<Person> persons = new ArrayList<Person>();
 for (int i = 0; i < 10; i++) {
    Person p = new Person();
    p.setName("name" + i);
    p.setAge(i * 5);
    p.setInsertTime(new Timestamp(System.currentTimeMillis()));
    persons.add(p);
 }
 String str = gson.toJson(persons);
 System.out.println(str);
 
 List<Person> ps = gson.fromJson(str, new TypeToken<List<Person>>(){}.getType());
 for(int i = 0; i < ps.size() ; i++)
 {
    Person p = ps.get(i);
    System.out.println(p.toString());
 }
 
 System.out.println(new Timestamp(System.currentTimeMillis()));
 }
}

class Person {
 private String name;
 private int age;
 private Timestamp insertTime;

 public String getName() {
 return name;
 }

 public void setName(String name) {
 this.name = name;
 }

 public int getAge() {
 return age;
 }

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

 public Timestamp getInsertTime() {
 return insertTime;
 }

 public void setInsertTime(Timestamp insertTime) {
 this.insertTime = insertTime;
 }

 @Override
 public String toString() {
 return name + "\t" + age + "\t" + insertTime;
 }
}

//实现序列化，反序列化接口
class TimestampTypeAdapter implements JsonSerializer<Timestamp>, JsonDeserializer<Timestamp> {
  public JsonElement serialize(Timestamp src, Type arg1, JsonSerializationContext arg2) {
    DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS");
    String dateFormatAsString = format.format(new Date(src.getTime()));
    return new JsonPrimitive(dateFormatAsString);
  }

  public Timestamp deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
    if (!(json instanceof JsonPrimitive)) {
      throw new JsonParseException("The date should be a string value");
    }

    try {
      DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SS");
      Date date = (Date) format.parse(json.getAsString());
      return new Timestamp(date.getTime());
    } catch (Exception e) {
      throw new JsonParseException(e);
    }
  }

}