个人建网站大概多少钱seo页面优化的方法

Java中关于JSON的基本使用

Java中可以操作json的类库jar有很多，网上一找一大片，每种封装的jar包有自己的方法，需要查阅资料使用，但无非就是json转对象，对象转json这些

Java中常见的json类jar包：Gson,Jackson,fastjson

转json：map使用 { } 包围，数组和list使用 [ ] 包围

package demo_json;import com.google.gson.Gson;
import org.junit.jupiter.api.Test;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class TestJson {@Testpublic void testWriteJson(){// 实例化Person对象，将Person对象转换为Json串Dog dog = new Dog("大力");Person person = new Person("liv",10,dog);// 将person对象转换成一个字符串 Gson,Jackson,fastjsonGson gson = new Gson();String jsonStr = gson.toJson(person);//{"name":"liv","age":10,"dog":{"name":"大力"}}System.out.println(jsonStr);}@Testpublic void testReadJson(){// 假设jsonStr为json串String jsonStr = "{\"name\":\"liv\",\"age\":10,\"dog\":{\"name\":\"大力\"}}";// 反序列化Json串为PersonGson gson = new Gson();Person person = gson.fromJson(jsonStr, Person.class);// 获取Person对象的属性值System.out.println(person.getName());System.out.println(person.getAge());System.out.println(person.getDog().getName());}@Testpublic void testMap(){Map data = new HashMap();data.put("1","ada");data.put("2","dad");Gson gson = new Gson();String jsonMap = gson.toJson(data);{"1":"ada","2":"dad"}System.out.println(jsonMap);String mapString = "{\"1\":\"ada\",\"2\":\"dad\"}";Map map = gson.fromJson(mapString, Map.class);//{1=ada, 2=dad}System.out.println(map);}@Testpublic void testList(){// List 与数组转成json效果一样List data = new ArrayList<String>();data.add("1");data.add("2");data.add("3");Gson gson = new Gson();String json = gson.toJson(data);//["1","2","3"]System.out.println(json);String[] listString = {"1","2","3"};String json1 = gson.toJson(listString);//["1","2","3"]System.out.println(json1);//对象使用{}包围， list和数组使用[]包围Person person = new Person("张三",10,new Dog("大黄"));List<Person> persons = new ArrayList<>();persons.add(person);String json2 = gson.toJson(persons);//[{"name":"张三","age":10,"dog":{"name":"大黄"}}]System.out.println(json2);}
}

package demo_json;public class Dog {private String name;public Dog() {}public Dog(String name) {this.name = name;}public String getName() {return name;}public void setName(String name) {this.name = name;}
}

package demo_json;public class Person {private String name;private int age;private Dog dog;public Person(String name, int age, Dog dog) {this.name = name;this.age = age;this.dog = dog;}public Person(){}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 Dog getDog() {return dog;}public void setDog(Dog dog) {this.dog = dog;}
}