{"0":"192.168.1.100","1":"192.168.1.101"} 是Map

{"0":"192.168.1.100","1":"192.168.1.101"}  我一看到，我就觉得这什么json数据啊，这怎么解析成java对象啊，原来它是Java中的Map对象。

下面是JSON的笔记

先定义一个Student类，如下

package com.dashuai.json;

// 标准的JavaBean： 所有属性都有get和set。必须有一个默认的构造方法
public class Student {

	private String name;
	private int age;

	public Student() {
		// TODO Auto-generated constructor stub
	}

	public Student(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}

	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;
	}

	@Override
	public String toString() {
		return "Student [name=" + name + ", age=" + age + "]";
	}

//	@Override
//	public String toString() {
//		return "{\"name\":\"" + name + "\", \"age\":" + age + "}";
//	}
	
}

下面是测试类

package com.dashuai.json;

import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;

public class Test3 {

	public static void main(String[] args) {

		Student student = new Student("zhangsan", 25);

		Gson gson = new Gson();

		String json = gson.toJson(student);

		System.out.println(json);

		Student stu1 = gson.fromJson(json, Student.class);

		System.out.println(stu1);
		
		List<Student> list = new ArrayList<Student>();
		
		for(int i=0;i<5;i++){
			list.add(new Student("lisi"+i, 23+i));
		}
		
		json = gson.toJson(list);
		
		System.out.println(json);
		
//		List<Student> list2 = gson.fromJson(json, List<?>.class);
		
		Type listType = new TypeToken<List<Student>>() {}.getType();
		
		List<Student> list2 = gson.fromJson(json, listType);
		
		for(Student s:list2){
			System.out.println(s);
		}
		
		Map<Integer,String> map = new HashMap<Integer,String>();
		
		for(int i=0;i<5;i++){
			map.put(i, "192.168.1.10"+i);
		}
		
		json = gson.toJson(map);
		System.out.println(json);
		
		Type mapType = new TypeToken<Map<Integer,String>>() {}.getType();
		Map<Integer,String> map2 = gson.fromJson(json, mapType);
		
		Set<Integer> set = map2.keySet();
		
		for(Integer i:set){
			System.out.println("key"+i+",value:"+map2.get(i));
		}
		
	}

}

运行结果：

{"name":"zhangsan","age":25}
Student [name=zhangsan, age=25]
[{"name":"lisi0","age":23},{"name":"lisi1","age":24},{"name":"lisi2","age":25},{"name":"lisi3","age":26},{"name":"lisi4","age":27}]
Student [name=lisi0, age=23]
Student [name=lisi1, age=24]
Student [name=lisi2, age=25]
Student [name=lisi3, age=26]
Student [name=lisi4, age=27]
{"0":"192.168.1.100","1":"192.168.1.101","2":"192.168.1.102","3":"192.168.1.103","4":"192.168.1.104"}
key0,value:192.168.1.100
key1,value:192.168.1.101
key2,value:192.168.1.102
key3,value:192.168.1.103
key4,value:192.168.1.104