客户端与服务器进行数据交互时，常常需要将数据在服务器端将数据转化成字符串并在客户端对json数据进行解析生成对象。但是用jsonObject和jsonArray解析相对麻烦：见博主博客：https://crycrycry.blog.csdn.net/article/details/109108341。利用谷歌的Gson和阿里的fastjson可以很方便的将下面四种常用的数据转换成json字符串，并能够将其解析成原数据对象。
类型一：JavaBean
类型二：List<JavaBean>
类型三：List<String>
类型四：List<Map<String,Object>>
一、Gson将上面的四种数据对象转换成json字符串的方法都是一样的
Gson gson = new Gson(); String jsonString = gson.toJson(obj);
类型1：Gson实现json字符串和JavaBean对象的相互转换
public class Demo {
public static void main(String
[] args
) {
Person person
= new Person("浙江","张三",1001);
Gson gson
= new Gson();
String jsonString
= gson
.toJson(person
);
System
.out
.println(jsonString
);
Person person1
= gson
.fromJson(jsonString
,Person
.class);
System
.out
.println(person1
.getName());
}
}
class Person{
private String region
;
private String name
;
private int id
;
public Person(String region
, String name
, int id
) {
this.region
= region
;
this.name
= name
;
this.id
= id
;
}
public String
getName() {
return name
;
}
}
打印结果： {“region”:“浙江”,“name”:“张三”,“id”:1001} 张三
类型2：Gson实现json字符串和List对象的相互转换
public class Demo {
public static void main(String
[] args
) {
Person person1
= new Person("浙江","张三",1001);
Person person2
= new Person("江苏","李四",1002);
List
<Person> persons
= new ArrayList<Person>();
persons
.add(person1
);
persons
.add(person2
);
Gson gson
= new Gson();
String jsonString
= gson
.toJson(persons
);
System
.out
.println(jsonString
);
List
<Person> persons2
= gson
.fromJson(jsonString
, new TypeToken<List
<Person>>(){}.getType());
for (Person p
:persons2
) {
System
.out
.println(p
.getName());
}
}
}
class Person{
private String region
;
private String name
;
private int id
;
public Person(String region
, String name
, int id
) {
this.region
= region
;
this.name
= name
;
this.id
= id
;
}
public String
getName() {
return name
;
}
}
打印结果： [{“region”:“浙江”,“name”:“张三”,“id”:1001},{“region”:“江苏”,“name”:“李四”,“id”:1002}] 张三 李四
类型3：Gson实现json字符串和List对象的相互转换
public class Demo {
public static void main(String
[] args
) {
List
<String> list
= new ArrayList<String>();
list
.add("gson1");
list
.add("gson2");
list
.add("gson3");
Gson gson
= new Gson();
String jsonString
= gson
.toJson(list
);
System
.out
.println("json字符串:" + jsonString
);
List
<String> list2
= gson
.fromJson(jsonString
, new TypeToken<List
<String>>(){}.getType());
for (String s
:list2
) {
System
.out
.println(s
);
}
}
}
打印结果： json字符串:[“gson1”,“gson2”,“gson3”] gson1 gson2 gson3
类型4：Gson实现json字符串和List<Map<String,Object>>对象的相互转换
public class Demo {
public static void main(String
[] args
) {
Map
<String,Object> map
= new HashMap<String,Object>();
map
.put("key1", "value1");
map
.put("key2", "value2");
Map
<String,Object> map2
= new HashMap<String,Object>();
map2
.put("key1", 1);
map2
.put("key2", 2);
List
<Map
<String,Object>> list
= new ArrayList<Map
<String,Object>>();
list
.add(map
);
list
.add(map2
);
Gson gson
= new Gson();
String jsonString
= gson
.toJson(list
);
System
.out
.println("json字符串:" + jsonString
);
List
<Map
<String,Object>> list2
= gson
.fromJson(jsonString
, new TypeToken<List
<Map
<String,Object>>>(){}.getType());
for (Map
<String,Object> m
:list2
) {
System
.out
.println(m
);
}
}
}
打印结果： json字符串:[{“key1”:“value1”,“key2”:“value2”},{“key1”:1,“key2”:2}] {key1=value1, key2=value2} {key1=1.0, key2=2.0}
