好的json解析

- 日理万妓 2022-06-11 07:56 100阅读 0赞

什么是JSON:

JSON即[JavaScript][] Object Natation, 它是一种轻量级的数据交换格式, 与XML一样, 是广泛被采用的客户端和服务端交互的解决方案.

JSON对象: JSON中对象(Object)以"\{"开始, 以"\}"结束. 对象中的每一个item都是一个key-value对, 表现为"key:value"的形式, key-value对之间使用逗号分隔. 如:\{"name":"coolxing", "age"=24, "male":true, "address":\{"street":"huiLongGuan", "city":"beijing", "country":"china"\}\}. JSON对象的key只能是string类型的, 而value可以是string, number, false, true, null, Object对象甚至是array数组, 也就是说可以存在嵌套的情况.

JSON数组: JSON数组(array)以"\["开始, 以"\]"结束, 数组中的每一个元素可以是string, number, false, true, null, Object对象甚至是array数组, 数组间的元素使用逗号分隔. 如\["coolxing", 24, \{"street":"huiLongGuan", "city":"beijing", "country":"china"\}\].

JSON数据的解析:解析JSON数据, 首先需要明确待解析的是JSON Object还是JSON array, 然后需要确定采用哪种解析技术. [ Android][Android]平台上一般有2种解析技术可供选择: [ android][Android]内置的org.json包和google的开源gson库. 以下将分别采用这两种技术解析JSON对象和JSON数组.

1. 采用android内置的org.json包解析JSON对象. 假设待解析的JSON数据为json = "\{\\"name\\":\\"coolxing\\", \\"age\\"=24, \\"male\\":true, \\"address\\":\{\\"street\\":\\"huiLongGuan\\", \\"city\\":\\"beijing\\", \\"country\\":\\"china\\"\}\}", 其中\\用于转义表达式中的双引号. 首先定义2个JavaBean:

Java代码 ![收藏代码][icon_star.png]

1.  public class Address \{
2.  private String street;
3.  private String city;
4.  private String country;
5.  
6.  public Address() \{
7.  super();
8.  \}
9.  
10. public Address(String street, String city, String country) \{
11. super();
12. this.street = street;
13. this.city = city;
14. this.country = country;
15. \}
16. 
17. public String getStreet() \{
18. return street;
19. \}
20. 
21. public void setStreet(String street) \{
22. this.street = street;
23. \}
24. 
25. public String getCity() \{
26. return city;
27. \}
28. 
29. public void setCity(String city) \{
30. this.city = city;
31. \}
32. 
33. public String getCountry() \{
34. return country;
35. \}
36. 
37. public void setCountry(String country) \{
38. this.country = country;
39. \}
40. 
41. @Override
42. public String toString() \{
43. return "Address \[street=" \+ street + ", city=" \+ city + ", country="
44. \+ country + "\]";
45. \}
46. 
47. \}

Java代码 ![收藏代码][icon_star.png]

1.  public class Person \{
2.  private String name;
3.  private int age;
4.  private boolean male;
5.  private Address address;
6.  
7.  public Person() \{
8.  super();
9.  \}
10. 
11. public Person(String name, int age, boolean male, Address address) \{
12. super();
13. this.name = name;
14. this.age = age;
15. this.male = male;
16. this.address = address;
17. \}
18. 
19. public String getName() \{
20. return name;
21. \}
22. 
23. public void setName(String name) \{
24. this.name = name;
25. \}
26. 
27. public int getAge() \{
28. return age;
29. \}
30. 
31. public void setAge(int age) \{
32. this.age = age;
33. \}
34. 
35. public boolean isMale() \{
36. return male;
37. \}
38. 
39. public void setMale(boolean male) \{
40. this.male = male;
41. \}
42. 
43. public Address getAddress() \{
44. return address;
45. \}
46. 
47. public void setAddress(Address address) \{
48. this.address = address;
49. \}
50. 
51. @Override
52. public String toString() \{
53. return "Person \[name=" \+ name + ", age=" \+ age + ", male=" \+ male
54. \+ ", address=" \+ address + "\]";
55. \}
56. 
57. \}

下面是具体的解析代码:

Java代码 ![收藏代码][icon_star.png]

1.  JSONObject jsonObject = new JSONObject(json);
2.  String name = jsonObject.getString("name");
3.  int age = jsonObject.getInt("age");
4.  boolean male = jsonObject.getBoolean("male");
5.  JSONObject addressJSON = jsonObject.getJSONObject("address");
6.  String street = addressJSON.getString("street");
7.  String city = addressJSON.getString("city");
8.  String country = addressJSON.getString("country");
9.  Address address = new Address(street, city, country);
10. Person person = new Person(name, age, male, address);
11. System.out.println(person);

LogCat的输出为Person \[name=coolxing, age=24, male=true, address=Address \[street=huiLongGuan, city=beijing, country=china\]\], 说明已经正确解析了JSON对象.

2. 采用gson库解析JSON对象. 假设带解析的JSON数据是json = "\{\\"name\\":\\"coolxing\\", \\"age\\"=24, \\"male\\":true, \\"address\\":\{\\"street\\":\\"huiLongGuan\\", \\"city\\":\\"beijing\\", \\"country\\":\\"china\\"\}\}", 首先需要到[http://code.google.com/p/google-gson/][http_code.google.com_p_google-gson]下载jar包, 并将其添加到项目中. 具体的解析代码如下:

Java代码 ![收藏代码][icon_star.png]

1.  Gson gson = new Gson();
2.  Person person = gson.fromJson(json, Person.class);
3.  System.out.println(person);

LogCat的输出为Person \[name=coolxing, age=24, male=true, address=Address \[street=huiLongGuan, city=beijing, country=china\]\], 说明已经正确解析了JSON对象, 是不是很简单?

3. 采用android内置的org.json包解析JSON数组. 假设待解析的JSON数据为json = "\[\{\\"name\\":\\"coolxing\\", \\"age\\"=24, \\"male\\":true, \\"address\\":\{\\"street\\":\\"huiLongGuan\\", \\"city\\":\\"beijing\\", \\"country\\":\\"china\\"\}\}, \{\\"name\\":\\"min\\", \\"age\\"=20, \\"male\\":false, \\"address\\":\{\\"street\\":\\"heiShiJiao\\", \\"city\\":\\"daLian\\", \\"country\\":\\"china\\"\}\}\]", 解析代码如下:

Java代码 ![收藏代码][icon_star.png]

1.  List<Person> persons = new ArrayList<Person>();
2.  JSONArray jsonArray = new JSONArray(json);
3.  for(int i = 0; i < jsonArray.length(); i++) \{
4.  JSONObject jsonObject = jsonArray.getJSONObject(i);
5.  String name = jsonObject.getString("name");
6.  int age = jsonObject.getInt("age");
7.  boolean male = jsonObject.getBoolean("male");
8.  JSONObject addressJSON = jsonObject.getJSONObject("address");
9.  String street = addressJSON.getString("street");
10. String city = addressJSON.getString("city");
11. String country = addressJSON.getString("country");
12. Address address = new Address(street, city, country);
13. Person person = new Person(name, age, male, address);
14. persons.add(person);
15. \}
16. System.out.println(persons);

LogCat的输出为\[Person \[name=coolxing, age=24, male=true, address=Address \[street=huiLongGuan, city=beijing, country=china\]\], Person \[name=min, age=20, male=false, address=Address \[street=heiShiJiao, city=daLian, country=china\]\]\], 说明已经正确解析了JSON数组.

4. 采用gson库解析JSON数组. 待解析的JSON数据同上, 具体代码为:

Java代码 ![收藏代码][icon_star.png]

1.  Gson gson = new Gson();
2.  Type listType = new TypeToken<List<Person>>()\{\}.getType();
3.  List<Person> persons = gson.fromJson(json, listType);

**new** TypeToken<List<Person>>()\{\}.getType(); 这句代码表示创建一个 TypeToken的匿名子类对象, 并调用对象的getType()方法.

org.json包和gson库还有很多其他有用的API, 需要的时候可查看文档. 比如有的时候需要通过java对象或java集合和数组生成json数据上传给服务器, 当然你可以自我构造json字符串, 但会很麻烦. 这个时候就可以使用其中的有关API, 方便的完成这项工作.

[JavaScript]: http://lib.csdn.net/base/javascript
[Android]: http://lib.csdn.net/base/android
[icon_star.png]: /images/20220611/ce9dcda30252413399106d75dabcac56.png
[http_code.google.com_p_google-gson]: http://code.google.com/p/google-gson/