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平台上一般有2种解析技术可供选择: 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:
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
public class Address {
private String street;
private String city;
private String country;
public Address() {
super
();
}
public Address(String street, String city, String country) {
super
();
this
.street = street;
this
.city = city;
this
.country = country;
}
public String getStreet() {
return
street;
}
public void setStreet(String street) {
this
.street = street;
}
public String getCity() {
return
city;
}
public void setCity(String city) {
this
.city = city;
}
public String getCountry() {
return
country;
}
public void setCountry(String country) {
this
.country = country;
}
@Override
public String toString() {
return
"Address [street="
+ street +
", city="
+ city +
", country="
+ country +
"]"
;
}
}
|
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
|
public class Person {
private String name;
private int age;
private boolean male;
private Address address;
public Person() {
super
();
}
public Person(String name, int age, boolean male, Address address) {
super
();
this
.name = name;
this
.age = age;
this
.male = male;
this
.address = address;
}
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 boolean isMale() {
return
male;
}
public void setMale(boolean male) {
this
.male = male;
}
public Address getAddress() {
return
address;
}
public void setAddress(Address address) {
this
.address = address;
}
@Override
public String toString() {
return
"Person [name="
+ name +
", age="
+ age +
", male="
+ male
+
", address="
+ address +
"]"
;
}
}
|
下面是具体的解析代码:
|
1
2
3
4
5
6
7
8
9
10
11
|
JSONObject jsonObject =
new
JSONObject(json);
String name = jsonObject.getString(
"name"
);
int age = jsonObject.getInt(
"age"
);
boolean male = jsonObject.getBoolean(
"male"
);
JSONObject addressJSON = jsonObject.getJSONObject(
"address"
);
String street = addressJSON.getString(
"street"
);
String city = addressJSON.getString(
"city"
);
String country = addressJSON.getString(
"country"
);
Address address =
new
Address(street, city, country);
Person person =
new
Person(name, age, male, address);
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/下载jar包, 并将其添加到项目中. 具体的解析代码如下:
|
1
2
3
|
Gson gson =
new
Gson();
Person person = gson.fromJson(json, Person.class);
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:
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
|
List<Person> persons =
new
ArrayList<Person>();
JSONArray jsonArray =
new
JSONArray(json);
for
(int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = jsonArray.getJSONObject(i);
String name = jsonObject.getString(
"name"
);
int age = jsonObject.getInt(
"age"
);
boolean male = jsonObject.getBoolean(
"male"
);
JSONObject addressJSON = jsonObject.getJSONObject(
"address"
);
String street = addressJSON.getString(
"street"
);
String city = addressJSON.getString(
"city"
);
String country = addressJSON.getString(
"country"
);
Address address =
new
Address(street, city, country);
Person person =
new
Person(name, age, male, address);
persons.add(person);
}
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:
|
1
2
3
|
Gson gson =
new
Gson();
Type listType =
new
TypeToken<List<Person>>(){}.getType();
List<Person> persons = gson.fromJson(json, listType);
|
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.