Android中使用Google的GSON框架解析JSON数据-方便快捷（含代码）

Android中使用Google的GSON框架解析JSON数据----方便快捷（含代码）

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:

package text.com.bean;

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 + "]";
	}

}

package text.com.bean;

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 + "]";
	}

}

首先使用方法一解析代码如下：

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:

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:

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:

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

测试用例：

package text.com;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Type;
import java.util.List;

import text.com.bean.Address;
import text.com.bean.Person;

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

public class JsonTest {
	String jsonString = "";

	public static void main(String[] args) {
		// Person p1 = new Person("zhangsan", 12, true, new Address("北京", "海淀区",
		// "30号"));
		// Person p2 = new Person("zhangsan", 12, true, new Address("北京", "海淀区",
		// "30号"));
		// Person p3 = new Person("zhangsan", 12, true, new Address("北京", "海淀区",
		// "30号"));
		// List<Person> list = new ArrayList<Person>();
		// list.add(p1);
		// list.add(p2);
		// list.add(p3);
		// Gson gson = new Gson();
		// Type typeOfT = new TypeToken<List<Person>>(){}.getType();
		// String json = gson.toJson(list, typeOfT);
		// System.out.println("json:"+json);

		// String str = readTxtFile("D:\\cjjworkspace\\Test\\json.txt");
		// System.out.println("文件内容：" + str);
		 Gson gson = new Gson();
		// Type typeOfT = new TypeToken<List<Person>>(){}.getType();
		// List<Person> personList = gson.fromJson(str, typeOfT);

		Person p1 = new Person("zhangsan", 12, true, new Address("北京", "海淀区", "30号"));
		Type typeOfT = new TypeToken<Person>(){}.getType();
		String str = gson.toJson(p1, typeOfT);
		System.out.println(str);
	}

	public static String readTxtFile(String filePath) {
		String encoding = "utf-8";
		StringBuilder sb = new StringBuilder();
		try {
			File file = new File(filePath);
			if (file.isFile() && file.exists()) { // 判断文件是否存在
				InputStreamReader read = new InputStreamReader(new FileInputStream(file), encoding);// 考虑到编码格式
				BufferedReader bufferedReader = new BufferedReader(read);
				String str = "";
				while ((str = bufferedReader.readLine()) != null) {
					sb.append(str);
				}
				read.close();
				return sb.toString();
			} else {
				System.out.println("找不到指定的文件");
				return null;
			}
		} catch (Exception e) {
			System.out.println("读取文件内容出错");
			e.printStackTrace();
		}
		return sb.toString();
	}
}

附带：gson-2.2.4.jar

           gson-2.2.4-javadoc.jar

           gson-2.2.4-sources.jar