GSON 学习

GSON 学习

GSONJava中很常用的json库，它是google自定义的json库，功能很强大，支持泛型，它也可以实现从json到java对象的装换，也可以从java对象转换成json数据。

导入GSON包

gardle中加入

compile 'com.google.code.gson:gson:2.3.1'

直接导入jar包

下载地址http://search.maven.org/#artifactdetails%7Ccom.google.code.gson%7Cgson%7C2.3.1%7Cjar

首先定义一个Peson实体

package com.example.xuyushi.autocompletetext;

/**
* Created by xuyushi on 15/6/22.
*/
public class Person {
public Person() {
super();
}

private String name;
private int age;
private String 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 String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}
}

class -> json

普通对象

Person person = new Person("zhangsan", 22, "beijing");
Gson gson = new Gson();
String str = gson.toJson(person);
Log.d(TAG, str);

LOG为

{"address":"beijing","name":"zhangsan","age":22}

数组对象

List<Person> persons = new ArrayList<Person>();
Person person1 = new Person("zhangsan", 22, "beijing");
Person person2 = new Person("lisi", 23, "shanghai");
Person person3 = new Person("wangwu", 24, "guangzhou");
persons.add(person1);
persons.add(person2);
persons.add(person3);
Gson gson = new Gson();
String str = gson.toJson(persons);
Log.d(TAG, str);

LOG为

[{"address":"beijing","name":"zhangsan","age":22},{"address":"shanghai","name":"lisi","age":23},{"address":"guangzhou","name":"wangwu","age":24}]

json -> class

普通对象

Person person = new Person("zhangsan", 22, "beijing");
Gson gson = new Gson();
String str = gson.toJson(person);
//    Log.d(TAG, str);

Person personFromJson = gson.fromJson(str, Person.class);
Log.d(TAG, personFromJson.getName());
Log.d(TAG, ""+personFromJson.getAge());
Log.d(TAG, personFromJson.getAddress());

LOG为

zhangsan

22

beijing

数组对象(难点)

List<Person> persons = new ArrayList<Person>();
Person person1 = new Person("zhangsan", 22, "beijing");
Person person2 = new Person("lisi", 23, "shanghai");
Person person3 = new Person("wangwu", 24, "guangzhou");
persons.add(person1);
persons.add(person2);
persons.add(person3);
Gson gson = new Gson();
String str = gson.toJson(persons);
//        Log.d(TAG, str);

List<Person> personsFromJson = new ArrayList<Person>();
//这里我们通过 Gson中的 TypeToken类是简便操作：这边typeOfT的用法是通过反射机制把T里面的对象的属性的值映射出来，然后通过将json字符串取得的值赋值上去就可以了。
//* getType()的意思就是表示将jsonString的字符串解析出来之后封装到List集合中，然后分别从T里面取出类型将其复制。
personsFromJson = gson.fromJson(str, new TypeToken<List<Person>>(){}.getType());
Log.d(TAG, personsFromJson.get(0).getName());
Log.d(TAG, personsFromJson.get(1).getName());
Log.d(TAG, personsFromJson.get(2).getName());

LOG为

zhangsan

lisi

wangwu