最近学习到了Json解析    尝试过 最早 org.json  
感觉 Gson 解析 json  还是很不错的  特此写了笔记 已供学习!

官网是最好的学习通道
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UserGuide 解释了Gson 解析 大部分应用

Gson  用来 JavaBean --> json 格式  ||     json 格式  -- > JavaBean

前者称  Gson 的 序列化  后者 Gson 的反序列化

Primitives Examples   //基本例子
ps Serialization :JavaBean --> json 格式

    Deserialization: json 格式  -- > JavaBean

(Serialization)
Gson gson = new Gson();
gson.toJson(1);            ==> prints 1
gson.toJson("abcd");       ==> prints "abcd"
gson.toJson(new Long(10)); ==> prints 10
int[] values = { 1 };
gson.toJson(values);       ==> prints [1]

(Deserialization)
int one = int.class);
Integer one = gson.fromJson("1", Integer.class);
Long.class);
Boolean false = Boolean.class);
String str = String anotherStr =


Object Examples //自定义类 class BagOfPrimitives {
  private int value1 = 1;
  private String value2 = "abc";
  private transient int value3 = 3;
  BagOfPrimitives() {
    // no-args constructor
  }
}

(Serialization)
BagOfPrimitives obj = new BagOfPrimitives();

String json = gson.toJson(obj); 
==> json is {"value1":1,"value2":"abc"}   //注意 这里没有出现 value3  = 3 
java 关键字transient 
如果用transient声明一个实例变量，当对象存储时，它的值不需要维持
Gson 也就不会序列化他


(Deserialization)
BagOfPrimitives obj2 = );  

Finer Points with Objects //小小细节 1.
  





Nested Classes (including Inner Classes) //嵌套类(包含内部类) ublic class A {
  public String a;

  class B {

    public String b;

    public B() {
      // No args constructor for B
    }
  }
}

//这是一个成员内部类 Gson 序列化A时  不会序列化 B
A a =new A();
a.a="aaaaaa";

A.B b =new a.new B();
b.b="bbbbbb";
Gson g =new Gson();
String atext = g.toJson(a);
System.out.println(atext);

json-->"a":"aaaaaa"

Array Examples  //数组例子

int[] ints = {1, 2, 3, 4, 5};
String[] strings = {"abc", "def", "ghi"};

(Serialization)
gson.toJson(ints);     ==> prints [1,2,3,4,5]

gson.toJson(strings);  ==> prints ["abc", "def", "ghi"]

(Deserialization)
int[] ints2 = );
==> ints2 will be same as ints

元素类型

Collections Examples    //集合<泛形>实例
Gson gson = new Gson();
Collection<Integer> ints = Lists.immutableList(1,2,3,4,5);

(Serialization)
String json = gson.toJson(ints); ==> json is [1,2,3,4,5]

(Deserialization)

//使用反序列化   如果要保持泛形 
Type collectionType = new TypeToken<Collection<Integer>>(){}.getType();
Collection<Integer> ints2 = gson.fromJson(json, collectionType);
ints2 is same as ints

Fairly hideous: note how we define the type of collection
Unfortunately, no way to get around this in Java

Serializing and Deserializing Generic Types   泛型类型 Type fooType = new TypeToken<Foo<Bar>>() {}.getType();
gson.toJson(foo, fooType);

gson.fromJson(json, fooType) Serializing and Deserializing Collection with Objects of Arbitrary Types 任意对像类型的集合 ['hello',5,{name:'GREETINGS',source:'guest'}]

The equivalent Collection containing this is:

Collection collection = new ArrayList();

collection.add("hello");

collection.add(5);

collection.add(new Event("GREETINGS", "guest"));

Where the Event class is defined as:

class Event {

  private String name;

  private String source;

  private Event(String name, String source) {

    this.name = name;

    this.source = source;

  }

}