Android parses json data, android parses json data

[Switch] parse json data for Android and parse json data for android

1. json format

2. json parsing 3. gson parsing 4. fastjson parsing 1. Json format a lightweight data exchange format. Xml and json are generally used for data transmission and exchange over the network. Two structures: 1) object (key-value set) {"id": "1001", "name": "zhangshan", "address": "shanghai"} 2) array (array object), with the key-value object included in []

{"Students": [{"sid": 1001, "name": "zhangsan", "addr": "Yichang", "pic": "111.jpg "}, {"sid": 1002, "name": "Jack", "addr": "Beijing", "pic": "222.jpg"}]}

 

Or:

{[{"Sid": 1001, "name": "zhangsan", "addr": "Yichang", "pic": "111.jpg"}, {" sid ": 1002, "name": "Jack", "addr": "Beijing", "pic": "222.jpg"}]}

2. json data generation and parsing of JSONObject represents a JSON object that can be converted between a Java object and a JSON string. JSONArray represents a JSON array, which can be used to convert a Java set (a collection element can be an object) to a JSON string. 1. Conversion between a Java object and a JSON string:

Student stu = new Student (1005, "James", "Wuhan", "zs.jpg ");

JSONObject jsonObject = new JSONObject (stu );

JsonObject. toString () is the string output: {"sid": 1005, "name": "Zhang San", "addr": "Wuhan", "pic ": "zs.jpg"} is parsed as an object:

JSONObject jsonObject = new JSONObject (str );

 

Iterator <String> iterator = jsonObject. keys ();

Student stu = new Student ();

 

While (iterator. hasNext ()){

// You can use java reflection to write generic methods.

String key = iterator. next ();

If (key. equals ("sid ")){

Stu. setSid (jsonObject. getInt (key ));

}

 

If (key. equals ("name ")){

Stu. setName (jsonObject. getString (key ));

}

 

If (key. equals ("sid ")){

Stu. setAddr (jsonObject. getString (key ));

}

 

If (key. equals ("sid ")){

Stu. setPic (jsonObject. getString (key ));

}

}

Method 2: Student stu = new Student (1005, "Zhang San", "Wuhan", "zs.jpg ");

JSONObject jsonObject = new JSONObject ();

JsonObject. put ("zs", stu );

 

Similarly, jsonObject. toString () is the string output {"zs": "{sid: 1005, name: James, addr: Wuhan, pic: zs.jpg }"}. Note that if Student does not overwrite the toString () method, the input is: {"zs": "org. itair. domain. Student @ 2666e815 "}

 

 

 

 

2. Conversion between a set and a JSON string 1. Conversion:

Student s1 = new Student (1001, "zhangsan", "yichang", "111 ");

Student s2 = new Student (1002, "Jack", "Beijing", "222 ");

 

List <Student> stus = new ArrayList <Student> ();

 

Stus. add (s1 );

Stus. add (s2 );

 

JSONArray array = new JSONArray (stus );

 

The array string is: [{"sid": 1001, "name": "zhangsan", "addr": "yichang", "pic": "111 "}, {"sid": 1002, "name": "Jack", "addr": "Beijing", "pic": "222"}]

Resolution: JSONArray jsonArray = new JSONArray ("json string to be parsed ");

For (int I = 0; I <jsonArray. length (); I ++ ){

JSONObject jsonObject2 = jsonArray. getJSONObject (I );

// Parse it into a specific object operation, new object, and get the value from jsonObject2 for loading

Iterator <String> iterator = jsonObject2.keys ();

While (iterator. hasNext ()){

String key = iterator. next ();

Object value = jsonObject2.get (key );

Map. put (key, value );

}

}

Method 2: conversion: Student s1 = new Student (1001, "zhangsan", "yichang", "111 ");

Student s2 = new Student (1002, "Jack", "Beijing", "222 ");

 

List <Student> stus = new ArrayList <Student> ();

 

Stus. add (s1 );

Stus. add (s2 );

 

JSONObject jsonObject = new JSONObject ();

JsonObject. put ("students", stus );

JsonObject string: {"students": [{"sid": 1001, "name": "zhangsan", "addr": "yichang", "pic ": "111" },{ "sid": 1002, "name": "Jack", "addr": "Beijing", "pic": "222"}]}

Resolution: The preceding conversion method is to put the set object in JSONObject. JSONObject jsonObject = new JSONObject ("json string to be parsed ");

JSONArray jsonArray = jsonObject. getJSONArray ("key"); // The key is the students put above.

The subsequent code is the same as above.

 

In Android projects, the Json String is generally not parsed into a collection of objects, but mostly into a List <Map <String, Object>

 

List <Map <String, Object> list = new ArrayList <Map <String, Object> ();

 

For (int I = 0; I <jsonArray. length (); I ++ ){

JSONObject jsonObject2 = jsonArray. getJSONObject (I );

Map <String, Object> map = new HashMap <String, Object> ();

Iterator <String> iterator = jsonObject2.keys ();

While (iterator. hasNext ()){

String key = iterator. next ();

Object value = jsonObject2.get (key );

Map. put (key, value );

}

 

List. add (map );

 

}

 

It is more convenient to parse it into an object set, or use Gson and fastjson.

 

3. GsontoJson (Object) converts the Object into a json String fromJson (String, Object) and converts the json String into an Object.