json数据与Gson工具类的使用

JS中使用JSON
JSON对象 --> JSON字符串：JSON.stringify(对象)
JSON字符串 --> JSON对象：JSON.parse(JSON字符串)

 <script type="text/javascript">
     var json={"name":"chen","age":18,"date":new Date(),"school":null,"hobby":[1,2,3],"gender":true};
     document.write(typeof json+"<br>");//object
     document.write(json+"<br>");//[object Object]
     document.write(json.name+"<br>");//chen
     document.write(json.hobby[0]+"<br>");//
     document.write("JSON转化成string<br>");
     var jsonStr=JSON.stringify(json);
     document.write(typeof jsonStr+"<br>");//string
     document.write(jsonStr+"<br>");//{"name":"chen","age":18,"date":"2017-08-17T13:15:32.981Z","school":null,"hobby":[1,2,3],"gender":true}
     //document.write(jsonStr.name+"<br>");//undefined出错
     //document.write(jsonStr.hobby[0]+"<br>");//undefined出错
     document.write("string转化成JSON<br>");
     var jsonObj=JSON.parse(jsonStr);
     document.write(typeof jsonObj+"<br>");//object
     document.write(jsonObj+"<br>");//[object Object]
     document.write(jsonObj.name+"<br>");//chen
     document.write(jsonObj.hobby[0]+"<br>");//
 </script>

JAVA中使用JSON

目前Java中用的比较多的JSON解析工具：

• json-lib --> 使用麻烦，解析性能最差
• Jackson --> 使用较麻烦，解析性能最好
• Gson --> 使用简单，解析性能中等
  • Gson是谷歌出的一款JSON解析工具，使用简单，且性能较好。

GSON工具类的使用

 // 将普通对象转换为JSON字符串！
 Student stu = new Student("尘", 18);
 System.out.println(stu);//com.test.Student@15db9742-----内存地址
 Gson gson = new Gson();
 String json = gson.toJson(stu);
 System.out.println(json);//{"name":"尘","age":18}
 Student fromJson1 = gson.fromJson(json, Student.class);
 System.out.println(fromJson1);//com.test.Student@25f38edc-----内存地址

 // 把Map转换成JSON字符串
  Map<String,String> map2 = new HashMap<String,String>();
  map2.put("hobby","篮球");
  map2.put("gender", "男");
  String json2 = gson.toJson(map2);
  System.out.println(json2);//{"gender":"男","hobby":"篮球"}
  Map<String,String> fromJson2 = gson.fromJson(json2, Map.class);
  System.out.println(fromJson2);//{gender=男, hobby=篮球}

 // 将List转换为JSON字符串
 List<Student> list = new ArrayList<Student>();
 list.add(new Student("Tom", 7));
 list.add(new Student("Jerry", 5));
 String json3 = gson.toJson(list);
 System.out.println(json3);//[{"name":"Tom","age":7},{"name":"Jerry","age":5}]
 List<Map<String, Object>> fromJson3 = gson.fromJson(json3, List.class);
 for (Map map3 : fromJson3) {
     System.out.println(map3.get("name"));
     //Tom
     //Jerry
 }

付gson-2.2.4.jar下载地址（百度云） 密码：9ngh