java与json

1.json的基本语法

1.表示一个对象

{"name":'"zhangsan","age":22}

{"name":"lisi","addr":{"city":"jinan","street":"huayuanlu"}}

属性名要添加引号

属性值如果是字符串，要添加引号

数据类型:string,number,boolean,null,object

2.表示一个对象数组

[{},{},{}]

 

2.Java处理json

1.首先引入json的jar包

2.

  // 对象转换为json字符串
  Student st = new Student();
  st.setId(1);
  st.setAge(22);
  st.setName("张三s");
  st.setAddr("jinan");
  JSONObject obj = JSONObject.fromObject(st);
  String str = obj.toString();
  System.out.println(str);// {"addr":"jinan","age":22,"id":1,"name":"张三s"}

  // 数组对象转换位json字符串
  Student s1 = new Student(2, 22, "李四", "济宁");
  Student s2 = new Student(3, 23, "王五", "青岛");
  Student s3 = new Student(4, 24, "赵六", "上海");
  Student[] ssarr = { s1, s2, s3 };
  JSONArray obj1 = JSONArray.fromObject(ssarr);
  String str1 = obj1.toString();
  System.out.println(str1);
  // list对象转换为json字符串
  Student s11 = new Student(2, 22, "李四1", "济宁1");
  Student s22 = new Student(3, 23, "王五1", "青岛1");
  Student s33 = new Student(4, 24, "赵六1", "上海1");
  List sslist = new ArrayList();
  sslist.add(s11);
  sslist.add(s22);
  sslist.add(s33);
  JSONArray obj2 = JSONArray.fromObject(sslist);
  String str2 = obj2.toString();
  System.out.println(str2);

3.json处理日期

原始的处理方法得到的是日期对象的json字符串

{"date":15,"day":5,"hours":11,"minutes":31,"month":10,"seconds":9,"time":1384486269320,"timezoneOffset":-480,"year":113}

 

1.首先写一个日期处理器工具类 implements JsonValueProcessor

public class DateProcessor implements JsonValueProcessor {
 String pattern ="yyyy-MM-dd";

 @Override
 public Object processArrayValue(Object arg0, JsonConfig arg1) {
  SimpleDateFormat sdf = new SimpleDateFormat(pattern);
  return sdf.format((Date) arg0);
 }

 @Override
 public Object processObjectValue(String arg0, Object arg1, JsonConfig arg2) {
  SimpleDateFormat sdf = new SimpleDateFormat(pattern);
  return sdf.format((Date) arg1);
 }

}

2.在对象转json的时候加上config参数

  // json处理日期
  JsonConfig config = new JsonConfig();
  config.registerJsonValueProcessor(Date.class, new DateProcessor());

  Student dd = new Student(2, 22, "李四1", "济宁1", new Date());
  JSONObject obj3 = JSONObject.fromObject(dd,config);
  String str3 = obj3.toString();
  System.out.println(str3);

 这样之后日期就是一个字符串了

"2013-11-15"