FastJson的常用操作

2017-06-05

常用操作包括以下内容:

  1. 对象与(JsonObject或JsonArray)与String的互换
  2. String转换为(JsonObject或JsonArray)如何保持顺序
  3. Eval的使用
  4. 值为null的(JsonObject或JsonArray)转换为String时如何保存

代码:

package Demo.Sample1;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONPath;
import com.alibaba.fastjson.parser.Feature;
import com.alibaba.fastjson.serializer.SerializerFeature; public class Sample { public static void main(String[] args) { Group group = GenerateGroup();
String ss="{\"id\":1.1,\"name\":\"admin\",\"users\":[{\"id\":2.2,\"name\":\"guest\"},{\"id\":3.3,\"name\":\"root\"}]}";
Group groupWithNull=GenerateGroupWithNull(); BasicObjectToStringCompare();
JsonObjectToStringCompare(ss);
NJsonObjectToStringCompare(group);
JsonStringSequence(group, ss);
JsonEval(ss,"$.users");
DealWithNullToStringString(groupWithNull);
} public static void BasicObjectToStringCompare()
{
System.out.println("---------- 基元类型 toString() toJSONString() 比较: ----------");
System.out.println("ZifuChuan");
System.out.println(JSON.toJSONString("ZifuChuan"));
System.out.println(true);
System.out.println(JSON.toJSONString(true));
System.out.println(1.1);
System.out.println(JSON.toJSONString(1.1));
} public static String NJsonObjectToStringCompare(Group group) {
String jsonString = JSON.toJSONString(group);
System.out.println("---------- 非JsonObject toString() toJSONString() 比较: ----------");
System.out.println(group.toString());
System.out.println(JSON.toJSONString(group));
return jsonString;
} public static String JsonObjectToStringCompare(String ss) {
Object o=JSON.parse(ss,Feature.OrderedField);
System.out.println("---------- JsonObject toString() toJSONString() 比较: ----------");
System.out.println(o.toString());
System.out.println(JSON.toJSONString(o));
return ss;
} public static void JsonStringSequence(Group group, String jsonString) {
System.out.println("---------- 是否有序: ----------");
Object o=JSON.parse(jsonString);
System.out.println(o.toString());; Object o1=JSON.parse(jsonString,Feature.OrderedField);
System.out.println(o1.toString()); Object o2 = JSON.toJSON(group);
System.out.println(o2.toString());
} public static void JsonEval(String ss,String jsonPath) {
System.out.println("---------- Json Eval: ----------");
Object o3=JSONPath.eval(JSON.parse(ss,Feature.OrderedField),jsonPath);
System.out.println(o3.toString());
} public static void DealWithNullToStringString(Group groupWithNull) {
System.out.println("---------- JsonObject with null emlement: ----------");
System.out.println(JSON.toJSONString(groupWithNull));
System.out.println(JSON.toJSONString(groupWithNull,SerializerFeature.WriteMapNullValue));
} private static Group GenerateGroup() {
Group group = new Group();
group.setId(1.1);
group.setName("admin"); User guestUser = new User();
guestUser.setId(2.2);
guestUser.setName("guest"); User rootUser = new User();
rootUser.setId(3.3);
rootUser.setName("root"); group.addUser(guestUser);
group.addUser(rootUser);
return group;
} private static Group GenerateGroupWithNull() {
Group group = new Group();
group.setId(1.1);
group.setName(""); User guestUser1 = new User();
guestUser1.setId(null);
guestUser1.setName("guest"); User guestUser2 = new User();
guestUser2.setId(3.3); User guestUser3 = new User(); group.addUser(guestUser1);
group.addUser(guestUser2);
group.addUser(guestUser3);
return group;
}
}

结果:

---------- 基元类型 toString() toJSONString() 比较: ----------
ZifuChuan
"ZifuChuan"
true
true
1.1
1.1
---------- JsonObject toString() toJSONString() 比较: ----------
{"id":1.1,"name":"admin","users":[{"id":2.2,"name":"guest"},{"id":3.3,"name":"root"}]}
{"id":1.1,"name":"admin","users":[{"id":2.2,"name":"guest"},{"id":3.3,"name":"root"}]}
---------- 非JsonObject toString() toJSONString() 比较: ----------
Demo.Sample1.Group@23ab930d
{"id":1.1,"name":"admin","users":[{"id":2.2,"name":"guest"},{"id":3.3,"name":"root"}]}
---------- 是否有序: ----------
{"name":"admin","id":1.1,"users":[{"name":"guest","id":2.2},{"name":"root","id":3.3}]}
{"id":1.1,"name":"admin","users":[{"id":2.2,"name":"guest"},{"id":3.3,"name":"root"}]}
{"name":"admin","id":1.1,"users":[{"name":"guest","id":2.2},{"name":"root","id":3.3}]}
---------- Json Eval: ----------
[{"id":2.2,"name":"guest"},{"id":3.3,"name":"root"}]
---------- JsonObject with null emlement: ----------
{"id":1.1,"name":"","users":[{"name":"guest"},{"id":3.3},{}]}
{"id":1.1,"name":"","users":[{"id":null,"name":"guest"},{"id":3.3,"name":null},{"id":null,"name":null}]}

参考:

[1] Introducing JSON

[2] FastJson 教程

05-11 17:30