FastJson的常用操作

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