FastJson的使用

fastjson生成和解析json数据

一、fastjson生成json数据

String
jsonStrng = JSON.toJSONString(object);

二、 fastjson
解析json字符串

1.
JavaBean

User user = JSON.parseObject(jsonString,
User.class);

2. List<JavaBean>

List<User> listPerson =JSON.parseArray(jsonString,

User.class);

3. List<String>

List<String> listString = JSON.parseArray(jsonString, String.class);

4. List<Map<String,Object>>

List<Map<String, Object>> listMap = JSON.parseObject(jsonString, new TypeReference<List<Map<String,Object>>>(){});

三、拓展

1）fastjson生成json数据时，导出空数据。

String jsonStr=JSON.toJSONString(userList,SerializerFeature.WriteMapNullValue);

2）fastjson解析json数据时需要将值为null的key也可以解析出来，就要用到fastjson的反射了。

List<Map<String,
Object>> listMap = JSON.parseObject(jsonString, new TypeReference<List<Map<String,Object>>>(){});

下面的是测试代码，仅供参考。

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
import com.alibaba.fastjson.serializer.SerializerFeature;

public class Test {

	public static void main(String[] args){
		List<Map<String,Object>> userList  =getUserList();
		String jsonStr=JSON.toJSONString(userList,features);
		System.out.println(jsonStr);
		List<Map<String, Object>> listMap = JSON.parseObject(jsonStr, new TypeReference<List<Map<String,Object>>>(){});

		for(Map<String, Object> map:listMap){
			System.out.println(JSON.toJSONString(map,features));
		}

	}

	public static SerializerFeature[] features=new SerializerFeature[]{
		SerializerFeature.WriteMapNullValue,
		SerializerFeature.WriteNullBooleanAsFalse,
		SerializerFeature.WriteNullListAsEmpty,
		SerializerFeature.WriteNullStringAsEmpty,
		SerializerFeature.WriteDateUseDateFormat
	};
	public static List<Map<String,Object>> getUserList(){
		List<Map<String,Object>> newList=new ArrayList<Map<String,Object>>();

		for(int i=0;i<5;i++){
			Map<String,Object> map=new HashMap<String,Object>();
			map.put("id", i);
			map.put("username","xxx"+i);
			map.put("sex","男"+i);
			map.put("age",null);
			map.put("dh",null);
			map.put("zz","ZZ"+i);
			newList.add(map);
		}
		return newList;
	}

}

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