fastjson序列化时去掉null字段

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.jiepu.rpc.thrift.server.entity.User;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

/**
* Created by Administrator on 2016/1/5.
*/
public class TestFastJson {

public static void main(String[] args){

List<User> list=new ArrayList<>();
for(int i=0;i<3;i++)
{
User entity=new User();
entity.setId((long) i);
entity.setPassword("");
entity.setUsername("来自中文"+i);
entity.setToken(UUID.randomUUID().toString());
//list.add(entity);
list.add(0,entity);
}
String json=JSON.toJSONString(list);
System.out.println(json);
/*
QuoteFieldNames———-输出key时是否使用双引号,默认为true
WriteMapNullValue——–是否输出值为null的字段,默认为false
WriteNullNumberAsZero—-数值字段如果为null,输出为0,而非null
WriteNullListAsEmpty—–List字段如果为null,输出为[],而非null
WriteNullStringAsEmpty—字符类型字段如果为null,输出为”“,而非null
WriteNullBooleanAsFalse–Boolean字段如果为null,输出为false,而非null
*/
//使用双引号
System.out.println(JSONObject.toJSONString(list, SerializerFeature.QuoteFieldNames));
//输出值为null的字段
System.out.println(JSONObject.toJSONString(list, SerializerFeature.WriteMapNullValue));
System.out.println(JSONObject.toJSONString(list, SerializerFeature.WriteNullNumberAsZero));
System.out.println(JSONObject.toJSONString(new ArrayList<>(), SerializerFeature.WriteNullListAsEmpty));
System.out.println(JSONObject.toJSONString(list, SerializerFeature.WriteNullStringAsEmpty));
System.out.println(JSONObject.toJSONString(list, SerializerFeature.SortField));
}
}

import com.alibaba.fastjson.annotation.JSONField;

public class User {

private Long id;
@JSONField(serialize = false)
private String username;
private String password;
/**动态授权令牌*/
private String token;
/**过期时间 */
private String expired;

public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public String getToken() {
return token;
}

public void setToken(String token) {
this.token = token;
}

public String getExpired() {
return expired;
}

public void setExpired(String expired) {
this.expired = expired;
}
}