fastjson使用
在项目中使用到了fastjson,故研究了一下。现将自己的几个测试用例和大家分享一下~
首先在pom.xml文件中,加入依赖:
<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.8</version> </dependency>
创建一个实体类:
public class XwjUser implements Serializable { private static final long serialVersionUID = 1L; private int id; private String message; private Date sendTime; // 这里手写字母大写,只是为了测试使用,是不符合java规范的 private String NodeName; private List<Integer> intList; public XwjUser() { super(); } public XwjUser(int id, String message, Date sendTime) { super(); this.id = id; this.message = message; this.sendTime = sendTime; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public Date getSendTime() { return sendTime; } public void setSendTime(Date sendTime) { this.sendTime = sendTime; } public String getNodeName() { return NodeName; } public void setNodeName(String nodeName) { NodeName = nodeName; } public List<Integer> getIntList() { return intList; } public void setIntList(List<Integer> intList) { this.intList = intList; } @Override public String toString() { return "XwjUser [id=" + id + ", message=" + message + ", sendTime=" + sendTime + ", intList=" + intList + "]"; } }
接下来看测试用例:
1、对象与json
@Test public void testObject() { XwjUser user = new XwjUser(1, "Hello World", new Date()); user.setNodeName("node"); // 第二个参数为是否格式化json String jsonStr = JSON.toJSONString(user, true); System.out.println("对象转为字符串:" + jsonStr); XwjUser userDes = JSON.parseObject(jsonStr, XwjUser.class); System.out.println("字符串转为对象:" + userDes); }
运行结果:
对象转为字符串:{ "id":1, "message":"Hello World", "nodeName":"node", "sendTime":1525222546733 } 字符串转为对象:XwjUser [id=1, message=Hello World, sendTime=Wed May 02 08:55:46 CST 2018, intList=null]
注意事项:
1、对象转json字符串时,对象中的NodeName首字母是大写,转出来是小写。
2、json转对象时,实体类中一定要加上默认的无参构造器
2、map与json
@Test public void testMap() { Map<String, Object> testMap = new HashMap<>(); testMap.put("name", "merry"); testMap.put("age", 30); testMap.put("date", new Date()); testMap.put("isDel", true); testMap.put("user", new XwjUser(1, "Hello World", new Date())); String jsonStr = JSON.toJSONString(testMap); System.out.println("Map转为字符串:" + jsonStr); Map<String, Object> mapDes = JSON.parseObject(jsonStr, new TypeReference<Map<String, Object>>() {}); System.out.println("字符串转map:" + mapDes); }
运行结果:
Map转为字符串:{"date":1525223256653,"name":"merry","isDel":true,"user":{"id":1,"message":"Hello World","sendTime":1525223256654},"age":30} 字符串转map:{date=1525223256653, name=merry, isDel=true, user={"id":1,"message":"Hello World","sendTime":1525223256654}, age=30}
3、list与json
@Test public void testMapList() { List<Map<String, Object>> mapList = new ArrayList<>(); Map<String, Object> map1 = new HashMap<>(); map1.put("name", "merry"); map1.put("age", 30); map1.put("date", new Date()); map1.put("isDel", true); Map<String, Object> map2 = new HashMap<>(); map2.put("name", "jim"); map2.put("age", 28); map2.put("isDel", false); mapList.add(map1); mapList.add(map2); String jsonStr = JSON.toJSONString(mapList); System.out.println("list转为字符串:" + jsonStr); // 传入泛型类型 List<Map> listDes = JSON.parseArray(jsonStr, Map.class); System.out.println("字符串转为list:" + listDes); }
运行结果:
list转为字符串:[{"date":1525223309870,"name":"merry","isDel":true,"age":30},{"name":"jim","isDel":false,"age":28}] 字符串转为list:[{date=1525223309870, name=merry, isDel=true, age=30}, {name=jim, isDel=false, age=28}]
注意:使用JSON.parseArray时,传入list中的泛型
4、json中日期格式化
@Test public void testDateFormat() { Date now = new Date(); String dateStr = JSON.toJSONString(now); System.out.println("默认日期:" + dateStr); // 按照指定格式格式化日期,格式为yyyy-MM-dd HH:mm:ss String dateStr2 = JSON.toJSONString(new Date(), SerializerFeature.WriteDateUseDateFormat); System.out.println("格式化日期:" + dateStr2); String dateStr3 = JSON.toJSONStringWithDateFormat(now, "yyyy-MM-dd HH:mm"); System.out.println("格式化日期:" + dateStr3); }
运行结果:
默认日期:1525223374867 格式化日期:"2018-05-02 09:09:34" 格式化日期:"2018-05-02 09:09"
5、json字符串输出单引号
@Test public void testSingleQuotes() { List<Object> list = new ArrayList<>(); list.add("home"); list.add("hello"); list.add(true); list.add(45.78); String listJson = JSON.toJSONString(list, SerializerFeature.UseSingleQuotes); System.out.println("转为单引号字符串:" + listJson); }
运行结果:
转为单引号字符串:['home','hello',true,45.78]
6、改变json字符串中默认不输出值为null字段
@Test public void testNull() { Map<String, Object> testMap = new HashMap<>(); testMap.put("name", "merry"); testMap.put("age", 30); testMap.put("date", null); // 缺省情况下,FastJSON不输入为值Null的字段 String jsonStr = JSON.toJSONString(testMap); System.out.println("转为字符串:" + jsonStr); String jsonStr2 = JSON.toJSONString(testMap, SerializerFeature.WriteMapNullValue); System.out.println("转为字符串:" + jsonStr2); }
运行结果:
转为字符串:{"name":"merry","age":30} 转为字符串:{"date":null,"name":"merry","age":30}
关于SerializerFeature中的常量属性含义,可以参考fastjson SerializerFeature详解
本文示例源码地址:https://github.com/xuwenjin/xwj_repo/tree/master/xwj-impl
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