一、需求：
页面返回数据
1 { 2 "code": 0, 3 "msg": "", 4 "count": "2", 5 "data": [{ 6 "keywords": "广东木材提供有限公司1", 7 "frequency": 4621, 8 "userNums": 4235 9 }, 10 { 11 "keywords": "广东木材提供有限公司2", 12 "frequency": 4621, 13 "userNums": 4235 14 }] 15 }
二、为此写了一个Firm类
1 public class Firm { 2 3 private String keywords; 4 private String frequency; 5 private String userNums; 6 7 public Testdata(String keywords, String frequency, String userNums) { 8 this.keywords = keywords; 9 this.frequency = frequency; 10 this.userNums = userNums; 11 } 12 }
三、在Controller方法中
1 @RequestMapping("/firm/listdata.action") 2 public @ResponseBody Map<String, Object> listData(){ 3 4 List<Testdata> tdList = new ArrayList<>(); 5 Testdata td1 = new Testdata("广东木材提供有限公司1","4621","4235"); 6 Testdata td2 = new Testdata("广东木材提供有限公司1","4621","4235"); 7 tdList.add(td1); 8 tdList.add(td2); 9 tdList.add(td3); 10 tdList.add(td4); 11 tdList.add(td5); 12 Map<String, Object> map = new HashMap<>(); 13 map.put("code", 0); 14 map.put("msg", ""); 15 map.put("count", 2); 16 map.put("data", tdList); 17 return map; 18 }
四、访问时浏览器报500异常
org.springframework.http.converter.HttpMessageNotWritableException: Could not write content: No serializer found for class cn.ssm.trading.domain.Firm and
no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )
(through reference chain: java.util.HashMap["data"]->java.util.ArrayList[0]);
nested exception is com.fasterxml.jackson.databind.JsonMappingException:
No serializer found for class cn.ssm.trading.domain.Firm and no properties discovered to create BeanSerializer
(to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) )
(through reference chain: java.util.HashMap["data"]->java.util.ArrayList[0])
五、解决
为Firm类实现序列化，为字段提供getter/setter以及无参构造方法
1 public class Firm implements Serializable { 2 3 private String keywords; 4 private String frequency; 5 private String userNums; 6 7 public String getKeywords() { 8 return keywords; 9 } 10 public void setKeywords(String keywords) { 11 this.keywords = keywords; 12 } 13 public String getFrequency() { 14 return frequency; 15 } 16 public void setFrequency(String frequency) { 17 this.frequency = frequency; 18 } 19 public String getUserNums() { 20 return userNums; 21 } 22 public void setUserNums(String userNums) { 23 this.userNums = userNums; 24 } 25 //无参构造方法 26 public Testdata() { 27 28 } 29 30 public Testdata(String keywords, String frequency, String userNums) { 31 this.keywords = keywords; 32 this.frequency = frequency; 33 this.userNums = userNums; 34 } 35 }