将JSON数据转换成JAVA的实体类

╰半夏微凉° 2023-10-03 15:53 24阅读 0赞

思路：首先将JSON格式的数据转换成JSONObject，然后将JSONObject转换成Java的实体类（其中类属性包括List等类型）

Java实体类：

SearchFilter 类

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 public class SearchFilter {
     2     private String groupOp;
     3     
     4     private List<SearchRule> rules;
     5 
     6     public String getGroupOp() {
     7         return groupOp;
     8     }
     9 
    10     public void setGroupOp(String groupOp) {
    11         this.groupOp = groupOp;
    12     }
    13 
    14     public List<SearchRule> getRules() {
    15         return rules;
    16     }
    17 
    18     public void setRules(List<SearchRule> rules) {
    19         this.rules = rules;
    20     }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

SearchRule 类：

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 public class SearchRule {
     2     private String field;
     3     private String op;
     4     private String data;
     5     public String getField() {
     6         return field;
     7     }
     8     public void setField(String field) {
     9         this.field = field;
    10     }
    11     public String getOp() {
    12         return op;
    13     }
    14     public void setOp(String op) {
    15         this.op = op;
    16     }
    17     public String getData() {
    18         return data;
    19     }
    20     public void setData(String data) {
    21         this.data = data;
    22     }
    23 
    24 
    25 }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 //导入的package
    2 import com.fasterxml.jackson.databind.ObjectMapper;
    3 import net.sf.json.JSONArray;
    4 import net.sf.json.JSONObject;

解析JSon格式字符串的方法

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 public SearchFilter jsonToSearchFilter(String filters) {
     2         SearchFilter searchFilter = null;
     3         try {
     4             JSONObject jsonobject = JSONObject.fromObject(filters);//将json格式的字符串转换成JSONObject 对象
     5             JSONArray array = jsonobject.getJSONArray("rules");    //如果json格式的字符串里含有数组格式的属性，将其转换成JSONArray，以方便后面转换成对应的实体
     6             List<SearchRule> rules = new ArrayList<SearchRule>();
     7             for (int i = 0; i < array.size(); i++) {
     8                 JSONObject object = (JSONObject) array.get(i);     //将array中的数据进行逐条转换
     9                 SearchRule rule = (SearchRule) JSONObject.toBean(object, SearchRule.class);  //通过JSONObject.toBean()方法进行对象间的转换
    10                 rules.add(rule);
    11             }
    12             String groupOp = jsonobject.getString("groupOp");  //简单的直接获取值
    13             searchFilter = new SearchFilter();                 //对SearchFilter对象进行组装
    14             searchFilter.setGroupOp(groupOp);
    15             searchFilter.setRules(rules);
    16         } catch (Exception e) {
    17             System.out.println("filters=" + filters.toString() + ".json转换成实体类出错");
    18             e.printStackTrace();
    19         }
    20         return searchFilter;
    21     }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

这里只进行了SearchFilter类中list<SearchRule>rule属性的对象转换，因为它是一个SearchRule对象数组，需要单独拿出来进行json转换成对象，如果直接对filter进行 SearchFilter进行实体转换会报错。如果对象中不含有list,array，map等集合，可以像8-9行一样进行对象转换。

测试：

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 public static void main(String[] args) {
    2         UserMgmtController con = new UserMgmtController();
    3         String filters="{\"groupOp\": \"OR\",\"rules\": [{\"field\": \"realname\",\"op\": \"eq\","+
    4                        "\"data\": \"1234\"},{\"field\": \"cityCode\",\"op\": \"ne\",\"data\": \"5678\"}]}";
    5         SearchFilter searchFilter =con.jsonToSearchFilter(filters);
    6         System.out.println("gop="+searchFilter.getGroupOp()+" rules.size="+searchFilter.getRules().size());
    7     }
    结果：gop=OR rules.size=2

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

将java对象转换成json格式：

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 //将Object 对象转换成 json
     2     public String objectToJson(Object obj) {
     3         ObjectMapper mapper = new ObjectMapper();
     4         // Convert object to JSON string
     5         String jsonStr = null;
     6         try {
     7             jsonStr = mapper.writeValueAsString(obj);
     8         } catch (IOException e) {
     9             log.error(obj + "entity 轉換成 json出錯", e);
    10             e.printStackTrace();
    11             System.out.println("entity 轉換成 json出錯");
    12         }
    13         return jsonStr;
    14     }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

将Object 转换成json字符串时，默认使用用是的驼峰方式，如果不想使用驼峰则可以增加红色部分设置，带下划线的也可以原样输出：

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

1 public String objectToJson(Object obj){
     2         ObjectMapper mapper = new ObjectMapper();
     3         String json =null;
     4         try {
     5             PropertyNamingStrategy.PascalCaseStrategy pp = new PropertyNamingStrategy.PascalCaseStrategy();            
     6             mapper.setPropertyNamingStrategy(pp);
     7             json = mapper.writeValueAsString(obj);
     8         } catch (JsonProcessingException e) {
     9             log.error("json对象转换失败",e);
    10             e.printStackTrace();
    11         }
    12         return json;
    13     }

![复制代码][48304ba5e6f9fe08f3fa1abda7d326ab.png]

结果：

"UpLoadDateTime":"2017-09-25 10:51:41","OrganizationId":"B3EA5A4D-7C60-4C21-AF09-494890467C34" ，"Test_Code":""

来源：[https://www.cnblogs.com/smallfa/p/10495508.html][https_www.cnblogs.com_smallfa_p_10495508.html]

[48304ba5e6f9fe08f3fa1abda7d326ab.png]: https://img-blog.csdnimg.cn/img_convert/48304ba5e6f9fe08f3fa1abda7d326ab.png
[https_www.cnblogs.com_smallfa_p_10495508.html]: https://www.cnblogs.com/smallfa/p/10495508.html