方式一：

下划线与驼峰命名转换：

public class Tool {

private static Pattern linePattern = Pattern.compile("_(\\w)");

/** 下划线转驼峰 */

public static String lineToHump(String str) {

str = str.toLowerCase();

Matcher matcher = linePattern.matcher(str);

StringBuffer sb = new StringBuffer();

while (matcher.find()) {

matcher.appendReplacement(sb, matcher.group(1).toUpperCase());

}

matcher.appendTail(sb);

return sb.toString();

}

/** 驼峰转下划线(简单写法，效率低于{

@link #humpToLine2(String)}) */

public static String humpToLine(String str) {

return str.replaceAll("[A-Z]", "_$0").toLowerCase();

}

private static Pattern humpPattern = Pattern.compile("[A-Z]");

/** 驼峰转下划线,效率比上面高 */

public static String humpToLine2(String str) {

Matcher matcher = humpPattern.matcher(str);

StringBuffer sb = new StringBuffer();

while (matcher.find()) {

matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());

}

matcher.appendTail(sb);

return sb.toString();

}

public static void main(String[] args) {

String lineToHump = lineToHump("f_parent_no_leader");

System.out.println(lineToHump);// fParentNoLeader

System.out.println(humpToLine(lineToHump));// f_parent_no_leader

System.out.println(humpToLine2(lineToHump));// f_parent_no_leader

}

}

不纠结""_"+matcher.group(0).toLowerCase()"的话，humpToLine2效率会比humpToLine高一些，看String#replaceAll方法源码即可。

方式二：

实体类：

1 import java.io.Serializable; 2 import lombok.AllArgsConstructor; 3 import lombok.Data; 4 import lombok.NoArgsConstructor; 5  6 @Data 7 @AllArgsConstructor 8 @NoArgsConstructor 9 public class User implements Serializable {10     /**11      * 12      */13     private static final long serialVersionUID = -329066647199569031L;14     15     private String userName;16     17     private String orderNo;18 }

帮助类：

1 import java.io.IOException; 2  3 import com.fasterxml.jackson.annotation.JsonInclude.Include; 4 import com.fasterxml.jackson.core.JsonProcessingException; 5 import com.fasterxml.jackson.databind.ObjectMapper; 6 import com.fasterxml.jackson.databind.PropertyNamingStrategy; 7  8 /** 9  * JSON的驼峰和下划线互转帮助类10  * 11  * @author yangzhilong12  *13  */14 public class JsonUtils {15 16     /**17      * 将对象的大写转换为下划线加小写，例如：userName-->user_name18      * 19      * @param object20      * @return21      * @throws JsonProcessingException22      */23     public static String toUnderlineJSONString(Object object) throws JsonProcessingException{24         ObjectMapper mapper = new ObjectMapper();25         mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);26         mapper.setSerializationInclusion(Include.NON_NULL);      27         String reqJson = mapper.writeValueAsString(object);28         return reqJson;29     }30 31     /**32      * 将下划线转换为驼峰的形式，例如：user_name-->userName33      * 34      * @param json35      * @param clazz36      * @return37      * @throws IOException38      */39     public static 
       
         T toSnakeObject(String json, Class
        
          clazz) throws IOException{40         ObjectMapper mapper = new ObjectMapper(); 　　        // mapper的configure方法可以设置多种配置（例如：多字段 少字段的处理） 　　　　　　 //mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); 41         mapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);42         T reqJson =  mapper.readValue(json, clazz);43         return reqJson;44     }45 }
        
       

单元测试类：

1 import java.io.IOException; 2  3 import org.junit.Test; 4  5 import com.alibaba.fastjson.JSONObject; 6 import com.fasterxml.jackson.core.JsonProcessingException; 7  8 public class JsonTest { 9     10     @Test11     public void testToUnderlineJSONString(){12         User user = new User("张三", "1111111");13         try {14             String json = JsonUtils.toUnderlineJSONString(user);15             System.out.println(json);16         } catch (JsonProcessingException e) {17             e.printStackTrace();18         }19     }20     21     @Test22     public void testToSnakeObject(){23         String json = "{\"user_name\":\"张三\",\"order_no\":\"1111111\"}";24         try {25             User user = JsonUtils.toSnakeObject(json, User.class);26             System.out.println(JSONObject.toJSONString(user));27         } catch (IOException e) {28             e.printStackTrace();29         }30     }31 }

测试结果：

1 {"user_name":"张三","order_no":"1111111"}2 3 {"orderNo":"1111111","userName":"张三"}

 

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