Java to Jackson JSON序列化：Money字段 [英] Java to Jackson JSON serialization: Money fields

问题描述

目前，我正在使用Jackson从我的基于Spring的Web应用程序发送JSON结果。

我遇到的问题是试图获得所有资金要输出2个小数位的字段。我无法使用 setScale（2）解决此问题，因为25.50之类的数字被截断为25.5等

<有没有其他人处理过这个问题？我正在考虑使用自定义的Jackson序列化程序创建Money类...您可以为字段变量创建自定义序列化程序吗？你可能......但即使如此，我怎么能让我的客户序列化器将数字添加为2位小数？

解决方案

您可以在货币领域使用自定义序列化程序。这是MoneyBean的一个例子。字段金额使用 @JsonSerialize（使用= ...）进行注释。

 公共类MoneyBean {
 // ... 
 
 @JsonProperty（amountOfMoney）
 @JsonSerialize（using = MoneySerializer.class）
 private BigDecimal数量; 
 
 // getters / setters ... 
} 
 
公共类MoneySerializer扩展JsonSerializer< BigDecimal> {
 @Override 
 public void serialize（BigDecimal value，JsonGenerator jgen，SerializerProvider provider）抛出IOException，
 JsonProcessingException {
 //把你想要的钱款放在这里
 jgen .writeString（value.setScale（2，BigDecimal.ROUND_HALF_UP）.toString（））; 
} 
} 
  

就是这样。现在以正确的方式打印BigDecimal。我使用一个简单的测试用例来显示它：

  @Test 
 public void jsonSerializationTest（）抛出异常{
 MoneyBean m = new MoneyBean（）; 
 m.setAmount（new BigDecimal（20.3））; 
 
 ObjectMapper mapper = new ObjectMapper（）; 
 assertEquals（{\amountOfMoney \：\20.30 \}，mapper.writeValueAsString（m））; 
} 
  

Currently, I'm using Jackson to send out JSON results from my Spring-based web application.

The problem I'm having is trying to get all money fields to output with 2 decimal places. I wasn't able to solve this problem using setScale(2), as numbers like 25.50 are truncated to 25.5 etc

Has anyone else dealt with this problem? I was thinking about making a Money class with a custom Jackson serializer... can you make a custom serializer for a field variable? You probably can... But even still, how could I get my customer serializer to add the number as a number with 2 decimal places?

解决方案

You can use a custom serializer at your money field. Here's an example with a MoneyBean. The field amount gets annotated with @JsonSerialize(using=...).

public class MoneyBean {
    //...

    @JsonProperty("amountOfMoney")
    @JsonSerialize(using = MoneySerializer.class)
    private BigDecimal amount;

    //getters/setters...
}

public class MoneySerializer extends JsonSerializer<BigDecimal> {
    @Override
    public void serialize(BigDecimal value, JsonGenerator jgen, SerializerProvider provider) throws IOException,
            JsonProcessingException {
        // put your desired money style here
        jgen.writeString(value.setScale(2, BigDecimal.ROUND_HALF_UP).toString());
    }
}

That's it. A BigDecimal is now printed in the right way. I used a simple testcase to show it:

@Test
public void jsonSerializationTest() throws Exception {
     MoneyBean m = new MoneyBean();
     m.setAmount(new BigDecimal("20.3"));

     ObjectMapper mapper = new ObjectMapper();
     assertEquals("{\"amountOfMoney\":\"20.30\"}", mapper.writeValueAsString(m));
}

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