java 如何让 Jackson 使用一种方法将类序列化为 JSON？
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How to have Hymanson use a method to serialize a class to JSON?
提问by pacoverflow
Let's say I have the following classes:
假设我有以下课程：
public class MyClass {
private Test t;
public MyClass() {
t = new Test(50);
}
}
public class Test {
private int test;
public Test(int test) {
this.test = test;
}
public String toCustomString() {
return test + "." + test;
}
}
When Hymanson serializes an instance of MyClass, it will look like the following:
当 Hymanson 序列化 的实例时MyClass，它将如下所示：
{"t":{"test":50}}
{"t":{"test":50}}
Is there any annotation I can put in the Testclass to force Hymanson to invoke the toCustomString()method whenever serializing a Testobject?
我可以在Test类中添加任何注释以强制 HymansontoCustomString()在序列化Test对象时调用该方法吗？
I'd like to see one of the following outputs when Hymanson serializes an instance of MyClass:
当 Hymanson 序列化 的实例时，我希望看到以下输出之一MyClass：
{"t":"50.50"}
{"t":"50.50"}
{"t":{"test":"50.50"}}
{"t":{"test":"50.50"}}
采纳答案by Sotirios Delimanolis
If you want to produce
如果你想生产
{"t":"50.50"}
you can use @JsonValuewhich indicates
您可以使用@JsonValuewhich 表示
that results of the annotated "getter" method (which means signature must be that of getters; non-void return type, no args) is to be used as the single value to serialize for the instance.
带注释的“getter”方法（这意味着签名必须是 getter 的签名；非空返回类型，没有参数）的结果将用作实例序列化的单个值。
@JsonValue
public String toCustomString() {
return test + "." + test;
}
If you want to produce
如果你想生产
{"t":{"test":"50.50"}}
you can use a custom JsonSerializer.
您可以使用自定义JsonSerializer.
class TestSerializer extends JsonSerializer<Integer> {
@Override
public void serialize(Integer value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException {
jgen.writeString(value + "." + value);
}
}
...
@JsonSerialize(using = TestSerializer.class)
private int test;
回答by mtyurt
You are looking for @JsonPropertyannotation. Just put it to your method:
您正在寻找@JsonProperty注释。只需将其放入您的方法中：
@JsonProperty("test")
public String toCustomString() {
return test + "." + test;
}
Also, Hymanson consistently denied to serialize MyClass, so to avoid problems you can add a simple getter to tproperty.
此外，Hymanson 一直拒绝序列化MyClass，因此为了避免出现问题，您可以向t属性添加一个简单的 getter 。
