Jackson如果其中一個 getter 拋出異常，如何序列化對象？例子：public class Example { public String getSomeField() { //some logic which will throw in example NPE throw new NullPointerException(); }}理想情況下我想得到JSON：{"someField":"null"}或者{"someField":"NPE"}
1 回答
倚天杖
TA貢獻1828條經驗 獲得超3個贊
最通用的方法可能是實現 custom BeanPropertyWriter。您可以通過創建類來注冊它BeanSerializerModifier。下面的示例展示了如何做到這一點。
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.BeanDescription;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.BeanPropertyWriter;
import com.fasterxml.jackson.databind.ser.BeanSerializerModifier;
import java.util.List;
import java.util.stream.Collectors;
public class JsonApp {
public static void main(String[] args) throws Exception {
SimpleModule module = new SimpleModule();
module.setSerializerModifier(new BeanSerializerModifier() {
@Override
public List<BeanPropertyWriter> changeProperties(SerializationConfig config, BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {
if (beanDesc.getBeanClass() == Response.class) {
return beanProperties.stream()
.map(SilentExceptionBeanPropertyWriter::new)
.collect(Collectors.toList());
}
return super.changeProperties(config, beanDesc, beanProperties);
}
});
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(module);
System.out.println(mapper.writeValueAsString(new Response(1, "ONE")));
System.out.println(mapper.writeValueAsString(new Response(-1, "MINUS")));
System.out.println(mapper.writeValueAsString(new Response(-1, null)));
}
}
class SilentExceptionBeanPropertyWriter extends BeanPropertyWriter {
public SilentExceptionBeanPropertyWriter(BeanPropertyWriter base) {
super(base);
}
@Override
public void serializeAsField(Object bean, JsonGenerator gen, SerializerProvider prov) throws Exception {
try {
super.serializeAsField(bean, gen, prov);
} catch (Exception e) {
Throwable cause = e.getCause();
gen.writeFieldName(_name);
gen.writeString(cause.getClass().getName() + ":" + cause.getMessage());
}
}
}
class Response {
private int count;
private String message;
public Response(int count, String message) {
this.count = count;
this.message = message;
}
public int getCount() {
if (count < 0) {
throw new IllegalStateException("Count is less than ZERO!");
}
return count;
}
public void setCount(int count) {
this.count = count;
}
public String getMessage() {
if (message == null) {
throw new NullPointerException("message can not be null!");
}
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
上面的例子打印：
{"count":1,"message":"ONE"}
{"count":"java.lang.IllegalStateException:Count is less than ZERO!","message":"MINUS"}
{"count":"java.lang.IllegalStateException:Count is less than ZERO!","message":"java.lang.NullPointerException:message can not be null!"}
添加回答
舉報
0/150
提交
取消