假设我有一颗 bean :
public class Msg {
private int code;
private Object data;
... Getter/setters...
}
我用这种测试代码将其转换为 JSON 或 XML:
public String convert() {
Msg msg = new Msg();
msg.setCode( 42 );
msg.setData( "Are you suggesting coconuts migrate?" );
ObjectMapper mapper = new ObjectMapper();
return mapper.writeValueAsString( msg );
}
输出将是这样的:
{"code":42,"data":"Are you suggesting coconuts migrate?"}
现在假设我想用一些动态名称替换“data”属性:
public String convert(String name) {
Msg msg = new Msg();
msg.setCode( 42 );
msg.setData( "Are you suggesting coconuts migrate?" );
ObjectMapper mapper = new ObjectMapper();
// ...DO SOMETHING WITH MAPPER ...
return mapper.writeValueAsString( msg );
}
如果我调用函数convert(“toto”),我会希望得到以下输出:
{"code":42,"toto":"Are you suggesting coconuts migrate?"}
如果我调用函数 convert( "groovy") 我希望得到以下输出:
{"code":42,"groovy":"Are you suggesting coconuts migrate?"}
当然,我可以在创建 JSON 后进行字符串替换,但如果您有通过编程方法得到的答案,我会接受。
谢谢
最佳答案
您可以使用PropertyNamingStrategy
类来覆盖类属性。查看该类的简单实现:
class ReplaceNamingStrategy extends PropertyNamingStrategy {
private static final long serialVersionUID = 1L;
private Map<String, String> replaceMap;
public ReplaceNamingStrategy(Map<String, String> replaceMap) {
this.replaceMap = replaceMap;
}
@Override
public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) {
if (replaceMap.containsKey(defaultName)) {
return replaceMap.get(defaultName);
}
return super.nameForGetterMethod(config, method, defaultName);
}
}
示例程序可能如下所示:
import java.io.IOException;
import java.util.Collections;
import java.util.Map;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
public class JacksonProgram {
public static void main(String[] args) throws IOException {
Msg msg = new Msg();
msg.setCode(42);
msg.setData("Are you suggesting coconuts migrate?");
System.out.println(convert(msg, "test"));
System.out.println(convert(msg, "toto"));
System.out.println(convert(msg, "groovy"));
}
public static String convert(Msg msg, String name) throws IOException {
ObjectMapper mapper = new ObjectMapper();
mapper.setPropertyNamingStrategy(new ReplaceNamingStrategy(Collections.singletonMap("data", name)));
return mapper.writeValueAsString(msg);
}
}
以上程序打印:
{"code":42,"test":"Are you suggesting coconuts migrate?"}
{"code":42,"toto":"Are you suggesting coconuts migrate?"}
{"code":42,"groovy":"Are you suggesting coconuts migrate?"}
关于java - Jackson - 在运行时修改属性而无需注释,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60515820/