将逗号分隔的键=值对转换为Java对象

Question

I'm trying to implement a HttpMessageConverter which would allow my program to talk over REST to an embedded smart controller.

The controller responds with strings such as:

ret=OK,htemp=27.0,hhum=-,otemp=27.0,err=0,cmpfreq=24

I have a Java object called SensorInfo.

public class SensorInfo {

   String ret;
   Double htemp;
   String hhum;
   Double otemp;
   Integer err;
   Integer cmpfreq;

   // getters and setters

}

What's the best way of mapping the controller response to the above Java object?

Answer 1

You can simply split the string and assign each element as needed. You have:

ret=OK,htemp=27.0,hhum=-,otemp=27.0,err=0,cmpfreq=24

Lets assume you have that stored in a variable called myStr . Then all you need to do is this:

String[] strSplit = myStr.split(" ");
SensorInfo info = new SensorInfo();
info.ret = afterEquals(strSplit[0]);
info.htemp = Double.parse(afterEquals(strsplit[1]));
info.hhum = afterEquals(strSplit[2]);
info.otemp= Double.parse(afterEquals(strSplit[3]));
info.err = Integer.parse(afterEquals(strSplit[4]));
info.cmpfreq = Integer.parse(afterEquals(strSplit[5]));

You will declare a method to extract the part of the response after the equals sign to make the above work:

private String afterEquals(String input) {
  input.substring(input.indexOf('=') + 1);
}

Note that this assumes the order of your response is fixed. If it isn't, you can easily modify this to look at each argument to see which variable to assign it to.

Answer 2

You should add error handling, as the following is not really error prone, but might help you:

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class ValueAssigner {
    // ret=OK,htemp=27.0,hhum=-,otemp=27.0,err=0,cmpfreq=24
    String ret;
    Double htemp;
    String hhum;
    Double otemp;
    Integer err;
    Integer cmpfreq;

    public static void main(String[] a) {
        System.out.println(new ValueAssigner("ret=OK,htemp=27.0,hhum=-,otemp=27.0,err=0,cmpfreq=24").getCmpfreq());
    }

    ValueAssigner(String in) {
        String[] split = in.split(",");
        for (String s : split) {
            Method method;
            String[] keyValue = s.split("=");
            try {
                method = this.getClass().getMethod("set" + ucFirst(keyValue[0]), String.class);
                method.invoke(this, keyValue[1]);
            } catch (IllegalArgumentException | InvocationTargetException | IllegalAccessException | SecurityException | NoSuchMethodException e) {
                // e.printStackTrace();
                // omitted here
            }

        }
    }

    private static String ucFirst(String in) {
        return in.substring(0, 1).toUpperCase() + in.substring(1);
    }


    public String getRet() {
        return ret;
    }

    public void setRet(String ret) {
        this.ret = ret;
    }

    public Double getHtemp() {
        return htemp;
    }

    public void setHtemp(String htemp) {
        this.htemp = Double.parse(htemp);
    }

    public String getHhum() {
        return hhum;
    }

    public void setHhum(String hhum) {
        this.hhum = hhum;
    }

    public Double getOtemp() {
        return otemp;
    }

    public void setOtemp(String otemp) {
        this.otemp = Double.parse(otemp);
    }

    public Integer getErr() {
        return err;
    }

    public void setErr(String err) {
        this.err = Integer.parse(err);
    }

    public Integer getCmpfreq() {
        return cmpfreq;
    }

    public void setCmpfreq(String cmpfreq) {
        this.cmpfreq = Integer.parse(cmpfreq);
    }
}