JAVA-CPP-STRUCT-BYTE

abstract class  StructMessage {
    public void fromBytes(byte[] b) throws IllegalAccessException {
        ByteBuffer bb = ByteBuffer.wrap(b);
        for (Field field : this.getClass().getDeclaredFields()) {
            field.setAccessible(true);
            Class t = field.getType();
            int size = 0;
            if(t == String.class && field.getName().toLowerCase().equals("name")) {
                size = 10;
            } else if(
                    t == Integer.class||
                            t == Long.class ||
                            t == Double.class ||
                            t == Float.class ||
                            t == Short.class ||
                            t == Byte.class
            ) {
                try {
                    size = (int) t.getField("BYTES").get(null);
                } catch (NoSuchFieldException e) {
                    e.printStackTrace();
                }
            }

            if(size == 0) {
                continue;
            }

            byte[] h = new byte[size];
            bb.get(h, 0, h.length);

            final ByteBuffer bc = ByteBuffer.wrap(h);

            if (t == Integer.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, bc.getInt());
            } else if (t == Long.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, bc.getLong());
            } else if (t == Double.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, bc.getDouble());
            } else if (t == Float.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, bc.getFloat());
            } else if (t == Short.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, bc.getShort());
            } else if (t == Byte.class) {
                bc.order(ByteOrder.LITTLE_ENDIAN);
                field.set(this, h[0]);
            } else if (t == String.class) {
                boolean vEnd = false;
                int c = 0;
                for (int i = 0; i < h.length; i++) {
                    if (h[i] == 0) {
                        vEnd = true;
                    }
                    if(h[i] != 0 && !vEnd){
                        c++;
                    }
                }
                byte[] slice = Arrays.copyOfRange(h, 0, c);
                field.set(this, new String(slice));
            }
        }
    }
    abstract  void valid() throws IllegalArgumentException;
}

class StructMessageDetail extends MT5EventsMessage {
    public Integer header;
    public Integer sid;
    public Long time;
    public Integer size;
    public String name;
   

    @Override
    public String toString() {
        return "StructMessageDetail {" +
                "header=" + header +
                ", sid=" + sid +
                ", time=" + time +
                ", size=" + size +
                ", name='" + name + '\'';
               
    }

    @Override
    void valid() {
        if(header==null || header != xxxxx){
            throw new IllegalArgumentException("Invalid packet for header");
        }
    }
}

cpp，java通过tcp 传输结构体转换成java 的类

transfer struct to java from cpp, convert byte array to java Object