java中構(gòu)造字節(jié)流的一種實(shí)現(xiàn)

HtmlCssJs 發(fā)布于2019-08-15 15:13 / 1386人閱讀

摘要：中構(gòu)造字節(jié)流的一種實(shí)現(xiàn)專門創(chuàng)建一個類來保存指定數(shù)提示數(shù)據(jù)超了設(shè)置一個值到第一位將列表中的數(shù)據(jù)合并成一個數(shù)據(jù)

import java.util.ArrayList;
import java.util.List;

/**
 * Created by kaven on 2018/4/2.
 */
public class TestBytes {

    /**
     * 專門創(chuàng)建一個類來保存指定byte數(shù)
     */
    public class MyByte {
        byte[] data;

        MyByte(int n) {
            data = new byte[n];
        }

        void setData(String s) {
            byte[] tmp = s.getBytes();

            // 提示數(shù)據(jù)超了
            if (tmp.length > data.length) {
                System.err.print("too many data");
            }

            for (int i = 0; i < this.data.length && i < tmp.length; i++) {
                data[i] = tmp[i];
            }
        }

        // 設(shè)置一個值到第一位
        void setData(int i) {
            data[0] = (byte) i;
        }

        byte[] getByte() {
            return data;
        }

        int size() {
            return data.length;
        }
    }


    void login() {

        MyByte msgType = new MyByte(1);
        MyByte userId = new MyByte(16);
        MyByte msg = new MyByte(12);

        msgType.setData(1);
        userId.setData("1");
        msg.setData("222");

        List list = new ArrayList();
        list.add(msgType);
        list.add(userId);
        list.add(msg);

        byte[] res = join(list);
        System.out.print(res.toString());
    }

    /**
     * 將列表中的數(shù)據(jù)合并成一個數(shù)據(jù)
     * @param list
     * @return
     */
    private byte[] join(List list) {
        int count = 0;
        for (int i = 0; i < list.size(); i++) {
            count += list.get(i).size();
        }
        byte[] res = new byte[count];

        int start = 0;
        for (int i = 0; i < list.size(); i++) {
            byte[] tmp = list.get(i).getByte();
            for (int j = 0; j < tmp.length; j++) {
                res[start] = tmp[j];
                start += 1;
            }
        }
        return res;
    }

    public static void main(String args[]) {
        TestBytes a = new TestBytes();
        a.login();
    }

}