net.dongliu.apk.parser.utils.Buffers Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of apk-parser Show documentation

There is a newer version: 2.6.10

package net.dongliu.apk.parser.utils;

import java.nio.ByteBuffer;

/**
 * utils method for byte buffer
 *
 * @author Liu Dong [email protected]
 */
public class Buffers {

    /**
     * get one unsigned byte as short type
     */
    public static short readUByte(ByteBuffer buffer) {
        byte b = buffer.get();
        return (short) (b & 0xff);
    }

    /**
     * get one unsigned short as int type
     */
    public static int readUShort(ByteBuffer buffer) {
        short s = buffer.getShort();
        return s & 0xffff;
    }

    /**
     * get one unsigned int as long type
     */
    public static long readUInt(ByteBuffer buffer) {
        int i = buffer.getInt();
        return i & 0xffffffffL;
    }

    /**
     * get bytes
     */
    public static byte[] readBytes(ByteBuffer buffer, int size) {
        byte[] bytes = new byte[size];
        buffer.get(bytes);
        return bytes;
    }


    /**
     * read utf16 strings, use strLen, not ending 0 char.
     */
    public static String readString(ByteBuffer buffer, int strLen) {
        StringBuilder sb = new StringBuilder(strLen);
        for (int i = 0; i < strLen; i++) {
            sb.append(buffer.getChar());
        }
        return sb.toString();
    }

    /**
     * read utf16 strings, ending with 0 char.
     */
    public static String readZeroTerminatedString(ByteBuffer buffer, int strLen) {
        StringBuilder sb = new StringBuilder(strLen);
        for (int i = 0; i < strLen; i++) {
            char c = buffer.getChar();
            if (c == '\0') {
                skip(buffer, (strLen - i - 1) * 2);
                break;
            }
            sb.append(c);
        }
        return sb.toString();
    }

    /**
     * skip count bytes
     */
    public static void skip(ByteBuffer buffer, int count) {
        buffer.position(buffer.position() + count);
    }
}