声明：本系列只供本人自学使用，勿喷。

当你需要从输入流中读取基本数据类型，或者往输出流中写入基本数据类型，就需要用DataInputStream或DataOutputStream来装饰流。

一、DataInputStream

public class DataInputStream extends FilterInputStream implements DataInput{
    public DataInputStream(InputStream in) {
        super(in);
    }
}

• 核心方法【DataInput接口的方法】

读取某类型，就连续read() n次（n=该类型占用字节数）

    public final char readChar() throws IOException {
        int ch1 = in.read();
        int ch2 = in.read();
        if ((ch1 | ch2) < 0)
            throw new EOFException();
        return (char)((ch1 << 8) + (ch2 << 0));
    }

    public final int readInt() throws IOException {
        int ch1 = in.read();
        int ch2 = in.read();
        int ch3 = in.read();
        int ch4 = in.read();
        if ((ch1 | ch2 | ch3 | ch4) < 0)
            throw new EOFException();
        return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
    }

二、DataInputStream

public class DataOutputStream extends FilterOutputStream implements DataOutput {
    public DataOutputStream(OutputStream out) {
        super(out);
    }
}

• 核心方法【DataOutput接口的方法】

写入某类型，就连续write() n次（n=该类型占用字节数）

    public final void writeChar(int v) throws IOException {
        out.write((v >>> 8) & 0xFF);
        out.write((v >>> 0) & 0xFF);
        incCount(2);
    }

    public final void writeInt(int v) throws IOException {
        out.write((v >>> 24) & 0xFF);
        out.write((v >>> 16) & 0xFF);
        out.write((v >>>  8) & 0xFF);
        out.write((v >>>  0) & 0xFF);
        incCount(4);
    }