转换流

转换流提供了在字节流和字符流之间的转换

Java API提供了两个转换流：

• InputStreamReader：将InputStream转换为Reader
• OutputStreamWriter：将Writer转换为OutputStream

常见的应用场景有：

• 文件字符编码的转码
• 读取指定编码的文本文件

// 读取gdk编码的文本文件，使用utf-8读取
public static void readFromGBK (File file) throws IOException {
    FileInputStream fis = null;
    InputStreamReader isr = null;

    try {
        fis = new FileInputStream(file);
        isr = new InputStreamReader(fis, "GBK");

        int len;
        char[] chars = new char[1024];
        while ((len = isr.read(chars)) > -1) {
            String str = new String(chars, 0, len);
            System.out.println(str);
        }
    } catch (IOException e) {
        throw e;
    } finally {
        if (isr != null) {
            isr.close();
        }
    }
}

// 修改文件编码，将utf-8文件修改为gbk编码文件
try (
    InputStreamReader isr  = new InputStreamReader(new FileInputStream("dir/1.txt"), "utf-8");
    OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("dir/1_gbk.txt"), "gbk")
)
{
    char[] chars = new char[1024];
    int len;

    while ((len = isr.read(chars)) > -1) {
        osw.write(chars, 0, len);
    }
} catch (IOException e) {
    e.printStackTrace();
}