如何在Base64中正确编码和解码字符串？

Question

我想在Base64中编码一个字符串，以便以后解码它。我编码它这样做：

public static String encryptString(String string) {     
    byte[] bytesEncoded = Base64.getEncoder().encode(string.getBytes());
    return (new String(bytesEncoded));
}

然后，使用UTF-8将编码的字符串存储在磁盘上。重新启动应用程序后，编码的字符串从磁盘重新加载，我正在尝试使用以下方法解码字符串：

public static String decryptString(String string) {
    byte[] valueDecoded = Base64.getDecoder().decode(string);
    return (new String(valueDecoded));
}

出了点问题，因为它给了我这个例外：

java.lang.IllegalArgumentException: Illegal base64 character d
at java.base/java.util.Base64$Decoder.decode0(Base64.java:743)
at java.base/java.util.Base64$Decoder.decode(Base64.java:535)
at java.base/java.util.Base64$Decoder.decode(Base64.java:558)

这是一步一步的追踪

1º我编码：{"configuration":{"shop":{"name":"","addressLine1":"","addressLine2":"","postalCode":"","city":"","country":"","phoneNumber":""}},"jointBets":[],"groups":[{"name":"Test","members":[]}]}

进入：eyJjb25maWd1cmF0aW9uIjp7InNob3AiOnsibmFtZSI6IiIsImFkZHJlc3NMaW5lMSI6IiIsImFkZHJlc3NMaW5lMiI6IiIsInBvc3RhbENvZGUiOiIiLCJjaXR5IjoiIiwiY291bnRyeSI6IiIsInBob25lTnVtYmVyIjoiIn19LCJqb2ludEJldHMiOltdLCJncm91cHMiOlt7Im5hbWUiOiJUZXN0IiwibWVtYmVycyI6W119XX0=

2º我将它存储在utf8的磁盘上

3º我从磁盘上检索它，它是这个字符串：

eyJjb25maWd1cmF0aW9uIjp7InNob3AiOnsibmFtZSI6IiIsImFkZHJlc3NMaW5lMSI6IiIsImFkZHJlc3NMaW5lMiI6IiIsInBvc3RhbENvZGUiOiIiLCJjaXR5IjoiIiwiY291bnRyeSI6IiIsInBob25lTnVtYmVyIjoiIn19LCJqb2ludEJldHMiOltdLCJncm91cHMiOlt7Im5hbWUiOiJUZXN0IiwibWVtYmVycyI6W119XX0=

4º我解码它并得到例外。

Answer 1

我的猜测是你没有指定一个字符集。尝试运行以下可能有和没有为String构造函数指定的字符集来验证。

   @Test
    public void base64Test() throws Exception{
        String string = "ABCDF";

        byte[] bytesEncoded = Base64.getEncoder().encode(string.getBytes());
        String encodedStr = (new String(bytesEncoded,Charset.forName("ISO-8859-1")));
        System.out.println(encodedStr);

        byte[] valueDecoded = Base64.getDecoder().decode(encodedStr);
        String decodedStr = (new String(valueDecoded,Charset.forName("ISO-8859-1")));
        System.out.println(decodedStr);
    }

Answer 2

然后，使用UTF-8将编码的字符串存储在磁盘上。重新启动应用程序后，编码的字符串从磁盘重新加载，我正在尝试使用以下方法解码字符串：

这似乎是一个失败点。很可能你的问题是OS / JDK依赖显然下面的代码似乎对我有用（Win 7，最新的JDK 1.8）：

public static void main(String[] args) throws IOException {
    String source = "{\"configuration\":{\"shop\":{\"name\":\"España\",\"addressLine1\":\"\",\"addressLine2\":\"\"," +
                "\"postalCode\":\"\",\"city\":\"\",\"country\":\"\",\"phoneNumber\":\"\"}},\"jointBets\":[]," +
                "\"groups\":[{\"name\":\"Test\",\"members\":[]}]}";

    // Encode string
    String encoded = encryptString(source);

    System.out.println("Base64 encoded: " + encoded);

    // Temp Dir
    String tempDir = System.getProperty("java.io.tmpdir");

    // Write to File
    try (BufferedWriter writer = new BufferedWriter(new FileWriter(tempDir + "data.txt"))) {
        writer.write(encoded);
    }

    // Read from File
    Path path = Paths.get(tempDir + "data.txt");

    Stream<String> lines = Files.lines(path);
    String dataFromFile = lines.collect(Collectors.joining("\n"));
    lines.close();

    // Compare content
    assert encoded.equals(dataFromFile);

    // Decode string
    String decoded = decryptString(dataFromFile);
    System.out.println("Base64 decoded: " + decoded);
}

public static String encryptString(String string) {
    byte[] bytesEncoded = Base64.getEncoder().encode(string.getBytes(StandardCharsets.UTF_8));
    return new String(bytesEncoded);
}

public static String decryptString(String string) {
    byte[] valueDecoded = Base64.getDecoder().decode(string);
    return new String(valueDecoded);
}

Base64编码：eyJjb25maWd1cmF0aW9uIjp7InNob3AiOnsibmFtZSI6IkVzcGHDsWEiLCJhZGRyZXNzTGluZTEiOiIiLCJhZGRyZXNzTGluZTIiOiIiLCJwb3N0YWxDb2RlIjoiIiwiY2l0eSI6IiIsImNvdW50cnkiOiIiLCJwaG9uZU51bWJlciI6IiJ9fSwiam9pbnRCZXRzIjpbXSwiZ3JvdXBzIjpbeyJuYW1lIjoiVGVzdCIsIm1lbWJlcnMiOltdfV19

Base64已解码：{“configuration”：{“shop”：{“name”：“España”，“addressLine1”：“”，“addressLine2”：“”，“postalCode”：“”，“city”：“”， “国家”： “”， “phoneNumber的”： “”}}， “jointBets”：[]， “基团”：[{ “名称”： “测试”， “成员”：[]}]}

Answer 3

旧的Base64实用程序添加行在Java 8中每76个字符中断。结果如下所示：

/9j/4AAQSkZJRgABAgAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0a
HBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIy
MjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCABkAGQDASIA
AhEBAxEB/8QAHwAAAQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQA
AAF9AQIDAAQRBRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3
ODk6Q0RFRkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWm
...

似乎这种行为随着某些版本而改变。至少在Java11中，解码器不再接受换行符。为了避免这个问题，你可以改变你的方法

public static String decryptString(String string) {
    byte[] valueDecoded = Base64.getDecoder().decode(string.replace("\n","").replace("\r","");
    return new String(valueDecoded);
}