Java 将文件编码为 Base64 字符串以匹配其他编码字符串
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/37066216/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Java Encode file to Base64 string To match with other encoded string
提问by Sanket Sawant
private static String encodeFileToBase64Binary(String fileName)
throws IOException {
File file = new File(fileName);
byte[] bytes = loadFile(file);
byte[] encoded = Base64.encodeBase64(bytes);
String encodedString = new String(encoded,StandardCharsets.US_ASCII);
return encodedString;
}
private static byte[] loadFile(File file) throws IOException {
InputStream is = new FileInputStream(file);
long length = file.length();
if (length > Integer.MAX_VALUE) {
// File is too large
}
byte[] bytes = new byte[(int)length];
int offset = 0;
int numRead = 0;
while (offset < bytes.length
&& (numRead=is.read(bytes, offset, bytes.length-offset)) >= 0) {
offset += numRead;
}
if (offset < bytes.length) {
throw new IOException("Could not completely read file "+file.getName());
}
is.close();
return bytes;
}
// to get encode string
// 获取编码字符串
String encoded=encodeFileToBase64Binary("file.fmr");
// encoded string is :
// 编码的字符串是：
Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkDZADP/SEC8AD6CSECqAEcGSED+AFJtO0CgAGCKZEC6AGuFZEDgAHz1ZECzAI6HZEENAJluNEBWAJ4ZZEB1AKkTZEECALbuZEA/ALqfSECCALySSECxAMP/ZECIAMURVUAXAN2jGkCnAOD8ZEAoAOWlZEBnAOyhLkCyAP/tZECHAQMSGkD8AQTdZECfASKFGkCHASUaGkA1ASy6ZEDAAS3JZEDPAS7NZEAnATG4ZEDxATzOZEBOAUPLZEBzAVbuGkCAAWF8NEDTAWsxLkDnAXa0LkC/AX2nLkC0AYojIEBMAYvkSEDJAa0fT0CsAbwVIIDqANTsZIDIAPfnZICbAQKHO4D5AR/XZIBlASS7IIEoASbYO4CsAUetLoDvAVXSZIDaAVvDO4EHAWrLZICsAX2fNIDnAYEwNIDQAZKnT4BfAZxtZAAA
//encoded string from file using some other source.
//使用其他来源从文件中编码的字符串。
Rk1SACAyMAAAAAFiAAABQAHgAMUAxQEAAABGNkCLACELSEDAADYDZEEYAGFxO0DGAGJ9SEC1AGkCSEA6AHWYVUDJAHp5ZEBEAHwVZECVAJgIZEEaALHrZEB4ALuOZEELAMFqZEEzAM/sNEDRANvwZEBkAN0VZECcAOIAZEEwAOjnLkEvAPXlO0CnAP71ZEB7AQYRNEBdAQ0eZED8ARDhZEDXASXcZECZAS3uGkBoAT4eO0AUAUMxSEA7AUYqZEDxAUnSZECmAVNDO0EIAXDHSEDYAXW7ZEEUAXXKSEEGAYY8IEEhAYrDNEDfAZ81ZEDQAcGqLoEBAC/7O4EGAE7zVYB+AP2QSICEARuLZIBnATUfO4D/ATXaZIDEATjSZIDRATrVZICnATvSNIBTATwnZIARAV1LGoB1AV2oO4CrAV68SIDnAWHGZIB+AWauNICVAX0ySICNAYytO4CJAZorSAAA
When i am trying to match both the encoded string , i am getting a missmatch.
please suggest method for encode file to base64 to match encoded string found from other source.
i have tried with StandardCharsets.UTF_8and StandardCharsets.US_ASCII.
当我试图匹配两个编码字符串时，我得到了一个不匹配。请建议将文件编码为 base64 以匹配从其他来源找到的编码字符串的方法。我试过StandardCharsets.UTF_8和StandardCharsets.US_ASCII。
回答by gfelisberto
You already using apache commons-codec so I recommend adding commons-io for reading the file. That way you can remove your loadFile() method and just have:
您已经在使用 apache commons-codec，所以我建议添加 commons-io 来读取文件。这样你就可以删除你的 loadFile() 方法，只需要：
private static String encodeFileToBase64Binary(String fileName) throws IOException {
File file = new File(fileName);
byte[] encoded = Base64.encodeBase64(FileUtils.readFileToByteArray(file));
return new String(encoded, StandardCharsets.US_ASCII);
}
回答by the hand of NOD
Since Java 8 you can use the class java.util.Base64and the corresponding inner classes:
从 Java 8 开始，您可以使用该类java.util.Base64和相应的内部类：
java.util.Base64.Encoderjava.util.Base64.Decoder
java.util.Base64.Encoderjava.util.Base64.Decoder
See JavaDoc: Base64-Doc
请参阅 JavaDoc：Base64-Doc
And a sample for the use: Example from Oracle
以及一个使用示例：来自 Oracle 的示例
回答by Big D.
This example worked great for me: https://grokonez.com/java/java-advanced/java-8-encode-decode-an-image-base64
这个例子对我很有用：https: //grokonez.com/java/java-advanced/java-8-encode-decode-an-image-base64
public static String encoder(String filePath) {
String base64File = "";
File file = new File(filePath);
try (FileInputStream imageInFile = new FileInputStream(file)) {
// Reading a file from file system
byte fileData[] = new byte[(int) file.length()];
imageInFile.read(fileData);
base64File = Base64.getEncoder().encodeToString(fileData);
} catch (FileNotFoundException e) {
System.out.println("File not found" + e);
} catch (IOException ioe) {
System.out.println("Exception while reading the file " + ioe);
}
return base64File;
}
回答by Patrick Favre
Here is a solution without any required dependencies (Apacha et al.) requiring only JDK 8+:
这是一个不需要任何依赖项（Apacha 等）的解决方案，只需要 JDK 8+：
import java.util.Base64;
import java.nio.file.Files;
private static String encodeFileToBase64(File file) {
try {
byte[] fileContent = Files.readAllBytes(file.toPath());
return Base64.getEncoder().encodeToString(fileContent);
} catch (IOException e) {
throw new IllegalStateException("could not read file " + file, e);
}
}
