[英]Java - Convert image to Base64
我在将gif图像转换为基本64字符串时遇到问题。
当我转换它时,代码加起来像100,000 AAAAAA,而图像真的很小!
这是我的代码:
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.util.ArrayList;
public class Main
{
public static void main(String[] args)
{
try
{
FileWriter fstream = new FileWriter("./out.txt");
BufferedWriter out = new BufferedWriter(fstream);
File folder = new File("./flags/");
File[] listOfFiles = folder.listFiles();
for (int i = 0; i < listOfFiles.length; i++)
{
if (listOfFiles[i].isFile())
{
Main.readFile(out, listOfFiles[i]);
}
}
out.close();
System.out.println("Done");
}
catch (Exception e) {}
}
public static void readFile(BufferedWriter out, File file)
{
try
{
byte[] byteArray = new byte[102400];
FileInputStream fis = new FileInputStream(file);
String base64String;
int bytesRead = 0;
while ((bytesRead = fis.read(byteArray)) != -1)
{
new String(byteArray, 0, bytesRead);
base64String = Base64.encode(byteArray);
out.write("public static ImageIcon getFlag" + file.getName() + "()");
out.newLine();
out.write("{");
out.newLine();
ArrayList<String> array = Main.cut(base64String);
out.write("return Utils.toImage(\"" + array.get(0) + "\"");
for (int i=1; i<array.size()-1; i++)
{
out.write("<tab>+\"" + array.get(i) + "\"");
}
out.write("<tab>\"" + array.get(array.size() - 1) + "\");");
out.newLine();
out.write("}");
out.newLine();
out.newLine();
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
public static ArrayList<String> cut(String in)
{
ArrayList<String> array = new ArrayList<String>();
while (in.length() > 76)
{
array.add( in.substring(0, 77) );
in = in.substring(77);
}
return array;
}
}
Basicaly,它在一个文本文件out.txt
写入了一堆带有base 64代码的java方法。
这是输出的(小)部分:
return Utils.toImage("R0lGODlhEAALANUAANPTAPZva/n5AfLySPz8iYqY3O01NgoksbGZa+kYGOskJKi05vb2XZ+r4+05O"<tab>+"Pv7eO3tKPv7bZak4dSvebC76tC2iPNISPX1UMkAAMm6U/NWTeYAAF5y1LqlevNaWpSh3e7uQ+1CQt"<tab>+"gAAKOv5Vds1C1IvpGf37a/7OnTYZ6q6NGkamd71/LyPusvLvFiTEFbx9rPb/HuaczATd7eAPAAAH2"<tab>+"N2vE+PMqiYuXQUsKufJqn4jlRxUlhy+CpelFnz/PxbyH5BAAAAAAALAAAAAAQAAsAAAaQwBVnSBIY"<tab>+"jzTaZsk5OSmEKOHxCAQ8nk1zMUo9Ir8Y42Kx2Dyi5qihi1QqkxzZZtCISBS2JNILoFQDdC0WIj4UO"<tab>+"hImDBMoLjcsBi0KISI8C4kFMB0uOAgykgkOGC8LJgUFFx0IqxAKCQkGGDsjpzUDLBkZEBCvCS0YJW"<tab>+"wfBQxjAyAgDpG/OwfOBzPRANMY1dVBADsAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>+"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"<tab>
谢谢。
编辑:我正在使用此问题的base64代码: https : //stackoverflow.com/a/4265472/1295422
byte[] byteArray = new byte[102400];
base64String = Base64.encode(byteArray);
无论您在阵列中实际使用多少数据,该代码都将编码102400个字节。
while ((bytesRead = fis.read(byteArray)) != -1)
你需要在某处使用bytesRead的值。
此外,这可能无法一次性将整个文件读入数组(它只读取I / O缓冲区中的数据),因此您的循环可能无法正常工作,您最终可能会在数组中找到半个图像。
我在这里使用Apache Commons IOUtils:
Base64.encode(FileUtils.readFileToByteArray(file));
首先,这行代码:
while ((bytesRead = fis.read(byteArray)) != -1)
相当于
while ((bytesRead = fis.read(byteArray, 0, byteArray.length)) != -1)
所以它从偏移量0写入byteArray,而不是从之前写入的位置写入。
你需要这样的东西:
int offset = 0;
int bytesRead = 0;
while ((bytesRead = fis.read(byteArray, offset, byteArray.length - offset) != -1) {
offset += bytesRead;
}
读完之后的数据(字节)后,可以将其转换为Base64。
但是存在更大的问题 - 你使用的是固定大小的数组,因此太大的文件将无法正确转换,并且代码也因为它而变得棘手。
我会抛弃字节数组并使用以下内容:
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
// commons-io IOUtils
IOUtils.copy(fis, buffer);
byte [] data = buffer.toByteArray();
Base64.encode(data);
或者像Thilo在FileUtils中那样进一步压缩它。
这条线
base64String = Base64.encode(byteArray);
将完整数组(102400字节)转换为Base64,而不仅仅是您已读取的字节数。 你需要传递它的字节数。
new String(byteArray, 0, bytesRead);
不修改数组。 您需要使用System.arrayCopy
将数组修剪为实际数据大小。 否则,您正在处理所有102400字节,其中大部分为零。
Late GraveDig ...只需将字节数组限制为文件大小即可。
FileInputStream fis = new FileInputStream( file );
byte[] byteArray= new byte[(int) file.length()];
您可以使用文件Object获取文件的长度来初始化数组:
int length = Long.valueOf(file.length()).intValue();
byte[] byteArray = new byte[length];
您可以创建一个大型数组,然后使用System.arrayCopy将其复制到新数组
int contentLength = 100000000;
byte[] byteArray = new byte[contentLength];
BufferedInputStream inputStream = new BufferedInputStream(connection.getInputStream());
while ((bytesRead = inputStream.read()) != -1)
{
byteArray[count++] = (byte)bytesRead;
}
byte[] destArray = new byte[count];
System.arraycopy(byteArray, 0, destArray , 0, count);
destArray将包含您想要的信息
我意识到这是一个古老的问题,但也许有人会发现我的代码示例很有用。 此代码在Base64中对文件进行编码,然后对其进行解码并将其保存在新位置。
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import org.apache.commons.codec.binary.Base64;
public class Base64Example {
public static void main(String[] args) {
Base64Example tempObject = new Base64Example();
// convert file to regular byte array
byte[] codedFile = tempObject.convertFileToByteArray("your_input_file_path");
// encoded file in Base64
byte[] encodedFile = Base64.encodeBase64(codedFile);
// print out the byte array
System.out.println(Arrays.toString(encodedFile));
// print the encoded String
System.out.println(encodedFile);
// decode file back to regular byte array
byte[] decodedByteArray = Base64.decodeBase64(encodedFile);
// save decoded byte array to a file
boolean success = tempObject.saveFileFromByteArray("your_output_file_path", decodedByteArray);
// print out success
System.out.println("success : " + success);
}
public byte[] convertFileToByteArray(String filePath) {
Path path = Paths.get(filePath);
byte[] codedFile = null;
try {
codedFile = Files.readAllBytes(path);
} catch (IOException e) {
e.printStackTrace();
}
return codedFile;
}
public boolean saveFileFromByteArray(String filePath, byte[] decodedByteArray) {
boolean success = false;
Path path = Paths.get(filePath);
try {
Files.write(path, decodedByteArray);
success = true;
} catch (Exception e) {
e.printStackTrace();
}
return success;
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.