[英]Java - Convert image to Base64
我在將gif圖像轉換為基本64字符串時遇到問題。
當我轉換它時,代碼加起來像100,000 AAAAAA,而圖像真的很小!
這是我的代碼:
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,它在一個文本文件out.txt
寫入了一堆帶有base 64代碼的java方法。
這是輸出的(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>
謝謝。
編輯:我正在使用此問題的base64代碼: https : //stackoverflow.com/a/4265472/1295422
byte[] byteArray = new byte[102400];
base64String = Base64.encode(byteArray);
無論您在陣列中實際使用多少數據,該代碼都將編碼102400個字節。
while ((bytesRead = fis.read(byteArray)) != -1)
你需要在某處使用bytesRead的值。
此外,這可能無法一次性將整個文件讀入數組(它只讀取I / O緩沖區中的數據),因此您的循環可能無法正常工作,您最終可能會在數組中找到半個圖像。
我在這里使用Apache Commons IOUtils:
Base64.encode(FileUtils.readFileToByteArray(file));
首先,這行代碼:
while ((bytesRead = fis.read(byteArray)) != -1)
相當於
while ((bytesRead = fis.read(byteArray, 0, byteArray.length)) != -1)
所以它從偏移量0寫入byteArray,而不是從之前寫入的位置寫入。
你需要這樣的東西:
int offset = 0;
int bytesRead = 0;
while ((bytesRead = fis.read(byteArray, offset, byteArray.length - offset) != -1) {
offset += bytesRead;
}
讀完之后的數據(字節)后,可以將其轉換為Base64。
但是存在更大的問題 - 你使用的是固定大小的數組,因此太大的文件將無法正確轉換,並且代碼也因為它而變得棘手。
我會拋棄字節數組並使用以下內容:
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
// commons-io IOUtils
IOUtils.copy(fis, buffer);
byte [] data = buffer.toByteArray();
Base64.encode(data);
或者像Thilo在FileUtils中那樣進一步壓縮它。
這條線
base64String = Base64.encode(byteArray);
將完整數組(102400字節)轉換為Base64,而不僅僅是您已讀取的字節數。 你需要傳遞它的字節數。
new String(byteArray, 0, bytesRead);
不修改數組。 您需要使用System.arrayCopy
將數組修剪為實際數據大小。 否則,您正在處理所有102400字節,其中大部分為零。
Late GraveDig ...只需將字節數組限制為文件大小即可。
FileInputStream fis = new FileInputStream( file );
byte[] byteArray= new byte[(int) file.length()];
您可以使用文件Object獲取文件的長度來初始化數組:
int length = Long.valueOf(file.length()).intValue();
byte[] byteArray = new byte[length];
您可以創建一個大型數組,然后使用System.arrayCopy將其復制到新數組
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將包含您想要的信息
我意識到這是一個古老的問題,但也許有人會發現我的代碼示例很有用。 此代碼在Base64中對文件進行編碼,然后對其進行解碼並將其保存在新位置。
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;
}
}
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