Question

有人可以告诉我将图像（最大200KB）转换为Base64字符串的代码吗？

我需要知道如何使用android，因为我必须添加上传图像的功能到我的主应用程序中的远程服务器，将它们作为字符串放入数据库的一行。

我在谷歌和StackOverflow中搜索，但我找不到简单的例子我还能找到一些例子，但他们并没有谈到转变为String。然后我需要转换为字符串以通过JSON上传到我的远程服务器。

Answer 1

您可以使用Base64 Android类：

String encodedImage = Base64.encodeToString(byteArrayImage, Base64.DEFAULT);

您必须将图像转换为字节数组。这是一个例子：

Bitmap bm = BitmapFactory.decodeFile("/path/to/image.jpg");
ByteArrayOutputStream baos = new ByteArrayOutputStream();  
bm.compress(Bitmap.CompressFormat.JPEG, 100, baos); //bm is the bitmap object   
byte[] b = baos.toByteArray();

*更新*

如果您使用较旧的SDK库（因为您希望它可以在具有较旧版本操作系统的手机上使用），您将无法打包Base64类（因为它刚刚出现在API级别8的版本中2.2）。

查看本文以获取解决方法：

http://androidcodemonkey.blogspot.com/2010/03/how-to-base64-encode-decode-android.html

Answer 2

您也可以通过简单Bitmap执行此操作，而不是使用InputStream。嗯，我不确定，但我认为它有点高效

InputStream inputStream = new FileInputStream(fileName);//You can get an inputStream using any IO API
byte[] bytes;
byte[] buffer = new byte[8192];
int bytesRead;
ByteArrayOutputStream output = new ByteArrayOutputStream();
try {
    while ((bytesRead = inputStream.read(buffer)) != -1) {
    output.write(buffer, 0, bytesRead);
}
} catch (IOException e) {
e.printStackTrace();
}
bytes = output.toByteArray();
String encodedString = Base64.encodeToString(bytes, Base64.DEFAULT);

Answer 3

如果您需要base64 over JSON，请查看Jackson：它明确支持二进制数据读/写为低级别（JsonParser，JsonGenerator）和数据绑定级别的base64。因此，您可以使用具有byte []属性的POJO，并自动处理编码/解码。而且非常有效，应该重要。

Answer 4

// put the image file path into this method
  public static String getFileToByte(String filePath){
      Bitmap bmp = null;
      ByteArrayOutputStream bos = null;
      byte[] bt = null;
      String encodeString = null;
       try{
        bmp = BitmapFactory.decodeFile(filePath);
        bos = new ByteArrayOutputStream();
        bmp.compress(Bitmap.CompressFormat.JPEG, 100, bos); 
        bt = bos.toByteArray();
        encodeString = Base64.encodeToString(bt, Base64.DEFAULT);
      }catch (Exception e){
        e.printStackTrace();
      }
      return encodeString;
}

Answer 5

此代码完成在我的项目中运行

profile_image.buildDrawingCache();
                Bitmap bmap = profile_image.getDrawingCache();
                String encodedImageData =getEncoded64ImageStringFromBitmap(bmap);


public String getEncoded64ImageStringFromBitmap(Bitmap bitmap) {
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress(CompressFormat.JPEG, 70, stream);
    byte[] byteFormat = stream.toByteArray();
    // get the base 64 string
    String imgString = Base64.encodeToString(byteFormat, Base64.NO_WRAP);

    return imgString;
}

Answer 6

如果您在 Android 上执行此操作，请从React Native codebase复制帮助：

import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import android.util.Base64;
import android.util.Base64OutputStream;
import android.util.Log;

// You probably don't want to do this with large files
// (will allocate a large string and can cause an OOM crash).
private String readFileAsBase64String(String path) {
  try {
    InputStream is = new FileInputStream(path);
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Base64OutputStream b64os = new Base64OutputStream(baos, Base64.DEFAULT);
    byte[] buffer = new byte[8192];
    int bytesRead;
    try {
      while ((bytesRead = is.read(buffer)) > -1) {
        b64os.write(buffer, 0, bytesRead);
      }
      return baos.toString();
    } catch (IOException e) {
      Log.e(TAG, "Cannot read file " + path, e);
      // Or throw if you prefer
      return "";
    } finally {
      closeQuietly(is);
      closeQuietly(b64os); // This also closes baos
    }
  } catch (FileNotFoundException e) {
    Log.e(TAG, "File not found " + path, e);
    // Or throw if you prefer
    return "";
  }
}

private static void closeQuietly(Closeable closeable) {
  try {
    closeable.close();
  } catch (IOException e) {
  }
}

Answer 7

Error: Could not find sdk.jar (com.appunfold:sdk:1.0.2).
Searched in the following locations:
http://dl.bintray.com/appunfold/android/com/appunfold/sdk/1.0.2/sdk-1.0.2.jar

Answer 8

以下是可能对您有用的伪代码：

public  String getBase64FromFile(String path)
      { 
         Bitmap bmp = null; 
         ByteArrayOutputStream baos = null;  
         byte[] baat = null;
         String encodeString = null;  
         try
          {   
            bmp = BitmapFactory.decodeFile(path);     
            baos = new ByteArrayOutputStream();                 
            bmp.compress(Bitmap.CompressFormat.JPEG, 100, baos);
            baat = baos.toByteArray(); 
            encodeString = Base64.encodeToString(baat, Base64.DEFAULT);
          }
          catch (Exception e)
          { 
           e.printStackTrace();  
          }  

        return encodeString;
     }

Answer 9

这是Kotlin中的编码和解码代码：

 fun encode(imageUri: Uri): String {
    val input = activity.getContentResolver().openInputStream(imageUri)
    val image = BitmapFactory.decodeStream(input , null, null)
    //encode image to base64 string
    val baos = ByteArrayOutputStream()
    image.compress(Bitmap.CompressFormat.JPEG, 100, baos)
    var imageBytes = baos.toByteArray()
    val imageString = Base64.encodeToString(imageBytes, Base64.DEFAULT)
    return imageString
}

fun decode(imageString: String) {

    //decode base64 string to image
    val imageBytes = Base64.decode(imageString, Base64.DEFAULT)
    val decodedImage = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.size)

    imageview.setImageBitmap(decodedImage)
}

Answer 10

在android中将图像转换为base64字符串

ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.yourimage); 
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos); 
byte[] imageBytes = baos.toByteArray(); 
String imageString = Base64.encodeToString(imageBytes, Base64.DEFAULT);

Answer 11

对于那些寻求将图像文件转换为Base64字符串而不进行压缩或先将其转换为位图的有效方法的人，可以改而encode the file as base64

val base64EncodedImage = FileInputStream(imageItem.localSrc).use {inputStream - >
    ByteArrayOutputStream().use {outputStream - >
            Base64OutputStream(outputStream, Base64.DEFAULT).use {
                base64FilterStream - >
                    inputStream.copyTo(base64FilterStream)
                base64FilterStream.flush()
                outputStream.toString()
            }
      }
}

希望这会有所帮助！

Answer 12

这是image encode和dcode的代码在xml文件中

 <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="yyuyuyuuyuyuyu"
        android:id="@+id/tv5"
        />

在java文件中

TextView textView5;
Bitmap bitmap;

textView5=(TextView) findViewById(R.id.tv5);

  bitmap= BitmapFactory.decodeResource(getResources(),R.drawable.logo);
        new AsyncTask<Void, Void, String>() {
            @Override
            protected String doInBackground(Void... voids) {
                ByteArrayOutputStream stream = new ByteArrayOutputStream();
                bitmap.compress(Bitmap.CompressFormat.JPEG, 70, stream);
                byte[] byteFormat = stream.toByteArray();
                // get the base 64 string
                String imgString = Base64.encodeToString(byteFormat, Base64.NO_WRAP);

                return imgString;
            }

            @Override
            protected void onPostExecute(String s) {
               textView5.setText(s);
            }
        }.execute();

Answer 13

我做一个静态函数。我认为它更有效。

public static String file2Base64(String filePath) {
        FileInputStream fis = null;
        String base64String = "";
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            fis = new FileInputStream(filePath);
            byte[] buffer = new byte[1024 * 100];
            int count = 0;
            while ((count = fis.read(buffer)) != -1) {
                bos.write(buffer, 0, count);
            }
            fis.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        base64String = Base64.encodeToString(bos.toByteArray(), Base64.DEFAULT);
        return base64String;

    }

简单又容易！

Answer 14

Kotlin 版本：

fun File.toBase64(): String? {
 val result: String?
 inputStream().use { inputStream ->
    val sourceBytes = inputStream.readBytes()
    result = Base64.encodeToString(sourceBytes, Base64.DEFAULT)
 }

 return result
}

Answer 15

使用此代码：

byte[ ] decodedString = Base64.decode(Base64String.getBytes(), Base64.DEFAULT);

Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);

如何将图像转换为Base64字符串？

15 个答案: