java 读取图片并转化为二进制字符串

本例子的目的在于测试往oracle数据库中插入blob字段

//以下代码源于：https://www.cnblogs.com/ywlx/p/4544179.html

public static String getImgStr(String imgFile){
      //将图片文件转化为字节数组字符串，并对其进行Base64编码处理

      
      InputStream in = null;
      byte[] data = null;
      //读取图片字节数组
      try
      {
          in = new FileInputStream(imgFile);        
          data = new byte[in.available()];
          in.read(data);
          in.close();
      }
      catch (IOException e)
      {
          e.printStackTrace();
      }
      return new String(Base64.encodeBase64(data));
  }

--

利用以上的思路写的一个测试

public class ReadImageTest {

    public static void main(String[] args) throws IOException {

          FileInputStream fis = new FileInputStream(new File("C:\\Users\\luzhifei\\Pictures\\hc_logo.png"));          
          String picStr="";
          byte[] read = null;
          int len = 0;
          read= new byte[fis.available()];
          fis.read(read);
          
          String baseStr= Base64.getEncoder().encodeToString(read);
          //System.out.println(  baseStr);
          byte[]  op= Base64.getDecoder().decode(baseStr);
         // System.out.println(new String(op));
          
          FileOutputStream fos = new FileOutputStream(new File("d:\\temp\\1.jpg"));
         
          fos.write(op,0,op.length  );
          fos.flush();
          fos.close();
    }

}

但是available()有一定的限制。

为了稳妥，严重建议采取以下方式：

public static void imageToBase64Str() throws IOException{
          FileInputStream fis = new FileInputStream(new File("C:\\Users\\luzhifei\\Pictures\\hc_logo.png"));
    
          byte[] read = new byte[1024];
          int len = 0;
          List<byte[]> blist=new ArrayList<byte[]>();
          int ttllen=0;
          while((len = fis.read(read))!= -1){
              byte[] dst=new byte[len];
              System.arraycopy(read, 0, dst, 0, len);
              ttllen+=len;
              blist.add(dst);
          }
          fis.close();
          
          byte[] dstByte=new byte[ttllen];
          int pos=0;
          for (int i=0;i<blist.size();i++){
              if (i==0){
                  pos=0;
              }
              else{
                pos+=blist.get(i-1).length;  
              }
              System.arraycopy(blist.get(i), 0, dstByte, pos, blist.get(i).length);
          }
          
          
          String baseStr= Base64.getEncoder().encodeToString(dstByte);
          
          byte[]  op= Base64.getDecoder().decode(baseStr);
          
          FileOutputStream fos = new FileOutputStream(new File("d:\\temp\\2.jpg"));
         
          fos.write(op,0,op.length  );
          fos.flush();
          fos.close();
    }