Java 将图像转换为字节数组,反之亦然
我试图通过android发送一个字节数组形式的图像,并在服务器端将其转换回png文件,在服务器端得到Java 将图像转换为字节数组,反之亦然,java,android,Java,Android,我试图通过android发送一个字节数组形式的图像,并在服务器端将其转换回png文件,在服务器端得到IllegalArgumentException 这是我的android代码,它将图像转换为字节数组,并将其作为请求发送到服务器: GestureOverlayView gestureView = (GestureOverlayView) findViewById(R.id.signaturePad); Bitmap bm = Bitmap.createBitmap(g
IllegalArgumentException
这是我的android代码,它将图像转换为字节数组,并将其作为请求发送到服务器:
GestureOverlayView gestureView = (GestureOverlayView) findViewById(R.id.signaturePad);
Bitmap bm = Bitmap.createBitmap(gestureView.getGesture().toBitmap(100, 100, 8, Color.WHITE));
FileOutputStream fos = openFileOutput("signature.png", Context.MODE_PRIVATE);
bm.compress(Bitmap.CompressFormat.PNG, 100, fos);
byte[] image_byte = fos.toString().getBytes();//Base64.encode(fos.toString().getBytes(), 0);
String strImage = image_byte.toString();
这是我的服务器端程序:
String imageString = request.getParameter("SignatureImage");
byte[] imageByte = imageString.getBytes();
try {
InputStream in = new ByteArrayInputStream(imageByte);
BufferedImage bImageFromConvert = ImageIO.read(in);
//Getting exception at this line
ImageIO.write(bImageFromConvert, "png", new File(
"E:/signature/signature.png"));
/*BufferedImage bufferedImage = ImageIO.read(new ByteArrayInputStream(imageByte));
ImageIO.write(bufferedImage, "jpg", new File("E:/signature/signature.jpg"));*/
} catch (IOException e) {
e.printStackTrace();
}
服务器上的异常为:
12:39:40,990 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/APDTest].[ImageRetrieve]] Servlet.service() for servlet ImageRetrieve threw exception: java.lang.IllegalArgumentException: im == null!
at javax.imageio.ImageIO.write(ImageIO.java:1457) [:1.6.0_32]
at javax.imageio.ImageIO.write(ImageIO.java:1521) [:1.6.0_32]
at com.apd.test.ImageRetrieve.doPost(ImageRetrieve.java:52) [:]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:754) [:1.0.0.Final]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [:1.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:6.1.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.1.0.Final]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:6.1.0.Final]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161) [:6.1.0.Final]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.1.0.Final]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.1.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:159) [:6.1.0.Final]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:6.1.0.Final]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.1.0.Final]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:6.1.0.Final]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.1.0.Final]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:6.1.0.Final]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [:6.1.0.Final]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654) [:6.1.0.Final]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951) [:6.1.0.Final]
试试这个代码
将图像转换为字节:用于
将字节转换为图像:用于
希望这将为您提供一些解决方案。您将图像写入客户端的文件输出流,该流将内容存储到物理文件中。然后尝试将
文件输出流的表示形式转换为字符串
作为图像内容。这不会起作用,该类的toString
方法不会提供写入流的内容,它只是打印一条几乎没有帮助的消息,如下所示:
java.io。FileOutputStream@761eec35
我相信您打算使用的是一个ByteArrayOutputStream
——这个类允许您检索通过其toString
方法编写的实际内容
在Android端(代码片段):
在服务器端(代码段):
我并没有试图保存图像并将其加载回去,我只是尝试使用手势覆盖层视图捕获签名,并在单击按钮时将其发送到服务器。。
yourSelectedImage = BitmapFactory.decodeFile(galleryFilePath);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
yourSelectedImage.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte[] b = baos.toByteArray();
final String encodedImage = response.toString();
byte[] decodedString = Base64.decode(encodedImage, Base64.DEFAULT);
decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
Bitmap bm = Bitmap.createBitmap(gestureView.getGesture().toBitmap(100,
100, 8, Color.WHITE));
ByteArrayOutputStream baos = new ByteArrayOutputStream(2056);
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte[] imageBytes = baos.toByteArray();
String encodedString = Base64.encodeToString(imageBytes, Base64.DEFAULT);
String imageString = request.getParameter("SignatureImage");
byte[] decodedBytes = Base64.decode(imageString, Base64.DEFAULT);
try {
InputStream in = new ByteArrayInputStream(decodedBytes);
BufferedImage bImageFromConvert = ImageIO.read(in);
ImageIO.write(bImageFromConvert, "png", new File(
"E:/signature/signature.png"));
} catch (IOException e) {
e.printStackTrace();
}