Question

我尝试使用此代码将ZIP文件转换为字节数组：

private static byte[] readZipFile(String zipFnm)
// read in fnm, returning it as a single string
{

  FileInputStream fileInputStream=null;

  File file = new File(zipFnm);

  byte[] bFile = new byte[(int) file.length()];

  try{
    //convert file into array of bytes
    fileInputStream = new FileInputStream(zipFnm);
    fileInputStream.read(bFile);
    fileInputStream.close();
  }catch(Exception e){
    e.printStackTrace();
  }
  return bFile;
}

这个代码用于通过调用writeByteToZip(fnm + ".zip");

将字节数组转换回ZIP

private static String writeByteToZip(String outFnm)
{
  try {
    FileOutputStream fileOuputStream = new FileOutputStream(outFnm); 
    fileOuputStream.write(bFile);
    fileOuputStream.close();            

  } catch ( IOException iox ){
    iox.printStackTrace();
  }
  return outFnm;
}  // end of writeByteToZip()

我做错了什么？我使用

获得正确的zip字节长度

byte[] bzip = readZipFile(zipFnm);

int totalLen1 = bzip.length;
System.out.println("Total byte length of zip: " + totalLen1);

我得到的是零大小的zip文件和Netbeans中的运行时错误：

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at java.io.FileOutputStream.write(FileOutputStream.java:305)
    at steg.Steg.writeByteToZip(Steg.java:402)
    at steg.Steg.save(Steg.java:292)
    at steg.frame1.jButton2ActionPerformed(frame1.java:349)
    at steg.frame1.access$300(frame1.java:24)
    at steg.frame1$4.actionPerformed(frame1.java:172)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6505)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6270)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4861)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4687)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

Answer 1

由于bFile为空，会导致您提供的堆栈跟踪。

原因可能是readZipFile方法中的以下行：

byte[] bFile = new byte[(int) file.length()];

在这里，您要分配一个本地变量，而不是您的类字段。尝试用以下代码替换该行：

bFile = new byte[file.length()];

您的代码也表明资源处理不佳。使用现有的库方法进行阅读（例如commons-io或Java 7 Files）或编写如下代码：

FileInputStream fileInputStream = null;
try {
  fileInputStream = new //...
} finally {
  if (fileInputStream != null) {
    fileInputStream.close();
  }
}

如果你有Java 7，你可以使用try-with-resources：

try (FileInputStream fileInputStream = new FileInputStream(zipFnm)) {
  // Use your stream
}

Answer 2

问题可能是bFile中的变量writeByteToZip()。确保它不是null。

将来，当您发布引发异常的代码时，请使用注释标记发生异常的行（// <-- NullPointerException here）

Answer 3

我没有检查你的代码。但我正在处理这样的要求。感觉就像分享我的代码一样。

读取zip文件并转换为字节数组：

public byte[] readXMLFile(){
        File file = new File("a.xml");

        byte[] b = new byte[(int) file.length()];
        try {
            FileInputStream fileInputStream = new FileInputStream(file);
            fileInputStream.read(b);
            fileInputStream.close();
        }catch (FileNotFoundException e) {
            System.out.println("File Not Found.");
            e.printStackTrace();
        }catch (IOException e1) {
            System.out.println("Error Reading The File.");
            e1.printStackTrace();
        }
        return b;
    }

从字节数组写入zip文件：

public void writeXMLFile(byte[] fileContent){
        try {
            FileOutputStream fos = new FileOutputStream("abc.xml");

            fos.write(fileContent);
            fos.close();
        }catch(FileNotFoundException ex){
            System.out.println("FileNotFoundException : " + ex);
        }catch(IOException ioe)  {
            System.out.println("IOException : " + ioe);
        }
    }

希望这有帮助。

Answer 4

如前所述，该文件可能不存在。

但是，我只是想提一下你可以使用的Java 7中的实用程序。 Files课程提供：

static byte[] readAllBytes(Path path)
static Path write(Path path, byte[] bytes, OpenOption... options)

接缝就像你需要的一样。无论文件是否为Zip都没关系，只需简单地获取字节，然后使用它们将它们写入其他文件即可。请注意，Java 7中的Path表示相关文件的路径。

如何将zip文件作为字节数组读取，然后将字节数组转换回zip文件？

4 个答案: