如何在CharArrayReader中读取ZipInputStream

Question

现在，我正在使用Google App Engine (GAE)开发一个应用程序。GAE不允许我创建临时文件夹来存储我的zipfile并从中读取。唯一的方法是从内存中读取它。压缩文件包含6个CSV文件，我需要将其读取到CSVReader中。

//part of the code

MultipartFormDataRequest multiPartRequest = null;

Hashtable files = multiPartRequest.getFiles();

UploadFile userFile = (UploadFile)files.get("bootstrap_file");

InputStream input = userFile.getInpuStream();

ZipInputStream zin = new ZipInputStream(input);

如何将ZipInputStream读取到char[]中，这是为我的CSVReader对象创建CharArrayReader所需的。

CSVReader reader = new CSVReader(CharArrayRead(char[] buf));

Answer 1

用InputStreamReader包装ZipInputStream以将字节转换为字符；然后调用inputStreamReader.read(char[] buf，int offset，int length)来填充char[]缓冲区，如下所示：

//part of the code
MultipartFormDataRequest multiPartRequest = null;
Hashtable files = multiPartRequest.getFiles();
UploadFile userFile = (UploadFile)files.get("bootstrap_file");
InputStream input = userFile.getInpuStream();
ZipInputStream zin = new ZipInputStream(input);

// wrap the ZipInputStream with an InputStreamReader    
InputStreamReader isr = new InputStreamReader(zin);
ZipEntry ze;
// ZipEntry ze gives you access to the filename etc of the entry in the zipfile you are currently handling
while ((ze = zin.getNextEntry()) != null) {
    // create a buffer to hold the entire contents of this entry
    char[] buf = new char[(int)ze.getSize()];
    // read the contents into the buffer
    isr.read(buf);
    // feed the char[] to CSVReader
    CSVReader reader = new CSVReader(CharArrayRead(buf));
}

如果您的CharArrayRead实际上是一个java.io.CharArrayReader，那么就不需要将其加载到char[]中，最好使用下面这样的代码：

InputStreamReader isr = new InputStreamReader(zin);
BufferedReader br = new BufferedReader(isr);
ZipEntry ze;
while ((ze = zin.getNextEntry()) != null) {
    CSVReader reader = new CSVReader(br);
}

如果你只有一个压缩文件(试图绕过1MB的限制)，那么这是可行的：

InputStreamReader isr = new InputStreamReader(zin);
zip.getNextEntry();
CSVReader reader = new CSVReader(isr, ...);