如何将InputStream转换为虚拟文件 [英] How to convert InputStream to virtual File

问题描述

我有一个方法，期望输入变量之一是java.io.File类型，但我得到的只是InputStream。我不能改变方法的签名。如何将InputStream转换成文件类型，实际上将文件写入文件系统？

解决方案

这样的东西应该可以工作。请注意，为了简单起见，我使用了Java 7功能（具有可关闭资源的try块）和来自Apache commons-io的IOUtils。如果你不能使用它们会更长一点，但是一样的想法。

  import org.apache.commons .io.IOUtils; 
 
 import java.io.File; 
 import java.io.FileOutputStream; 
 import java.io.IOException; 
 import java.io.InputStream; 
 
 public class StreamUtil {
 
 public static final String PREFIX =stream2file; 
 public static final String SUFFIX =.tmp; 
 
 public static文件stream2file（InputStream in）throws IOException {
 final File tempFile = File.createTempFile（PREFIX，SUFFIX）; 
 tempFile.deleteOnExit（）; 
 try（FileOutputStream out = new FileOutputStream（tempFile））{
 IOUtils.copy（in，out）; 
} 
 return tempFile; 
} 
 
} 
  

I have a method which expects the one of the input variable to be of java.io.File type but what I get is only InputStream. I cannot change the signature of the method. How can I convert the InputStream into File type with out actually writing the file on to the filesystem?.

解决方案

Something like this should work. Note that for simplicity, I've used a Java 7 feature (try block with closeable resource), and IOUtils from Apache commons-io. If you can't use those it'll be a little longer, but the same idea.

import org.apache.commons.io.IOUtils;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class StreamUtil {

    public static final String PREFIX = "stream2file";
    public static final String SUFFIX = ".tmp";

    public static File stream2file (InputStream in) throws IOException {
        final File tempFile = File.createTempFile(PREFIX, SUFFIX);
        tempFile.deleteOnExit();
        try (FileOutputStream out = new FileOutputStream(tempFile)) {
            IOUtils.copy(in, out);
        }
        return tempFile;
    }

}

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