如何从InputStream中读取字节？

Question

我想测试我写入OutputStream（文件OuputStream）的字节与我从相同的InputStream中读取的字节相同。

测试看起来像

@Test 
    public void testStreamBytes() throws PersistenceException, IOException, ClassNotFoundException { 
     String uniqueId = "TestString"; 
     final OutputStream outStream = fileService.getOutputStream(uniqueId); 
     new ObjectOutputStream(outStream).write(uniqueId.getBytes()); 
     final InputStream inStream = fileService.getInputStream(uniqueId); 
    } 

我意识到InputStream没有getBytes()。

如何测试像

assertEquals(inStream.getBytes(), uniqueId.getBytes()) 

谢谢

Answer 1

试试这个（IOUtils是公共-IO）

byte[] bytes = IOUtils.toByteArray(instream); 

Answer 2

Java不提供你想要什么，但你可以使用类似于PrintWriter和Scanner的文件包装流：

new PrintWriter(outStream).print(uniqueId); 
String readId = new Scanner(inStream).next(); 
assertEquals(uniqueId, readId); 

Answer 3

您可以从inputstream中读取数据并写入ByteArrayOutputStream，然后使用toByteArray()方法将其转换为字节数组。

Answer 4

你可以使用ByteArrayOutputStream

ByteArrayOutputStream buffer = new ByteArrayOutputStream(); 

int nRead; 
byte[] data = new byte[16384]; 

while ((nRead = inStream.read(data, 0, data.length)) != -1) { 
    buffer.write(data, 0, nRead); 
} 

buffer.flush(); 

，并检查使用：

assertEquals(buffer.toByteArray(), uniqueId.getBytes()); 

Answer 5

为什么不尝试这样的事情？

@Test 
public void testStreamBytes() 
    throws PersistenceException, IOException, ClassNotFoundException { 
    final String uniqueId = "TestString"; 
    final byte[] written = uniqueId.getBytes(); 
    final byte[] read = new byte[written.length]; 
    try (final OutputStream outStream = fileService.getOutputStream(uniqueId)) { 
    outStream.write(written); 
    } 
    try (final InputStream inStream = fileService.getInputStream(uniqueId)) { 
    int rd = 0; 
    final int n = read.length; 
    while (rd <= (rd += inStream.read(read, rd, n - rd))) 
     ; 
    } 
    assertEquals(written, read); 
}