去除的InputStream

Question

换行符我想删除所有换行符（用于\ n和\ r \ n）的从java.io.InputStream，而读取文件，相应的方法是这样的：

/** 
* @param target {@linkplain File} 
* @return {@linkplain InputStream} 
* @throws Exception 
*/ 
protected InputStream initInput(final File file) 
    throws Exception { 
    InputStream stream = null; 
    try { 
     if (file.isDirectory()) { 
      // throw exception 
     } 
     if (!file.exists()) { 
      // throw another exception 
     } 
     // 
     // *remove newlines here* 
     // 
     stream = new FileInputStream(file); 

    } catch (FileNotFoundException e) { 
     // throw another exception 
    } 
    return stream; 
} 

Answer 1

您可以自己申请java.io.FileInputStream，并以读取时跳过\r和\n的方式覆盖读取方法。

海尔是样品实施（没有任何错误处理）

import java.io.File; 
import java.io.FileDescriptor; 
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.IOException; 

public class NoNewLineFileInputStream extends FileInputStream { 

    public NoNewLineFileInputStream(String filepath) throws FileNotFoundException { 
     super(filepath); 
    } 

    public NoNewLineFileInputStream(File file) throws FileNotFoundException { 
     super(file); 
    } 

    public NoNewLineFileInputStream(FileDescriptor filedescriptor) { 
     super(filedescriptor); 
    } 

    @Override 
    public int read(byte[] b) throws IOException { 
     return this.read(b, 0, b.length); 
    } 

    @Override 
    public int read(byte[] b, int off, int len) throws IOException { 
     int n = 0, c; 
     do { 
      c = this.read(); 
      if(c != -1) { 
       b[off + n] = (byte) c; 
       n++; 
       len--; 
      } else { 
       return c; 
      } 
     } while(c != -1 && len > 0); 
     return n; 
    } 


    @Override 
    public int read() throws IOException { 
     int c; 
     do { 
      c = super.read(); 
     } while(c != -1 && (c == '\n' || c == '\r')); 
     return c; 
    } 
} 

而对于一些基本的测试...

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

import junit.framework.Assert; 

import org.junit.BeforeClass; 
import org.junit.Test; 

public class NoNewLineFileInputStreamTest { 

    private final static String txt = "testnl.txt"; 

    @BeforeClass 
    public static void genTestFile() throws IOException { 
     OutputStream os = new FileOutputStream(txt); 
     os.write((
       "Hello\n" + 
       ",\r\n" + 
       "World!\r" + 
       "").getBytes()); 
     os.close(); 
    } 

    @Test 
    public void readInt() throws IOException { 
     InputStream is = new NoNewLineFileInputStream(txt); 
     int c = is.read(); 
     while(c != -1) { 
      Assert.assertTrue(c != '\n' && c != '\r'); 
      c = is.read(); 
     } 
     is.close(); 
    } 

    @Test 
    public void readBytes() throws IOException { 
     InputStream is = new NoNewLineFileInputStream(txt); 
     int l = is.available(); 
     if(l > 0) { 
      byte[] content = new byte[l]; 
      int n = is.read(content); 
      String expected = "Hello,World!"; 
      Assert.assertEquals(expected.getBytes().length, n); 
      Assert.assertEquals(expected, new String(content, 0, n)); 
     } 
     is.close(); 
    } 

    @Test 
    public void readBytesOffset() throws IOException { 
     InputStream is = new NoNewLineFileInputStream(txt); 
     int l = is.available(); 
     if(l > 0) { 
      byte[] content = new byte[l*3]; 
      int n = is.read(content, 3, 5); 
      String expected = "Hello"; 
      Assert.assertEquals(expected.getBytes().length, n); 
      Assert.assertEquals(expected, new String(content, 3, n)); 
     } 
     is.close(); 
    } 
} 

你的方法是这样的

/** 
* @param target {@linkplain File} 
* @return {@linkplain InputStream} 
* @throws Exception 
*/ 
protected InputStream initInput(final File file) 
    throws Exception { 
    InputStream stream = null; 
    try { 
     if (file.isDirectory()) { 
      // throw exception 
     } 
     if (!file.exists()) { 
      // throw another exception 
     } 
     // 
     // read operations using this implementation will jump over all '\n' and '\r' 
     // 
     stream = new NoNewLineFileInputStream(file); 

    } catch (FileNotFoundException e) { 
     // throw another exception 
    } 
    return stream; 
} 

对于与您可能想要覆盖的抽象类更好地兼容所有的方法在你的课堂上。

Answer 2

使用阿帕奇共享郎和StringUtils.chomp功能

Answer 3

你可以将其转换为字符串，并与没有更换新行字符：

InputStream is = new ByteArrayInputStream("file content".getBytes()); 

    //read it with BufferedReader 
    BufferedReader br = new BufferedReader(new InputStreamReader(is)); 

    StringBuilder sb = new StringBuilder(); 

    String line; 
    while ((line = br.readLine()) != null) { 
     sb.append(line.replace("\r","").replace("\n",""))  


    System.out.println(sb.toString()); 

考虑到你的文本不包含“\ n”和“\ r”，这对你来说是很好的选择。