去除的InputStream

Question

換行符我想刪除所有換行符（用於\ n和\ r \ n）的從java.io.InputStream，而讀取文件，相應的方法是這樣的：

/** 
* @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

您可以自己申請java.io.FileInputStream，並以讀取時跳過\r和\n的方式覆蓋讀取方法。

海爾是樣品實施（沒有任何錯誤處理）

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; 
    } 
} 

而對於一些基本的測試...

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(); 
    } 
} 

你的方法是這樣的

/** 
* @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; 
} 

對於與您可能想要覆蓋的抽象類更好地兼容所有的方法在你的課堂上。

Answer 2

使用阿帕奇共享郎和StringUtils.chomp功能

Answer 3

你可以將其轉換爲字符串，並與沒有更換新行字符：

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()); 

考慮到你的文本不包含「\ n」和「\ r」，這對你來說是很好的選擇。