IO流_自定义类模拟LineNumberReader的获取行号功能案例

布满荆棘的人生 2022-07-12 11:51 129阅读 0赞

package cn.itcast_09;
    
    import java.io.IOException;
    import java.io.Reader;
    
    public class MyLineNumberReader {
    	private Reader r;
    	private int lineNumber = 0;
    
    	public MyLineNumberReader(Reader r) {
    		this.r = r;
    	}
    
    	public int getLineNumber() {
    		return lineNumber;
    	}
    
    	public void setLineNumber(int lineNumber) {
    		this.lineNumber = lineNumber;
    	}
    
    	public String readLine() throws IOException {
    		lineNumber++;
    
    		StringBuilder sb = new StringBuilder();
    
    		int ch = 0;
    		while ((ch = r.read()) != -1) {
    			if (ch == '\r') {
    				continue;
    			}
    
    			if (ch == '\n') {
    				return sb.toString();
    			} else {
    				sb.append((char) ch);
    			}
    		}
    
    		if (sb.length() > 0) {
    			return sb.toString();
    		}
    
    		return null;
    	}
    
    	public void close() throws IOException {
    		this.r.close();
    	}
    }

package cn.itcast_09;
    
    import java.io.FileReader;
    import java.io.IOException;
    
    /*
     * 测试MyLineNumberReader类
     */
    public class MyLineNumberReaderTest {
    	public static void main(String[] args) throws IOException {
    		// MyLineNumberReader mlnr = new MyLineNumberReader(new FileReader(
    		// "my.txt"));
    		MyLineNumberReader2 mlnr = new MyLineNumberReader2(new FileReader(
    				"my.txt"));
    
    		// mlnr.setLineNumber(10);
    
    		String line = null;
    		while ((line = mlnr.readLine()) != null) {
    			System.out.println(mlnr.getLineNumber() + ":" + line);
    		}
    
    		// 释放资源
    		mlnr.close();
    	}
    }

终级代码

package cn.itcast_09;
    
    import java.io.IOException;
    import java.io.Reader;
    
    import cn.itcast_08.MyBufferedReader;
    
    public class MyLineNumberReader2 extends MyBufferedReader {
    	private Reader r;
    	private int lineNumber = 0;
    
    	public MyLineNumberReader2(Reader r) {
    		super(r);
    	}
    
    	public int getLineNumber() {
    		return lineNumber;
    	}
    
    	public void setLineNumber(int lineNumber) {
    		this.lineNumber = lineNumber;
    	}
    
    	@Override
    	public String readLine() throws IOException {
    		lineNumber++;
    		return super.readLine();
    	}
    }