Java语言如何将标准流重定向到普通文件？

Question

标准输入流为键盘，标准输出流为显示器。
在Java语言中，如何重定向到普通的2个文件，in.txt和out.txt
请给出代码示例

Answer 1

// All writes to this print stream are copied to two print streams
    public class TeeStream extends PrintStream {
        PrintStream out;
        public TeeStream(PrintStream out1, PrintStream out2) {
            super(out1);
            this.out = out2;
        }
        public void write(byte buf[], int off, int len) {
            try {
                super.write(buf, off, len);
                out.write(buf, off, len);
            } catch (Exception e) {
            }
        }
        public void flush() {
            super.flush();
            out.flush();
        }
    }Here's an example that uses the class:    
    try {
        // Tee standard output
        PrintStream out = new PrintStream(new FileOutputStream("out.log"));
        PrintStream tee = new TeeStream(System.out, out);
    
        System.setOut(tee);
    
        // Tee standard error
        PrintStream err = new PrintStream(new FileOutputStream("err.log"));
        tee = new TeeStream(System.err, err);
    
        System.setErr(tee);
    } catch (FileNotFoundException e) {
    }
    
    // Write to standard output and error and the log files
    System.out.println("welcome");
    System.err.println("error");

Answer 2

 File infile = new File("d:\\in.txt");   
 
File outFile = new File("d:\\out.txt");  InputStream input = new FileInputStream(file);        
                                           
 
OutputStream Out=new FileOutputStream(zipFile);      int temp = 0;                                      while ((temp = input.read()) != -1) {                Out.write(temp);                        }  
         input.close();                           
 
         Out.close();   

Answer 3

变量写错了，再来一次
     File infile = new File("d:\\in.txt"); 
     File outFile = new File("d:\\out.txt"); 
     InputStream input = new FileInputStream(infile);                                                 
     OutputStream out=new FileOutputStream(outFile);     
     int temp = 0;                          
     while ((temp = input.read()) != -1) { 
                 out.write(temp);             
             } 
      input.close();                         
      out.close(); 

Answer 4

try this:System.setOut(
    new PrintStream(
        new FileOutputStream("C:\\out.txt")
    )
);
System.setIn(
    new FileInputStream("C:\\in.txt")
);