[Java] IO-04 打印流 PrintStream 语言促进人的思维 扩展眼界 ： log4j

import java.io.*;

// 语言促进人的思维
public class TestPrintStream1 {
    public static void main(String[] args) {
        PrintStream ps = null;
        try {
            FileOutputStream fos = new FileOutputStream("d:\bak\log.dat");
            ps = new PrintStream(fos);
        } catch (IOException e) {
            e.printStackTrace();
        }
        if (ps != null) {
            System.setOut(ps);
        }
        int ln = 0;
        for (char c = 0; c <= 60000; c++) {
            System.out.print(c + " ");
            if (ln++ >= 100) {
                System.out.println();
                ln = 0;
            }
        }
    }
}

import java.io.*;

public class TestPrintStream2 {
    public static void main(String[] args) {
        String filename = args[0];
        if (filename != null) {
            list(filename, System.out);
        }
    }

    public static void list(String f, PrintStream fs) {
        try {
            BufferedReader br = new BufferedReader(new FileReader(f));
            String s = null;
            while ((s = br.readLine()) != null) {
                fs.println(s);
            }
            br.close();
        } catch (IOException e) {
            fs.println("无法读取文件");
        }
    }
}

import java.util.*;
import java.io.*;

public class TestPrintStream3 {
    public static void main(String[] args) {
        String s = null;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            FileWriter fw = new FileWriter("d:\share\logfile.log", true); // Log4J  // 追加
            PrintWriter log = new PrintWriter(fw);
            while ((s = br.readLine()) != null) {
                if (s.equalsIgnoreCase("exit"))
                    break;
                System.out.println(s.toUpperCase());
                log.println("-----");
                log.println(s.toUpperCase());
                log.flush();
            }
            log.println("===" + new Date() + "===");
            log.flush();
            log.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}