🔖 JAVA IO 示例

dunwu · dunwu · commit 7b099fe84ca9 · 2018-07-01T21:57:06.000+08:00
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/BufferedReaderDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/BufferedReaderDemo.java
@@ -0,0 +1,24 @@
+package io.github.dunwu.javase.io;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+/**
+ * @author Zhang Peng
+ */
+public class BufferedReaderDemo {
+
+    public static void main(String args[]) throws IOException {
+        BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
+        while (true) {
+            System.out.print("请输入内容：");
+            String str = buf.readLine();
+            if (str.equalsIgnoreCase("exit")) {
+                System.out.print("退出");
+                break;
+            }
+            System.out.println("输入的内容为：" + str);
+        }
+    }
+}
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/PrintStreamDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/PrintStreamDemo.java
@@ -0,0 +1,23 @@
+package io.github.dunwu.javase.io;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.OutputStream;
+import java.io.PrintStream;
+
+/**
+ * @author Zhang Peng
+ */
+public class PrintStreamDemo {
+
+    public static void main(String arg[]) throws Exception {
+        final String filepath = "d:\\test.txt";
+        // 如果现在是使用 FileOuputStream 实例化，意味着所有的数据都会输出到文件中
+        OutputStream os = new FileOutputStream(new File(filepath));
+        PrintStream ps = new PrintStream(os);
+        ps.print("Hello ");
+        ps.println("World!!!");
+        ps.printf("姓名：%s；年龄：%d", "张三", 18);
+        ps.close();
+    }
+}
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/ScannerDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/ScannerDemo.java
@@ -0,0 +1,45 @@
+package io.github.dunwu.javase.io;
+
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Scanner;
+
+/**
+ * @author Zhang Peng
+ */
+public class ScannerDemo {
+
+    public static void main(String args[]) {
+        Scanner scan = new Scanner(System.in);    // 从键盘接收数据
+        int i = 0;
+        float f = 0.0f;
+        System.out.print("输入整数：");
+        if (scan.hasNextInt()) {    // 判断输入的是否是整数
+            i = scan.nextInt();    // 接收整数
+            System.out.println("整数数据：" + i);
+        } else {
+            System.out.println("输入的不是整数！");
+        }
+
+        System.out.print("输入小数：");
+        if (scan.hasNextFloat()) {    // 判断输入的是否是小数
+            f = scan.nextFloat();    // 接收小数
+            System.out.println("小数数据：" + f);
+        } else {
+            System.out.println("输入的不是小数！");
+        }
+
+        Date date = null;
+        String str = null;
+        System.out.print("输入日期（yyyy-MM-dd）：");
+        if (scan.hasNext("^\\d{4}-\\d{2}-\\d{2}$")) {    // 判断
+            str = scan.next("^\\d{4}-\\d{2}-\\d{2}$");    // 接收
+            try {
+                date = new SimpleDateFormat("yyyy-MM-dd").parse(str);
+            } catch (Exception e) {}
+        } else {
+            System.out.println("输入的日期格式错误！");
+        }
+        System.out.println(date);
+    }
+}
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemErrDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemErrDemo.java
@@ -0,0 +1,20 @@
+package io.github.dunwu.javase.io;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintStream;
+
+/**
+ * @author Zhang Peng
+ */
+public class SystemErrDemo {
+
+    public static void main(String args[]) throws IOException {
+        OutputStream bos = new ByteArrayOutputStream();        // 实例化
+        PrintStream ps = new PrintStream(bos);        // 实例化
+        System.setErr(ps);    // 输出重定向
+        System.err.print("此处有误");
+        System.out.println(bos);    // 输出内存中的数据
+    }
+}
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemInDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemInDemo.java
@@ -0,0 +1,27 @@
+package io.github.dunwu.javase.io;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * System.in 示例
+ * @author Zhang Peng
+ */
+public class SystemInDemo {
+
+    public static void main(String args[]) throws IOException {
+        InputStream input = System.in;
+        StringBuffer buf = new StringBuffer();
+        System.out.print("请输入内容：");
+        int temp = 0;
+        while ((temp = input.read()) != -1) {
+            char c = (char) temp;
+            if (c == '\n') {
+                break;
+            }
+            buf.append(c);
+        }
+        System.out.println("输入的内容为：" + buf);
+        input.close();
+    }
+}
diff --git a/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemOutDemo.java b/codes/basics/src/main/java/io/github/dunwu/javase/io/SystemOutDemo.java
@@ -0,0 +1,21 @@
+package io.github.dunwu.javase.io;
+
+import java.io.FileOutputStream;
+import java.io.OutputStream;
+import java.io.PrintStream;
+
+/**
+ * 重定向 System.out 输出流
+ * @author Zhang Peng
+ */
+public class SystemOutDemo {
+
+    public static void main(String args[]) throws Exception {
+        OutputStream out = new FileOutputStream("d:\\test.txt");
+        PrintStream ps = new PrintStream(out);
+        System.setOut(ps);
+        System.out.println("人生若只如初见，何事秋风悲画扇");
+        ps.close();
+        out.close();
+    }
+}
