Java 单字节、多字节读取文本文档中的内容

参考1：Java中try()catch{}的使用方法

参考2：The try-with-resources Statement

文本文档位于工程下，使用鼠标右键点击工程，选择new -> File，即可创建。

文本文档的格式：GBK

例1：单字节读取

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 public class Main {

     public static void main(String[] args) {
         System.out.println(System.getProperty("user.dir"));

         File file = new File("text.txt");
         InputStream inputStream = null;

         try {
             if ((file.exists()) && (file.isFile())) {
                 inputStream = new FileInputStream(file);
                 int data = -1;
                 do {
                     data = inputStream.read();
                     if (data != -1) {
                         System.out.print((char) data);
                     } else {
                         System.out.print(data);
                     }
                 } while (data != -1);
                 System.out.println();
             } else if (!file.exists()) {
                 System.out.println("The " + file.getName() + " does not exist.");
             } else if (!file.isFile()) {
                 System.out.println("The " + file.getName() + " is not a file.");
             }
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } finally {
             try {
                 if (inputStream != null) {
                     // Closes this input stream and releases any system resources associated with the stream.
                     inputStream.close();
                     System.out.println("Close the input stream.");
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
     }
 }

改写例1：

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 public class Main {

     public static void main(String[] args) {
         System.out.println(System.getProperty("user.dir"));

         File file = new File("text.txt");

         try (InputStream inputStream = new FileInputStream(file)) {
             if ((file.exists()) && (file.isFile())) {
                 int data = -1;
                 do {
                     data = inputStream.read();
                     if (data != -1) {
                         System.out.print((char) data);
                     } else {
                         System.out.print(data);
                     }
                 } while (data != -1);
                 System.out.println();
             } else if (!file.exists()) {
                 System.out.println("The " + file.getName() + " does not exist.");
             } else if (!file.isFile()) {
                 System.out.println("The " + file.getName() + " is not a file.");
             }
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e1) {
             e1.printStackTrace();
         }
     }
 }

多字节读取

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;

 public class IOTest02 {

     public static void main(String[] args) {
         File src = new File("src.txt");
         InputStream is = null;

         try {
             is = new FileInputStream(src);
             byte[] buffer = new byte[1024 * 1];                    // 1k bytes
             int length = -1;
             while ((length = is.read(buffer)) != -1) {
                 String str = new String(buffer, 0, length);        // decode
                 System.out.print(str);
             }
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         } finally {
             try {
                 if (is != null) {
                     is.close();
                     System.out.println("\n\nInputStream Closed.");
                 }
             } catch (IOException e) {
                 e.printStackTrace();
             }
         }
     }
 }