1
public static void readFile(String filePath) throws IOException {
2
    File file = new File(filePath);
3
    if (!file.exists() || !file.isFile()) {
4
      System.out.println("file is not exist");
5
    } else {
6
      FileInputStream fileInputStream = new FileInputStream(file); //创建文件输入流
7
      byte[] read = new byte[1024];
8
      while (fileInputStream.read(read) != -1) {
9
        System.out.println("read content:" + read);
10
      }
11
      fileInputStream.close(); // 关闭流 释放资源
12
    }
13

14
  }

1
public static void writeFile(byte[] content) throws IOException {
2
    File file = new File("D:\\Jser\\data\\test\\writeFile.xml"); //获取写文件的位置
3
    if (!file.exists())
4
      file.createNewFile();
5
    FileOutputStream fileOutputStream = new FileOutputStream(file); //创建文件输出流
6
    fileOutputStream.write(content); // content 表示写入文件的内容
7
    fileOutputStream.close();  //关闭流 释放资源
8
  }

1
import java.io.File;
2
import java.io.FileInputStream;
3
import java.io.FileOutputStream;
4
import java.io.IOException;
5
import java.io.RandomAccessFile;
6
import java.nio.ByteBuffer;
7
import java.nio.channels.FileChannel;
8

9
public class TestIO {
10

11
  public static void main(String[] args) throws IOException {
12
    String originFilePath = "D:\\Jser\\data\\git-rep\\jdp\\note\\Program-StudyPlan.md";
13
    String aimFilePath = "D:\\Jser\\data\\test\\aimFile.md";
14
    copyFile(originFilePath, aimFilePath);
15
//    testRandonAccessFile();
16
  }
17

18
  /*
19
   * 读文件
20
   */
21
  public static void readFile(String filePath) throws IOException {
22
    File file = new File(filePath);
23
    if (!file.exists() || !file.isFile()) {
24
      System.out.println("file is not exist");
25
    } else {
26
      FileInputStream fileInputStream = new FileInputStream(file);
27
      byte[] read = new byte[1024];
28
      while (fileInputStream.read(read) != -1) {
29
        System.out.println("read content:" + read);
30
      }
31
      fileInputStream.close();
32
    }
33

34
  }
35

36
  /**
37
   * 写文件
38
   * @throws IOException
39
   */
40
  public static void writeFile(byte[] content) throws IOException {
41
    File file = new File("D:\\Jser\\data\\test\\writeFile.xml");
42
    if (!file.exists())
43
      file.createNewFile();
44
    FileOutputStream fileOutputStream = new FileOutputStream(file);
45
    fileOutputStream.write(content);
46
    fileOutputStream.close();
47
  }
48

49
  /*
50
   * 文件复制 -> 读取一个文件复制到另一个地方
51
   */
52
  public static void copyFile(String originFilePath, String aimPath) {
53
    File originFile = new File(originFilePath);
54
    if (!originFile.exists()) {
55
      System.err.println("file is not exists!");
56
      return;   //文件不存在
57
    }
58
    File aimFile = new File(aimPath);
59
    FileInputStream fi = null;
60
    FileOutputStream fo = null;
61
    try {
62
      byte[] content = new byte[1024];   //每次读文件内容的字节数组
63
      if (!aimFile.exists())
64
        aimFile.createNewFile();
65
            // 通过路径转化为 输入流 和 输出流
66
      fi = new FileInputStream(originFile);  //输入流
67
      fo = new FileOutputStream(aimFile);  //输出流
68
      while (fi.read(content) != -1) { //输入流将数据读取到字节数组，如果返回值为 -1 表示文件已经读完
69
        fo.write(content); //输出流将数组内容写入文件
70
      }
71
    } catch (IOException e) {
72
      System.err.println("read file exception!");
73
      try {
74
        // close resources;
75
        if (fo != null)
76
          fo.close();
77
        if (fi != null)
78
          fi.close();
79
      } catch (IOException es) {
80
        // TODO Auto-generated catch block
81
        es.printStackTrace();
82
      }
83
    } finally {
84
      try {
85
        if (fo != null)
86
          fo.close();
87
        if (fi != null)
88
          fi.close();
89
      } catch (IOException e) {
90
        // TODO Auto-generated catch block
91
        e.printStackTrace();
92
      }
93
    }
94
  }
95

96
    /*
97
    * java 涉及NIO的 RandomAccessFile 类
98
    */
99
  private static void testRandonAccessFile() throws IOException {
100
    RandomAccessFile aFile = new RandomAccessFile("D:\\Jser\\data\\git-rep\\config\\maven\\settings.xml", "rw");
101
    FileChannel channel = aFile.getChannel();
102
    File file = new File("D:\\Jser\\data\\test\\creatFile.xml");
103
    if (!file.getParentFile().exists())
104
      file.getParentFile().mkdirs();
105

106
    if (!file.isFile()) {
107
      System.err.println("file is not exist!");
108
      System.exit(0);
109
    }
110
    if (!file.exists())
111
      file.createNewFile();
112

113
    FileOutputStream newFile = new FileOutputStream(file);
114
    ByteBuffer buffer = ByteBuffer.allocate(1024);
115
    int i = 0;
116
    while (channel.read(buffer) != -1) {
117
      i++;
118
      buffer.flip();
119
      while (buffer.hasRemaining()) {
120
        newFile.write(buffer.get());
121
      }
122
      buffer.clear();
123
    }
124
    aFile.close();
125
    newFile.close();
126
    System.out.println("文件读取次数：" + i);
127
  }
128

129
}