File类的总结:
1.文件和文件夹的创建
2.文件的读取
3.文件的写入
4.文件的复制(字符流、字节流、处理流)
5.以图片地址下载图片
文件和文件夹
相关函数
(boolean) mkdir() 创建此抽象路径名指定的目录
(boolean) mkdirs() 创建此抽象路径名指定的目录,包括所有必需但不存在的父目录。
(boolean) delete() 删除此抽象路径名表示的文件或目录
(boolean) createNewFile() 当不存在此路径名指定名称的文件时,创建一个新的空文件。
创建文件
public static void NewFile(String pathString) {
File file = new File(pathString);
if (!file.exists()) {
try {
if (file.createNewFile()) {
System.out.println("文件创建成功");
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
} else {
System.out.println("文件已存在");
}
}
创建文件夹
public static void NewFileBox(String pathString) {
File file2 = new File(pathString);
if (!file2.exists()) {
if (file2.mkdirs()) {
System.out.println("文件夹成功");
}
} else {
System.out.println("文件夹存在");
file2.delete();//销毁文件
}
}
应用:
public static void main(String[] args) {
NewFile("test/file.txt");
NewFileBox("test/a/a/a/a");
}
Writer写入文件
用FileWriter写入文件
public static void ForFileWriter(String string,String fileName) {
File file = new File(fileName);
try {
FileWriter fWriter = new FileWriter(file);
fWriter.write(string);
fWriter.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
用BufferedWriter写入文件
public static void ForBufferedWriter(String string,String desFile) {
BufferedWriter bWriter = null;
try {
bWriter = new BufferedWriter(new FileWriter(new File(desFile)));
bWriter.write(string.toString());
bWriter.close();
} catch (Exception e) {
e.printStackTrace();
}
}
应用:
public static void main(String[] args) {
ForFileWriter("用FileWriter写入文件", "test/writer1.txt");
ForBufferedWriter("用BufferedWriter写入文件", "test/writer2.txt");
}
Reader读取文件
用FileReader读取文件
public static void testReadByReader(String fileName){
File file = new File(fileName);
FileReader fis = null;
try {
fis = new FileReader(file);
char[] arr = new char[1024 * 1000 * 6];
int len = fis.read(arr);
String data = new String(arr, 0, len);
fis.close();
System.out.println(fileName+"中按FileReader读取的文件内容是:\n"+data);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
用FileInputStream读取文件
public static void testReadByInputStream(String fileName){
File file = new File(fileName);
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
byte[] arr = new byte[1024 * 1000 * 6];
int len = fis.read(arr);
String data = new String(arr, 0, len);
fis.close();
System.out.println(fileName+"中按FileInputStream读取的文件内容是:\n"+data);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
用BufferedReader读取文件
public static void testReadByBufferedReader(String fileName) {
BufferedReader bReader = null;
String line = null;
StringBuffer buffer = new StringBuffer();
try {
bReader =new BufferedReader(new FileReader(new File(fileName)));
while ((line = bReader.readLine())!=null) {
buffer.append(line).append("\n");
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
System.out.println(fileName+"中按BufferedReader读取的文件内容是:\n"+buffer.toString());
}
应用:
public static void main(String[] args) {
testReadByInputStream("res/我.txt");
testReadByReader("res/我.txt");
testReadByBufferedReader("res/我.txt");
}
文件的复制操作
字符流复制
public static void FileCopy1(String readfile,String writeFile) {
try {
FileReader input = new FileReader(readfile);
FileWriter output = new FileWriter(writeFile);
int read = input.read();
while ( read != -1 ) {
output.write(read);
read = input.read();
}
input.close();
output.close();
} catch (IOException e) {
System.out.println(e);
}
}
字节流复制
public static void FileCopy2(String readfile,String writeFile) {
try {
FileInputStream input = new FileInputStream(readfile);
FileOutputStream output = new FileOutputStream(writeFile);
int read = input.read();
while ( read != -1 ) {
output.write(read);
read = input.read();
}
input.close();
output.close();
} catch (IOException e) {
System.out.println(e);
}
}
处理流复制
public static void FileCopy3(String readfile,String writeFile) {
BufferedReader bReader = null;
BufferedWriter bWriter = null;
String line = null;
try {
bReader = new BufferedReader(new FileReader(new File(readfile)));
bWriter = new BufferedWriter(new FileWriter(new File(writeFile)));
while ((line = bReader.readLine())!=null) {
bWriter.write(line);
bWriter.newLine();
}
bWriter.close();
bReader.close();
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
}
应用:
public static void main(String[] args) {
FileCopy1("res/我.txt", "test/1.txt");
FileCopy2("res/我.txt", "test/2.txt");
FileCopy3("res/我.txt", "test/3.txt");
FileCopy2("res/me.jpg", "test/33.jpg");
}
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