java——IO流

public void deleteFile(File file){
//分析：
//1.首先判断该路径file是否存在，如果不存在，即终止删除程序，如果存在，进行第2步：
//2.判断路径file是文件还是文件夹，若为文件，则直接删除，若为文件夹，则进入第3布：
//3.判断文件夹是否为空，若为空，直接删除该文件夹
//4.若不为空，则记录文件夹下所有文件列表，利用for-each与递归算法删除所有内容，最后删除该文件夹本身
if(!file.exists()){
return;
}
if(file.isFile()){
file.delete();
System.out.println("正在删除文件："+file.getAbsolutePath());
return;
}
if(file.isDirectory()){
if(file.list().length==0){
file.delete();
System.out.println("正在删除文件夹："+file.getAbsolutePath());
return;
}
File[] file1 = file.listFiles();
for(File f:file1){
deleteFile(f);
}
file.delete();
}
}

public void getCountTest() throws IOException{
//注意：两个流不能同时访问同一个文件！
//DataOutputStream data1 = new DataOutputStream(new FileOutputStream(file));
//该数据输出流每执行一次都会将原file路径下文件内容刷新一次（即覆盖）
File file = new File("E:/count");
if(!file.exists()){//判断file路径是否存在
file.createNewFile();//创建file路径指定的文件count
}
DataInputStream data = new DataInputStream(new FileInputStream(file));
int x;
try {
x=data.readInt();
data.close();
} catch (EOFException e) { //若x=data.readInt();读不到数据(如果此输入流在读取这四个字节之前到达末尾)，则会抛出EOFException异常
data.close();//在使用输出对象data1之前关闭输入管道，避免同时操作
DataOutputStream data1 = new DataOutputStream(new FileOutputStream(file));
data1.writeInt(1);
data1.flush();
data1.close();
System.out.println("程序第"+1+"次运行");
return;
}
DataOutputStream data1 = new DataOutputStream(new FileOutputStream(file));
data1.writeInt(++x);
System.out.println("程序第"+x+"次运行");
data1.flush();
data1.close();
}

@Test
public void testCopy() throws IOException {
File file1 = new File("E:\\");
File file2 = new File("E:\\Desktop\\饮水机项目_20161221_4");
copyOne(file1,file2);
}
public void copyOne(File file1,File file2) throws IOException{
if(!file2.exists()){
return;
}
if(file2.isFile()){
InputStream in = new FileInputStream(file2);
OutputStream out = new FileOutputStream(new File(file1,file2.getName()));
byte[] b = new byte[1024*1024];
int len=-1;
while((len=in.read(b))!=-1){
out.write(b,0,len);
}
in.close();
out.flush();
out.close();
return;
}
if(file2.isDirectory()){
File temp = new File(file1,file2.getName());
temp.mkdir();
if(file2.list().length==0){
return;
}
File[] fi = file2.listFiles();
for(File f:fi){
copyOne(temp,f);
}
}
}

@Test
public void codeChange() throws Exception{
//桥接流：字节流通向字符流的桥接流
InputStreamReader in = new InputStreamReader(
new FileInputStream("E:/my.java"),"GBK"); //解码
//桥接流：字符流通向字节流的桥接流
OutputStreamWriter out = new OutputStreamWriter(
new FileOutputStream("E:/your.java"),"UTF-8"); //编码
int k = -1;
while((k=in.read())!=-1){
out.write(k);
}
in.close();
out.flush();
out.close();
}
@Test //通过桥接字符流的便捷流(子类流)FileReader和FileWriter来快速实现
public void codeChange2() throws Exception{
FileReader in = new FileReader("E:/my.txt"); //解码
FileWriter out = new FileWriter("E:/your.txt"); //编码
int k = -1;
while((k=in.read())!=-1){
out.write(k);
}
in.close();
out.flush();
out.close();
}

//方法一：
@Test
public void scannerTest() throws Exception{
Scanner scanner = new Scanner(System.in);
PrintWriter out = new PrintWriter("E:/myWrite");
String line = null;
while(!(line=scanner.nextLine()).equals("exit")){
out.println(line);
}
scanner.close();
out.flush();
out.close();
}
//方法二：
@Test
public void bufferedReaderTest() throws Exception{
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
PrintWriter out = new PrintWriter("E:/myWrite");
String line = null;
while(!(line=in.readLine()).equals("exit")){
out.println(line);
}
in.close();
out.flush();
out.close();
}

private static int count;
@Test
public void testGetAllCount() throws Exception{
File file = new File("D:/workspace/Test");
getAllCount(file);
System.out.println(count);
}
public void getAllCount(File file) throws Exception{
if(!file.exists()){
return;
}
if(file.isFile()){
BufferedReader buffer = new BufferedReader(
new InputStreamReader(new FileInputStream(file)));
String line=null;
while((line=buffer.readLine())!=null){
if(line.trim().length()!=0){
count++;
}
}
buffer.close();
}
if(file.isDirectory()){
for(File f:file.listFiles()){
getAllCount(f);
}
}
}