Android-IO流之文件输入输出字节流FileInputStream/FileOutputStream

目录

4. FileInputStream/FileOutputStream
   --4.1 FileOutputStream文件输出流
   --4.2 FileInputStream文件输入流
   --4.3 使用FileInputStream和FileOutputStream进行拷贝

4.FileInputStream/FileOutputStream

4.1 FileOutputStream文件输出流

1.FileOutputStream常用构造方法

public FileOutputStream(File file)
public FileOutputStream(File file, boolean append) //append为true则会在原来文件的基础上写，而不会覆盖。

2.重要方法

void write(byte[] b)
void write(byte[] b, int off, int len)
void write(int b)

3.使用FileOutputStream写文件

File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录
File saveFile = new File(sdCardDir, "a.txt");

FileOutputStream outStream = null;
try{
   outStream = new FileOutputStream(saveFile);
   outStream.write("test".getBytes());
}catch (Exception e) {
   e.printStackTrace();
}finally {
  if(outStream!=null){
     outStream.close();
  }
}

4.2 FileInputStream文件输入流

1. FileInputStream常用构造方法

public FileInputStream(String name)
public FileInputStream(File file)

2.重要方法

public int read() //返回读取的下一个字节 如果没有返回-1
public int read(byte b[]) //返回读取的总字节数，没有返回-1
public int read(byte b[], int off, int len) //返回读取的总字节数，没有返回-1

3.使用FileInputStream读文件

File sdCardDir = Environment.getExternalStorageDirectory();//获取SDCard目录
File saveFile = new File(sdCardDir, "a.txt");

FileInputStream fis = null;
try {
    fis = new FileInputStream(saveFile);
    byte[] buffer = new byte[1024];
    int len = -1;
    StringBuilder sb = new StringBuilder();
    while ((len = fis.read(buffer)) != -1) {
       sb.append(new String(buffer,0,len));
    }
    Log.d("xl", sb.toString());
} catch (Exception e) {
    e.printStackTrace();
}finally {
    if(fis!=null){
        fis.close();
    }
}

4.3 使用FileInputStream和FileOutputStream进行拷贝

File dir = Environment.getExternalStorageDirectory();
File file = new File(dir, "abc.txt");
File dst = new File(dir, "dst.text");

//进行拷贝
FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(dst);
int len = -1;
byte[] buffer = new byte[1024];
while ((len = fis.read(buffer)) != -1) {
    fos.write(buffer, 0, len);
}
fis.close();
fos.close();