69期-Java SE-021-IO流-2-001-002

Writer 常用方法

```java
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

public class Test {
    public static void main(String[] args) {
        File file = new File("/Users/southwind/Desktop/test.txt");
        try {
            Writer writer = new FileWriter(file);
//            writer.write(20320);
//            writer.write(22909);
//            writer.write("你好");
//            char[] chars = {'你','好','世','界'};
//            writer.write(chars,2,2);
            writer.write("你好HelloWorld", 2, 2);
            writer.flush();
            writer.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
}
```



### 处理流

FileReader 继承自 InputStreamReader，即输入转换流，通过这个类可以将字节流转为字符流，字节是基本单位，相当于基础管道，同理，FileWriter 继承自 OutputStreamWriter。

InputStreamReader 和 OutputStreamWriter 分别是 Reader 和 Writer 的子类。

```java
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class Test2 {
    public static void main(String[] args) {
        try {
            //基础的字节输入流
            InputStream inputStream = new FileInputStream("/Users/southwind/Desktop/test.txt");
            //添加处理流
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            char[] chars = new char[1024];
            int length = inputStreamReader.read(chars);
            System.out.println(chars);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
```



```java
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

public class Test3 {
    public static void main(String[] args) {
        String str = "你好 世界 Hello World";
        File file = new File("/Users/southwind/Desktop/test2.txt");
        try {
            OutputStream outputStream = new FileOutputStream(file);
            OutputStreamWriter outputStreamWriter = new OutputStreamWriter(outputStream);
            Writer writer = outputStreamWriter;
            writer.write(str);
            writer.flush();
            writer.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
```



### 缓冲流

输入缓冲流

字节输入缓冲流：BufferedInputStream

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

public class Test4 {
    public static void main(String[] args) {
        File file = new File("/Users/southwind/Desktop/test.txt");
        InputStream inputStream;
        try {
            inputStream = new FileInputStream(file);
            BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
//            int temp = 0;
//            while((temp = bufferedInputStream.read())!=-1) {
//                System.out.println(temp);
//            }
            byte[] bytes = new byte[1024];
            int length = bufferedInputStream.read(bytes,10,10);
            for(byte byt:bytes) {
                System.out.println(byt);
            }
            bufferedInputStream.close();
            inputStream.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
```



字符输入缓冲流 BufferedReader

```java
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class Test5 {
    public static void main(String[] args) {
        File file = new File("/Users/southwind/Desktop/test.txt");
        try {
            Reader reader = new FileReader(file);
            BufferedReader bufferedReader = new BufferedReader(reader);
//            String str = "";
//            while((str = bufferedReader.readLine())!=null) {
//                System.out.println(str);
//            }
//            int temp = 0;
//            while((temp = bufferedReader.read())!=-1) {
//                System.out.println(temp);
//            }
            char[] chars = new char[1024];
            int length = bufferedReader.read(chars,10,10);
            for(char cha:chars) {
                System.out.println(cha);
            }
            bufferedReader.close();
            reader.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
```



输出缓冲流

字节输出缓冲流 BufferedOutputStream

```java
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class Test6 {
    public static void main(String[] args) {
        File file = new File("/Users/southwind/Desktop/test2.txt");
        try {
            OutputStream outputStream = new FileOutputStream(file);
            BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);
            String str = "20世纪90年代，硬件领域出现了单片式计算机系统，这种价格低廉的系统一出现就立即引起了自动控制领域人员的注意，因为使用它可以大幅度提升消费类电子产品（如电视机顶盒、面包烤箱、移动电话等）的智能化程度。";
            byte[] bytes = str.getBytes();
            bufferedOutputStream.write(bytes,10,10);
            bufferedOutputStream.flush();
            bufferedOutputStream.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
}
```