字符流

字符输入流

Reader类常用方法
int read( )
int read(char[] c)
read(char[] c,int off,int len)
void close( )
FileReader(File file)
FileReader(String name)

       //一个字符一个字符的读FileReader fr=new FileReader("a.txt");int tmp;StringBuffer sb=new StringBuffer();while ((tmp = fr.read()) != -1) {sb.append((char)tmp);//读出来的是字符的整数形式 转型}System.out.println(sb.toString());

        FileReader fr=new FileReader("a.txt");char[] c=new char[(int)(new File("a.txt").length())];//获取文件的长度 long类型强制转换int//一次性全部读入fr.read(c);System.out.println(c);//重写了String方法

        //数组长度不等于文件的长度FileReader fr=new FileReader("a.txt");char[] c=new char[5];int tem;while ((tem = fr.read(c)) != -1) {System.out.print(new String(c,0,tem));}

字符输出流

Writer类常用方法
write(String str)
write(String str,int off,int len)
void close()
void flush()
FileWriter (File file)
FileWriter (String name)

        FileReader fr=new FileReader("a.txt");char[] c=new char[(int)(new File("a.txt").length())];fr.read(c);System.out.println(c);FileWriter fw=new FileWriter("b.txt");fw.write(c);fw.close();fr.close();

缓冲流

使用FileReader类与BufferedReader类 提高字符流读取文本文件的效率
使用FileWriter类与BufferedWriter类 提高字符流写文本文件的效率

public static String readBuffer(String path)throws IOException {FileReader fr=new FileReader(path);BufferedReader br=new BufferedReader(fr);//参数是Reader类型String tmp;StringBuilder sb=new StringBuilder();while ((tmp = br.readLine()) != null) {//一行一行的读sb.append(tmp+"\n");}br.close();//后开先关fr.close();//先开后关return sb.toString();}public static void writeBuffer(String path,String s,boolean isAppend)throws IOException{FileWriter fw=new FileWriter(path,isAppend);BufferedWriter bw=new BufferedWriter(fw);bw.write(s);//可以直接字符串做参数bw.close();fw.close();}public static void main(String[] args)throws IOException {String s=readBuffer("a.txt");System.out.println(s);writeBuffer("b.txt",s,true);}

转换流

public static String readCharset(String path)throws IOException{FileInputStream fis=new FileInputStream(path);//设置编码格式InputStreamReader isr=new InputStreamReader(fis,"GBK");BufferedReader br=new BufferedReader(isr);String tmp;StringBuilder sb=new StringBuilder();while ((tmp = br.readLine()) != null) {//一行一行地读sb.append(tmp+"\n");}br.close();isr.close();fis.close();return sb.toString();}public static void writeCharset(String path,String s,boolean isAppend,String charsetName)throws IOException{FileOutputStream fos=new FileOutputStream(path,isAppend);OutputStreamWriter osw=new OutputStreamWriter(fos,charsetName);
//        BufferedWriter bw=new BufferedWriter(osw);
//        bw.write(s);
//        bw.close();osw.write(s);//可以直接用OutputStreamWriterosw.close();fos.close();}public static void main(String[] args)throws IOException {String s=readCharset("a.txt");//已经转换过了System.out.println(s);writeCharset("b.txt",s,true,"UTF-8");}

读写二进制文件

DataInputStream类
FileInputStream的子类
与FileInputStream类结合使用读取二进制文件
DataOutputStream类
FileOutputStream的子类
与FileOutputStream类结合使用写二进制文件

FileInputStream fis=new FileInputStream(inPath);DataInputStream dis=new DataInputStream(fis);byte[] b=new byte[dis.available()];dis.read(b);
//        System.out.println(new String(b));FileOutputStream fos=new FileOutputStream(outPath);DataOutputStream dos=new DataOutputStream(fos);dos.write(b);dos.close();fos.close();dis.close();fis.close();}public static void main(String[] args) throws IOException {copy("D:/IOTest/picture.jpg","picture");}

Java序列化和反序列化

序列化是将对象的状态写入到特定的流中的过程
反序列化则是从特定的流中获取数据重新构建对象的过程

public class Student implements Serializable {//实体类实现序列化接口private int id;private String name;private double score;@Overridepublic String toString() {return "Student{" +"id=" + id +", name='" + name + '\'' +", score=" + score +'}';}public Student(int id, String name, double score) {this.id = id;this.name = name;this.score = score;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getScore() {return score;}public void setScore(double score) {this.score = score;}
}

public static void writeObject(String path, boolean isAppend, Object obj)throws IOException {//先将对象写到文件中FileOutputStream fos=new FileOutputStream(path,false);//创建对象输出流ObjectOutputStream oos=new ObjectOutputStream(fos);oos.writeObject(obj);//装对象oos.close();fos.close();}public static Object readObject(String path) throws IOException, ClassNotFoundException {//读出来FileInputStream fis=new FileInputStream(path);//创建对象输入流ObjectInputStream ois=new ObjectInputStream(fis);Object o=ois.readObject();ois.close();fis.close();return o;}public static void main(String[] args) throws IOException, ClassNotFoundException {Student s=new Student(1,"zz",100);writeObject("obj.txt",true,s);Object o=readObject("obj.txt");if(o instanceof Student){Student stu=(Student)o;System.out.println(stu);}}

总结：
基本流
1、字节流 FileInputStream FileOutputStream
2、字符流
1）FileReader FileWriter
2）缓冲流 BufferedReader BufferedWriter 参数是Reader Writer
3）转换流 InputStreamReader OutputStreamWriter
二进制流
序列化和反序列化
a 65 01000001一个字节 字节–65
字节流
字节流- 转换流 设置编码
utf-8 国际标准 使用三个字节存储一个中文
GBK 中国 使用两个字节存储一个中文
往里面工程下的文件里写 要注意与工程的编码格式一致