Java IO流

IO流

1. FileInputStream/FileOutputStream

public class FileInputStreamTest {    public static void main(String[] args) throws IOException {        //创建字节输入流        FileInputStream fis = new FileInputStream("E:\\20160928JavaBase\\Test\\aaa\\qqq.txt");        //创建一个长度为1024的“竹筒”        byte[] bbuf = new byte[1024];        //用于保存实际读取的字节数        int hasRead = 0;        //使用循环来重复“取水”的过程        while((hasRead = fis.read(bbuf)) > 0){            //取出“竹筒”中的水滴（字节），将字节数组转换成字符串输入！            System.out.print(new String(bbuf,0,hasRead));        }        fis.close();    }

public class FileOutputStreamTest {    public static void main(String[] args) throws IOException{        FileInputStream fis = null;        FileOutputStream fos = null;        try {            fis = new FileInputStream("E:\\20160928JavaBase\\Test\\aaa\\qqq.txt");            fos = new FileOutputStream("E:\\20160928JavaBase\\Test\\bbb\\qqq.txt");            byte[] bbuf = new byte[32];            int hasRead = 0;            while((hasRead = fis.read(bbuf))>0){                //每读取一次，即写入文件输出流，读了多少，就写了多少                fos.write(bbuf, 0, hasRead);            }        }finally{            if(fis != null){                fis.close();            }            if(fos != null){                fos.close();            }        }    }}

public static void main(String[] args) throws IOException{        FileInputStream in = null;        FileOutputStream out = null;        String fatherPath = "E:\\20160928JavaBase\\Test\\";        //来源文件：读取内容        in = new FileInputStream(fatherPath+"aaa\\qqq.txt");        //目标文件：写入内容        out = new FileOutputStream(fatherPath+"bbb\\qqq.txt");        //按字节读取        byte[] bytearray = new byte[1024];        try {            do{                in.read(bytearray,0,1024);                out.write(bytearray);            }while(in.available() > 0);            System.out.println("执行完毕！");        } finally{            if(in != null){                in.close();            }            if(out != null){                out.close();            }        }

2. FileReader/FileWriter

public class FileReaderTest {    public static void main(String[] args) throws IOException {        FileReader fr = null;        try {            fr = new FileReader("E:\\20160928JavaBase\\Test\\aaa\\qqq.txt");            char[] cbuf = new char[32];            int hasRead = 0;            while((hasRead = fr.read(cbuf))>0){                System.out.print(new String(cbuf, 0, hasRead));            }        }finally{            if(fr != null){                fr.close();            }        }    }}

public class FileWriterTest {    public static void main(String[] args) throws IOException{        FileWriter fw = null;        try {            fw = new FileWriter("E:\\20160928JavaBase\\Test\\aaa\\qqqq.txt");            fw.write("你好！\r\n");            fw.write("你dsc好！\r\n");            fw.write("你好ererer！\r\n");            fw.write("你好erererer！\r\n");            fw.write("你好ererererere！\r\n");        } finally{            if(fw != null){                fw.close();            }        }    }}

3. PrintStream

public class PrintStreamTest {    public static void main(String[] args) throws IOException {        PrintStream ps = null;        try {            //创建一个节点输出流：FileOutStream            FileOutputStream fos = new FileOutputStream("E:\\20160928JavaBase\\Test\\aaa\\test.txt");            //以PrintStream 来包装 FileOutputStream            ps = new PrintStream(fos);            //使用PrintStream执行输出            ps.println("普通字符串");            //直接使用PrintStream输出对象            ps.println(new PrintStreamTest());        }finally{            ps.close();        }    }}

package com.hz.practice;import java.io.BufferedInputStream;import java.io.BufferedReader;import java.io.FileOutputStream;import java.io.IOException;import java.io.PrintStream;/** * 处理流：输出很强势 * @author ztw * */public class Test03 {    public static void main(String[] args) throws IOException {        PrintStream ps = null;        try {            FileOutputStream fos = new FileOutputStream("E:\\20160928JavaBase\\Test\\aaa\\eee.txt");            ps = new PrintStream(fos);            ps.println("普通字符串");            ps.println(new Test03());        } finally{            ps.close();        }    }}

3. RandomAccessFile

public class RandomAccessFileTest {    public static void main(String[] args) {        File file = new File("E:\\20160928JavaBase\\Test01\\gg\\bbb.txt");        try {            randomAccessFile(file);        } catch (IOException e) {            e.printStackTrace();        }    }    public static void randomAccessFile(File file) throws IOException {        RandomAccessFile raf = null;        try {            raf = new RandomAccessFile(file, "rw");//"rw"读写权限            System.out.println("文件指针的位置，初始位置为0:"+raf.getFilePointer());            //指针移动到什么位置            raf.seek(5);            byte[] bbuf = new byte[1024];            int hasRead = 0;            while((hasRead = raf.read(bbuf))>0){                System.out.println(new String(bbuf,0,hasRead));            }            raf.seek(raf.length());            raf.write("你好我的世界".getBytes());        } finally{            if(raf != null){                raf.close();            }        }    }}

public class InsertContent {    public static void main(String[] args) {        try {            insert("E:\\20160928JavaBase\\Test01\\gg\\bbb.txt", 5, "世界你好");        } catch (IOException e) {            e.printStackTrace();        }    }    public static void insert(String file,long pos,String content) throws IOException {        RandomAccessFile raf = null;        //定义一个临时存储文件        File tmp = File.createTempFile("tmp", null);        FileInputStream tmpFis = null;        FileOutputStream tmpFos = null;        //当JVM结束就自动删除文件        tmp.deleteOnExit();        try {            raf = new RandomAccessFile(file, "rw");            tmpFis = new FileInputStream(tmp);            tmpFos = new FileOutputStream(tmp);            //获取要插入的指针位置            raf.seek(pos);            byte[] bbuf = new byte[63];            int hasRead = 0;            while((hasRead = raf.read(bbuf)) > 0 ){                tmpFos.write(bbuf, 0, hasRead);            }            //插入内容            //又获取到要插入的指针位置            raf.seek(pos);            //追加内容            raf.write(content.getBytes());            while((hasRead = tmpFis.read(bbuf)) > 0){                raf.write(bbuf, 0, hasRead);            }        } finally{                raf.close();        }    }}

4. InputStreamReader

package com.hz.practice;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;public class KeyinTest {    public static void main(String[] args) {        BufferedReader br = null;        try {            //将System.in对象转换成Reader对象            InputStreamReader reader = new InputStreamReader(System.in);            //将普通的Reader包装成BufferedReader            br = new BufferedReader(reader);            String buffer = null;            //采用循环方式来一行一行的读取            while((buffer = br.readLine()) != null){                //如果读取的字符串为“exit”,程序退出                if(buffer.equals("exit")){                    System.exit(1);                }                //打印读取内容                System.out.println("输入内容为：" + buffer);            }        } catch (Exception e) {            e.printStackTrace();        }finally{            try {                br.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}

5. InputStreamReader

package com.hz.practice;import java.io.BufferedReader;import java.io.InputStreamReader;/** * Java虚拟机读写其他进程的数据 * @author ztw * */public class ReadFromProcess {    public static void main(String[] args) {        BufferedReader br = null;        try {            //运行javac命令，返回运行该命令的子进程            Process p = Runtime.getRuntime().exec("javac ReadFromProcess.java");            br = new BufferedReader(new InputStreamReader(p.getErrorStream()));            String buffer = null;            while((buffer = br.readLine())!= null){                System.out.println(buffer);            }        } catch (Exception e) {            e.printStackTrace();        }finally{            try {                if(br != null){                    br.close();                }            } catch (Exception e2) {                // TODO: handle exception            }        }    }}

6. ObjectOutputStream/ObjectInputStream

package com.hz.test;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;import java.io.Serializable;public class Person implements Serializable{//Serializable序列化    private String name;    private int age;    public Person(String name, int age) {        super();        this.name = name;        this.age = age;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    private void writeObject(ObjectOutputStream out) throws IOException {        out.writeObject(new StringBuffer(name).reverse());        out.writeInt(age);    }    private void readObject(ObjectInputStream in) throws IOException,ClassNotFoundException {        this.name = ((StringBuffer)in.readObject()).reverse().toString();        this.age = in.readInt();    }}

package com.hz.test;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectInputStream;import java.io.ObjectOutputStream;public class PersonSerialible {    public static void main(String[] args) {        ObjectOutputStream fos = null;        ObjectInputStream fis = null;        try {            fos = new ObjectOutputStream(new FileOutputStream("test.txt"));            Person p = new Person("张三", 15);            fos.writeObject(p);            fis = new ObjectInputStream(new FileInputStream("test.txt"));            Person p2 = (Person) fis.readObject();            System.out.println(p2.getName()+p2.getAge());        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } catch (ClassNotFoundException e) {            e.printStackTrace();        }finally{            if(fos != null){                try {                    fos.close();                    fos = null;                } catch (IOException e) {                    e.printStackTrace();                }            }            if(fis != null){                try {                    fis.close();                    fis = null;                } catch (IOException e) {                    e.printStackTrace();                }            }        }    }}

7. FileChannel(新版本后的流)

public class FileChannelTest {    public static void main(String[] args) {        FileChannel inChannel = null;        FileChannel outChannel = null;        try {            File f = new File("E:\\20160928JavaBase\\Test\\ccc\\FileChannelTest.txt");            inChannel = new FileInputStream(f).getChannel();            MappedByteBuffer buffer = inChannel.map(FileChannel.MapMode.READ_ONLY, 0, f.length());            Charset charset = Charset.forName("GBK");            outChannel = new FileOutputStream("a.txt").getChannel();            //直接将buffer里的数据全部输出            outChannel.write(buffer);            buffer.clear();            //创建解码器（CharsetDecoder）对象            CharsetDecoder decoder = charset.newDecoder();            //使用解码器将ByteBuffer转换成CharBuffer            CharBuffer charBuffer = decoder.decode(buffer);            //CharBuffer的toString方法可以获取对应的字符串            System.out.println(charBuffer);        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }finally{            try {                if(inChannel !=null){                    inChannel.close();                }                if(outChannel != null){                    outChannel.close();                }            } catch (IOException e) {                e.printStackTrace();            }        }    }}

package com.hz.test;import java.nio.charset.Charset;import java.util.Properties;import java.util.SortedMap;/** * 获取JDK所支持的全部字符 * @author ztw * */public class CharsetTest {    public static void main(String[] args) {        SortedMap<String,Charset> map = Charset.availableCharsets();        for (String alias : map.keySet()) {            System.out.println(alias + "------>"+map.get(alias));        }        Properties name = System.getProperties();        System.out.println(name);    }}