3.16Java基础总结 IO全部

I/O全部

in.read 读入
out.write 写出

Java操作流的通用方法
1、创建管道
2、读写操作
3、关闭管道
关闭管道从小到大，全部都关闭，增强代码的健壮性

流的分类：
字节流：InputStream、BufferedInputStream、FileInputStream Out
字符流：Reader、Writer、BufferedReader
对象流：
写入文件→序列化
从文件读取对象，反序列化，产生对象，要实现serializable接口

写操作时，多一步flush操作，冲刷，立即生效
构造加一个true ，从末尾处write

File文件类常用方法
exists isdirectory createNewfile mkdir isFile

常用流new的过程
FileInputStream → BufferedInputStream

FIleOutputStream → BufferedOutputStream → DataOutputStream

File → FileOutputStream → PrintSteam

FileReader → BufferedReader

FileInputStream → InputStreamReader → BufferedReader

package com.io;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
/*I/O流
 
 in,read,读操作,从数据源读，流入
 * 
 */
public class InputStreamTest {
    public static void main(String[] args) {
        //File
        //String filePath
        try {
            InputStream in = new FileInputStream("file/test.txt");
            
//            int i = 0;
//            
//            while(true){
//                if((i = in.read()) != -1){
//                    System.out.println(i);
//                }else{
//                    break;
//                }
//            }
            
            int i = 0;
            byte[] by = new byte[1024];
            while(true){
                if((i = in.read(by)) != -1){
                    
                }else{
                    break;
                }
            }
            
            String info = new String(by);
            
            String [] a = info.split("@");
            
            System.out.println(a[0] + " "  + a[1].trim());
            
            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
}

package com.io;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

public class OutputStreamTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        try {
            OutputStream out = new FileOutputStream("file/test.txt", true);
            String str = "zhangsan@123";
            
            out.write(str.getBytes());
            
            out.flush();//多一步刷新操作
            out.close();
        } catch (FileNotFoundException e) {
            
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

package com.io;

//按字节读取TXT文件
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;




public class ReadByChars {
    public static void main(String[] args) {        
        File file = new File("d:/bankinfo.txt");
        InputStream in = null;
        byte[] tempByte = new byte[1024];
        int byteread = 0;
        try {
            System.out.println("以字节为单位读取文件内容，一次读多个字节：");
            in = new FileInputStream(file);
            while ((byteread = in.read(tempByte)) != -1) {
                System.out.write(tempByte, 0, byteread);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

package com.io;

//按行读取TXT文件

import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.IOException;

public class ReadLine {

    public static void main(String[] args) {
        File file = new File("d:/bankinfo.txt");
        BufferedReader reader = null;
        String tempString = null;
        int line = 1;

        try {
            System.out.println("以行为单位读取文件内容，一次读一整行：");
            reader = new BufferedReader(new FileReader(file));
            while ((tempString = reader.readLine()) != null) {
                System.out.println("Line" + line + ':' + tempString);
                line++;
            }
            reader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

package com.io;

import java.io.*;
  public class DataStreamTest {
      public static void main( String args[] ) {
        int data[] = {100,101,102,103,104,105};
        int t;
        try{
            DataOutputStream out = new  DataOutputStream (new  FileOutputStream("dest.txt"));
            for(int i = 0; i < data.length; i++) 
                out.writeInt(data[i]);
            out.close();
             DataInputStream in = new  DataInputStream (new  FileInputStream("dest.txt"));
             for(int i = 0;i < data.length; i++) {
                 t = in.readInt();
            System.out.print(" "+t);
             }
             System.out.println( );
             in.close();
        }catch(IOException e){
            System.out.println(e.getMessage());}
          }
}

package com.io;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashSet;
import java.util.Set;

/**
 * Date: 2016-3-18-下午2:56:15
 * Class_name: ObjectStreamDemo.java
 * Package_name: com.lovo.demo_17
 * Author: ZhangYue
 * Description: 
 */
public class ObjectStreamDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        
        //ObjectOutputStream
        
        try {
            ObjectOutputStream outObj = new ObjectOutputStream(new FileOutputStream("file/object.txt"));
            
            Student stu1 = new Student("张三", 22, "男");
            Student stu2 = new Student("李四", 24, "男");
            
            Set<Student> stus = new HashSet<Student>();
            stus.add(stu1);
            stus.add(stu2);
            
            outObj.writeObject(stus);
            
            outObj.close();
            
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        
        //ObjectInputStream 
        try {
            ObjectInputStream inObj = new ObjectInputStream(new FileInputStream("file/object.txt"));
            
            Object obj = inObj.readObject();
            
            Set<Student> stu = (Set<Student>)obj;
            
            for(Student su : stu){
                System.out.println(su.getName());
                System.out.println(su.getAge());
                System.out.println(su.getGender());
            }
            
            inObj.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }

}

package com.io;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
//package com.b510.txt;
//d:/bankinfo.txt
/**
 * @author Hongten
 * 读写TXT原码
 * @time 2011-12-12 2011
 */
public class WriteReadTxt {
    public static void main(String[] args) {
        WriteReadTxt myFile = new WriteReadTxt();
        try {
            for (int i = 0; i < 5; i++) {
                myFile.creatTxtFile("b510");
                myFile.writeTxtFile("现在写入数字" + i);
                String str = myFile.readDate();
                System.out.println("*********
" + str);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static String path = "d:/";
    private static String filenameTemp;

    
    // 创建文件
    public static boolean creatTxtFile(String name) throws IOException {
        boolean flag = false;
        filenameTemp = path + name + ".txt";
        File filename = new File(filenameTemp);
        if (!filename.exists()) {
            filename.createNewFile();
            flag = true;
        }
        return flag;
    }


    //写文件
    //newStr
    public static boolean writeTxtFile(String newStr) throws IOException {
        // 先读取原有文件内容，然后进行写入操作
        boolean flag = false;
        String filein = newStr + "
";
        String temp = "";

        FileInputStream fis = null;
        InputStreamReader isr = null;
        BufferedReader br = null;

        FileOutputStream fos = null;
        PrintWriter pw = null;
        try {
            // 文件路径
            File file = new File(filenameTemp);
            // 将文件读入输入流
            fis = new FileInputStream(file);
            isr = new InputStreamReader(fis);
            br = new BufferedReader(isr);
            StringBuffer buf = new StringBuffer();

            // 保存该文件原有的内容
            for (int j = 1; (temp = br.readLine()) != null; j++) {
                buf = buf.append(temp);
                // System.getProperty("line.separator")
                // 行与行之间的分隔符 相当于“
”
                buf = buf.append(System.getProperty("line.separator"));
            }
            buf.append(filein);

            fos = new FileOutputStream(file);
            pw = new PrintWriter(fos);
            pw.write(buf.toString().toCharArray());
            pw.flush();
            flag = true;
        } catch (IOException e1) {
            // TODO 自动生成 catch 块
            throw e1;
        } finally {
            if (pw != null) {
                pw.close();
            }
            if (fos != null) {
                fos.close();
            }
            if (br != null) {
                br.close();
            }
            if (isr != null) {
                isr.close();
            }
            if (fis != null) {
                fis.close();
            }
        }
        return flag;
    }

    /**
     * 读取数据
     */
    public void readData1() {
        try {
            FileReader read = new FileReader(filenameTemp);
            BufferedReader br = new BufferedReader(read);
            String row;
            while ((row = br.readLine()) != null) {
                System.out.println(row);
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public String readDate() {
        // 定义一个待返回的空字符串
        String strs = "";
        try {
            FileReader read = new FileReader(new File(filenameTemp));
            StringBuffer sb = new StringBuffer();
            char ch[] = new char[1024];
            int d = read.read(ch);
            while (d != -1) {
                String str = new String(ch, 0, d);
                sb.append(str);
                d = read.read(ch);
            }
            System.out.print(sb.toString());
            String a = sb.toString().replaceAll("@@@@@", ",");
            strs = a.substring(0, a.length() - 1);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return strs;
    }
}

1、使用字节流将10个学生的成绩写入文件 score.txt
2、使用字符流将这些成绩读取出来,并保存到List集合中
3、创建Student类（姓名、学号、成绩），以成绩集合里的成绩为依据，创建学生对象（姓名、学号自定）
4、使用对象流将所有的学生对象写入文件 student.txt

package com.io.teacher;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Date: 2016-3-18-下午4:03:50
1、使用字节流将10个学生的成绩写入文件 score.txt
2、使用字符流将这些成绩读取出来,并保存到List集合中
3、创建Student类（姓名、学号、成绩），以成绩集合里的成绩为依据，创建学生对象（姓名、学号自定）
4、使用对象流将所有的学生对象写入文件 student.txt
 */
public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        byte[] scores = new byte[10];
        scores[0] = 40;
        scores[1] = 50;
        scores[2] = 60;
        scores[3] = 70;
        scores[4] = 80;
        scores[5] = 90;
        scores[6] = 100;
        scores[7] = 110;
        scores[8] = 120;
        scores[9] = 121;
        
        //存入成绩
        StudentStream.saveScore(scores, "file/score.txt");
        
        //读出成绩
        byte[] scors = StudentStream.readScore("file/score.txt");
        
        //装入List
        List<Integer> scoreList = new ArrayList<Integer> ();
        for(int i = 0; i < scors.length; i++){
            scoreList.add((int)scors[i]);
        }
        
        Set<Student> stus = new HashSet<Student>();    
        
        //以成绩为依据创建学生对象
        for(Integer in : scoreList){
            stus.add(new Student("张三" + in, in*2 , in));
//            System.out.println(in);
        }
        
        //对象流将学生对象写入文件student.txt
        StudentStream.saveStudents(stus, "file/student.txt");
    }

}

package com.io.teacher;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.util.Set;

/**
 * Date: 2016-3-18-下午4:00:53
 * Class_name: StudentStream.java
 * Package_name: com.lovo.demo_17_2
 * Author: ZhangYue
 * Description: 
 */
public class StudentStream {

    
    public static void saveScore(byte[] scores, String filePath){
        
        try {
            File file = new File(filePath);
    
            if(!file.exists()){
                file.createNewFile();
            }
            
            OutputStream out = new FileOutputStream(file);
            out.write(scores);
            out.close();
            
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static byte[] readScore(String filePath){
        byte[] by = new byte[20];
        
        try {
            File file = new File(filePath);
            
            if(!file.exists()){
                file.createNewFile();
            }
            
            InputStream in = new FileInputStream(file);
            
            int count = in.available();
            
            by = new byte[count];
            
            in.read(by);
            
            in.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        return by;
    }
    
    public static void saveStudents(Set<Student> stus, String filePath){
        try {
            File file = new File(filePath);
            
            if(!file.exists()){
                file.createNewFile();
            }
            
            ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(file));
            
            out.writeObject(stus);
            
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

package com.io.teacher;



import java.io.Serializable;

public class Student implements Serializable{

    private String name;
    private int number;
    private int score;
    
    public Student() {
        super();
    }

    public Student(String name, int number, int score) {
        super();
        this.name = name;
        this.number = number;
        this.score = score;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    public int getScore() {
        return score;
    }

    public void setScore(int score) {
        this.score = score;
    }
    
    
    
}