java用文件流实现查看下载次数

需求： 点击一个按钮的次数或者是展示文件，游戏被下载的次数

实现： 开辟一个流文件，用来保存被下载的次数，然后读文件中value，点击一次value加1，再将此value保存到流文件中。
三种方法：

package cn.tr.test;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;

public class TestDemo {

    private static int in ;
    private static File file;

    public static void main(String[] args) {

        fun2();
    }

    public static void fun(){
        /** 初始化文件中的值为0*/
        try {
            OutputStream out = new FileOutputStream(file);
            String str = "00";
            out.write(str.getBytes());
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
    public static void fun2() {

        file= new File("d:/test/d.txt");
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        try {
            /** 读取文件中的内容 */
            if (file.exists()&&file.length()==0) {
                fun();
            }
            InputStream is = new FileInputStream(file);
            byte b[] = new byte[(int) file.length()];
            for (int i = 0; i < b.length; i++) {
                // 值字节在0-255 范围之内是作为int 来返回的
                b[i] = (byte) is.read();
            }
            in =Integer.parseInt(new String(b));
            in++;
            System.out.println("读出来的"+in);

            /**再写入到文件中 */
            OutputStream out = new FileOutputStream(file);
            String str = String.valueOf(in);
            byte[] bytes = str.getBytes();
            for (int i = 0; i < bytes.length; i++) {
                out.write(bytes[i]);   // 一个字节一个字节的写入
            }
            is.close();
            out.close();
            System.out.println("写入的"+in);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void fun3(){

        file= new File("d:/test/d.txt");
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        /** 先读出来*/
        try {
            if (file.exists()&&file.length()==0) {
                fun();
            }
            Reader reader = new FileReader(file);
            char[] c = new char[(int)file.length()];
            int temp = 0;
            int len =0;
            while((temp=reader.read()) != -1){
                c[len]=(char)temp;
                len++;
            }
            reader.close();
            System.out.println("初始值"+new String(c,0,len));
            in =Integer.parseInt(new String(c,0,len));
            in++;
            System.out.println("下载一次："+in);
        /** 再写进去*/
            Writer writer = new FileWriter(file);
            writer.write(in+"");
            writer.close();
            System.out.println("再写进去："+in);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void fun4(){
        Reader reader;  
        Writer writer;
        file= new File("d:/test/d.txt");
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        try {
            if (file.exists()&&file.length()==0) {
                fun();
            }
            /** 读出来*/
            reader = new FileReader(file);
            BufferedReader br = new BufferedReader(reader);
            char [] c = new char[(int)file.length()];
            int len = 0;
            int temp = 0;
            while((temp=br.read())!= -1){
                c[len]=(char)temp;
                len++;
            }

            in =Integer.parseInt(new String(c, 0, len));
            in++;
            System.out.println("读出来："+ in);
            /** 写进去*/
            writer =new FileWriter(file);
            BufferedWriter bw = new BufferedWriter(writer);
            bw.write(in+"");
            System.out.println("写进去："+in);
            br.close();
            bw.close();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }   

}