Java 图片或文件与byte数组互相转换，文件读取工具类

package mblog.base.utils.niuqi;

import javax.imageio.stream.FileImageInputStream;
import javax.imageio.stream.FileImageOutputStream;
import java.io.*;
import java.util.UUID;

/**
 * @author SongBin on 2018/7/6.
 */
public class CommonUtil {
    public static String getUID(){
        UUID uuid = UUID.randomUUID();
        return uuid.toString();
    }

    //图片到byte数组
    public static byte[] image2byte(File filePath){
        byte[] data = null;
        FileImageInputStream input = null;
        try {
            input = new FileImageInputStream(filePath);
            ByteArrayOutputStream output = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            int numBytesRead = 0;
            while ((numBytesRead = input.read(buf)) != -1) {
                output.write(buf, 0, numBytesRead);
            }
            data = output.toByteArray();
            output.close();
            input.close();
        }
        catch (FileNotFoundException ex1) {
            ex1.printStackTrace();
        }
        catch (IOException ex1) {
            ex1.printStackTrace();
        }
        return data;
    }
    //byte数组到图片
    public static void byte2image(byte[] data,String path){
        if(data.length<3||path.equals("")) return;
        try{
            FileImageOutputStream imageOutput = new FileImageOutputStream(new File(path));
            imageOutput.write(data, 0, data.length);
            imageOutput.close();
            System.out.println("Make Picture success,Please find image in " + path);
        } catch(Exception ex) {
            System.out.println("Exception: " + ex);
            ex.printStackTrace();
        }
    }

    //文件到byte数组
    public static byte[] file2byte(File filePath){
        byte[] data = null;
        FileInputStream input = null;
        try {
            input = new FileInputStream(filePath);
            ByteArrayOutputStream output = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            int numBytesRead = 0;
            while ((numBytesRead = input.read(buf)) != -1) {
                output.write(buf, 0, numBytesRead);
            }
            data = output.toByteArray();
            output.close();
            input.close();
        }
        catch (FileNotFoundException ex1) {
            ex1.printStackTrace();
        }
        catch (IOException ex1) {
            ex1.printStackTrace();
        }
        return data;
    }
    //byte数组到文件
    public static void byte2file(byte[] data,String path){
        if(data.length<3||path.equals("")) return;
        try{
            FileImageOutputStream imageOutput = new FileImageOutputStream(new File(path));
            imageOutput.write(data, 0, data.length);
            imageOutput.close();
            System.out.println("Make Picture success,Please find image in " + path);
        } catch(Exception ex) {
            System.out.println("Exception: " + ex);
            ex.printStackTrace();
        }
    }
    //byte数组到16进制字符串
    public static String byte2string(byte[] data){
        if(data==null||data.length<=1) return "0x";
        if(data.length>200000) return "0x";
        StringBuffer sb = new StringBuffer();
        int buf[] = new int[data.length];
        //byte数组转化成十进制
        for(int k=0;k<data.length;k++){
            buf[k] = data[k]<0?(data[k]+256):(data[k]);
        }
        //十进制转化成十六进制
        for(int k=0;k<buf.length;k++){
            if(buf[k]<16) sb.append("0"+Integer.toHexString(buf[k]));
            else sb.append(Integer.toHexString(buf[k]));
        }
        return "0x"+sb.toString().toUpperCase();
    }

    //读取文件内容转为字符串
    public String fileRead(String filePath) throws Exception {
        InputStream input = new FileInputStream(filePath);
        String charset = "utf-8";
        BufferedReader reader = new BufferedReader(new InputStreamReader(input,charset));
        StringBuilder sb = new StringBuilder();
        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return sb.toString();
    }
}

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