首先, 其实应该把标题改为——给任意图片右上角套上红色消息数目框;

代码如下:

//主程序:

package cn.sourcecodes.main;

import cn.sourcecodes.utils.DecorationUtil;

import javax.imageio.ImageIO;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Scanner;

/**

* Created by cn.sourcecodes on 2016/11/26.

*/

public class DecoratePicture {

public static final String OUTPUT_DIRECTORY = "d://decoratedPictures/";

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

//如果输出文件夹不存在, 创建它

File dir = new File(DecoratePicture.OUTPUT_DIRECTORY);

if(!dir.exists()) {

System.out.println("not exist");

dir.mkdir();

}

boolean isQuit = false;

while(!isQuit) {

String inputPath;

String messageNum;

System.out.println("请输入文件路径如(d://test/test.jpg, 开头盘符后必须接 // 否则生成文件文件名不规范)");

inputPath = input.nextLine();

System.out.println("请输入消息数: ");

messageNum = input.nextLine();

File file = new File(inputPath);

try {

BufferedImage sourceImage = ImageIO.read(file);

DecorationUtil.getAfterCombine(Integer.valueOf(messageNum), sourceImage);

String outputPath = DecoratePicture.OUTPUT_DIRECTORY + "decorated_" + getFileName(inputPath);//输出文件路径

OutputStream output = new FileOutputStream(outputPath);

String format = getFileName(inputPath).split("\\.")[1]; //获取文件格式名, 比如 jpg

ImageIO.write(sourceImage, format, output);

output.close();

System.out.println("quit 退出, 任意字符继续");

String action = input.nextLine();

if(action.equals("quit")) {

isQuit = true;

}

} catch (IOException e) {

System.out.println("文件不存在");

} catch (NumberFormatException e) {

System.out.println("输入的不是数字");

} catch (Exception e) {

System.out.println("未知异常");

}

}

}

//获取传入文件的文件名

public static String getFileName(String path) {

String temp = path.substring(4); //去掉前面盘符, 如: d://

//分割获取最后一个,就是文件名

String[] splitTemp = temp.split("/");

String fileName = splitTemp[splitTemp.length-1];

return fileName;

}

}

//工具类 package cn.sourcecodes.utils;

import java.awt.*;

import java.awt.font.FontRenderContext;

import java.awt.geom.Ellipse2D;

import java.awt.geom.Rectangle2D;

import java.awt.image.BufferedImage;

/**

* Created by cn.sourcecodes on 2016/11/26.

*/

public class DecorationUtil {

public static void getAfterCombine(int messageNum, BufferedImage bufferedImage) {

int pictureWidth = bufferedImage.getWidth();

int pictureHeight = bufferedImage.getHeight();

Graphics2D graphics2D = bufferedImage.createGraphics();

BufferedImage messageImage = getMessageCircle(messageNum, pictureWidth, pictureHeight);

int diameter;

//消息圆圈直径为宽或者高的 1/3

if(pictureWidth < pictureHeight) {

diameter = pictureWidth / 3;

} else {

diameter = pictureHeight / 3;

}

int hideSize = diameter / 20; //右边和上边隐藏的像素

graphics2D.drawImage(messageImage, null, (pictureWidth + hideSize - diameter), -hideSize);

}

//圆框的bufferedImage, 需要传入显示的消息数, 原图片宽高

public static BufferedImage getMessageCircle(int messageNum, int pictureWidth, int pictureHeight) {

String numberStr;

if(messageNum > 99) {

numberStr = "99+";

} else if(messageNum < 0) {

numberStr = "0";

} else {

numberStr = String.valueOf(messageNum);

}

int diameter;

//消息圆圈直径为宽或者高的 1/3

if(pictureWidth < pictureHeight) {

diameter = pictureWidth / 3;

} else {

diameter = pictureHeight / 3;

}

//这样构造的bufferedImage背景是黑色的

BufferedImage bufferedImage = new BufferedImage(diameter, diameter, BufferedImage.TYPE_3BYTE_BGR);

Graphics2D g2d = bufferedImage.createGraphics();

//背景透明的bufferedImage

bufferedImage = g2d.getDeviceConfiguration().createCompatibleImage(diameter, diameter, Transparency.TRANSLUCENT);

g2d.dispose();//释放

//下面开始画消息框

Graphics2D graphics2D = bufferedImage.createGraphics();

//先画红色圆圈

graphics2D.setPaint(Color.RED);

Ellipse2D ellipse = new Ellipse2D.Double(0, 0, diameter, diameter);

graphics2D.fill(ellipse);

//画消息, 消息要画在正中间

int fontSize = diameter / 2; //字体大小为直径 2/6

Font font = new Font("SansSerif", Font.PLAIN, fontSize);

graphics2D.setFont(font);

//获取包含字符串 numberStr 的矩形, 通过它来获取字符串占的宽高

FontRenderContext context = graphics2D.getFontRenderContext();

Rectangle2D bounds = font.getStringBounds(numberStr, context);

double x = (diameter - bounds.getWidth()) / 2;

double y = (diameter - bounds.getHeight()) / 2;

double acsent = -bounds.getY(); //上坡度;

double baseY = y + acsent;

//画消息

graphics2D.setPaint(Color.WHITE);

graphics2D.drawString(numberStr, (int)x, (int)baseY);

graphics2D.dispose();

return bufferedImage;

}

}