java 给图片加文字水印

java给图片加水印，在网上有很多资料，但我想要一个能自适应图片大小，将水印加在图片中间或右下角，这个问题我觉得应该是一个算法的问题
得根据图片大小调整水印文字的字体大小，及显示缩进比例

package com.jc.ts.services;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.ImageFormatException;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
 *添加图片水印的服务类
 * */
public class WaterMark {
  /**
   * @param sizeContext添加水印文字
   * @param request 请求流对象
   * @param request 响应流对象
   * */
   @SuppressWarnings("deprecation")
 public   static   void  createMarkSize(String sizeContext,HttpServletRequest request,HttpServletResponse response)   {
    try {
     String path=request.getRealPath(request.getServletPath());
     FileInputStream in=new FileInputStream(path);
     Image src=ImageIO.read(in);
     int w=src.getWidth(null);
     int h=src.getHeight(null);
     BufferedImage img=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);//构建画板
     Graphics g=img.getGraphics();//得到画笔
     g.drawImage(src,0,0,w,h,null);//把源图片写入画板
     g.setColor(Color.red);
     g.drawString(sizeContext,10,5);  // 添加文字
     g.dispose();//生成图片
     JPEGImageEncoder e=JPEGCodec.createJPEGEncoder(response.getOutputStream());
     e.encode(img);
     response.getOutputStream().close();
  } catch (FileNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (ImageFormatException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
  /** 
    * @param localPath 添加水印LOGO路径
    * @param request 请求流对象
    * @param request 响应流对象
    **/
    @SuppressWarnings("deprecation")
  public   static   void  createMarkLogo(String localPath,HttpServletRequest request,HttpServletResponse response)   {
     try {
      FileInputStream file=new FileInputStream(localPath);
      Image fimg=ImageIO.read(file);
      int fw=fimg.getWidth(null);
      int fh=fimg.getHeight(null);
      String path=request.getRealPath(request.getServletPath());
      FileInputStream in=new FileInputStream(path);
      Image src=ImageIO.read(in);
      int w=src.getWidth(null);
      int h=src.getHeight(null);
      BufferedImage img=new BufferedImage(w,h,BufferedImage.TYPE_INT_RGB);//构建画板
      Graphics g=img.getGraphics();//得到画笔
      g.drawImage(src,0,0,w,h,null);//把原图片写入画板
      g.drawImage(fimg,w-20,h-15,fw,fh,null);//把水印图片写入画板
      g.dispose();//生成图片
      JPEGImageEncoder e=JPEGCodec.createJPEGEncoder(response.getOutputStream());
      e.encode(img);
      response.getOutputStream().close();
   } catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (ImageFormatException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }

}

      /** 
    * @param localPath 添加水印图片路径
    * @param request 请求流对象
    * @param request 响应流对象
                  * @param width   水印图片的宽度
                  * @param height  水印图片的长度
    **/
    @SuppressWarnings("deprecation")
  public   static   void  createMarkLogo(String localPath,HttpServletRequest request,HttpServletResponse response,int width,int height)   {
     try {
      FileInputStream file=new FileInputStream(localPath);
      Image fimg=ImageIO.read(file);
      int fw=fimg.getWidth(null);
      int fh=fimg.getHeight(null);
      String path=request.getRealPath(request.getServletPath());
      FileInputStream in=new FileInputStream(path);
      Image src=ImageIO.read(in);
      int w=src.getWidth(null);//w为你过滤图片的宽度
      int h=src.getHeight(null);//h为你过滤图片的长度
      BufferedImage img=new BufferedImage(w+width,h+height,BufferedImage.TYPE_INT_RGB);//构建画板(画板的宽度为两个图片之和)
      Graphics g=img.getGraphics();//得到画笔
      g.drawImage(src,0,0,w,h,null);//把原图片写入画板
      g.drawImage(fimg,width,height,fw,fh,null);//把水印图片写入画板
      g.dispose();//生成图片
      JPEGImageEncoder e=JPEGCodec.createJPEGEncoder(response.getOutputStream());
      e.encode(img);
      response.getOutputStream().close();
   } catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (ImageFormatException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   } catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }

}   
注意第三个方法的注释地方g.drawImage(fimg,width,height,fw,fh,null);根据参数你在调调(放原图下面的)

过滤器调用
package com.jc.ts.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.jc.ts.services.WaterMark;

public class WaterFilter implements Filter {

 public void destroy() {
  // TODO Auto-generated method stub

 }
 public void doFilter(ServletRequest arg0, ServletResponse arg1,
   FilterChain arg2) throws IOException, ServletException {
    HttpServletRequest request=(HttpServletRequest)arg0;
    HttpServletResponse response=(HttpServletResponse)arg1;
    //WaterMark.createMarkSize("南京ts", request, response);
                 //WaterMark.createMarkLogo("D:\\workspace\\mybook\\WebRoot\\images\\logo\\book.jpg", request, response);
    WaterMark.createMarkLogo("D:\\workspace\\mybook\\WebRoot\\images\\logo\\book.jpg", request, response,20,30);
                   //注意路径为绝对路径且三个效果不能同时执行
   
 }

 public void init(FilterConfig arg0) throws ServletException {
  // TODO Auto-generated method stub

 }

}

 web.xml配置(写在servlet上面)

<filter>
  <description>This is the description of my J2EE component</description> 
  <display-name>This is the display name of my J2EE component</display-name> 
  <filter-name>WaterFilter</filter-name> 
  <filter-class>com.jc.ts.filter.WaterFilter</filter-class> 
  </filter>
希望你能满意。。。。。。