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Java如何实现图片裁剪预览功能

2019年07月22日  | 移动技术网IT编程  | 我要评论

在项目中，我们需要做些类似头像上传，图片裁剪的功能，ok看下面文章！
需要插件：jquery jcrop
后端代码：

package org.csg.upload;
 
import java.awt.rectangle;
import java.awt.image.bufferedimage;
import java.io.file;
import java.io.fileinputstream;
import java.io.ioexception;
import java.util.iterator;
import javax.imageio.imageio;
import javax.imageio.imagereadparam;
import javax.imageio.imagereader;
import javax.imageio.stream.imageinputstream;
public class upload {
 /**
  * @author 小夜的传说
  * @param path1 图片原路径
  * @param path2 裁剪后存储的路径
  * @param x x轴
  * @param y y轴
  * @param w
  * @param h
  */
 public static void cutimage(string path1,string path2,int x,int y,int w,int h){
  fileinputstream fileinputstream=null;
  imageinputstream iis=null;
   
  try {
   //读取图片文件，建立文件输入流
   fileinputstream=new fileinputstream(path1);
   //创建图片的文件流 迭代器
   iterator<imagereader> it = imageio.getimagereadersbyformatname("jpg");
   imagereader reader=it.next();
   //获取图片流 建立文图 文件流
   iis=imageio.createimageinputstream(fileinputstream);
   //获取图片默认参数
   reader.setinput(iis, true);
   imagereadparam param=reader.getdefaultreadparam();
   //定义裁剪区域
   rectangle rect=new rectangle(x,y,w,h);
   param.setsourceregion(rect);
   bufferedimage bi=reader.read(0,param);
   imageio.write(bi, "jpg", new file(path2));
  } catch (exception e) {
   e.printstacktrace();
   system.out.println("裁剪失败");
  }finally{
   try {
    if(fileinputstream!=null){
     fileinputstream.close();
    }
    if(iis!=null){
     iis.close();
    }
   } catch (ioexception e) {
    e.printstacktrace();
   }
    
  }
 }
}

访问代码：

<%@ page language="java" import="java.util.*,org.csg.upload.*" pageencoding="utf-8"%>
<%
 //图片的相对路径
 string imagpath=request.getparameter("imgpath");
 string relpath=request.getrealpath("/");//获取图片服务器绝对地址
 string newfilename=new date().gettime()+".jpg";
 //实际图片路径
 string path1=relpath+imagpath;
 //裁剪后存储到服务器的图片路径
 string path2=relpath+"/images/"+newfilename;
  
 int x=integer.parseint(request.getparameter("x"));
 int y=integer.parseint(request.getparameter("y"));
 int w=integer.parseint(request.getparameter("w"));
 int h=integer.parseint(request.getparameter("h"));
 try{
 upload.cutimage(path1, path2, x, y, w, h);
 out.print("<img src='images/"+newfilename+"'/>");
 }catch(exception e){
 e.printstacktrace();
 out.print("图片裁剪失败");
 }
%>

jsp代码：

<%@ page language="java" import="java.util.*" pageencoding="utf-8"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en">
<html>
 <head>
 <title>jsp开发头像裁剪</title>
 <meta http-equiv="pragma" content="no-cache">
 <meta http-equiv="cache-control" content="no-cache">
 <meta http-equiv="expires" content="0"> 
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
 <meta http-equiv="description" content="this is my page">
 <link rel="stylesheet" href="css/jquery.jcrop.css" type="text/css" />
 <script type="text/javascript" src="js/jquery.min.js"></script>
 <script type="text/javascript" src="js/jquery.jcrop.min.js"></script>
  <style type="text/css">
  *{margin: 0;padding: 0;}
  .cut{
   margin-top: 20px;
  }
  #preview-pane {
   display: block;
   position: absolute;
   z-index: 2000;
   top: 10px;
   right: -280px;
   padding: 6px;
   border: 1px rgba(0,0,0,.4) solid;
   background-color: white;
   -webkit-border-radius: 6px;
   -moz-border-radius: 6px;
   border-radius: 6px;
   -webkit-box-shadow: 1px 1px 5px 2px rgba(0, 0, 0, 0.2);
   -moz-box-shadow: 1px 1px 5px 2px rgba(0, 0, 0, 0.2);
   box-shadow: 1px 1px 5px 2px rgba(0, 0, 0, 0.2);
 }
  
 #preview-pane .preview-container {
  width: 250px;
  height: 170px;
  overflow: hidden;
 }
  </style>
  <script type="text/javascript">
   $(function(){
    var jcrop_api,
   boundx="",
   boundy="",
   $preview = $('#preview-pane'),
   $pcnt = $('#preview-pane .preview-container'),
   $pimg = $('#preview-pane .preview-container img'),
   xsize = $pcnt.width(),
   ysize = $pcnt.height();
    $('#cutimage').jcrop({
     onchange:showcoords,//获取选中的值
     onselect:showcoords,//获取拖拽的值
     aspectratio: xsize / ysize
    },function(){
     var bounds = this.getbounds();
     boundx = bounds[0];
     boundy = bounds[1];
     jcrop_api = this;
     $preview.appendto(jcrop_api.ui.holder);
    });
    function showcoords(c){
     var x=c.x;
     var y=c.y;
     var w=c.w;
     var h=c.h;
     $("#x1").val(parseint(x));
     $("#y1").val(parseint(y));
     $("#w").val(parseint(w));
     $("#h").val(parseint(h));
    if (parseint(c.w) > 0){
     var rx = xsize / c.w;
     var ry = ysize / c.h;
     $pimg.css({
      width: math.round(rx * boundx) + 'px',
      height: math.round(ry * boundy) + 'px',
      marginleft: '-' + math.round(rx * c.x) + 'px',
      margintop: '-' + math.round(ry * c.y) + 'px'
     });
     }
    }
   });
  </script>
 </head>
 <body>
 <h1>java开发qq头像裁剪系统</h1>
 <div class="cut">
  <img id="cutimage" alt="" src="images/1.jpg" >
  <div id="preview-pane">
   <div class="preview-container">
    <img src="images/1.jpg" class="jcrop-preview" alt="preview" />
   </div>
  </div>
 </div>
 <form action="success.jsp" method="post" >
  <input type="text" value="images/1.jpg" name="imgpath">
  x轴:<input type="text" size="4" id="x1" name="x" />
  y轴:<input type="text" size="4" id="y1" name="y"/>
  宽度:<input type="text" size="4" id="w" name="w"/>
  高度:<input type="text" size="4" id="h" name="h"/>
  <input type="submit" value="裁剪"/>
 </form>
 </body>
</html>

效果图：

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