java实现上传图片进行切割的方法

本文实例讲述了java实现上传图片进行切割的方法。分享给大家供大家参考。具体分析如下：

为什么我要进行上传的图片进行切割呢，我这个项目的图片是部门logo，每个部门都可以选择不同的logo，但是要应对浏览器的兼容以及拉伸，我选择了把一张图片切成左、中、右和剩下的部分，因为左边和中变可能会有图案或者字所以不能拉伸，拉伸的只是右边的部分，剩下的部分自适应就可以了。所以用了javax的imagereader来操作。最后以blob类型保存数据库中。
首先要在form表单里面写上enctype="multipart/form-data"

<form method="post" id="mainform" action="${ctx }/admin/department!save.action" enctype="multipart/form-data">

下面在表单中写上上传组件

<tr> 
 <td style="width: 100px;"> 
     <strong>上传logo：</strong> 
     <input type="hidden" name="suffix" id="suffix" value="${depart.departmentlogo.suffix }"/> 
 </td> 
 <td style="width: 225px;"> 
     <input type="file" name="logofile" id="logofile" onchange="checkfile();"/> 
 </td> 
</tr> 
<tr> 
 <td style="width: 100px;"></td> 
 <td style="width: 225px;"> 
     <span class="red">（图片格式：jpg,jpeg,bmp,gif,png;</span><br/> 
     <span class="red">推荐大小：1120×80像素）</span> 
 </td> 
</tr>

图片检查的checkfile()方法用于检查图片是否以规定格式结尾以及是否没有选择

function checkfile(){ 
         
        var value = $("#logofile").val(); 
        if(!value){ 
            alert("请选择您要上传的图片！"); 
            return false; 
        }else{ 
            if(value.lastindexof(".jpg") != -1){ 
                $("#suffix").val("jpg"); 
                return true; 
            }else if(value.lastindexof(".jpeg") != -1){ 
                $("#suffix").val("jpeg"); 
                return true; 
            }else if(value.lastindexof(".gif") != -1){ 
                $("#suffix").val("gif"); 
                return true; 
            }else if(value.lastindexof(".bmp") != -1){ 
                $("#suffix").val("bmp"); 
                return true; 
            }else if(value.lastindexof(".png") != -1){ 
                $("#suffix").val("png"); 
                return true; 
            }else{ 
                alert("对不起，您上传文件格式有误，请选择指定格式的图片文件上传"); 
                return false; 
            } 
        } 
}

下面就是进行后台的save操作了。

public string save() throws exception { 
        httpservletrequest request = servletactioncontext.getrequest() ; 
        string departid = request.getparameter("id") ; 
        string departname = request.getparameter("name") ; 
        string companyid = request.getparameter("companyid") ; 
        //图片后缀 
        string suffix = request.getparameter("suffix"); 
        list<menu> listmenu = new arraylist<menu>() ; 
        company company = new company() ; 
        company.setid(long.valueof(companyid)) ; 
        if(this.logofile != null && departname != null && companyid != null && suffix != null){ 
            //获取解析图片的imagereader 
            iterator<imagereader> imagereaders = imageio.getimagereadersbyformatname(suffix); 
            imagereader imagereader = imagereaders.next(); 
            //把图片以字节流的形式传入 
            inputstream logostream = new bufferedinputstream(new fileinputstream(this.logofile)); 
            //转为图片输入流 
            imageinputstream imageinputstream = imageio.createimageinputstream(logostream); 
            imagereader.setinput(imageinputstream, true); 
            int imagewidth = imagereader.getwidth(0); 
            //固定高度80 
            int imageheight = 80; 
            //设置左中右和剩下的宽度 
            int leftwidth = imagewidth / 2; 
            int middlewidth = (imagewidth - leftwidth) / 3; 
            int rightwidth = 5; 
            int retainwidth = imagewidth - leftwidth -middlewidth - 5; 
             
            imagereadparam readparam = imagereader.getdefaultreadparam(); 
            bufferedimage bimage = null; 
            //裁剪左半部分 
            //根据宽和高获得矩形 
            rectangle leftimagerectangle = new rectangle(0, 0, leftwidth, imageheight); 
            readparam.setsourceregion(leftimagerectangle); 
            bimage = imagereader.read(0, readparam);  
            //字节数组输出流 
            bytearrayoutputstream leftbytearrayoutputstream = new bytearrayoutputstream(); 
            imageio.write(bimage, suffix, leftbytearrayoutputstream); 
            //获得字节数组 
            byte[] leftimagedata = leftbytearrayoutputstream.tobytearray(); 
            leftbytearrayoutputstream.close(); 
            //hibernate创建一个blob类型 
            blob leftblob = hibernate.createblob(leftimagedata, this.departmentmanager.getsession()); 
             
            //裁剪中部部分 
            rectangle middleimagerectangle = new rectangle(leftwidth, 0 , middlewidth, imageheight); 
            readparam.setsourceregion(middleimagerectangle); 
            bimage = imagereader.read(0, readparam); 
             
            bytearrayoutputstream middlearrayoutputstream = new bytearrayoutputstream(); 
            imageio.write(bimage, suffix, middlearrayoutputstream); 
            byte[] middleimagedata = middlearrayoutputstream.tobytearray(); 
            middlearrayoutputstream.close(); 
            blob middleblob = hibernate.createblob(middleimagedata, this.departmentmanager.getsession()); 
             
            //裁剪右半部分 
            rectangle rightimagerectangle = new rectangle(leftwidth + middlewidth, 0, rightwidth, imageheight); 
            readparam.setsourceregion(rightimagerectangle); 
            bimage = imagereader.read(0, readparam); 
             
            bytearrayoutputstream rightarrayoutputstream = new bytearrayoutputstream(); 
            imageio.write(bimage, suffix, rightarrayoutputstream); 
            byte[] rightimagedata = rightarrayoutputstream.tobytearray(); 
            rightarrayoutputstream.close(); 
            blob rightblob = hibernate.createblob(rightimagedata, this.departmentmanager.getsession()); 
             
            //保留部分 
            rectangle retainrectangle = new rectangle(leftwidth + middlewidth + rightwidth, 0, retainwidth, imageheight); 
            readparam.setsourceregion(retainrectangle); 
            bimage = imagereader.read(0, readparam); 
             
            bytearrayoutputstream retainarrayoutputstream = new bytearrayoutputstream(); 
            imageio.write(bimage, suffix, retainarrayoutputstream); 
            byte[] retainimagedata = retainarrayoutputstream.tobytearray(); 
            retainarrayoutputstream.close(); 
            blob retainblob = hibernate.createblob(retainimagedata, this.departmentmanager.getsession()); 
             
            if(!departid.equals("") && departid!=null){ 
                department d = this.departmentmanager.findbyid(long.valueof(departid)) ; 
                if(this.checkedauthids != null){ 
                    for(int i=0;i<checkedauthids.size();i++){ 
                        menu menu = new menu() ; 
                        menu.setid(checkedauthids.get(i)) ; 
                        listmenu.add(menu) ; 
                    } 
                    d.setmenus(listmenu) ; 
                } 
                d.getdepartmentlogo().setleftpartimage(leftblob); 
                d.getdepartmentlogo().setmiddlepartimage(middleblob); 
                d.getdepartmentlogo().setrightpartimage(rightblob); 
                d.getdepartmentlogo().setretainpartimage(retainblob); 
                d.getdepartmentlogo().setcreatetime(new date()); 
                d.getdepartmentlogo().setsuffix(suffix); 
                d.setname(departname) ; 
                d.setparentid(0l) ; 
                d.setnodetype(1) ; 
                d.setgrade(1) ; 
                d.setcompany(company) ; 
                this.departmentmanager.save(d) ; 
            }else{ 
                integer parentnodetype = 0 ; 
                department dd = new department() ; 
                if(this.checkedauthids!=null && this.checkedauthids.size() != 0){ 
                    for(int i=0;i<checkedauthids.size();i++){ 
                        menu menu = new menu() ; 
                        menu.setid(checkedauthids.get(i)) ; 
                        listmenu.add(menu) ; 
                    } 
                    dd.setmenus(listmenu) ; 
                }else{ 
                    dd.setmenus(null) ; 
                } 
                departmentlogo departmentlogo = new departmentlogo() ; 
                departmentlogo.setcreatetime(new date()); 
                departmentlogo.setleftpartimage(leftblob); 
                departmentlogo.setmiddlepartimage(middleblob); 
                departmentlogo.setrightpartimage(rightblob); 
                departmentlogo.setretainpartimage(retainblob); 
                departmentlogo.setsuffix(suffix); 
                dd.setdepartmentlogo(departmentlogo); 
                dd.getdepartmentlogo().setdepartment(dd); 
                dd.setid(this.departmentmanager.findmaxid()+1) ; 
                dd.setname(departname) ; 
                dd.setparentid(0l) ; 
                dd.setnodetype(1) ; 
                dd.setgrade(1) ; 
                dd.setordertype(0) ; 
                dd.setcompany(company) ; 
                dd.setflag(0) ; 
                this.departmentmanager.save(dd) ; 
            } 
        } 
        return "reload"; 
}

下面就是显示了，我是用的qui，所以在top.jsp上面的css中进行动态显示

<style type="text/css"> 
.welcome-hide{width: 210px;white-space: nowrap;overflow: hidden;text-overflow: ellipsis;} 
#leftlogo{background: url(${ctx }/admin/department-logo!showlogo.action?position=left) no-repeat;width: ${leftwidth}px;height: 80px;} 
#middlelogo{background: url(${ctx }/admin/department-logo!showlogo.action?position=middle) no-repeat;width: ${middlewidth}px;height: 80px;} 
#rightlogo,#toptablestyle{background: url(${ctx }/admin/department-logo!showlogo.action?position=right) repeat-x;height: 80px;} 
#retainlogo{background: url(${ctx }/admin/department-logo!showlogo.action?position=retain) no-repeat;width: ${retainwidth}px;height: 80px;} 
</style>

department-logo!showlogo.action中的showlogo方法就是加载图片的方法

public string showlogo() { 
         
        httpservletrequest request = servletactioncontext.getrequest(); 
        loginuser loginuser = (loginuser)((securitycontext)request.getsession(). 
                getattribute("spring_security_context")).getauthentication().getprincipal(); 
        list<departmentlogo> logos = this.logomanager.findall(); 
        for (departmentlogo departmentlogo : logos) { 
            if (loginuser.getuser().getdepartment().getid().equals(departmentlogo.getdepartment().getid())) { 
                string param = request.getparameter("position"); 
                blob blob = null; 
                if (param != null) { 
                    try { 
                        if (param.equals("left")) { 
                            blob = departmentlogo.getleftpartimage(); 
                            imagelogo = blob.getbinarystream(); 
                            return "showlogo"; 
                        }else if (param.equals("middle")) { 
                            blob = departmentlogo.getmiddlepartimage(); 
                            imagelogo = blob.getbinarystream(); 
                            return "showlogo"; 
                        }else if (param.equals("right")) { 
                            blob = departmentlogo.getrightpartimage(); 
                            imagelogo = blob.getbinarystream(); 
                            return "showlogo"; 
                        }else if (param.equals("retain")) { 
                            blob = departmentlogo.getretainpartimage(); 
                            imagelogo = blob.getbinarystream(); 
                            return "showlogo"; 
                        } 
                    } catch (exception e) { 
                        e.printstacktrace(); 
                    } 
                } 
            } 
        } 
        return null; 
}

当然返回的地址应该选择struts2中的type="stream"

@results({ 
    @result(name = "showlogo", type = "stream", params = {"contenttype", "image/jpeg," 
            + "image/bmp,image/png,image/gif,image/jpeg",  
            "inputname", "imagelogo", "buffersize", "4096"}) 
})

那么top.jsp中的width是怎么得到的呢？
实在加载菜单的时候得到的，下面是menu中的方法

httpservletrequest request = servletactioncontext.getrequest(); 
list<departmentlogo> logos = this.logomanager.findall(); 
for (departmentlogo departmentlogo : logos) { 
    if (user.getdepartment().getid().equals(departmentlogo.getdepartment().getid())) { 
 request.setattribute("leftwidth", imageio.read(departmentlogo. 
  getleftpartimage().getbinarystream()).getwidth()); 
 request.setattribute("middlewidth", imageio.read(departmentlogo. 
  getmiddlepartimage().getbinarystream()).getwidth()); 
 request.setattribute("retainwidth", imageio.read(departmentlogo. 
  getretainpartimage().getbinarystream()).getwidth()); 
 break; 
    } 
}

这样就完成了一个上传显示功能。

这个就是我上传的测试图片。

希望本文所述对大家的java程序设计有所帮助。