Springmvc+mybatis processing Picture (a): Upload image

Always feel that uploading image files and so on is very difficult, so the final processing of pictures, found that it is not so difficult to start the text.

Idea: Save the file of the foreground upload to the Mutipartfile type field, then convert the Mulipartfile to the byte[] array in the Pojo class, and finally into the database Longblob type field
1. Database design, set the picture newspic field type to Longblob or blob

2. Prepare the jar package: Commons-fileupload and Commons-io, I use Commons-fileupload-1.3.1.jar and Commons-io-2.4.jar, can also be downloaded here.
3. Configuring the Upload file in Springmvc-config.xml

class= "Org.springframework.web.multipart.commons.CommonsMultipartResolver" >    <property name= " Defaultencoding ">        <value>UTF-8</value>    </property>    <property name=" Maxuploadsize ">        <value>32505856</value><!--upload file size limit 31m,31*1024*1024---    </ property>    <property name= "maxinmemorysize" >        <value>4096</value>    </property ></bean>

When you upload a file in a form form, you must specify the Enctype property value as Multipart/form-data, which means that the file is transferred as a binary stream. Otherwise the error will not be uploaded.
Because the enctype= "Multipart/form-data" attribute is added to the form form, the data is converted to binary, resulting in a null value for the received value, so configure the Multipartresolver in the spring configuration file
4. addnews.jsp

enctype= "Multipart/form-data">    <table>        <tr>            <td>                name= " Newspicture "/>            </td>        </tr>        <!--omitting the code for other fields--    </table></form >

5. Newsmapper.java and Newsdynasqlprovider.java
(1) Newsmapper.java

// Insert News @SelectProvider dynamically (Type=newsdynasqlprovider.  Class, method= "Insertnews")void Save (news News);

(2) Newsdynasqlprovider.java

//Dynamic Insertion PublicString Insertnews (FinalNews News) {    return NewSQL () {{Insert_into ("News"); if(News.getnewstitle ()! =NULL&&!news.getnewstitle (). Equals ("") {VALUES ("Newstitle", "#{newstitle}"); }            if(News.getnewsabstract ()! =NULL&&!news.getnewsabstract (). Equals ("") {VALUES ("Newsabstract", "#{newsabstract}"); }            if(News.getnewsauthor ()! =NULL&&!news.getnewsauthor (). Equals ("") {VALUES ("Newsauthor", "#{newsauthor}"); }            if(News.getnewstime ()! =NULL&&!news.getnewstime (). Equals ("") {VALUES ("Newstime", "#{newstime}"); }            if(News.getnewscontent ()! =NULL&&!news.getnewscontent (). Equals ("") {VALUES ("Newscontent", "#{newscontent}"); }            if(News.getnewspic ()! =NULL&&!news.getnewspic (). Equals ("") {VALUES ("Newspic", "#{newspic,jdbctype=blob}"); }}}.tostring ();}

6. Testservice.java and Testserviceimpl.java
(1) Testservice.java

/**@param @throws */void throws Exception;

(2) Testserviceimpl.java

@Override  Public void multipartfile newspic throws Exception {    byte[] B1 =   newspic.getbytes ();    News.setnewspic (B1);    Newsmapper.save (news);}

7. Newscontroller.java

/*** Process Add request *@paramString flag Flag, 1 for Jump to add page, 2 for add action *@paramNews Headlines to add *@paramModelandview MV *@throwsException **/@RequestMapping (Value= "/addnewst")  PublicModelandview Addnewst (String flag, @ModelAttribute News news,multipartfile newspicture, Modelandview MV, HttpSession session)throwsexception{if(Flag.equals ("1") {mv.setviewname ("Addnews"); }Else{testservice.addnewsandpic (news, newspicture); Mv.setviewname ("Redirect:/htnews"); }     returnMV;}

8. News.java

 Public classNewsImplementsserializable{PrivateInteger NewsID; PrivateString Newstitle; PrivateString newsabstract; PrivateString Newsauthor; @DateTimeFormat (Pattern= "Yyyy-mm-dd HH:mm:ss")    PrivateDate Newstime; PrivateString newscontent; Private byte[]Newspic;//News Photos         PublicNews () {Super(); }    //Setter and Getter}

Ref: 50413864
Second,. JSP improved, after reading the path of the Input:file, display the local picture

#imagePreview {width:160px;   height:120px; Filter:progid:DXImageTransform.Microsoft.AlphaImageLoader (Sizingmethod=Scale ); }   </style>var loadimagefile=(function () {if(window. FileReader) {var opreviewimg=NULL, Ofreader =Newwindow. FileReader (), Rfilter=/^ (?: image\/bmp|image\/cis\-cod|image\/gif|image\/ief|image\/jpeg|image\/jpeg|image\/jpeg|image\/pipeg|image\ /png|image\/svg\+xml|image\/tiff|image\/x\-cmu\-raster|image\/x\-cmx|image\/x\-icon|image\/x\-portable\-anymap |image\/x\-portable\-bitmap|image\/x\-portable\-graymap|image\/x\-portable\-pixmap|image\/x\-rgb|image\/x\- Xbitmap|image\/x\-xpixmap|image\/x\-xwindowdump) $/i; Ofreader.onload=function (ofrevent) {if(!opreviewimg) {var Newpreview= document.getElementById ("Imagepreview"); Opreviewimg=NewImage (); OPreviewImg.style.width= (newpreview.offsetwidth). toString () + "px"; OPreviewImg.style.height= (newpreview.offsetheight). toString () + "px";       Newpreview.appendchild (OPREVIEWIMG); } opreviewimg.src=OFREvent.target.result;                   }; returnfunction () {var afiles= document.getElementById ("Imageinput"). files; if(Afiles.length = = 0) {return; } if(!rfilter.test (Afiles[0].type)) {Alert ("You must select a valid Image file!");return; } Ofreader.readasdataurl (afiles[0]); }                   }       if(Navigator.appname = = = "Microsoft Internet Explorer") {       returnfunction () {alert (document.getElementById ("Imageinput"). Value); document.getElementById ("Imagepreview"). Filters.item ("DXImageTransform.Microsoft.AlphaImageLoader"). src = document.getElementById (" Imageinput "). Value;   }       }       })(); </script></body>
Effect
Ref: 38046939
------------------------------------------------------Dividing line------------------------------------------------------------
Error encountered:
1. After the Springmvc form is submitted, the controller receives a value of NULL,

The error is as follows:
April, 2018 10:43:33 for Servlets [SPRINGMVC] in the context with path [/   Java.lang.NullPointerException] with root Causejava.lang.NullPointerExceptionat Com.game.controller.NewsController.addNewst (Newscontroller.java:58)
Cause: No configuration multipartresolver, ref: 79076455
------------------------------------------------------Dividing line------------------------------------------------------------
BLOB data types in MySQL
In a computer, a blob is a field type that is often used to store binary files in a database, a typical blob is a picture or a sound file.
In MySQL, BLOBs are a series of types, including: Tinyblob, BLOBs, Mediumblob, Longblob, the only difference between these types is the maximum size of the storage file.

 
 
 
  
  
 
   
 
    
Type
 
    
Size (units: bytes)
 
   
 
   
 
    
Tinyblob
 
    
Maximum 255
 
   
 
   
 
    
Blob
 
    
65K Max
 
   
 
   
 
    
Mediumblob
 
    
16M Max
 
   
 
   
 
    
Longblob
 
    
4G Max

 
   
 
  
 
 
 
Springmvc+mybatis processing Picture (a): Upload image