Java_day25_uuid, package upload, JSP

JSP and upload encapsulation

I. Introduction to JSP

1.jsp is the Java Server Pages　　 enables dynamic generation of HTML code in a page using Java as a scripting language

2.jsp First and HTML differences, HTML can be placed directly in the browser to execute, but the JSP must start Tomcat to see the effect

3. Components: 1. Static content; 2. directives; 3. Expressions; 4. Scripts; 5. Statements; 6. Notes

3.1 Notes: JSP has HTML-used annotations, Java-used annotations, and its own comments

　　　　　　　The first: As with HTML annotations, this comment is the first one that can be seen on the client

The second JSP comment, which is not visible at the client, is erased at compile time <%--Comment--

The third is standard Java annotations, which can only be written in the JSP script//annotation; /* Comment */

3.2 Instructions: JSP page can be added at the top of the current page configuration and other information　　　　 called JSP directives

Page directive: The configuration information of the current pages, most commonly used

Include: In one page, embed another file in it

Taglib: Introducing Tag Libraries

3.3 Script: <%--jsp script--%> can write any Java code, but cannot define methods, global variables. All JSP scripts are mixed with HTML code into the _jspservice method.

3.4 Static content: All written in the JSP file is not wrapped by any JSP tag, is static content, that is, all the HTML code, is static content

3.5 declaration: Used to write custom methods, member variables of the

3.6 expression: is in HTML code, in order to use the global variables defined in the declaration, or the local variables defined in the script exists that the expression is not complex logic, only values can be used

Two. Upload the package

public class Smartupload {

Private HttpServlet servlet;//

Private servletfileupload sfu;//for uploading global variables

Private file uploaddir;//The folder used to create the uploaded file

Private hashmap<string,string> parameters;//used to store normal form data

Private hashmap<string,file> files;//used to store file names and files for uploading files

　　　　

Public Smartupload (HttpServlet httpservlet) {

This.servlet = HttpServlet; Constructs a method for manipulating a Servlet object that uses this wheel

Inintdir ();//Initialize the upload folder

SFU = new Servletfileupload ();//

Sfu.setfileitemfactory (New Diskfileitemfactory ());// initialize Servletfileupload

Parameters = new hashmap<> ();//Initialize Object

Files = new hashmap<> (); Initialize Object }

private void Initdir () {

String Uploadpath = Servlet.getservletcontext (). Getrealpath ("") +file.separator+ "upload";//stitching Upload file path

Uploaddir = new File (Uploadpath); Creating a File object by stitching paths

if (!uploaddir.exists ()) {//Judgment folder is present

Uploaddir.mkdirs (); } //Does not exist create folder

public void Parse (HttpServletRequest request) {//Parse request

list<fileitem> Fileitems = sfu.parserequest (request);//parse request into List

if (fileitems! = null) {//Judgment NOT NULL

for (Fileitem fileitem:fileitems) {//Traverse list

if (Fileitem.isformfield ()) {//To determine whether the form data

String key = Fileitem.getfieldname ();//Get Key

String value = fileitem.getstring ("Utf-8");//Get value

Parameter.put (Key,value);//Deposit in HashMap

}else {//Not form data

String filename = fileitem.getname ();//Get file name

if (Stringutils.isempty (fileName)) {//reference is a package under Apache

Continue;}

String realname = testuuid.handfilename (filename);//use UUID to generate a new file name

File File = new (uploaddir,realname);//Create files by folder and file name

Fileitem.write (file);//write files

Files.put (filename,file);//Save file name and file object HashMap

public string GetParameter (string key) {

return Parameter.get (key);}

Public map<string,string> Getparametermap () {

return parameters;}

Public map<string,file> Getuploadfiles () {

return files;}

Three. Request Domain

　　　put values in the request domain, values are stored as Key-value , andkey can only be string,value any object

Stored value: Request.setattribute ("msg", msg);//key-value pair form

Value: Request.getattribute ("MSG");//value by key

Java_day25_uuid, package upload, JSP