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Posted to commits@struts.apache.org by lu...@apache.org on 2017/04/18 05:38:36 UTC
[4/5] struts-site git commit: updated the hello-world-using-struts2
page
updated the hello-world-using-struts2 page
Project: http://git-wip-us.apache.org/repos/asf/struts-site/repo
Commit: http://git-wip-us.apache.org/repos/asf/struts-site/commit/b2e8be34
Tree: http://git-wip-us.apache.org/repos/asf/struts-site/tree/b2e8be34
Diff: http://git-wip-us.apache.org/repos/asf/struts-site/diff/b2e8be34
Branch: refs/heads/master
Commit: b2e8be34409c5f31db6fc735d5aa53859142a9c9
Parents: 4ca26c0
Author: Stefaan Dutry <st...@gmail.com>
Authored: Mon Apr 17 17:42:08 2017 +0200
Committer: Stefaan Dutry <st...@gmail.com>
Committed: Mon Apr 17 17:42:08 2017 +0200
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.../attachments/helloworld_hello_action.png | Bin 0 -> 7009 bytes
.../attachments/helloworld_index_action.png | Bin 0 -> 9653 bytes
.../hello-world-using-struts2.md | 108 +++++++++----------
5 files changed, 49 insertions(+), 59 deletions(-)
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http://git-wip-us.apache.org/repos/asf/struts-site/blob/b2e8be34/source/getting-started/hello-world-using-struts2.md
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diff --git a/source/getting-started/hello-world-using-struts2.md b/source/getting-started/hello-world-using-struts2.md
index dd62365..be719a3 100644
--- a/source/getting-started/hello-world-using-struts2.md
+++ b/source/getting-started/hello-world-using-struts2.md
@@ -6,7 +6,7 @@ title: Hello World using Struts 2
When you click on a hyperlink or submit an HTML form in a Struts 2 web application, the input is not sent to another server page, but to a Java class that you provide. These classes are called Actions. After the Action fires, a Result selects a resource to render the response. The resource is generally a server page, but it can also be a PDF file, an Excel spreadsheet, or a Java applet window.
-Suppose you want to create a simple "Hello World" example that displays a welcome message. After setting up an empty basic Struts 2 web application (see [How To Create A Struts 2 Web Application](#PAGE_14811860)), to create a "Hello World" example, you need to do four things:
+Suppose you want to create a simple "Hello World" example that displays a welcome message. After setting up an empty basic Struts 2 web application (see [How To Create A Struts 2 Web Application](how-to-create-a-struts2-web-application.html)), to create a "Hello World" example, you need to do four things:
1. Create a class to store the welcome message (the model)
@@ -20,17 +20,22 @@ By creating these components, we are separating the work flow into three well-kn
Let's look at an example model class, Action, server page, and mapping. If you like, fire up your Java IDE, and enter the code as we go.
-> This tutorial assumes you've completed the [How To Create A Struts 2 Web Application](#PAGE_14811860) tutorial and have a working basic Struts project. The example code for this tutorial, helloworld, is available for checkout from the Struts 2 GitHub repository at [https://github.com/apache/struts-examples](https://github.com/apache/struts-examples). The example projects use Maven to manage the artifact dependencies and to build the .war files.
+> This tutorial assumes you've completed the [How To Create A Struts 2 Web Application](how-to-create-a-struts2-web-application.html) tutorial and have a working basic Struts project. The example code for this tutorial, helloworld, is available for checkout from the Struts 2 GitHub repository at [https://github.com/apache/struts-examples](https://github.com/apache/struts-examples). The example projects use Maven to manage the artifact dependencies and to build the .war files.
### The Code
-Let's modify either the basic_struts project to add a model class to store our message, a view that displays our message, an Action class to act as the controller, and a configuration that ties everything together.
+Let's modify the basic-struts project to add the following:
+
+- a model class to store our message
+- a view that displays our message
+- an Action class to act as the controller
+- a configuration that ties everything together
> The [Struts 2 user mailing list](http://struts.apache.org/mail.html) is an excellent place to get help. If you are having a problem getting this application to work search the Struts 2 mailing list. If you don't find an answer to your problem, post a question on the mailing list.
#### Step 1 - Create The Model Class MessageStore.java
-If you're using the Basic_Struts2_Ant project to start with create the MessageStore class in the src folder and if you're using the Basic_Struts2_Mvn class create the MessageStore class in src/main/java. Be sure to note the package statement below.
+Create the `MessageStore` class in `src/main/java`. Be sure to note the package statement below.
> Note that in the code shown below the JavaDoc comments are omitted. In the download example, JavaDoc comments are included.
@@ -40,25 +45,19 @@ If you're using the Basic_Struts2_Ant project to start with create the MessageSt
package org.apache.struts.helloworld.model;
public class MessageStore {
-
private String message;
-
+
public MessageStore() {
- setMessage("Hello Struts User");
+ message = "Hello Struts User";
}
public String getMessage() {
return message;
}
-
- public void setMessage(String message) {
- this.message = message;
- }
-
}
```
-Note the use of public set and get methods to allow access to the private message String attribute. The Struts 2 framework requires that objects you want to expose to the view (`HelloWorld.jsp`) follow the [JavaBean-style conventions](http://en.wikipedia.org/wiki/JavaBean#JavaBean_conventions).
+Note the use of the public getter method to allow access to the private message String attribute. The Struts 2 framework requires that objects you want to expose to the view (`HelloWorld.jsp`) follow the [JavaBean-style conventions](http://en.wikipedia.org/wiki/JavaBean#JavaBean_conventions).
#### Step 2 - Create The Action Class HelloWorldAction.java
@@ -72,52 +71,45 @@ Note the package and import statements below.
package org.apache.struts.helloworld.action;
import org.apache.struts.helloworld.model.MessageStore;
+
import com.opensymphony.xwork2.ActionSupport;
public class HelloWorldAction extends ActionSupport {
-
- private static final long serialVersionUID = 1L;
-
private MessageStore messageStore;
- public String execute() throws Exception {
+ public String execute() {
messageStore = new MessageStore() ;
+
return SUCCESS;
}
public MessageStore getMessageStore() {
return messageStore;
}
-
- public void setMessageStore(MessageStore messageStore) {
- this.messageStore = messageStore;
- }
-
}
```
-The Struts 2 framework will create an object of the `HelloWorldAction`�class and call the execute method in response to a user's action (clicking on a hyperlink that sends a specific URL to the Servlet container).
+The Struts 2 framework will create an object of the `HelloWorldAction` class and call the execute method in response to a user's action (clicking on a hyperlink that sends a specific URL to the Servlet container).
-In this example, the execute method creates an object of class `MessageStore`�and then returns the String constant `SUCCESS`.
+In this example, the execute method creates an object of class `MessageStore` and then returns the String constant `SUCCESS`.
-Note also the public getter and setter methods for the private `MessageStore`�object. Since we want to make the `MessageStore`�object available to the view page, `HelloWorld.jsp`,�we need to follow the [JavaBean-style](http://en.wikipedia.org/wiki/JavaBean\#JavaBean_conventions) of providing get and set methods.
+Note also the public getter method for the private `MessageStore` object. Since we want to make the `MessageStore`�object available to the view page, `HelloWorld.jsp`,�we need to follow the [JavaBean-style](http://en.wikipedia.org/wiki/JavaBean\#JavaBean_conventions) of providing getter and setter methods where needed.
#### Step 3 - Create The View HelloWorld.jsp
-We need a server page to present the message that is stored in the model class `MessageStore`. Create the below JSP in the `WebContent`�folder (if using Ant) or in `src/main/webapp` (if using Maven).
+We need a server page to present the message that is stored in the model class `MessageStore`. Create the below JSP in the `src/main/webapp` folder.
**HelloWorld.jsp**
-```html
-<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
+```jsp
+<!DOCTYPE html>
+<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
-<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
- <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Hello World!</title>
</head>
-
<body>
<h2><s:property value="messageStore.message" /></h2>
</body>
@@ -134,47 +126,45 @@ We'll learn more about tags in the next tutorial. See the _Struts Tags_ for mor
We need a mapping to tie the URL, the `HelloWorldAction`�class (controller), and the `HelloWorld.jsp`�(the view) together. The mapping tells the Struts 2 framework which class will respond to the user's action (the URL), which method of that class will be executed, and what view to render based on the String result that method returns.
-Edit the `struts.xml` file (in the Mvn project that file is in the src/main/resources folder) to add the action mapping. Place the action node (action name="hello") between the opening and closing package node, just after the action mapping with the name="index". Your complete struts.xml should look like:
+Edit the `struts.xml` file (in the Mvn project that file is in the src/main/resources folder) to add the action mapping. Place the action node (action name="hello") between the opening and closing package node, just after the action mapping with the name="index". Your complete `struts.xml` should look like:
**struts.xml**
```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
- "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
- "http://struts.apache.org/dtds/struts-2.0.dtd">
-
+ "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
+ "http://struts.apache.org/dtds/struts-2.5.dtd">
<struts>
+ <constant name="struts.devMode" value="true" />
- <constant name="struts.devMode" value="true" />
-
- <package name="basicstruts2" extends="struts-default">
- <action name="index">
- <result>/index.jsp</result>
- </action>
+ <package name="basicstruts2" extends="struts-default">
+ <action name="index">
+ <result>/index.jsp</result>
+ </action>
- <action name="hello" class="org.apache.struts.helloworld.action.HelloWorldAction" method="execute">
- <result name="success">/HelloWorld.jsp</result>
- </action>
- </package>
+ <action name="hello" class="org.apache.struts.helloworld.action.HelloWorldAction" method="execute">
+ <result name="success">/HelloWorld.jsp</result>
+ </action>
+ </package>
</struts>
```
#### Step 5 - Create The URL Action
-In index.jsp (see WebContent folder for Ant project and src/main/webapp for Mvn project) let's add an Action URL the user can click on to tell the Struts 2 framework to run the execute method of the HelloWorldAction class and render the HelloWorld.jsp view.
+Let's add an Action URL inside `index.jsp` (see `src/main/webapp` folder) so the user can click on a link to tell the Struts 2 framework to run the execute method of the `HelloWorldAction` class and render the `HelloWorld.jsp` view.
First add the taglib directive at the top of the jsp `<%@ taglib prefix="s" uri="/struts-tags" %>`. Next add this p tag `<p><a href="<s:url action='hello'/>">Hello World</a></p>` after the h1 tag. Your new index.jsp should look like:
**index.jsp**
-```html
-<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
+```jsp
+<!DOCTYPE html>
+<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
-<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
- <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+ <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Basic Struts 2 Application - Welcome</title>
</head>
<body>
@@ -184,31 +174,31 @@ First add the taglib directive at the top of the jsp `<%@ taglib prefix="s" uri=
</html>
```
-The Struts url tag creates the URL with an action of hello. The hello action was mapped to the HelloWorldAction class and its execute method. When the user clicks on the above URL it will cause the Struts 2 framework to run the execute method of the HelloWorldAction class. After that method returns the String success, the view page HelloWorld.jsp will be rendered.
+The Struts url tag creates the URL with an action of hello. The hello action was mapped to the `HelloWorldAction` class and its `execute` method. When the user clicks on the above URL it will cause the Struts 2 framework to run the execute method of the `HelloWorldAction` class. After that method returns the String `success` (constant `SUCCESS`), the view page `HelloWorld.jsp` will be rendered.
#### Step 6 - Build the WAR File and Run The Application
-Execute `mvn clean package` to create the war file.
+Execute `mvn jetty:run` to run the application.
-Copy the war file to your Servlet container. After your Servlet container successfully deploys the war file go to this URL [http://localhost:8080/helloworld/index.action](http://localhost:8080/helloworld/index.action) where you should see the following:
+Go to this URL [http://localhost:8080/helloworld/index.action](http://localhost:8080/helloworld/index.action) where you should see the following:
-
+
Click on the Hello World link and you should get the HelloWorld.jsp page:
-
+
### How the Code Works
-Your browser sends to the web server a request for the URL [http://localhost:8080/Hello_World_Struts2_Ant/hello.action](http://localhost:8080/Hello_World_Struts2_Ant/hello.action).
+Your browser sends to the web server a request for the URL [http://localhost:8080/helloworld/hello.action](http://localhost:8080/helloworld/hello.action).
-1. The container receives from the web server a request for the resource `hello.action`. According to the settings loaded from the [web.xml](//struts.apache.org/docs/webxml.html) , the container finds that all requests are being routed to `org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter`, including the `*.action` requests. The StrutsPrepareAndExecuteFilter is the entry point into the framework.
+1. The container receives from the web server a request for the resource `hello.action`. According to the settings loaded from the [web.xml](//struts.apache.org/docs/webxml.html) , the container finds that all requests are being routed to `org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter`, including the `*.action` requests. The StrutsPrepareAndExecuteFilter is the entry point into the framework.
2. The framework looks for an action mapping named "hello", and it finds that this mapping corresponds to the class "HelloWorldAction". The framework instantiates the Action and calls the Action's `execute` method.
-3. The `execute` method creates the MessageStore object and returns `SUCCESS`. The framework checks the action mapping to see what page to load if `SUCCESS` is returned. The framework tells the container to render as the response to the request, the resource `HelloWorld.jsp`.
+3. The `execute` method creates the MessageStore object and returns `SUCCESS` (=`"success"`). The framework checks the action mapping to see what page to load if `SUCCESS` is returned. The framework tells the container to render as the response to the request, the resource `HelloWorld.jsp`.
-4. As the page `HelloWorld.jsp` is being processed, the `<s:property value="messageStore.message" />` tag calls the getter `getMessageStore` of the `HelloWorld` Action and then calls the `getMessage` of the MessageStore object returned by `getMessageStore`, and the tag merges into the response the value of the message attribute.
+4. As the page `HelloWorld.jsp` is being processed, the `<s:property value="messageStore.message" />` tag calls the getter `getMessageStore` of the `HelloWorld` Action and then calls the `getMessage` of the MessageStore object returned by `getMessageStore`. The tag merges the value of the message attribute into the response.
5. A pure HTML response is sent back to the browser.