Struts2's configuration file method summary

Struts2

After learning the basics of JAVA, you must face the learning of three major frameworks. As a beginner, you must understand the principles of the three major frameworks. The design purpose is the primary task. Only after grasping the design purpose of the framework can you learn and use the framework in a targeted manner. Here we will introduce the strue2 framework.

What is Struts2?

Struts2 is a very excellent MVC framework, based on Model2 design model

Developed from the two classic frameworks of traditional Struts1 and WebWork

Strust2 core features

(1) Allow POJO (Plain Old Java Objects) objects as Action

(2) Action's execute method is no longer coupled with the Servlet API, making it easier to test

(3) Support more view technologies (JSP, FreeMarker, Velocity)

(4) Interceptor mechanism based on Spring AOP idea is easier to expand

(5) More powerful and easier to use input verification function

The result node of the struts2 configuration file

The result node is a child of the action node, which represents a destination that may be visited after the action method is executed;

The Action method name corresponds to the method attribute of the action node;

Each Action method will return a String value and correspond to the name attribute of the result node one by one. The result node determines the response different results based on the name attribute value;

The result node has two properties, name (the name of the result, that is, the return value of the action method, default is SUCCESS) and type (the type of the response result, default is dispatcher)

As shown in circle 1 in the above figure, the value of the result node represents a destination that the struts2 request will go to.

result node's result type (type)

dispatcher (forward)

dispatcher is the default result type of the struts2 framework and is also the most commonly used result type. This type has a default parameter location, which is generally omitted. The following two writing methods are equivalent:

The dispatcher result type forwards control to the specified resource in the application. If you need to forward control to an external resource, you should use the redirect result type

redirect (redirect)

• redirect result type will redirect the response to another resource instead of forwarding it to that resource
• redirect also has the default parameter location, and there is also a parse parameter to indicate whether the location value is considered an OGNL expression to interpret. The default value is true

chain (forward to an action)

• Specify the result response type as chain, which can be used to form an action chain, that is, the previous action forwards control to the next action, and the state of the previous action is still saved in the next action
• chain accepts parameters such as actionName and method, where actionName specifies the name of the target action, which is the default property, method specifies the method of the target action, and the default value is executed

redirectAction (redirect to an action)

• redirectAction redirects the response to another action, and has the default parameter actionName
• Redirecting to an action can be implemented concisely using redirect, but forwarding to an action cannot be implemented using dispatcher. The following two writing methods are equivalent.

Wildcard mapping

struts2 provides a wildcard mapping mechanism to simplify multiple mapping relationships similar to each other into one mapping relationship

Wildcard mapping rules

• If an action requests multiple matching actions, the one without a wildcard will win.
• If the specified action cannot be found, struts2 will try to match the URL with any action containing a wildcard.
• The substring of the URI string matched by a wildcard can be referenced using {1} {2}, for example, the four actions are
• update-hello, query-hello, delete-hello, save-hello Then the action in the struts.xml file
• The name attribute of the name can be name = -hello, and {1} can be used to represent the occupied area in the entire action node.
• {1} can also be used in class to represent class name
• {0} Match the entire URL
• If struts2 finds multiple matches with wildcards, matches in order

As shown in the figure, in the first package, * can represent four of them in the second package.

Summarize

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