極客書

GWT - UiBinder

UiBinder是一個框架，用於分離用戶界面的功能和視圖。

  • UiBinder框架允許開發人員將gwt應用程式構建爲HTML頁面，並在其中配置gwt小部件。

  • UiBinder框架使得與比Java原始碼更熟悉XML、HTML和CSS的UI設計人員的協作更加容易

  • UIBinder提供了一種定義用戶界面的聲明方式。

  • UIBinder將程序邏輯與UI分離。

  • UIBinder與JSP與servlet類似。

UiBinder Workflow

Step 1 - Create UI Declaration XML File

創建一個基於XML/HTML的用戶界面聲明文件。我們在示例中創建了一個Login.ui.xml文件。

<ui:UiBinder xmlns:ui = 'urn:ui:com.google.gwt.uibinder'
   xmlns:gwt = 'urn:import:com.google.gwt.user.client.ui' 
   xmlns:res = 'urn:with:com.tutorialspoint.client.LoginResources'>
   <ui:with type = "com.tutorialspoint.client.LoginResources" field = "res">
   </ui:with>
   <gwt:HTMLPanel>
   ...  
   </gwt:HTMLPanel>
</ui:UiBinder>

Step 2 - Use ui:field for Later Binding

使用XML/HTML元素中的ui:field屬性將XML中的ui欄位與JAVA文件中的ui欄位關聯起來，以便以後綁定。

<gwt:Label ui:field = "completionLabel1" />
<gwt:Label ui:field = "completionLabel2" />

Step 3 - Create Java counterpart of UI XML

通過擴展複合窗口小部件，創建基於Java的XML布局對應項。我們在示例中創建了一個Login.java文件。

package com.tutorialspoint.client;
   ...
public class Login extends Composite {
   ...
}

Step 4 - Bind Java UI fields with UiField annotation

使用Login.java中的@UiField注釋指定對應的類成員以綁定到Login.ui.XML中基於XML的欄位

public class Login extends Composite {
   ...
   @UiField
   Label completionLabel1;

   @UiField
   Label completionLabel2;  
   ...
}

Step 5 - Bind Java UI with UI XML with UiTemplate annotation

指示GWT使用@UiTemplate注釋綁定基於java的組件Login.java和基於XML的布局Login.ui.XML

public class Login extends Composite {

   private static LoginUiBinder uiBinder = GWT.create(LoginUiBinder.class);

   /*
    * @UiTemplate is not mandatory but allows multiple XML templates
    * to be used for the same widget. 
    * Default file loaded will be <class-name>.ui.xml
    */
   
   @UiTemplate("Login.ui.xml")
   interface LoginUiBinder extends UiBinder<Widget, Login> {
   }
   ...
}

Step 6 - Create CSS File

創建一個外部CSS文件Login.CSS和基於Java的ResourceLoginResources.Java與CSS樣式等效的文件

.blackText {
   font-family: Arial, Sans-serif;
   color: #000000;
   font-size: 11px;
   text-align: left;
}
...

Step 7 - Create Java based Resource File for CSS File

package com.tutorialspoint.client;
...
public interface LoginResources extends ClientBundle {
   public interface MyCss extends CssResource {
      String blackText();

      ...
   }

   @Source("Login.css")
   MyCss style();
}

Step 8 - Attach CSS resource in Java UI Code file.

使用基於Java的widget類的控制項附加外部CSS文件Login.CSS

public Login() {
   this.res = GWT.create(LoginResources.class);
   res.style().ensureInjected();
   initWidget(uiBinder.createAndBindUi(this));
}

UIBinder Complete Example

這個例子將引導您通過簡單的步驟來展示UIBinder在GWT中的使用。按照以下步驟更新我們在GWT-Create application−一章中創建的GWT應用程式;

Step Description
1 Create a project with a name HelloWorld under a package com.tutorialspoint as explained in the GWT - Create Application chapter.
2 Modify HelloWorld.gwt.xml, HelloWorld.css, HelloWorld.html and HelloWorld.java as explained below. Keep rest of the files unchanged.
3 Compile and run the application to verify the result of the implemented logic.

下面是修改後的模塊描述符的內容。

<?xml version = "1.0" encoding = "UTF-8"?>
<module rename-to = 'helloworld'>
   <!-- Inherit the core Web Toolkit stuff.                        -->
   <inherits name = 'com.google.gwt.user.User'/>

   <!-- Inherit the default GWT style sheet.                       -->
   <inherits name = 'com.google.gwt.user.theme.clean.Clean'/>
   <!-- Inherit the UiBinder module.                               -->
   <inherits name = "com.google.gwt.uibinder.UiBinder"/>
   <!-- Specify the app entry point class.                         -->
   <entry-point class = 'com.tutorialspoint.client.HelloWorld'/>
  
   <!-- Specify the paths for translatable code                    -->
   <source path ='client'/>
   <source path = 'shared'/>

</module>

下面是修改後的樣式表文件war/HelloWorld.css的內容。

body {
   text-align: center;
   font-family: verdana, sans-serif;
}

h1 {
   font-size: 2em;
   font-weight: bold;
   color: #777777;
   margin: 40px 0px 70px;
   text-align: center;
}

下面是修改後的HTML宿主文件war/HelloWorld.HTML的內容。

<html>
   <head>
      <title>Hello World</title>
      <link rel = "stylesheet" href = "HelloWorld.css"/>
      <script language = "javascript" src = "helloworld/helloworld.nocache.js">
      </script>
   </head>

   <body>
      <h1>UiBinder Demonstration</h1>
      <div id = "gwtContainer"></div>
   </body>
</html>

現在創建一個新的UiBinder模板和所有者類（File→new→UiBinder）。

GWT UiBinder Wizard Step 1

選擇項目的客戶端包，然後將其命名爲Login。保留所有其他默認值。單擊Finish按鈕，插件將創建一個新的UiBinder模板和所有者類。

GWT UiBinder Wizard Step 2 

.blackText {
   font-family: Arial, Sans-serif;
   color: #000000;
   font-size: 11px;
   text-align: left;
}

.redText {
   font-family: Arial, Sans-serif;
   color: #ff0000;
   font-size: 11px;
   text-align: left;
}

.loginButton {
   border: 1px solid #3399DD;
   color: #FFFFFF;
   background: #555555;
   font-size: 11px;
   font-weight: bold;
   margin: 0 5px 0 0;
   padding: 4px 10px 5px;
   text-shadow: 0 -1px 0 #3399DD;
}

.box {
   border: 1px solid #AACCEE;
   display: block;
   font-size: 12px;
   margin: 0 0 5px;
   padding: 3px;
   width: 203px;
}

.background {
   background-color: #999999;
   border: 1px none transparent;
   color: #000000;
   font-size: 11px;
   margin-left: -8px;
   margin-top: 5px;
   padding: 6px;
}


package com.tutorialspoint.client;

import com.google.gwt.resources.client.ClientBundle;
import com.google.gwt.resources.client.CssResource;

public interface LoginResources extends ClientBundle {
   /**
    * Sample CssResource.
    */
   public interface MyCss extends CssResource {
      String blackText();

      String redText();

      String loginButton();

      String box();

      String background();
   }

   @Source("Login.css")
   MyCss style();
}


<ui:UiBinder xmlns:ui = 'urn:ui:com.google.gwt.uibinder'
   xmlns:gwt = 'urn:import:com.google.gwt.user.client.ui' 
   xmlns:res = 'urn:with:com.tutorialspoint.client.LoginResources'>
   
   <ui:with type = "com.tutorialspoint.client.LoginResources" field = "res">
   </ui:with>
   
   <gwt:HTMLPanel>
      <div align = "center">
         
         <gwt:VerticalPanel res:styleName = "style.background">
            <gwt:Label text = "Login" res:styleName = "style.blackText" />
            <gwt:TextBox ui:field="loginBox" res:styleName = "style.box" />
            <gwt:Label text = "Password" res:styleName = "style.blackText" />
            <gwt:PasswordTextBox ui:field = "passwordBox" res:styleName = "style.box" />
            
            <gwt:HorizontalPanel verticalAlignment = "middle">
               <gwt:Button ui:field = "buttonSubmit" text="Submit"
                  res:styleName = "style.loginButton" />
               <gwt:CheckBox ui:field = "myCheckBox" />
               <gwt:Label ui:field = "myLabel" text = "Remember me"
                  res:styleName = "style.blackText" />
            </gwt:HorizontalPanel>
            
            <gwt:Label ui:field = "completionLabel1" res:styleName = "style.blackText" />
            <gwt:Label ui:field = "completionLabel2" res:styleName = "style.blackText" />
         </gwt:VerticalPanel>
         
      </div>
   </gwt:HTMLPanel>
   
</ui:UiBinder> 


package com.tutorialspoint.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiField;
import com.google.gwt.uibinder.client.UiHandler;
import com.google.gwt.uibinder.client.UiTemplate;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.Widget;

public class Login extends Composite {

   private static LoginUiBinder uiBinder = GWT.create(LoginUiBinder.class);

   /*
    * @UiTemplate is not mandatory but allows multiple XML templates
    * to be used for the same widget. 
    * Default file loaded will be <class-name>.ui.xml
    */
   @UiTemplate("Login.ui.xml")
   interface LoginUiBinder extends UiBinder<Widget, Login> {
   }

   @UiField(provided = true)
   final LoginResources res;

   public Login() {
      this.res = GWT.create(LoginResources.class);
      res.style().ensureInjected();
      initWidget(uiBinder.createAndBindUi(this));
   }

   @UiField
   TextBox loginBox;

   @UiField
   TextBox passwordBox;

   @UiField
   Label completionLabel1;

   @UiField
   Label completionLabel2;

   private Boolean tooShort = false;

   /*
    * Method name is not relevant, the binding is done according to the class
    * of the parameter.
    */
   @UiHandler("buttonSubmit")
   void doClickSubmit(ClickEvent event) {
      if (!tooShort) {
         Window.alert("Login Successful!");
      } else {
         Window.alert("Login or Password is too short!");
      }
   }

   @UiHandler("loginBox")
   void handleLoginChange(ValueChangeEvent<String> event) {
      if (event.getValue().length() < 6) {
         completionLabel1.setText("Login too short (Size must be > 6)");
         tooShort = true;
      } else {
         tooShort = false;
         completionLabel1.setText("");
      }
   }

   @UiHandler("passwordBox")
   void handlePasswordChange(ValueChangeEvent<String> event) {
      if (event.getValue().length() < 6) {
         tooShort = true;
         completionLabel2.setText("Password too short (Size must be > 6)");
      } else {
         tooShort = false;
         completionLabel2.setText("");
      }
   }
}


package com.tutorialspoint.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.RootPanel;

public class HelloWorld implements EntryPoint {
   public void onModuleLoad() {
      RootPanel.get().add(new Login());   
   }    
}

完成所有更改後，讓我們以開發模式編譯並運行應用程式，就像我們在「gwt-創建應用程式」一章中所做的那樣。如果你的申請一切順利，這將產生以下結果;