Eclipse RCP应用程序中使用Databinding(邦定)

1. Eclipse Databinding概述

Eclipse Databinding可以在你的模型和用户界面之间建立一种关联。当任何一方（模型或用户界面）发生变化时，都可以同步到另一方。另外你可以使用默认的或者是自定义的数据验证器（validator）来验证数据同时可以使用转换器（converter）在模型和界面之间转换数据。下面我们用一个应用程序来演示Databinding功能。在这个程序中我们在界面中显示一个Person对象，用户可以在界面中修改Person对象的值。也可以通过一个按钮来触发事件来直接修改模型。任何一端的变化都会同步到另一端。

1. Domain Model

1.1. 概述

首先创建一个可复用的数据模型。所以我们把数据模型封装到一个独立的插件(plugin)中以方便复用。

1.2. 创建插件

创建一个名为“de.vogella.databinding.person.model”的插件项目。不要创建activator,不要选这“This plug-in will make contributions to th UI”,也不要选择“Do you want to create a rich client application”.

点击"Finish". 为了能够在用户界面和模型之间直接使用Databinding,模型必须实现PropertyChangeSupport接口。这样Eclipse Databinding框架就可以监听到在模型中的变化了。创建一个名为de.vogella.databinding.person.model 和如下的文件。

Java代码

package de.vogella.databinding.person.model;

import java.beans.PropertyChangeEvent;

import java.beans.PropertyChangeListener;

import java.beans.PropertyChangeSupport;

public class Person implements PropertyChangeListener {

private String firstName;

private String lastName;

private boolean married;

private String gender;

private Integer age;

private Address address;

private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(

this);

public Person() {

}

public void addPropertyChangeListener(String propertyName,

PropertyChangeListener listener) {

propertyChangeSupport.addPropertyChangeListener(propertyName, listener);

}

public void removePropertyChangeListener(PropertyChangeListener listener) {

propertyChangeSupport.removePropertyChangeListener(listener);

}

public String getFirstName() {

return firstName;

}

public String getGender() {

return gender;

}

public String getLastName() {

return lastName;

}

public boolean isMarried() {

return married;

}

public void setFirstName(String firstName) {

propertyChangeSupport.firePropertyChange("firstName", this.firstName,

this.firstName = firstName);

}

public void setGender(String gender) {

propertyChangeSupport.firePropertyChange("gender", this.gender,

this.gender = gender);

}

public void setLastName(String lastName) {

propertyChangeSupport.firePropertyChange("lastName", this.lastName,

this.lastName = lastName);

}

public void setMarried(boolean isMarried) {

propertyChangeSupport.firePropertyChange("married", this.married,

this.married = isMarried);

}

public Integer getAge() {

return age;

}

public void setAge(Integer age) {

propertyChangeSupport.firePropertyChange("age", this.age,

this.age = age);

}

public Address getAddress() {

return address;

}

public void setAddress(Address address) {

address.addPropertyChangeListener("country", this);

propertyChangeSupport.firePropertyChange("address", this.address,

this.address = address);

}

@Override

public String toString() {

return firstName + " " + lastName;

}

@Override

public void propertyChange(PropertyChangeEvent event) {

propertyChangeSupport.firePropertyChange("address", null, address);

}

Java代码

package de.vogella.databinding.person.model;

import java.beans.PropertyChangeListener;

import java.beans.PropertyChangeSupport;

public class Address {

private String street;

private String number;

private String postalCode;

private String city;

private String country;

private PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(

this);

public void addPropertyChangeListener(String propertyName,

PropertyChangeListener listener) {

propertyChangeSupport.addPropertyChangeListener(propertyName, listener);

}

public void removePropertyChangeListener(PropertyChangeListener listener) {

propertyChangeSupport.removePropertyChangeListener(listener);

}

public Address() {

}

public Address(String postalCode, String city, String country) {

this.postalCode = postalCode;

this.city = city;

this.country = country;

}

public String getStreet() {

return street;

}

public void setStreet(String street) {

propertyChangeSupport.firePropertyChange("street", this.street,

this.street = street);

}

public String getNumber() {

return number;

}

public void setNumber(String number) {

propertyChangeSupport.firePropertyChange("number", this.number,

this.number = number);

}

public String getPostalCode() {

return postalCode;

}

public void setPostalCode(String postalCode) {

propertyChangeSupport.firePropertyChange("postalCode", this.postalCode,

this.postalCode = postalCode);

}

public String getCity() {

return city;

}

public void setCity(String city) {

propertyChangeSupport.firePropertyChange("citry", this.city,

this.city = city);

this.city = city;

}

public String getCountry() {

return country;

}

public void setCountry(String country) {

propertyChangeSupport.firePropertyChange("country", this.country,

this.country = country);

}

public String toString() {

String s = "";

s += street != null ? street + " " : "";

s += number != null ? number + " " : "";

s += postalCode != null ? postalCode + " " : "";

s += city != null ? city + " " : "";

s += country != null ? country + " " : "";

return s;

}

打开 META－INF 文件夹中的 MANIFEST.MF 文件。选中"Runtime"选项页。把de.vogella.databinding.person.model 加入到 Exported Packages 中。这样其他插件就可以访问到这个包了。

2. 绑定到SWT控件

2.1. RCP项目

通过“Hello RCP”模板创建一个名为“de.vogella.databinding.person.swt”的Eclipse RCP项目（具体的可以参考Create your first Eclipse RCP ）。

2.2. 依赖模块

把“de.vogella.databinding.person.model”插件添加到当前项目的依赖中。

2.3. 添加Eclipse Databinding的依赖

把"org.eclipse.core.databinding", "org.eclipse.core.databinding.beans", "org.eclipse.jface.databinding" 和 "org.eclipse.core.databinding.property" 添加到当前项目的依赖中。

2.4. 用户界面

向当前RCP项目添加一个视图（view）,并创建这个视图的实现类 “de.vogella.databinding.person.PersonView ” 把这个视图添加到透视图中去。(可以参考 Eclipse RCP Tutorial ) 实现代码如下所示

Java代码

package de.vogella.databinding.person.swt;

import org.eclipse.core.databinding.DataBindingContext;

import org.eclipse.core.databinding.beans.BeanProperties;

import org.eclipse.core.databinding.beans.BeansObservables;

import org.eclipse.core.databinding.observable.value.IObservableValue;

import org.eclipse.jface.databinding.swt.SWTObservables;

import org.eclipse.swt.SWT;

import org.eclipse.swt.events.SelectionAdapter;

import org.eclipse.swt.events.SelectionEvent;

import org.eclipse.swt.layout.GridData;

import org.eclipse.swt.layout.GridLayout;

import org.eclipse.swt.widgets.Button;

import org.eclipse.swt.widgets.Combo;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Label;

import org.eclipse.swt.widgets.Layout;

import org.eclipse.swt.widgets.Text;

import org.eclipse.ui.part.ViewPart;

import de.vogella.databinding.person.model.Address;

import de.vogella.databinding.person.model.Person;

public class PersonView extends ViewPart {

public static final String ID = "de.vogella.databinding.person.swt.View";

private Person person;

private Text firstName;

private Text ageText;

private Button marriedButton;

private Combo genderCombo;

private Text countryText;

public PersonView() {

}

@Override

public void createPartControl(Composite parent) {

person = new Person();

Address address = new Address();

address.setCountry("Deutschland");

person.setAddress(address);

person.setFirstName("John");

person.setLastName("Doo");

person.setGender("Male");

person.setAge(12);

person.setMarried(true);

// Lets put thing to order

Layout layout = new GridLayout(2, false);

parent.setLayout(layout);

Label firstLabel = new Label(parent, SWT.NONE);

firstLabel.setText("Firstname: ");

firstName = new Text(parent, SWT.BORDER);

GridData gridData = new GridData();

gridData.horizontalAlignment = SWT.FILL;

gridData.grabExcessHorizontalSpace = true;

firstName.setLayoutData(gridData);

Label ageLabel = new Label(parent, SWT.NONE);

ageLabel.setText("Age: ");

ageText = new Text(parent, SWT.BORDER);

gridData = new GridData();

gridData.horizontalAlignment = SWT.FILL;

gridData.grabExcessHorizontalSpace = true;

ageText.setLayoutData(gridData);

Label marriedLabel = new Label(parent, SWT.NONE);

marriedLabel.setText("Married: ");

marriedButton = new Button(parent, SWT.CHECK);

Label genderLabel = new Label(parent, SWT.NONE);

genderLabel.setText("Gender: ");

genderCombo = new Combo(parent, SWT.NONE);

genderCombo.add("Male");

genderCombo.add("Female");

Label countryLabel = new Label(parent, SWT.NONE);

countryLabel.setText("Country");

countryText = new Text(parent, SWT.BORDER);

Button button1 = new Button(parent, SWT.PUSH);

button1.setText("Write model");

button1.addSelectionListener(new SelectionAdapter() {

@Override

public void widgetSelected(SelectionEvent e) {

System.out.println("Firstname: " + person.getFirstName());

System.out.println("Age " + person.getAge());

System.out.println("Married: " + person.isMarried());

System.out.println("Gender: " + person.getGender());

System.out.println("Country: "

+ person.getAddress().getCountry());

}

});

Button button2 = new Button(parent, SWT.PUSH);

button2.setText("Change model");

button2.addSelectionListener(new SelectionAdapter() {

@Override

public void widgetSelected(SelectionEvent e) {

person.setFirstName("Lars");

person.setAge(person.getAge() + 1);

person.setMarried(!person.isMarried());

if (person.getGender().equals("Male")) {

} else {

person.setGender("Male");

}

if (person.getAddress().getCountry().equals("Deutschland")) {

person.getAddress().setCountry("USA");

} else {

person.getAddress().setCountry("Deutschland");

}

});

// Now lets do the binding

bindValues();

}

@Override

public void setFocus() {

}

private void bindValues() {

// The DataBindingContext object will manage the databindings

DataBindingContext bindingContext = new DataBindingContext();

IObservableValue uiElement;

IObservableValue modelElement;

// Lets bind it

uiElement = SWTObservables.observeText(firstName, SWT.Modify);

modelElement = BeansObservables.observeValue(person, "firstName");

// The bindValue method call binds the text element with the model