Question

我正在尝试使SuggestBox仅在输入2个字符后显示建议。我的想法是使用DefaultSuggestionDisplay类在文本长度为1时隐藏建议。我试图在SuggestionBox本身及其TextBox上附加不同的处理程序，如KeyPressHandler和KeyUpHandler，但它们似乎都不起作用。你有任何建议＆＃34;？：d

Answer 1

您可以扩展SuggestBox并覆盖showSuggestionList()方法。

添加KeyUpHandler无法正常工作，因为您添加了另一个KeyUpHandler，而不是替换SuggestBox添加到其自己的TextBox中的那个。

编辑：

@Override
showSuggestionList() {
    if (getTextBox().getValue().length() > 1) {
        super.showSuggestionList();
    }
}

Answer 2

您可以扩展DefaultSuggestionDisplay并覆盖showSuggestions方法：

public class MySuggestionDisplay extends DefaultSuggestionDisplay {
    @Override
    protected void showSuggestions(SuggestBox suggestBox, Collection<? extends Suggestion> suggestions, boolean isDisplayStringHTML, boolean isAutoSelectEnabled, SuggestionCallback callback) {
        if(suggestBox.getText().length() > 1)
            super.showSuggestions(suggestBox, suggestions, isDisplayStringHTML, isAutoSelectEnabled, callback);
    }
}

您必须将新显示传递给SuggestBox构造函数：

public class MySuggestBox extends SuggestBox {
    public MySuggestBox() {
        super(
            new MySuggestOracle(),
            new TextBox(), 
            new MySuggestionDisplay());
    }
}

在此构造函数中，您应该提供：

您自己的SuggestOracle班级（此处名为MySuggestOracle） - 我想您有一个
TextBox - 这是输入文字的默认小部件（您可以自己提供，只需要实现HasText）
SuggestionDisplay - 使用覆盖showSuggestions方法的方法。

这是完整的工作示例代码，显示至少输入2个字符的建议：

import java.util.ArrayList;
import java.util.Collection;

import com.google.gwt.user.client.ui.SuggestBox;
import com.google.gwt.user.client.ui.SuggestOracle;
import com.google.gwt.user.client.ui.SuggestOracle.Suggestion;
import com.google.gwt.user.client.ui.TextBox;

public class MySuggestBox extends SuggestBox {

    public MySuggestBox() {
        super(
            new SuggestOracle() {
                @Override
                public void requestSuggestions(Request request, Callback callback) {
                    ArrayList<Suggestion> suggestions = new ArrayList<Suggestion>();
                    suggestions.add(new MySuggestion("aaa"));
                    suggestions.add(new MySuggestion("bbb"));
                    suggestions.add(new MySuggestion("ccc"));
                    suggestions.add(new MySuggestion("ddd"));

                    Response response = new Response();
                    response.setSuggestions(suggestions);
                    callback.onSuggestionsReady(request, response);
                }
            }, 
            new TextBox(), 
            new MySuggestionDisplay());
    }

    public static class MySuggestionDisplay extends DefaultSuggestionDisplay {
        @Override
        protected void showSuggestions(SuggestBox suggestBox, Collection<? extends Suggestion> suggestions, boolean isDisplayStringHTML, boolean isAutoSelectEnabled, SuggestionCallback callback) {
            if(suggestBox.getText().length() > 1)
                super.showSuggestions(suggestBox, suggestions, isDisplayStringHTML, isAutoSelectEnabled, callback);
        }
    }

    public static class MySuggestion implements Suggestion {

        private String text;

        public MySuggestion(String text) {
            this.text = text;
        }

        @Override
        public String getDisplayString() {
            return text;
        }

        @Override
        public String getReplacementString() {
            return text;
        }
    }
}

如何在输入2个字符后在GWT SuggestBox中显示建议？

2 个答案: