如何在Handlebars.java中使用json

Question

我正在尝试使用handlebars.java来应用json数据。我从https://github.com/jknack/handlebars.java中取了下面的例子，它适用于handlebars.js，我希望同样的方法也适用于handlebars.java

public class TestHandlebars {
    public static void main(String[] args) throws Exception {
        String json = "{\"name\": \"world\"}";
        Handlebars handlebars = new Handlebars();
        handlebars.registerHelper("json", Jackson2Helper.INSTANCE);

        Context context = Context
            .newBuilder(json)
            .resolver(JsonNodeValueResolver.INSTANCE,
                    JavaBeanValueResolver.INSTANCE,
                    FieldValueResolver.INSTANCE,
                    MapValueResolver.INSTANCE,
                    MethodValueResolver.INSTANCE
            )
            .build();
        Template template = handlebars.compileInline("Hello {{name}}!");
        System.out.println(template.apply(context));
    }
}

我期望输出结果为

你好，世界！

而我得到的只是

您好！

我遗漏了什么？我在https://github.com/jknack/handlebars.java上见过像Jackson views和java模型"Blog“这样的例子，但是不使用java模型对象就不能实现吗？

Answer 1

我刚刚发现将json作为JsonNode对象传递是可行的。

public class TestHandlebars {
    public static void main(String[] args) throws Exception {
        String json = "{\"name\": \"world\"}";
        JsonNode jsonNode = new ObjectMapper().readValue(json, JsonNode.class);
        Handlebars handlebars = new Handlebars();
        handlebars.registerHelper("json", Jackson2Helper.INSTANCE);

        Context context = Context
            .newBuilder(jsonNode)
            .resolver(JsonNodeValueResolver.INSTANCE,
                    JavaBeanValueResolver.INSTANCE,
                    FieldValueResolver.INSTANCE,
                    MapValueResolver.INSTANCE,
                    MethodValueResolver.INSTANCE
            )
            .build();
        Template template = handlebars.compileInline("Hello {{name}}!");
        System.out.println(template.apply(context));
    }
}

Answer 2

使用Gson，你可以很容易地做到这一点，而不需要注册一堆转换器。

String data = "{\"subject\": \"World\"}";
String decoration = "Hello {{subject}}!";

Handlebars handlebars = new Handlebars();
Gson gson = new Gson();

Type type = new TypeToken<Map<String, Object>>(){}.getType();
Map<String, Object> map = gson.fromJson(data, type);   

Template template = handlebars.compileInline(decoration);
Context context = Context.newBuilder(map).build();

String output = template.apply(context);