java - 速度模板不起作用

Question

我正在尝试使用速度模板解析 json。这是我的 json 字符串，

{\n  \"firstName\": \"Tom\",\n  \"lastName\": \"Geller\",\n  \"department\": \"Retail\",\n  \"manager\": \"Steve\",\n  \"joiningDate\": \"03/08/2011\",\n  \"employees\": [\n    {\n      \"firstName\": \"Paul\",\n      \"lastName\": \"Balmer\",\n      \"department\": \"Retail\",\n      \"manager\": \"Tom Geller\",\n      \"joiningDate\": \"06/21/2014\"\n    },\n    {\n      \"firstName\": \"Eric\",\n      \"lastName\": \"S\",\n      \"department\": \"Retail\",\n      \"manager\": \"Tom Geller\",\n      \"joiningDate\": \"09/13/2014\"\n    }\n  ]\n}

这是我的速度模板，

$firstName $lastName belongs to $department Department. 
His manager is $manager and joining date is $joiningDate.

Employees reporting to him are, 
#foreach( $employee in $employees )
    $employee.firstName $employee.lastName
#end

这是打印的输出。它不会打印报告员工，

Tom Geller belongs to Retail Department. 
His manager is Steve and joining date is 03/08/2011.

Employees reporting to him are, 

这是java代码，

public class VelocityTemplateDemo {

protected VelocityEngine velocity;

public VelocityTemplateDemo() {
    velocity = new VelocityEngine();
    velocity.init();
}

public String publish(String templatePath, String jsonString) throws IOException {
    JSONObject jsonObj = new JSONObject(jsonString);
    VelocityContext context = new VelocityContext();
    for (Object key : jsonObj.keySet()) {
        String keyString = String.valueOf(key);
        context.put(keyString, jsonObj.get(keyString));
    }
    Writer writer = new StringWriter();
    velocity.mergeTemplate(templatePath, "UTF-8", context, writer);
    writer.flush();
    return writer.toString();
}

public static void main(String[] args) throws IOException {
    String str = "{\n  \"firstName\": \"Tom\",\n  \"lastName\": \"Geller\",\n  \"department\": \"Retail\",\n  \"manager\": \"Steve\",\n  \"joiningDate\": \"03/08/2011\",\n  \"employees\": [\n    {\n      \"firstName\": \"Paul\",\n      \"lastName\": \"Balmer\",\n      \"department\": \"Retail\",\n      \"manager\": \"Tom Geller\",\n      \"joiningDate\": \"06/21/2014\"\n    },\n    {\n      \"firstName\": \"Eric\",\n      \"lastName\": \"S\",\n      \"department\": \"Retail\",\n      \"manager\": \"Tom Geller\",\n      \"joiningDate\": \"09/13/2014\"\n    }\n  ]\n}";
    String result = new VelocityTemplateDemo().publish("/src/main/resources/template.vm", str);
    System.out.println(result);
}

}

Answer 1

由于 $employees 是一个 JSONArray，我发现有两个可能的原因:

• 您使用的是 Apache Velocity 1.7 之前的版本(Velocity 1.7 中添加了对 Iterable 接口(interface)的支持)
• 您使用的是 20150729 之前的 json.org 版本(该版本将 Iterable 接口(interface)添加到 JSONArray 类中)