Jackson将json字符串转换成泛型List/map

url: http://www.cnblogs.com/quanyongan/archive/2013/04/16/3024993.html

Jackson处理一般的JavaBean和Json之间的转换只要使用ObjectMapper 对象的readValue和writeValueAsString两个方法就能实现。但是如果要转换复杂类型Collection如 List<YourBean>，那么就需要先反序列化复杂类型 为泛型的Collection Type。

如果是ArrayList<YourBean>那么使用ObjectMapper 的getTypeFactory().constructParametricType(collectionClass, elementClasses);

如果是HashMap<String,YourBean>那么 ObjectMapper 的getTypeFactory().constructParametricType(HashMap.class,String.class, YourBean.class);

public final ObjectMapper mapper = new ObjectMapper();
    
    public static void main(String[] args) throws Exception{ 
        JavaType javaType = getCollectionType(ArrayList.class, YourBean.class);
        List<YourBean> lst =  (List<YourBean>)mapper.readValue(jsonString, javaType);
    }  
       /**  
        * 获取泛型的Collection Type 
        * @param collectionClass 泛型的Collection  
        * @param elementClasses 元素类  
        * @return JavaType Java类型  
        * @since 1.0  
        */  
    public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) {  
        return mapper.getTypeFactory().constructParametricType(collectionClass, elementClasses);  
    }