前言

之前在网上看过很多的geojson的方法，都很繁琐，而且每次生成一种geojson的时候，都必须重新书写一个新方法，拼接一种新的geojson字符串返回给前端。但是这从代码的耦合性角度来说却是十分的不合理

实现方式

通过反射获取类的属性，匹配到需要进行拼接字符串的类，获取集合中的每个实体的对应属性值进行自动拼接geojson字符串的方法 具体代码实现方式如下：

public class ToGeojsonUtils {

    //private Logger logger = LoggerFactory.getLogger(getClass());

    /**
     * 将存储实体类的集合，转化成geojson字符串
     * @param obj 需要转化成实体类的集合
     * @param entity 实体类的class文件
     * @param fieleName 属性名字
     * @param fieldType 属性类型
     * @param geometry geometry类型
     * @return
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static String objectToGeojsonString(List obj,
                                        Class entity,
                                        String fieleName,
                                        String fieldType, String geometry){
        List<String> fieldname= RequestParameterUtils.getInstance().splitString(fieleName);
        List<String> fieldtype=RequestParameterUtils.getInstance().splitString(fieldType);
        if(obj==null){
            return "[]";
        }else if(obj.size()==0){
            return "[]";
        }else{
            String result = null;
            //处理拼接在geojson中的属性名字以及类型
            if(fieldname.size()==fieldtype.size()){
            }else{
                //logger.info("属性名字以及类型格式不对！");
                return "";
            }
            try {
                Class clazz=entity;
                String geojsonContent="";
                List<Method> fieldGetMethods=new ArrayList<Method>();
                StringBuilder content=new StringBuilder();
                for(int i=0;i<fieldname.size();i++){
                    if(i==0) {
                        content.append("geometry");
                        content.append(":");
                        content.append(geometry);
                        content.append(",");
                    }else {
                        content.append(fieldname.get(i));
                        content.append(":");
                        content.append(fieldtype.get(i));
                        content.append(",");
                    }
                    String name=fieldname.get(i);
                    String methodname="get"+name.substring(0, 1).toUpperCase() + name.substring(1);
                    Method method=clazz.getMethod(methodname);
                    fieldGetMethods.add(method);
                }
                geojsonContent=content.toString();
                SimpleFeatureType TYPE = DataUtilities.createType("Link",geojsonContent);
                FeatureJSON fjson = new FeatureJSON(new GeometryJSON(13));
                DefaultFeatureCollection featureCollection = new DefaultFeatureCollection();
                for (int i=0 ; i<obj.size() ; i++) {
                    SimpleFeatureBuilder featureBuilder = new SimpleFeatureBuilder(TYPE);
                    for(Method method:fieldGetMethods){
                        featureBuilder.add(method.invoke(obj.get(i)));
                    }
                    SimpleFeature feature = featureBuilder.buildFeature(null);
                    featureCollection.add(feature);
                }
                StringWriter writer = new StringWriter();
                fjson.writeFeatureCollection(featureCollection, writer);
                result=writer.toString();
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return result;
        }
    }

}