java 反射机制构建JSON字符串

接着上一篇文章、今天继续学习利用java 反射机制构建JSON字符串。

JSON的格式跟使用的方式方法就不讲了、这个百度一下就有......好了今天心情很糟糕、直接上代码吧！

import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.List;import com.test.hzw.bean.test_user;import com.test.hzw.dao.impl.DaoImpl;/** * Json转换测试类 * @author 胡汉三 * */@SuppressWarnings({"unchecked","unused"})public class Reflect004 {/** * @param args * @throws Exception  */public static void main(String[] args) throws Exception {DaoImpl dao = new DaoImpl();test_user u = new test_user();String sqlPage = "SELECT * FROM test_user WHERE id <= ";sqlPage += " (SELECT id FROM test_user ORDER BY id LIMIT "+(2-1)*20+", 1) ";sqlPage += " ORDER BY id LIMIT 20 " ;  /* * 从数据库查询并获得集合 *  * PS: 该方法是上一篇文章的内容 */List<test_user> listT = (List<test_user>)dao.findList(u, sqlPage, new ArrayList());String s = ToJsonByList(listT);System.out.println(s);  System.out.println(ToJsonByAll(listT.get(0)).toString());} /** * 根据List集合生成Json数组格式字符串(只支持bean方式) * @param <T> * @param list 集合对象 * @return */public static <T> String ToJsonByList(List<T> list){StringBuffer b = new StringBuffer("[");if(list!=null&&list.size()>0){for (int i = 0; i < list.size(); i++){Object o = list.get(i);try {//调用ToJsonByBean方法StringBuffer s = ToJsonByBean(o);if(s!=null&&!s.equals("")){b.append(s).append(","); }} catch (Exception e) {     e.printStackTrace();} }   }b.append("]");return b.replace(b.lastIndexOf(","),b.lastIndexOf(",") + 1 ,"").toString();}/**      * 根据javaBean生成Json对象格式字符串      * @param object 任意javaBean类型对象      * @return 拼接好的StringBuffer对象      */  public static StringBuffer ToJsonByBean(Object object) throws Exception{          Class clazz = object.getClass();  //获得Class对象        Field[] fields = clazz.getDeclaredFields();  //获得Class对象的字段数组        StringBuffer sb = new StringBuffer("{");         /*         * 循环字段数组         */        for (Field field : fields) {                String fieldName = field.getName(); //获得字段名称               //获得字段对应的get方法对象            Method method = clazz.getMethod("get" + change(fieldName), null);              //调用get方法获得字段的值            Object property = method.invoke(object, null);                          /*             * 生成json字符串数据             */            if(property == null){                  sb.append("\""+fieldName+"\":\"\",");                }else{            if (field.getType().getName().equals("java.lang.Boolean"))            sb.append("\""+fieldName+"\":"+Boolean.valueOf(property.toString())+",");               else            sb.append("\""+fieldName+"\":\""+property+"\",");             }          }                     sb.append("}");                  return sb.replace(sb.lastIndexOf(","),sb.lastIndexOf(",") + 1 ,"");      }            /**      * @param src 源字符串      * @return 字符串，将src的第一个字母转换为大写，src为空时返回null      */      public static String change(String src) {          if (src != null) {              StringBuffer sb = new StringBuffer(src);              sb.setCharAt(0, Character.toUpperCase(sb.charAt(0)));              return sb.toString();          } else {              return null;          }      }          /**      * 生成Json数组格式字符串      * @param object 任意类型对象      * @return 拼接好的StringBuffer对象      */      public static StringBuffer ToJsonByAll(Object object) throws Exception{          Class clazz = object.getClass();          Field[] fields = clazz.getDeclaredFields();          StringBuffer sb = new StringBuffer("{[");          for (Field field : fields) {              String fieldName = field.getName();              Method method = clazz.getMethod("get" + change(fieldName), null);              Object property = method.invoke(object, null);              if(property == null){                    sb.append("\"\",");              }else{                  sb.append("\"" + property + "\",");              }          }                 sb.append("]}");                  return sb.replace(sb.lastIndexOf(","),sb.lastIndexOf(",") + 1 ,"");      }    }

o()o 唉！

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