JAVA反射机制，把JavaBean属性转成字符串

JAVA反射机制，把JavaBean属性转成字符串

package  com.jetsum.util;

import  java.io.StringReader;
import  java.lang.reflect.Field;
import  java.util.ArrayList;
import  java.util.List;
import  java.util.Map;
import  java.util.Set;

import  antlr.RecognitionException;
import  antlr.TokenStreamException;

import  com.sdicons.json.mapper.JSONMapper;
import  com.sdicons.json.mapper.MapperException;
import  com.sdicons.json.model.JSONArray;
import  com.sdicons.json.model.JSONValue;
import  com.sdicons.json.parser.JSONParser;

public   class  JsonUtil  {

    /** *//**
     * JAVA对象转换成JSON字符串
     * @param obj
     * @return
     * @throws MapperException
     */    
    public static String objectToJsonStr(Object obj) throws MapperException{
        JSONValue jsonValue = JSONMapper.toJSON(obj);  
        String jsonStr = jsonValue.render(false);
        return jsonStr;
    }
    
    /** *//**
     * 重载objectToJsonStr方法
     * @param obj 需要转换的JAVA对象
     * @param format 是否格式化
     * @return
     * @throws MapperException
     */
    public static String objectToJsonStr(Object obj,boolean format) throws MapperException{
        JSONValue jsonValue = JSONMapper.toJSON(obj);  
        String jsonStr = jsonValue.render(format);
        return jsonStr;
    }    
    
    /** *//**
     * JSON字符串转换成JAVA对象
     * @param jsonStr
     * @param cla
     * @return
     * @throws MapperException
     * @throws TokenStreamException
     * @throws RecognitionException
     */
    @SuppressWarnings({ "rawtypes", "unchecked" })
    public static Object jsonStrToObject(String jsonStr,Class<?> cla) throws MapperException, TokenStreamException, RecognitionException{
        Object obj = null;
        try{
            JSONParser parser = new JSONParser(new StringReader(jsonStr));    
            JSONValue jsonValue = parser.nextValue();              
            if(jsonValue instanceof com.sdicons.json.model.JSONArray){
                List list = new ArrayList();
                JSONArray jsonArray = (JSONArray) jsonValue;
                for(int i=0;i<jsonArray.size();i++){
                    JSONValue jsonObj = jsonArray.get(i);
                    Object javaObj = JSONMapper.toJava(jsonObj,cla); 
                    list.add(javaObj);
                }
                obj = list;
            }else if(jsonValue instanceof com.sdicons.json.model.JSONObject){
                obj = JSONMapper.toJava(jsonValue,cla); 
            }else{
                obj = jsonValue;
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        return obj; 
    }
    
    /** *//**
     * 将JAVA对象转换成JSON字符串
     * @param obj
     * @return
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    @SuppressWarnings("rawtypes")
    public static String simpleObjectToJsonStr(Object obj,List<Class> claList) throws IllegalArgumentException, IllegalAccessException{
        if(obj==null){
            return "null";
        }
        String jsonStr = "{";
        Class<?> cla = obj.getClass();
        Field fields[] = cla.getDeclaredFields();
        for (Field field : fields) {
            field.setAccessible(true);
            if(field.getType() == long.class){
                jsonStr += "\""+field.getName()+"\":"+field.getLong(obj)+",";
            }else if(field.getType() == double.class){
                jsonStr += "\""+field.getName()+"\":"+field.getDouble(obj)+",";
            }else if(field.getType() == float.class){
                jsonStr += "\""+field.getName()+"\":"+field.getFloat(obj)+",";
            }else if(field.getType() == int.class){
                jsonStr += "\""+field.getName()+"\":"+field.getInt(obj)+",";
            }else if(field.getType() == boolean.class){
                jsonStr += "\""+field.getName()+"\":"+field.getBoolean(obj)+",";
            }else if(field.getType() == Integer.class||field.getType() == Boolean.class
                    ||field.getType() == Double.class||field.getType() == Float.class                    
                    ||field.getType() == Long.class){                
                jsonStr += "\""+field.getName()+"\":"+field.get(obj)+",";
            }else if(field.getType() == String.class){
                jsonStr += "\""+field.getName()+"\":\""+field.get(obj)+"\",";
            }else if(field.getType() == List.class){
                String value = simpleListToJsonStr((List<?>)field.get(obj),claList);
                jsonStr += "\""+field.getName()+"\":"+value+",";                
            }else{        
                if(claList!=null&&claList.size()!=0&&claList.contains(field.getType())){
                    String value = simpleObjectToJsonStr(field.get(obj),claList);
                    jsonStr += "\""+field.getName()+"\":"+value+",";                    
                }else{
                    jsonStr += "\""+field.getName()+"\":null,";
                }
            }
        }
        jsonStr = jsonStr.substring(0,jsonStr.length()-1);
        jsonStr += "}";
            return jsonStr;        
    }
    
    /** *//**
     * 将JAVA的LIST转换成JSON字符串
     * @param list
     * @return
     * @throws IllegalArgumentException
     * @throws IllegalAccessException
     */
    @SuppressWarnings("rawtypes")
    public static String simpleListToJsonStr(List<?> list,List<Class> claList) throws IllegalArgumentException, IllegalAccessException{
        if(list==null||list.size()==0){
            return "[]";
        }
        String jsonStr = "[";
        for (Object object : list) {
            jsonStr += simpleObjectToJsonStr(object,claList)+",";
        }
        jsonStr = jsonStr.substring(0,jsonStr.length()-1);
        jsonStr += "]";        
        return jsonStr;
    }    
    
    /** *//**
     * 将JAVA的MAP转换成JSON字符串，
     * 只转换第一层数据
     * @param map
     * @return
     */
    public static String simpleMapToJsonStr(Map<?,?> map){
        if(map==null||map.isEmpty()){
            return "null";
        }
        String jsonStr = "{";
        Set<?> keySet = map.keySet();
        for (Object key : keySet) {
            jsonStr += "\""+key+"\":\""+map.get(key)+"\",";        
        }
        jsonStr = jsonStr.substring(0,jsonStr.length()-1);
        jsonStr += "}";
        return jsonStr;
    }
}

文章详细参考: http://blog.csdn.net/sjiang2142/article/details/6770672

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