Java关于JSON数据格式转换

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/**    

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 * @Title JSONUtils.java  

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 * @Package com.fbtt.site.utils  

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 * @author huangsm  

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 * @email huangsanm@gmail.com  

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 * @date 2011-7-22 下午02:50:42  

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 * @remark  

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 * @version V1.0 

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 */ 

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package com.fbtt.axst.utils; 

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import java.beans.PropertyDescriptor; 

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import java.sql.Date; 

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import java.util.List; 

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import java.util.Map; 

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import org.apache.commons.beanutils.PropertyUtils; 

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/**  

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 * @ClassName: JSONUtils  

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 * @author huangsm 

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 * @date 2011-7-22 下午02:50:42  

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 * @remark   

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 */

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public class JSONUtils { 

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    public static String stringToJson(String s) { 

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        if (s == null) { 

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            return nullTOJson(); 

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        } 

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        StringBuilder sb = new StringBuilder(); 

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        for (int i = 0; i < s.length(); i++) { 

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            char ch = s.charAt(i); 

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            switch (ch) { 

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            case '"': 

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                sb.append("\\\""); 

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                break; 

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            case '\\': 

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                sb.append("\\\\"); 

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                break; 

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            case '\b': 

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                sb.append("\\b"); 

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                break; 

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            case '\f': 

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                sb.append("\\f"); 

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                break; 

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            case '\n': 

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                sb.append("\\n"); 

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                break; 

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            case '\r': 

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                sb.append("\\r"); 

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                break; 

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            case '\t': 

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                sb.append("\\t"); 

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                break; 

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            case '/': 

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                sb.append("\\/"); 

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                break; 

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            default: 

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                if (ch >= '\u0000' && ch <= '\u001F') { 

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                    String ss = Integer.toHexString(ch); 

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                    sb.append("\\u"); 

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                    for (int k = 0; k < 4 - ss.length(); k++) { 

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                        sb.append('0'); 

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                    } 

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                    sb.append(ss.toUpperCase()); 

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                } else { 

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                    sb.append(ch); 

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                } 

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            } 

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        } 

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        return sb.toString(); 

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    } 

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    /*** 

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     * 对象转换成为json 

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     * 这里是描述这个方法的作用 

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     * @return 

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     * @author Java   

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     * @date 2011-7-22 下午02:59:13 

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     */

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    public static String objectToJson(Object obj){ 

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        StringBuffer json = new StringBuffer(); 

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        if (obj == null) { 

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            json.append("\"\""); 

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        } else if (obj instanceof Integer) { 

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            json.append("\"").append(numberToJson((Integer)obj)).append("\""); 

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        } else if (obj instanceof Boolean) { 

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            json.append("\"").append(booleanToJson((Boolean)obj)).append("\""); 

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        } else if (obj instanceof String) { 

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            json.append("\"").append(stringToJson(obj.toString())).append("\""); 

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        } else if (obj instanceof Object[]) { 

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            json.append("\"").append(arrayToJson((Object[])obj)).append("\""); 

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        } else if (obj instanceof List) { 

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            json.append("\"").append(listToJson((List<?>)obj)).append("\""); 

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        } else if (obj instanceof Map) { 

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            json.append("\"").append(mapToJson((Map<?, ?>)obj)).append("\""); 

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        } else if(obj instanceof java.sql.Date){ 

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            json.append("\"").append(dateToJson((Date)obj)).append("\""); 

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        } else if(obj instanceof java.util.Date){ 

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            json.append("\"").append(dateToJson((Date)obj)).append("\""); 

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        } else { 

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            json.append("\"").append(stringToJson(obj.toString())).append("\""); 

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        } 

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        return json.toString(); 

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    } 

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    /** 

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     * 这里是描述这个方法的作用 

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     * @param obj 

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     * @return {["pname":"val"],["pname":"val"]...} 

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     * @author Java   

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     * @date 2011-7-22 下午03:02:49  

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     */ 

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    public static String beanToJson(Object obj) { 

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        StringBuffer json = new StringBuffer("{"); 

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        try { 

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            PropertyDescriptor[] pds = PropertyUtils.getPropertyDescriptors(obj); 

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            if(pds != null && pds.length > 0){ 

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                for (PropertyDescriptor pd : pds) { 

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                    if(pd.getName().equals("class")) 

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                        continue; 

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                    String pname = objectToJson(pd.getName()); 

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                    String val = objectToJson(pd.getReadMethod().invoke(obj)); 

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                    json.append(pname); 

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                    json.append(":"); 

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                    json.append(val); 

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                    json.append(","); 

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                } 

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                json.setCharAt(json.length() - 1, '}'); 

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            }else{ 

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                json.append("}"); 

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            } 

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        } catch (Exception e) { 

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            e.printStackTrace(); 

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        } 

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        return json.toString(); 

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    } 

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    public static String beanToJson(Object obj, String params) { 

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        StringBuffer json = new StringBuffer("{"); 

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        try { 

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            PropertyDescriptor[] pds = PropertyUtils.getPropertyDescriptors(obj); 

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            if(pds != null && pds.length > 0){ 

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                for (PropertyDescriptor pd : pds) { 

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                    String pname = pd.getName(); 

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                    if(pname.equals("class")) 

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                        continue; 

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                    if(params.indexOf(pname) == -1) 

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                        continue; 

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                    pname = objectToJson(pname); 

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                    String val = objectToJson(pd.getReadMethod().invoke(obj)); 

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                    json.append(pname); 

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                    json.append(":"); 

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                    json.append(val); 

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                    json.append(","); 

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                } 

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                json.setCharAt(json.length() - 1, '}'); 

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            }else{ 

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                json.append("}"); 

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            } 

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        } catch (Exception e) { 

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            e.printStackTrace(); 

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        } 

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        return json.toString(); 

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    } 

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    /** 

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     * 这里是描述这个方法的作用 

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     * @param obj 

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     * @return 

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     * @see  

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     * @author Java   

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     * @date 2011-7-22 下午03:02:27  

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     */ 

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    public static String mapToJson(Map<?, ?> map) { 

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        StringBuilder json = new StringBuilder(); 

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        json.append("{"); 

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        if (map != null && map.size() > 0) { 

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            for (Object key : map.keySet()) { 

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                json.append("" + objectToJson(key) + ""); 

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                json.append(":"); 

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                json.append("" + objectToJson(map.get(key)) + ""); 

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                json.append(","); 

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            } 

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            json.setCharAt(json.length() - 1, '}'); 

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        } else { 

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            json.append("}"); 

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        } 

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        return json.toString(); 

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    } 

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    /** 

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     * 这里是描述这个方法的作用 

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     * @param obj 

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     * @return 

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     * @author Java   

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     * @date 2011-7-22 下午03:02:15  

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     */ 

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    public static String listToJson(List<?> list) { 

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        StringBuffer json = new StringBuffer(); 

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        json.append("["); 

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        if (list != null && list.size() > 0) { 

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            for (Object obj : list) { 

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                json.append(beanToJson(obj)); 

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                json.append(","); 

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            } 

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            json.setCharAt(json.length() - 1, ']'); 

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        } else { 

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            json.append("]"); 

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        } 

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        return json.toString(); 

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    } 

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    public static String listToJson(List<?> list, String params) { 

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        StringBuffer json = new StringBuffer(); 

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        json.append("["); 

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        if (list != null && list.size() > 0) { 

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            for (Object obj : list) { 

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                json.append(beanToJson(obj, params)); 

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                json.append(","); 

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            } 

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            json.setCharAt(json.length() - 1, ']'); 

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        } else { 

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            json.append("]"); 

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        } 

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        return json.toString(); 

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    } 

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    /** 

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     * 这里是描述这个方法的作用 

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     * @param obj 

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     * @return 

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     * @see  

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     * @author Java   

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     * @date 2011-7-22 下午03:02:05  

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     */ 

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    private static String arrayToJson(Object[] array) { 

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         StringBuilder json = new StringBuilder(); 

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        json.append("{"); 

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        if (array != null && array.length > 0) { 

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            for (Object obj : array) { 

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                json.append(objectToJson(obj)); 

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                json.append(","); 

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            } 

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            json.setCharAt(json.length() - 1, ']'); 

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        } else { 

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            json.append("}"); 

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        } 

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        return json.toString(); 

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    } 

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    public static String dateToJson(Date date){ 

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        return date.toString(); 

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    } 

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    public static String numberToJson(Number number) { 

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        return number.toString(); 

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    } 

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    public static String booleanToJson(Boolean bool) { 

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        return bool.toString(); 

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    } 

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    public static String nullTOJson(){ 

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        return ""; 

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    } 

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    /** 

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     * 非空验证 

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     * 这里是描述这个方法的作用 

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     * @param arg0 

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     * @return 

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     * @author Java   

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     * @date 2011-7-22 下午02:51:43 

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     */

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    public static Boolean isNull(Object arg0){ 

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        if(arg0 == null) return true; 

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        String arg = (String) arg0; 

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        return ("".equals(arg.trim()) || "null".equals(arg)) ? true : false; 

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    } 

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}
有的方法有重构，其中多了一个参数，其中这个参数的作用是当你一个类有的字段不需要转换的时候，你只需把需要转换的字段属性通过逗号分隔传入就可以了！