json JsonUtil[转]


客户端使用javascript解析满足json格式要求的字符串,十分容易,只要使用eval函数就可以了。不过有个技巧,就是要在字符串两端加上括号。
也即以这个方式来使用:var obj = eval("("+json_string+")");

举个例子:
var str = "{‘name’:'wallimn’,'email’:[email protected],’blog’:'http://blog.csdn.net/wallimn’}";
var json = eval("("+str+")");
alert(json.name);//这样就可以取到对应的值了。

那么在服务器端,如何方便快捷的生成JSON格式要求的字符串呢。好象有现成的jar包工具可供使用(JSON-lib是个较有名的开源项目,但具有很多用不到的复杂功能,执行还要依赖于几个jar包,过于庞大)。但实际上这个工作是非常简单的。我自己写了一个简单的工具类,支持多种数据类型(简单类型、BEAN对象、List、Map以及数组),支持JSON嵌套。很简单,相信大家一看就知道了。








    package com.json.util;  
    import java.lang.reflect.Array;  
    import java.lang.reflect.Field;  
    import java.lang.reflect.Method;  
    import java.text.SimpleDateFormat;  
    import java.util.Date;  
    import java.util.HashMap;  
    import java.util.List;  
    import java.util.Map;  
    import java.util.Set;  
    import java.util.Map.Entry;  
    /** 
     * 用来输出JSON字符串,交给Javascript在页面上进行处理。支持JSON对象的嵌套,支持数组  
 
     */  
    public class JsonUtil {  
        private Map<String, Object> jsonMap = new HashMap<String, Object>();  
        private static SimpleDateFormat formatter = new SimpleDateFormat(  
                "yyyy-MM-dd");  
        public void clear() {  
            jsonMap.clear();  
        }  
        /** 
         * @param key 
         * @param value 
         *             支持简单类型(即原生类型的包装器类)、bean对象、List<Object>、Map<String,Object>以及数组 
         * @return 
         */  
        public Map<String, Object> put(String key, Object value) {  
            jsonMap.put(key, value);  
            return jsonMap;  
        }  
        // 判断是否要加引号  
        private static boolean isNoQuote(Object value) {  
            return (value instanceof Integer || value instanceof Boolean  
                    || value instanceof Double || value instanceof Float  
                    || value instanceof Short || value instanceof Long || value instanceof Byte);  
        }  
        private static boolean isQuote(Object value) {  
            return (value instanceof String || value instanceof Character);  
        }  
        @SuppressWarnings("unchecked")  
        @Override  
        /* 
         * 返回形如{‘apple’:'red’,'lemon’:'yellow’}的字符串 
         */  
        public String toString() {  
            StringBuffer sb = new StringBuffer();  
            sb.append("{");  
            Set<Entry<String, Object>> set = jsonMap.entrySet();  
            for (Entry<String, Object> entry : set) {  
                Object value = entry.getValue();  
                if (value == null) {  
                    continue;// 对于null值,不进行处理,页面上的js取不到值时也是null  
                }  
                sb.append("’").append(entry.getKey()).append("’:");  
                if (value instanceof JsonUtil) {  
                    sb.append(value.toString());  
                } else if (isNoQuote(value)) {  
                    sb.append(value);  
                } else if (value instanceof Date) {  
                    sb.append("’").append(formatter.format(value)).append("’");  
                } else if (isQuote(value)) {  
                    sb.append("’").append(value).append("’");  
                } else if (value.getClass().isArray()) {  
                    sb.append(ArrayToStr((int[]) value));  
                } else if (value instanceof Map) {  
                    sb.append(fromObject((Map<String, Object>) value).toString());  
                } else if (value instanceof List) {  
                    sb.append(ListToStr((List<Object>) value));  
                } else {  
                    sb.append(fromObject(value).toString());  
                }  
                sb.append(",");  
            }  
            int len = sb.length();  
            if (len > 1) {  
                sb.delete(len - 1, len);  
            }  
            sb.append("}");  
            return sb.toString();  
        }  
        public static String ArrayToStr(Object array) {  
            if (!array.getClass().isArray())  
                return "[]";  
            StringBuffer sb = new StringBuffer();  
            sb.append("[");  
            int len = Array.getLength(array);  
            Object v = null;  
            for (int i = 0; i < len; i++) {  
                v = Array.get(array, i);  
                if (v instanceof Date) {  
                    sb.append("'").append(formatter.format(v)).append("'").append(  
                            ",");  
                } else if (isQuote(v)) {  
                    sb.append("'").append(v).append("'").append(",");  
                } else if (isNoQuote(v)) {  
                    sb.append(i).append(",");  
                } else {  
                    sb.append(fromObject(v)).append(",");  
                }  
            }  
            len = sb.length();  
            if (len > 1)  
                sb.delete(len - 1, len);  
            sb.append("]");  
            return sb.toString();  
        }  
        @SuppressWarnings("unchecked")  
        public static String ListToStr(List<Object> list) {  
            if (list == null)  
                return null;  
            StringBuffer sb = new StringBuffer();  
            sb.append("[");  
            Object value = null;  
            for (java.util.Iterator<Object> it = list.iterator(); it.hasNext();) {  
                value = it.next();  
                if (value instanceof Map) {  
                    sb.append(fromObject((Map) value).toString()).append(",");  
                } else if (isNoQuote(value)) {  
                    sb.append(value).append(",");  
                } else if (isQuote(value)) {  
                    sb.append("'").append(value).append("'").append(",");  
                } else {  
                    sb.append(fromObject(value).toString()).append(",");  
                }  
            }  
            int len = sb.length();  
            if (len > 1)  
                sb.delete(len - 1, len);  
            sb.append("]");  
            return sb.toString();  
        }  
        /** 
         * 从一个bean装载数据,返回一个JsonUtil对象。  
         *  
         * @param object 
         * @return 
         */  
        @SuppressWarnings("unchecked")  
        public static JsonUtil fromObject(Object bean) {  
            JsonUtil json = new JsonUtil();  
            if (bean == null)  
                return json;  
            Class cls = bean.getClass();  
            Field[] fs = cls.getDeclaredFields();  
            Object value = null;  
            String fieldName = null;  
            Method method = null;  
            int len = fs.length;  
            for (int i = 0; i < len; i++) {  
                fieldName = fs[i].getName();  
                try {  
                    method = cls.getMethod(getGetter(fieldName), (Class[]) null);  
                    value = method.invoke(bean, (Object[]) null);  
                } catch (Exception e) {  
                    // System.out.println(method.getName());  
                    // e.printStackTrace();  
                    continue;  
                }  
                json.put(fieldName, value);  
            }  
            return json;  
        }  
        /** 
         * 从Map中装载数据  
         * @param map 
         * @return 
         */  
        public static JsonUtil fromObject(Map<String, Object> map) {  
            JsonUtil json = new JsonUtil();  
            if (map == null)  
                return json;  
            json.getMap().putAll(map);  
            return json;  
        }  
        private static String getGetter(String property) {  
            return "get" + property.substring(0, 1).toUpperCase()  
                    + property.substring(1, property.length());  
        }  
        public Map<String, Object> getMap() {  
            return this.jsonMap;  
        }  
    }  

至于类的使用,非常简单了,示例如下:
Java代码

    JsonUtil util = new JsonUtil();  
    util.put("name", "wallimn");  
    util.put("blog", "http://blog.csdn.net/wallimn");  
    util.put("ttt", true);  
    util.put("dd", 1.3d);  
    util.put("ff", 1.3f);  
    util.put("date", new java.util.Date());  
    int []a = new int[]{2,3,4,5};  
    util.put("arr", a);  
      
    Map<String,Object> map1 = new HashMap<String,Object>();  
    map1.put("name", "wallimn");  
    map1.put("age", 2);  
    Map<String,Object> map2 = new HashMap<String,Object>();  
    map2.put("name", "wal2limn");  
    map2.put("age", 22);  
      
    util.put("map1", map1);  
    util.put("map2", map2);  
    List<Map<String,Object>> list = new LinkedList<Map<String,Object>>();  
    list.add(map1);  
    list.add(map2);  
    util.put("listMap", list);  
    TestBean t = new TestBean("wallimn","男");  
    util.put("beanObject", t);  
      
    List<Integer> li = new LinkedList<Integer>();  
    li.add(1);  
    li.add(1);  
    li.add(1);  
    util.put("listInteger", li);  
    //System.out.println(JsonUtil.fromObject(map1));  
    System.out.println(util);  
{'dd':1.3,
'ttt':true,
'map1': {'age':2,'name':'wallimn'},
'ff':1.3,
'map2': {'age':22,'name':'wal2limn'},
'arr':[0,1,2,3],
'listMap': [{'age':2,'name':'wallimn'}, {'age':22,'name':'wal2limn'}],
'date':'2009-02-05′,
'listInteger': [1,1,1],
'name':'wallimn',
'beanObject':{'sex':'男 ','name':'wallimn'},
'blog':'http://blog.csdn.net/wallimn'
}  

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