解析json和封装json

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.Map;
import java.util.Set;

public final class JsonUtil
{

        /**
         * 把对象封装为JSON格式
         *
         * @param o
         *            对象
         * @return JSON格式
         */
        @SuppressWarnings("unchecked")
        public static String toJson(final Object o)
        {
                if (o == null)
                {
                        return "null";
                }
                if (o instanceof String) //String
                {
                        return string2Json((String) o);
                }
                if (o instanceof Boolean) //Boolean
                {
                        return boolean2Json((Boolean) o);
                }
                if (o instanceof Number) //Number
                {
                        return number2Json((Number) o);
                }
                if (o instanceof Map) //Map
                {
                        return map2Json((Map<String, Object>) o);
                }
                if (o instanceof Collection) //List  Set
                {
                        return collection2Json((Collection) o);
                }
                if (o instanceof Object[]) //对象数组
                {
                        return array2Json((Object[]) o);
                }

                if (o instanceof int[])//基本类型数组
                {
                        return intArray2Json((int[]) o);
                }
                if (o instanceof boolean[])//基本类型数组
                {
                        return booleanArray2Json((boolean[]) o);
                }
                if (o instanceof long[])//基本类型数组
                {
                        return longArray2Json((long[]) o);
                }
                if (o instanceof float[])//基本类型数组
                {
                        return floatArray2Json((float[]) o);
                }
                if (o instanceof double[])//基本类型数组
                {
                        return doubleArray2Json((double[]) o);
                }
                if (o instanceof short[])//基本类型数组
                {
                        return shortArray2Json((short[]) o);
                }
                if (o instanceof byte[])//基本类型数组
                {
                        return byteArray2Json((byte[]) o);
                }
                if (o instanceof Object) //保底收尾对象
                {
                        return object2Json(o);
                }

                throw new RuntimeException("不支持的类型: " + o.getClass().getName());
        }

        /**
         * 将 String 对象编码为 JSON格式，只需处理好特殊字符
         *
         * @param s
         *            String 对象
         * @return JSON格式
         */
        static String string2Json(final String s)
        {
                final StringBuilder sb = new StringBuilder(s.length() + 20);
                sb.append('\"');
                for (int i = 0; i < s.length(); i++)
                {
                        final char c = s.charAt(i);
                        switch (c)
                        {
                        case '\"':
                                sb.append("\\\"");
                                break;
                        case '\\':
                                sb.append("\\\\");
                                break;
                        case '/':
                                sb.append("\\/");
                                break;
                        case '\b':
                                sb.append("\\b");
                                break;
                        case '\f':
                                sb.append("\\f");
                                break;
                        case '\n':
                                sb.append("\\n");
                                break;
                        case '\r':
                                sb.append("\\r");
                                break;
                        case '\t':
                                sb.append("\\t");
                                break;
                        default:
                                sb.append(c);
                        }
                }
                sb.append('\"');
                return sb.toString();
        }

        /**
         * 将 Number 表示为 JSON格式
         *
         * @param number
         *            Number
         * @return JSON格式
         */
        static String number2Json(final Number number)
        {
                return number.toString();
        }

        /**
         * 将 Boolean 表示为 JSON格式
         *
         * @param bool
         *            Boolean
         * @return JSON格式
         */
        static String boolean2Json(final Boolean bool)
        {
                return bool.toString();
        }

        /**
         * 将 Collection 编码为 JSON 格式 (List,Set)
         *
         * @param c
         * @return
         */
        static String collection2Json(final Collection<Object> c)
        {
                final Object[] arrObj = c.toArray();
                return toJson(arrObj);
        }

        /**
         * 将 Map<String, Object> 编码为 JSON 格式
         *
         * @param map
         * @return
         */
        static String map2Json(final Map<String, Object> map)
        {
                if (map.isEmpty())
                {
                        return "{}";
                }
                final StringBuilder sb = new StringBuilder(map.size() << 4); //4次方
                sb.append('{');
                final Set<String> keys = map.keySet();
                for (final String key : keys)
                {
                        final Object value = map.get(key);
                        sb.append('\"');
                        sb.append(key); //不能包含特殊字符
                        sb.append('\"');
                        sb.append(':');
                        sb.append(toJson(value)); //循环引用的对象会引发无限递归
                        sb.append(',');
                }
                // 将最后的 ',' 变为 '}':
                sb.setCharAt(sb.length() - 1, '}');
                return sb.toString();
        }

        /**
         * 将数组编码为 JSON 格式
         *
         * @param array
         *            数组
         * @return JSON 格式
         */
        static String array2Json(final Object[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4); //4次方
                sb.append('[');
                for (final Object o : array)
                {
                        sb.append(toJson(o));
                        sb.append(',');
                }
                // 将最后添加的 ',' 变为 ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String intArray2Json(final int[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final int o : array)
                {
                        sb.append(Integer.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String longArray2Json(final long[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final long o : array)
                {
                        sb.append(Long.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String booleanArray2Json(final boolean[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final boolean o : array)
                {
                        sb.append(Boolean.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String floatArray2Json(final float[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final float o : array)
                {
                        sb.append(Float.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String doubleArray2Json(final double[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final double o : array)
                {
                        sb.append(Double.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String shortArray2Json(final short[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final short o : array)
                {
                        sb.append(Short.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        static String byteArray2Json(final byte[] array)
        {
                if (array.length == 0)
                {
                        return "[]";
                }
                final StringBuilder sb = new StringBuilder(array.length << 4);
                sb.append('[');
                for (final byte o : array)
                {
                        sb.append(Byte.toString(o));
                        sb.append(',');
                }
                // set last ',' to ']':
                sb.setCharAt(sb.length() - 1, ']');
                return sb.toString();
        }

        public static String object2Json(final Object bean)
        {
                //数据检查
                if (bean == null)
                {
                        return "{}";
                }
                final Method[] methods = bean.getClass().getMethods(); //方法数组
                final StringBuilder sb = new StringBuilder(methods.length << 4); //4次方
                sb.append('{');

                for (final Method method : methods)
                {
                        try
                        {
                                final String name = method.getName();
                                String key = "";
                                if (name.startsWith("get"))
                                {
                                        key = name.substring(3);

                                        //防死循环
                                        final String[] arrs =
                                        { "Class" };
                                        boolean bl = false;
                                        for (final String s : arrs)
                                        {
                                                if (s.equals(key))
                                                {
                                                        bl = true;
                                                        continue;
                                                }
                                        }
                                        if (bl)
                                        {
                                                continue; //防死循环
                                        }
                                }
                                else if (name.startsWith("is"))
                                {
                                        key = name.substring(2);
                                }
                                if (key.length() > 0 && Character.isUpperCase(key.charAt(0)) && method.getParameterTypes().length == 0)
                                {
                                        if (key.length() == 1)
                                        {
                                                key = key.toLowerCase();
                                        }
                                        else if (!Character.isUpperCase(key.charAt(1)))
                                        {
                                                key = key.substring(0, 1).toLowerCase() + key.substring(1);
                                        }
                                        final Object elementObj = method.invoke(bean);

                                        //System.out.println("###" + key + ":" + elementObj.toString());

                                        sb.append('\"');
                                        sb.append(key); //不能包含特殊字符
                                        sb.append('\"');
                                        sb.append(':');
                                        sb.append(toJson(elementObj)); //循环引用的对象会引发无限递归
                                        sb.append(',');
                                }
                        }
                        catch (final Exception e)
                        {
                                //e.getMessage();
                                throw new RuntimeException("在将bean封装成JSON格式时异常：" + e.getMessage(), e);
                        }
                }
                if (sb.length() == 1)
                {
                        return bean.toString();
                }
                else
                {
                        sb.setCharAt(sb.length() - 1, '}');
                        return sb.toString();
                }
        }

        private JsonUtil()
        {
        }
}