JsonUtils 类，将任意数据格式转换为Json格式

 

 

 

package json;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class JsonUtils
{

    public static void main(String[] args)
    {
        String s = "a\\b\\c/d,ef,g";
        String json = "";
        json = stringToJson(s);

        System.out.println(json);

        TestBean bean = new TestBean();
        bean.setId(1);
        bean.setName("nnname");
        bean.setDesc("desc");

        json = objectToJson(bean);
        System.out.println("objectToJson:" + json);

        json = beanToJson(bean);
        System.out.println("beanToJson:" + json);

        List<TestBean> list = new ArrayList<TestBean>();
        list.add(new TestBean(1, "n1", "d1"));
        list.add(new TestBean(2, "n2", "d2"));
        list.add(new TestBean(3, "n3", "d3"));
        json = listToJson(list);
        System.out.println("listToJson:" + json);

    }

    public static String stringToJson(String s)
    {
        if (s == null)
        {
            return nullToJson();
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++)
        {
            char ch = s.charAt(i);
            switch (ch)
            {
            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;
            case '/':
                sb.append("\\/");
                break;
            default:
                if (ch >= '\u0000' && ch <= '\u001F')
                {
                    String ss = Integer.toHexString(ch);
                    sb.append("\\u");
                    for (int k = 0; k < 4 - ss.length(); k++)
                    {
                        sb.append('0');
                    }
                    sb.append(ss.toUpperCase());
                } else
                {
                    sb.append(ch);
                }
            }
        }
        return sb.toString();
    }

    public static String nullToJson()
    {
        return "";
    }

    public static String objectToJson(Object obj)
    {
        StringBuilder json = new StringBuilder();
        if (obj == null)
        {
            json.append("\"\"");
        } else if (obj instanceof Number)
        {
            json.append(numberToJson((Number) obj));
        } else if (obj instanceof Boolean)
        {
            json.append(booleanToJson((Boolean) obj));
        } else if (obj instanceof String)
        {
            json.append("\"").append(stringToJson(obj.toString())).append("\"");
        } else if (obj instanceof Object[])
        {
            json.append(arrayToJson((Object[]) obj));
        } else if (obj instanceof List)
        {
            json.append(listToJson((List<?>) obj));
        } else if (obj instanceof Map)
        {
            json.append(mapToJson((Map<?, ?>) obj));
        } else if (obj instanceof Set)
        {
            json.append(setToJson((Set<?>) obj));
        } else
        {
            json.append(beanToJson(obj));
        }
        return json.toString();
    }

    public static String numberToJson(Number number)
    {
        return number.toString();
    }

    public static String booleanToJson(Boolean bool)
    {
        return bool.toString();
    }

    /** */
    /** */
    /** */
    /**
     * @param bean
     *            bean对象
     * @return String
     */
    public static String beanToJson(Object bean)
    {
        StringBuilder json = new StringBuilder();
        json.append("{");
        PropertyDescriptor[] props = null;
        try
        {
            props = Introspector.getBeanInfo(bean.getClass(), Object.class).getPropertyDescriptors();
        } catch (IntrospectionException e)
        {
        }
        if (props != null)
        {
            for (int i = 0; i < props.length; i++)
            {
                try
                {
                    String name = objectToJson(props[i].getName());
                    String value = objectToJson(props[i].getReadMethod().invoke(bean));
                    json.append(name);
                    json.append(":");
                    json.append(value);
                    json.append(",");
                } catch (Exception e)
                {
                }
            }
            json.setCharAt(json.length() - 1, '}');
        } else
        {
            json.append("}");
        }
        return json.toString();
    }

    /** */
    /** */
    /** */
    /**
     * @param list
     *            list对象
     * @return String
     */
    public static String listToJson(List<?> list)
    {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (list != null && list.size() > 0)
        {
            for (Object obj : list)
            {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else
        {
            json.append("]");
        }
        return json.toString();
    }

    /** */
    /** */
    /** */
    /**
     * @param array
     *            对象数组
     * @return String
     */
    public static String arrayToJson(Object[] array)
    {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (array != null && array.length > 0)
        {
            for (Object obj : array)
            {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else
        {
            json.append("]");
        }
        return json.toString();
    }

    /** */
    /** */
    /** */
    /**
     * @param map
     *            map对象
     * @return String
     */
    public static String mapToJson(Map<?, ?> map)
    {
        StringBuilder json = new StringBuilder();
        json.append("{");
        if (map != null && map.size() > 0)
        {
            for (Object key : map.keySet())
            {
                json.append(objectToJson(key));
                json.append(":");
                json.append(objectToJson(map.get(key)));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, '}');
        } else
        {
            json.append("}");
        }
        return json.toString();
    }

    /** */
    /** */
    /** */
    /**
     * @param set
     *            集合对象
     * @return String
     */
    public static String setToJson(Set<?> set)
    {
        StringBuilder json = new StringBuilder();
        json.append("[");
        if (set != null && set.size() > 0)
        {
            for (Object obj : set)
            {
                json.append(objectToJson(obj));
                json.append(",");
            }
            json.setCharAt(json.length() - 1, ']');
        } else
        {
            json.append("]");
        }
        return json.toString();
    }

}

 

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stringToJson:a\\b\\c\/d,ef,g
objectToJson:{"desc":"desc","id":1,"name":"nnname"}
beanToJson:{"desc":"desc","id":1,"name":"nnname"}
listToJson:[{"desc":"d1","id":1,"name":"n1"},{"desc":"d2","id":2,"name":"n2"},{"desc":"d3","id":3,"name":"n3"}]