java 对象（List/Map/Set）转json类

package com.ciecc.utils;

import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.bict.test.UserTest;
public class JsonUtil {
private static Log log = LogFactory.getLog(JsonUtil.class);
public static String object2json(Object obj) {
StringBuilder json = new StringBuilder();
if (obj == null) {
json.append("\"\"");
} else if (obj instanceof String || obj instanceof Integer || obj instanceof Float || obj instanceof Boolean || obj instanceof Short || obj instanceof Double || obj instanceof Long || obj instanceof BigDecimal || obj instanceof BigInteger || obj instanceof Byte) {
json.append("\"").append(string2json(obj.toString())).append("\"");
} else if (obj instanceof Object[]) {
json.append(array2json((Object[]) obj));
} else if (obj instanceof List) {
json.append(list2json((List<?>) obj));
} else if (obj instanceof Map) {
json.append(map2json((Map<?, ?>) obj));
} else if (obj instanceof Set) {
json.append(set2json((Set<?>) obj));
} else {
json.append(bean2json(obj));
}
return json.toString();
}
public static String bean2json(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 = object2json(props[i].getName());
String value = object2json(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();
}
public static String list2json(List<?> list) {
StringBuilder json = new StringBuilder();
json.append("[");
if (list != null && list.size() > 0) {
for (Object obj : list) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String array2json(Object[] array) {
StringBuilder json = new StringBuilder();
json.append("[");
if (array != null && array.length > 0) {
for (Object obj : array) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String map2json(Map<?, ?> map) {
StringBuilder json = new StringBuilder();
json.append("{");
if (map != null && map.size() > 0) {
for (Object key : map.keySet()) {
json.append(object2json(key));
json.append(":");
json.append(object2json(map.get(key)));
json.append(",");
}
json.setCharAt(json.length() - 1, '}');
} else {
json.append("}");
}
return json.toString();
}
public static String set2json(Set<?> set) {
StringBuilder json = new StringBuilder();
json.append("[");
if (set != null && set.size() > 0) {
for (Object obj : set) {
json.append(object2json(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
public static String string2json(String s) {
if (s == null)
return "";
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 void main(String args[]) {
List<UserTest> userList = new ArrayList<UserTest>();
userList.add(new UserTest("linbo","北京服装学院",25));
StringBuilder sb = new StringBuilder();
System.out.println(list2json(userList));
}
}