JSON实用类,用来实现对象和JSON字符串的互相转换
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* JSON实用类
* 用来实现对象和JSON字符串的互相转换
*
* @author aven
* @date 2015-01-14
*/
public class JSONUtil {
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(",']');
} 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(",'}');
} 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(",']');
} 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 <T> T json2Object(String jsonString,Class<T> pojoCalss) {
if (pojoCalss == null || jsonString == null || jsonString.trim().isEmpty()){
return null;
}
try {
T pojo = (T)pojoCalss.newInstance();
Field[] fields = pojo.getClass().getDeclaredFields();
String simpleName = "";
for (Field f : fields) {
try{
if (f.getName() == null) {
continue;
}
if (f.getModifiers() > 2) {
continue;
}
f.setAccessible(true);
simpleName = f.getType().getSimpleName();
String propName = "\"" + f.getName() + "\":";
Integer idx = jsonString.indexOf(propName);
if (idx == -1){
continue;
}
Integer idxStart = idx + propName.length();
if (jsonString.length() < idxStart){
continue;
}
String valStart = jsonString.substring(idxStart,idxStart+1);
if (valStart.equals("[")){
valStart = "]";
}else if (valStart.equals("{")){
valStart = "}";
}else{
if (!valStart.equals("\"")){
valStart = ",";
}
}
String propValue = null;
Integer idxEnd = -1;
if (valStart.equals(",")){
idxEnd = jsonString.indexOf(valStart,idxStart);
if (idxEnd == -1){
continue;
}
propValue = jsonString.substring(idxStart,idxEnd);
}else{
idxEnd = jsonString.indexOf(valStart,idxStart + 1);
if (idxEnd == -1){
continue;
}
propValue = jsonString.substring(idxStart + 1,idxEnd);
}
if (propValue == null){
continue;
}
if (simpleName.equals("String") || simpleName.equals("Object")) {
f.set(pojo,propValue);
continue;
}
if (simpleName.equals("Long") || simpleName.equals("long")) {
f.set(pojo,getLong(propValue));
continue;
}
if (simpleName.equals("Integer") || simpleName.equals("int")) {
f.set(pojo,getInteger(propValue));
continue;
}
if (simpleName.equals("Boolean")) {
f.set(pojo,getBoolean(propValue));
continue;
}
if (simpleName.equals("Double")) {
f.set(pojo,getDouble(propValue));
continue;
}
if (simpleName.equals("Float")) {
f.set(pojo,getFloat(propValue));
continue;
}
if (simpleName.equals("Byte")) {
f.set(pojo,getByte(propValue));
continue;
}
if (simpleName.equals("List")) {
f.set(pojo,getList(propValue));
continue;
}
}catch(Exception ex){
ex.printStackTrace();
}
}
return pojo;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public static Long getLong(String propValue){
Long val = 0L;
try{
val = Long.parseLong(propValue);
}catch(Exception el){}
return val;
}
public static Integer getInteger(String propValue){
Integer val = 0;
try{
val = Integer.parseInt(propValue);
}catch(Exception el){}
return val;
}
public static Boolean getBoolean(String propValue){
Boolean val = ("1".equals(propValue) || "true".equalsIgnoreCase(propValue));
return val;
}
public static Double getDouble(String propValue){
Double val = 0D;
try{
val = Double.parseDouble(propValue);
}catch(Exception el){}
return val;
}
public static Float getFloat(String propValue){
Float val = 0F;
try{
val = Float.parseFloat(propValue);
}catch(Exception el){}
return val;
}
public static Byte getByte(String propValue){
Byte val = 0;
try{
val = Byte.parseByte(propValue);
}catch(Exception el){}
return val;
}
public static List<String> getList(String propValue){
List<String> valList = new ArrayList<String>();
if (propValue != null && !propValue.trim().isEmpty()){
try{
String[] aptEvents = propValue.replace("\"","").toLowerCase().split(",");
valList = java.util.Arrays.asList(aptEvents);
}catch(Exception ex){
ex.printStackTrace();
}
}
return valList;
}
public static void main(String[] args) {
String json = JSONUtil.object2json(new Data());
System.out.println(json);
}
}
原文地址:https://blog.csdn.net/testcs_dn/article/details/42748553
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