超精简的json输出类

json，这玩意比较火爆，地球人都知道。网上json的解析包也非常多，然而大部分时候，我们只是需要在服务端输出json格式到客户端，甚至我经常做的是在调试日志里面输出变量的值，所以就自己写了个非常精简的json格式输出包。

package com.kievnsoft.json;
import java.io.IOException;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.Map;

public class JsonObject {
private static final char[] numbers = new char[]{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
private Calendar calendar = Calendar.getInstance();
private StringBuilder sb = new StringBuilder();
private boolean dateToText;
private char[] ints = new char[16];
public JsonObject(Object value) throws Exception {
this(value, false);
}
public JsonObject(Object value, boolean dateToText) throws Exception {
super();
this.dateToText = dateToText;
makeJson(value);
}
@Override
public String toString() {
return sb.toString();
}
public static String toJson(Object value) throws Exception {
return toJson(value, false);
}
public static String toJson(Object value, boolean dateToText) throws Exception {
JsonObject jo = new JsonObject(value);
return jo.toString();
}
private void makeJson(Object value) throws Exception {
if(value == null) {
sb.append("null");
return;
}

if(value instanceof String) {
jsonString(value.toString());
}
else if(value instanceof Number) {
sb.append(value.toString());
}
else if(value instanceof Date) {
if(!dateToText)
sb.append(((Date)value).getTime());
else {
sb.append('"');
calendar.setTime((Date)value);
formatInt(calendar.get(Calendar.YEAR
7fe0
), 4);
sb.append(ints, 0, 4).append('-');
formatInt(calendar.get(Calendar.MONTH), 2);
sb.append(ints, 0, 2).append('-');
formatInt(calendar.get(Calendar.DAY_OF_MONTH), 2);
sb.append(ints, 0, 2).append(' ');
formatInt(calendar.get(Calendar.HOUR_OF_DAY), 2);
sb.append(ints, 0, 2).append(':');
formatInt(calendar.get(Calendar.MINUTE), 2);
sb.append(ints, 0, 2).append(':');
formatInt(calendar.get(Calendar.SECOND), 2);
sb.append(ints, 0, 2);
sb.append('"');
}
}
else if(value instanceof Collection) {
sb.append('[');
for(Object o : (Collection)value) {
makeJson(o);
sb.append(',');
}
sb.setCharAt(sb.length() - 1, ']');
}
else if(value instanceof Map) {
sb.append('{');
for(Map.Entry v : ((Map)value).entrySet()) {
makeJson(v.getKey());
sb.append(':');
makeJson(v.getValue());
sb.append(',');
}
sb.setCharAt(sb.length() - 1, '}');
}
else if(value.getClass().isArray()) {
sb.append('[');
int n = Array.getLength(value);
for(int i = 0; i < n; ++i) {
makeJson(Array.get(value, i));
sb.append(',');
}
sb.setCharAt(sb.length() - 1, ']');
}
else if(value instanceof Boolean) {
sb.append(value);
}
else if(value instanceof Character) {
jsonString(String.valueOf(value));
}
else if(value instanceof Enum) {
jsonString(((Enum)value).toString());
}
else {
sb.append('{');
Class cls = value.getClass();
Method[] ms = cls.getMethods();
for(Method v : ms) {
String msn = v.getName();
if(!msn.startsWith("get")
|| msn.charAt(3) == '_'
|| msn.equals("getClass")
|| v.getParameterTypes().length > 0)
continue;
sb.append(Character.toLowerCase(msn.charAt(3)));
sb.append(msn, 4, msn.length()).append(':');
makeJson(v.invoke(value));
sb.append(',');
}
sb.setCharAt(sb.length() - 1, '}');
}
}
private void jsonString(String str) throws IOException {
char c;
sb.append('"');
for(int i = 0; i < str.length(); ++i) {
c = str.charAt(i);
switch (c) {
case '"': sb.append("///""); break;
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); break;
}
}
sb.append('"');
}

private void formatInt(int value, int length) {
for(int i = length - 1; i >= 0; --i) {
if(value > 0) {
ints[i] = numbers[value % 10];
value = value / 10;
}
else ints[i] = '0';
}
}
}