java map转json servlet response

//给前端放回json数据
Map<String, Object> map = new HashMap<>();
map.put("name", "bb");
map.put("age", "cc");
map.put("good", "dd"); JSONWrapper wap = new JSONWrapper();
String data = wap.write(map);
System.out.println(data);

import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;public class JSONWrapper { private static final String COMMA = ",";
private static final String MARKS = "\"";
private static final String COLON = ":";
private static final String BRACKET_LEFT = "[";
private static final String BRACKET_RIGHT = "]";
private static final String BRACE_LEFT = "{";
private static final String BRACE_RIGHT = "}";
private static final String STR_VERSION_UID = "serialVersionUID";
final StringBuilder json = new StringBuilder(); public String write(Map<String, Object> jsonMap) {
try {
appendMap(jsonMap);
} catch (RuntimeException e) {
e.printStackTrace();
}
return json.toString();
} private void appendMap(Map<String, Object> map) {
json.append(BRACE_LEFT);
Iterator<String> keys = map.keySet().iterator();
while (keys.hasNext()) {
String key = keys.next();
appendObj(key, map.get(key), keys.hasNext());
}
json.append(BRACE_RIGHT);
} private void appendObj(String key, Object obj, boolean hasNext) {
if (obj == null || STR_VERSION_UID.equals(key)) {
return;
}
if (key != null) {
json.append(MARKS).append(key).append(MARKS).append(COLON);
}
if (isNumber(obj)) {
appendNum(obj);
} else if (isString(obj)) {
appendString(obj.toString());
} else if (isArray(obj)) {
appendArray(obj);
} else if (isList(obj)) {
appendList((List<?>) obj);
} else if (isMap(obj)) {
appendMap2((Map<?, ?>) obj);
} else {
appendBean(obj);
}
if (hasNext) {
json.append(COMMA);
}
} private void appendBean(Object obj) {
json.append(BRACE_LEFT);
Map<String, Object> map = getBeanValue(obj);
Iterator<String> keys = map.keySet().iterator();
String key;
while (keys.hasNext()) {
key = keys.next();
appendObj(key, map.get(key), keys.hasNext());
}
json.append(BRACE_RIGHT);
} private static Map<String, Object> getBeanValue(Object obj) {
Map<String, Object> map = new HashMap<>();
try {
Field[] fields = obj.getClass().getDeclaredFields();
Object obj2;
for (Field field : fields) {
field.setAccessible(true);
obj2 = field.get(obj);
field.setAccessible(false);
if (obj2 != null) {
map.put(field.getName(), obj2);
}
}
} catch (IllegalArgumentException | IllegalAccessException e) {
//logger.error("getBeanValue faild", e);
}
return map;
} private void appendMap2(Map<?, ?> map) {
json.append(BRACKET_LEFT);
Iterator<?> keys = map.keySet().iterator();
while (keys.hasNext()) {
String key = (String) keys.next();
appendObj(key, map.get(key), keys.hasNext());
}
json.append(BRACKET_RIGHT);
} private void appendList(List<?> list) {
json.append(BRACKET_LEFT);
int len = list.size();
for (int i = 0; i < len; i++) {
appendObj(null, list.get(i), i != (len - 1));
}
json.append(BRACKET_RIGHT);
} private void appendArray(Object obj) {
json.append(BRACKET_LEFT);
int len = Array.getLength(obj);
for (int i = 0; i < len; i++) {
appendObj(null, Array.get(obj, i), i != (len - 1));
}
json.append(BRACKET_RIGHT);
} private void appendNum(Object obj) {
json.append(obj);
} private void appendString(String str) {
if (str.indexOf("\n") != -1) {
str = str.replaceAll("\\n", "\\\\n");
}
if (str.indexOf("\t") != -1) {
str = str.replaceAll("\\t", "\\\\t");
}
if (str.indexOf("\r") != -1) {
str = str.replaceAll("\\r", "\\\\r");
}
json.append(MARKS).append(str).append(MARKS);
} private static boolean isMap(Object obj) {
return obj instanceof Map;
} private static boolean isList(Object obj) {
return obj instanceof List;
} private static boolean isArray(Object obj) {
return obj.getClass().isArray();
} private static boolean isString(Object obj) {
return obj instanceof CharSequence || obj instanceof Character;
} private static boolean isNumber(Object obj) {
return obj instanceof Integer || obj instanceof Boolean || obj instanceof Double || obj instanceof Long
|| obj instanceof Byte || obj instanceof Float || obj instanceof Short;
}}