public class JsonTest {
public static void main(String[] args) {
String jsonString = "{\"str\":\"string\",\"num\":100,\"boolean\":true,\"obj\":{\"key1\":\"value1\",\"key2\":\"value2\"},\"list\":[{\"list1\":\"list1\"},{\"list2\":\"list2\"}]}";
JSONReader jr = new JSONReader();
Map map = (Map) jr.read(jsonString);
System.out.println("Json解析完成");
System.out.println("Map----" + map.toString());
System.out.println("list----" + map.get("list").getClass().getName() + ":" + map.get("list"));
System.out.println("str----" + map.get("str").getClass().getName() + ":" + map.get("str"));
System.out.println("num----" + map.get("num").getClass().getName() + ":" + map.get("num"));
System.out.println("boolean----" + map.get("boolean").getClass().getName() + ":" + map.get("boolean"));
System.out.println("obj----" + map.get("obj").getClass().getName() + ":" + map.get("obj"));
}
}输出
Json解析完成 Map----{str=string, boolean=true, obj={key1=value1, key2=value2}, num=100, list=[{list1=list1}, {list2=list2}]} list----java.util.ArrayList:[{list1=list1}, {list2=list2}] str----java.lang.String:string num----java.lang.Long:100 boolean----java.lang.Boolean:true obj----java.util.HashMap:{key1=value1, key2=value2}
package top.feb13th.json;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class JSONReader {
private static final Object OBJECT_END = new Object();
private static final Object ARRAY_END = new Object();
private static final Object COLON = new Object();
private static final Object COMMA = new Object();
public static final int FIRST = 0;
public static final int CURRENT = 1;
public static final int NEXT = 2;
private static Map<Character, Character> escapes = new HashMap<Character, Character>();
static {
escapes.put(Character.valueOf('"'), Character.valueOf('"'));
escapes.put(Character.valueOf('\\'), Character.valueOf('\\'));
escapes.put(Character.valueOf('/'), Character.valueOf('/'));
escapes.put(Character.valueOf('b'), Character.valueOf('\b'));
escapes.put(Character.valueOf('f'), Character.valueOf('\f'));
escapes.put(Character.valueOf('n'), Character.valueOf('\n'));
escapes.put(Character.valueOf('r'), Character.valueOf('\r'));
escapes.put(Character.valueOf('t'), Character.valueOf('\t'));
}
private CharacterIterator it;
private char c;
private Object token;
private StringBuffer buf = new StringBuffer();
private char next() {
c = it.next();
return c;
}
private void skipWhiteSpace() {
while (Character.isWhitespace(c)) {
next();
}
}
public Object read(CharacterIterator ci, int start) {
it = ci;
switch (start) {
case FIRST:
c = it.first();
break;
case CURRENT:
c = it.current();
break;
case NEXT:
c = it.next();
break;
}
return read();
}
public Object read(CharacterIterator it) {
return read(it, NEXT);
}
public Object read(String string) {
return read(new StringCharacterIterator(string), FIRST);
}
private Object read() {
skipWhiteSpace();
char ch = c;
next();
switch (ch) {
case '"':
token = string();
break;
case '[':
token = array();
break;
case ']':
token = ARRAY_END;
break;
case ',':
token = COMMA;
break;
case '{':
token = object();
break;
case '}':
token = OBJECT_END;
break;
case ':':
token = COLON;
break;
case 't':
next();
next();
next(); // assumed r-u-e
token = Boolean.TRUE;
break;
case 'f':
next();
next();
next();
next(); // assumed a-l-s-e
token = Boolean.FALSE;
break;
case 'n':
next();
next();
next(); // assumed u-l-l
token = null;
break;
default:
c = it.previous();
if (Character.isDigit(c) || c == '-') {
token = number();
}
}
//logger.debug("token: " + token);
System.out.println("token: " + token); // enable this line to see the token stream
return token;
}
private Object object() {
Map<Object, Object> ret = new HashMap<Object, Object>();
Object key = read();
while (token != OBJECT_END) {
read(); // should be a colon
if (token != OBJECT_END) {
ret.put(key, read());
if (read() == COMMA) {
key = read();
}
}
}
return ret;
}
private Object array() {
List<Object> ret = new ArrayList<Object>();
Object value = read();
while (token != ARRAY_END) {
ret.add(value);
if (read() == COMMA) {
value = read();
}
}
return ret;
}
private Object number() {
int length = 0;
boolean isFloatingPoint = false;
buf.setLength(0);
if (c == '-') {
add();
}
length += addDigits();
if (c == '.') {
add();
length += addDigits();
isFloatingPoint = true;
}
if (c == 'e' || c == 'E') {
add();
if (c == '+' || c == '-') {
add();
}
addDigits();
isFloatingPoint = true;
}
String s = buf.toString();
return isFloatingPoint
? (length < 17) ? (Object) Double.valueOf(s) : new BigDecimal(s)
: (length < 19) ? (Object) Long.valueOf(s) : new BigInteger(s);
}
private int addDigits() {
int ret;
for (ret = 0; Character.isDigit(c); ++ret) {
add();
}
return ret;
}
private Object string() {
buf.setLength(0);
while (c != '"') {
if (c == '\\') {
next();
if (c == 'u') {
add(unicode());
} else {
Object value = escapes.get(Character.valueOf(c));
if (value != null) {
add(((Character) value).charValue());
}
}
} else {
add();
}
}
next();
return buf.toString();
}
private void add(char cc) {
buf.append(cc);
next();
}
private void add() {
add(c);
}
private char unicode() {
int value = 0;
for (int i = 0; i < 4; ++i) {
switch (next()) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
value = (value << 4) + c - '0';
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
value = (value << 4) + c - 'k';
break;
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
value = (value << 4) + c - 'K';
break;
}
}
return (char) value;
}
}输出
token: str token: java.lang.Object@2a098129 token: string token: java.lang.Object@198e2867 token: num token: java.lang.Object@2a098129 token: 100 token: java.lang.Object@198e2867 token: boolean token: java.lang.Object@2a098129 token: true token: java.lang.Object@198e2867 token: obj token: java.lang.Object@2a098129 token: key1 token: java.lang.Object@2a098129 token: value1 token: java.lang.Object@198e2867 token: key2 token: java.lang.Object@2a098129 token: value2 token: java.lang.Object@3ada9e37 token: {key1=value1, key2=value2} token: java.lang.Object@198e2867 token: list token: java.lang.Object@2a098129 token: list1 token: java.lang.Object@2a098129 token: list1 token: java.lang.Object@3ada9e37 token: {list1=list1} token: java.lang.Object@198e2867 token: list2 token: java.lang.Object@2a098129 token: list2 token: java.lang.Object@3ada9e37 token: {list2=list2} token: java.lang.Object@5cbc508c token: [{list1=list1}, {list2=list2}] token: java.lang.Object@3ada9e37 token: {str=string, boolean=true, obj={key1=value1, key2=value2}, num=100, list=[{list1=list1}, {list2=list2}]}