java校驗json

⑴ java 實現檢測一個json字元串是否是正確格式

ScriptEngineManagersem=newScriptEngineManager();
ScriptEnginese=sem.getEngineByName("js");
Stringjsonstr="
[{}]";
try{
if(!jsonstr.matches("^[
f	\x20]*[\{\[][\s\S]*")){
thrownewScriptException("必須以{或[開頭");
}
se.eval("("+jsonstr+")");
System.out.println("是json格式");
}catch(ScriptExceptione){
Stringexp=e.toString().replaceAll(".*\:(.*)","$1");
System.err.println(exp.replaceAll("\(.+(?=at)",""));
}

⑵ java校驗json格式及內容

代碼如下
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;

public class JsonValidator {

private CharacterIterator it;
private char c;
private int col;

public JsonValidator(){
}

/**
* 驗證一個字元串是否是合法的JSON串
*
* @param input 要驗證的字元串
* @return true-合法 ，false-非法
*/
public boolean validate(String input) {
input = input.trim();
boolean ret = valid(input);
return ret;
}

private boolean valid(String input) {
if ("".equals(input)) return true;

boolean ret = true;
it = new StringCharacterIterator(input);
c = it.first();
col = 1;
if (!value()) {
ret = error("value", 1);
} else {
skipWhiteSpace();
if (c != CharacterIterator.DONE) {
ret = error("end", col);
}
}

return ret;
}

private boolean value() {
return literal("true") || literal("false") || literal("null") || string() || number() || object() || array();
}

private boolean literal(String text) {
CharacterIterator ci = new StringCharacterIterator(text);
char t = ci.first();
if (c != t) return false;

int start = col;
boolean ret = true;
for (t = ci.next(); t != CharacterIterator.DONE; t = ci.next()) {
if (t != nextCharacter()) {
ret = false;
break;
}
}
nextCharacter();
if (!ret) error("literal " + text, start);
return ret;
}

private boolean array() {
return aggregate('[', ']', false);
}

private boolean object() {
return aggregate('{', '}', true);
}

private boolean aggregate(char entryCharacter, char exitCharacter, boolean prefix) {
if (c != entryCharacter) return false;
nextCharacter();
skipWhiteSpace();
if (c == exitCharacter) {
nextCharacter();
return true;
}

for (;;) {
if (prefix) {
int start = col;
if (!string()) return error("string", start);
skipWhiteSpace();
if (c != ':') return error("colon", col);
nextCharacter();
skipWhiteSpace();
}
if (value()) {
skipWhiteSpace();
if (c == ',') {
nextCharacter();
} else if (c == exitCharacter) {
break;
} else {
return error("comma or " + exitCharacter, col);
}
} else {
return error("value", col);
}
skipWhiteSpace();
}

nextCharacter();
return true;
}

private boolean number() {
if (!Character.isDigit(c) && c != '-') return false;
int start = col;
if (c == '-') nextCharacter();
if (c == '0') {
nextCharacter();
} else if (Character.isDigit(c)) {
while (Character.isDigit(c))
nextCharacter();
} else {
return error("number", start);
}
if (c == '.') {
nextCharacter();
if (Character.isDigit(c)) {
while (Character.isDigit(c))
nextCharacter();
} else {
return error("number", start);
}
}
if (c == 'e' || c == 'E') {
nextCharacter();
if (c == '+' || c == '-') {
nextCharacter();
}
if (Character.isDigit(c)) {
while (Character.isDigit(c))
nextCharacter();
} else {
return error("number", start);
}
}
return true;
}

private boolean string() {
if (c != '"') return false;

int start = col;
boolean escaped = false;
for (nextCharacter(); c != CharacterIterator.DONE; nextCharacter()) {
if (!escaped && c == '\\') {
escaped = true;
} else if (escaped) {
if (!escape()) {
return false;
}
escaped = false;
} else if (c == '"') {
nextCharacter();
return true;
}
}
return error("quoted string", start);
}

private boolean escape() {
int start = col - 1;
if (" \\\"/bfnrtu".indexOf(c) < 0) {
return error("escape sequence \\\",\\\\,\\/,\\b,\\f,\\n,\\r,\\t or \\uxxxx ", start);
}
if (c == 'u') {
if (!ishex(nextCharacter()) || !ishex(nextCharacter()) || !ishex(nextCharacter())
|| !ishex(nextCharacter())) {
return error("unicode escape sequence \\uxxxx ", start);
}
}
return true;
}

private boolean ishex(char d) {
return "0123456789abcdefABCDEF".indexOf(c) >= 0;
}

private char nextCharacter() {
c = it.next();
++col;
return c;
}

private void skipWhiteSpace() {
while (Character.isWhitespace(c)) {
nextCharacter();
}
}

private boolean error(String type, int col) {
System.out.printf("type: %s, col: %s%s", type, col, System.getProperty("line.separator"));
return false;
}
public static void main(String[] args){
String jsonStr = "{\"website\":\"open-open.com\"}";
System.out.println(jsonStr+":"+new JsonValidator().validate(jsonStr));
}
}

⑶ Java用於校驗一個字元串是否是合法的JSON格式

ScriptEngineManager sem = new ScriptEngineManager();ScriptEngine se = sem.getEngineByName("js");String jsonstr = " \r\n [{}]";try { if (!jsonstr.matches("^[\r\n\f\t\\x20]*[\\{\\[][\\s\\S]*")) { throw new ScriptException("必拍亮須以{或[開頭"); } se.eval("(" + jsonstr + ")"纖遲); System.out.println("是json格式襲豎寬");} catch (ScriptException e) { String exp = e.toString().replaceAll(".*\\:(.*)", "$1"); System.err.println(exp.replaceAll("\\(.+(?=at)", ""));}

⑷ java 判斷json中是否有某值

try
		{
			json.put("id",如毀和"loo");
			json.put("pass","123");
			
			String[]names=JSONObject.getNames(json);
			for(inti=余枯0;i<names.length;i++)
			{
				if(json.get(names[i]).equals("渣盯loo"))
				{
					System.out.println("存在！");
				}
			}
		}catch(Exceptione)
		{
		}

⑸ java 判斷一個字元串是否是json格式

ScriptEngineManagersem=newScriptEngineManager();
		ScriptEnginese=sem.getEngineByName("js");
		Stringjsonstr="({name:1,obj:3,[dd]})";
		try
		{
			System.out.println(se.eval(jsonstr));
		}
		catch(ScriptExceptione)
		{
			System.out.println("json格式有誤");
		}

⑹ 判斷json對象是否為空 java 中怎樣對jsonarray做非空判斷

一共有三種方式。
創建JSONArray jsonarray=new JSONArray ();
方法一：判物猜穗斷對象是否為空 jsonarray!=null
方法二：JSONArray是集合、數組可以用jsonarray.length()>0
方法三：jsonarray.toString()是否是「」空字兆叢符串，!「」.equals(jsonarray.toString())
一般用方法二就可以判斷[]了，方法一和方法三結罩卜合使用。

⑺ java校驗json數據是否合法要怎麼寫數據是別的公司傳過來的！

現在有很多JSON的工具包，可以將json字元串轉換為json對象凱豎燃，你try/catch住你轉換的代碼，如果轉換成功，則表示json是合法的，反之這表示json數據盯虛有問題。但要纖櫻驗證數據是否符合你的業務要求，需要你自己寫方法驗證。
JSON工具可以使用 Jackson，fastjson等，具體使用方法在網上搜索。

⑻ 求助，java如何判斷json中的null

JSON很好識別的，如果你不確定是否是JSON格式那麼你用json_decode對那個字元串進行解碼判斷，PHP官方對這個函數的返回值的說明是:返回值JSON編碼的。值true，false和空(不區分大小寫)返回TRUE，FALSE和NULL。如果的JSON不能被解碼或者如果編碼的數據是深度超過遞歸限制，則返回NULL。