Java post請求傳送json資料在filter中解析方法
大家都知道Java的servlet分get和post請求方式,在servlet或者在集成了springMVC、Struts2的框架的情況下獲取請求的引數。那麼有時候我們需要在攔截其中獲取ServletRequest的引數就不那麼容易了。因為在ServletRequst中,如果是get請求我們可以通過request.getParameter(“”)來獲取get的引數或者是form提交的post引數,但是如果是ajax提交的post請求的application/json請求,那麼在get的時候就無法獲取到值了,有人會想我通過request的請求流來解析json文字,這樣做是可以的,但 是有個問題就是如果在攔截其中呼叫了ServletRequest的getInputStream方法,那麼在後面的servlet中或者你整合的框架中的control層就無法呼叫getInputStream方法來解析獲取引數了。
有了上面的疑問,我們就有了分析,解決辦法的途徑。通過對HttpServletRequest的分析結合資料,最後得出結論就是改寫ServletRequst的getInputStream方法便可以解決問題。我們可以分析一下HttpServletRequest的中的stream只能被read一次,那麼我們可以在filter中呼叫getInputSteam獲取json字串,然後通過獲取的json文字去生成新的stream來給ServletRequest,後面的control就可以繼續獲取stream(我們自己用json文字生成)。有了這個思路我們就來看看程式碼。
第一部分,改寫ServletRequest:
public classPostServletRequestextendsHttpServletRequestWrapper{
private String body=null;
/**
* Constructs a request object wrapping the given request.
* @param request
* @throws IllegalArgumentException if the request is null
*/
public PostServletRequest(HttpServletRequest request,String body) {
super (request);
this.body=body;
}
@Override
public ServletInputStream getInputStream() throws IOException {
ServletInputStream inputStream = null;
if(StringUtil.isNotEmpty(body)){
inputStream = new PostServletInputStream(body);
}
return inputStream;
}
@Override
public BufferedReader getReader() throws IOException {
String enc = getCharacterEncoding();
if(enc == null) enc = "UTF-8";
return new BufferedReader(new InputStreamReader(getInputStream(), enc));
}
}
第二本分,ServletInputStream的改寫:
public classPostServletInputStreamextendsServletInputStream {
private InputStream inputStream;
private String body ;//解析json之後的文字
public PostServletInputStream(String body) throws IOException {
this.body=body;
inputStream = null;
}
private InputStream acquireInputStream() throws IOException {
if(inputStream == null) {
inputStream = new ByteArrayInputStream(body.getBytes());//通過解析之後傳入的文字生成inputStream以便後面control呼叫
}
return inputStream;
}
public void close() throws IOException {
try {
if(inputStream != null) {
inputStream.close();
}
}
catch(IOException e) {
throw e;
}
finally {
inputStream = null;
}
}
public int read() throws IOException {
return acquireInputStream().read();
}
public boolean markSupported() {
return false;
}
public synchronized void mark(int i) {
throw new UnsupportedOperationException("mark not supported");
}
public synchronized void reset() throws IOException {
throw new IOException(new UnsupportedOperationException("reset not supported"));
}
}
第三部分:在filter中的呼叫
//解析post的json引數
String body = getBody((HttpServletRequest)request);
Map paramMap = JsonUtil.json2Map(body);
if(null != paramMap){
wpcCd = (String)paramMap.get("wpcCd");
}
//使用解析資料重新生成ServletRequest,供doChain呼叫
request =getRequest(request,body);
getBody方法:
private String getBody(HttpServletRequest request) throws IOException {
String body = null;
StringBuilder stringBuilder = new StringBuilder();
BufferedReader bufferedReader = null;
try {
InputStream inputStream = request.getInputStream();
if (inputStream != null) {
bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
char[] charBuffer = new char[128];
int bytesRead = -1;
while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {
stringBuilder.append(charBuffer, 0, bytesRead);
}
} else {
stringBuilder.append("");
}
} catch (IOException ex) {
throw ex;
}finally {
if(null != bufferedReader){
bufferedReader.close();
}
}
body = stringBuilder.toString();
return body;
}
/**
* 將post解析過後的request進行封裝改寫
* @param request
* @param body
* @return
*/
private ServletRequest getRequest(ServletRequest request ,String body){
String enctype = request.getContentType();
if (StringUtils.isNotEmpty(enctype) && enctype.contains("application/json")){
return new PostServletRequest((HttpServletRequest) request,body);
}
return request;
}
如果在其他地方也有用到類似,可根據實際應用自己封裝改寫getInputStream即可。到此結束。謝謝!