前言
我们在进行请求进行拦截的时候经常会碰上这样一个问题，我们想要在拦截器filter中获取request的请求，如果使用请求中默认的getInputStream()方法或者getReader()方法获取数据，但是在后面的Controller中使用@ResquestBody注解，我们读取不到request的body中的值，这是因为request的body中的数据只能通过getInputStream()和getReader()方法读取一次，要解决这个问题，我们要对重写request请求的getInputStream()和getReader()方法。
获取POST请求的输入流，并修改
一般在POST请求中我们携带的信息是application/json格式的。在一些场景中我们要对这些POST请求中的application/json信息进行获取、解析。
先看代码：
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| public class XssRequestWrapper extends HttpServletRequestWrapper {
private static Policy policy = null;
private static final AntiSamy antiSamy = new AntiSamy();
private String body;
private Map<String, String> parameters = new HashMap<String, String>();
private byte[] bytes;
private boolean isInit = false;
private static final String DEFAULT_CHARSET_NAME = "UTF-8";
private ObjectMapper objectMapper = new ObjectMapper();
public XssRequestWrapper(HttpServletRequest request) throws IOException {
super(request);
try {
String contentType = request.getContentType();
if(contentType.contains(";")){
contentType = contentType.substring(0,contentType.indexOf(";"));
}
initBytes();
if(contentType.equals(MediaType.APPLICATION_JSON_VALUE)){
parseJsonParameters();
}
} catch (IOException e) {
throw new RuntimeException("IOException", e);
}
}
private void initBytes() throws IOException {
isInit = true;
StringBuilder buffer = new StringBuilder();
BufferedReader reader = this.getHttpServletRequest().getReader();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
body = buffer.toString();
bytes = body.getBytes(DEFAULT_CHARSET_NAME);
}
private void parseJsonParameters() throws IOException {
StringBuilder stringBuilder = new StringBuilder("{");
if (null != body && body.length() > 0) {
JsonNode node = objectMapper.readTree(body);
Iterator<String> fieldNames = node.getFieldNames();
for (; fieldNames.hasNext();) {
String key = fieldNames.next();
String value = node.get(key).toString();
if (value.length() > 2 && value.startsWith("\"")) {
String valueTemp = value.substring(1,value.length()-1);
valueTemp = StringEscapeUtils.unescapeJava(valueTemp);
valueTemp = StringEscapeUtils.escapeJava(valueTemp);
valueTemp = "\"" + valueTemp + "\"";
parameters.put(key, valueTemp);
} else {
parameters.put(key, value);
}
}
}
for(String key:parameters.keySet()){
String value = parameters.get(key);
stringBuilder.append("\""+key+"\":"+value+",");
}
stringBuilder.deleteCharAt(stringBuilder.length()-1);
stringBuilder.append("}");
try {
bytes = stringBuilder.toString().getBytes(DEFAULT_CHARSET_NAME);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
private HttpServletRequest getHttpServletRequest() {
return (HttpServletRequest) super.getRequest();
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(getInputStream()));
}
@Override
public ServletInputStream getInputStream() throws IOException {
if (!isInit)
initBytes();
final ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
return new ServletInputStream() {
@Override
public int read() throws IOException {
return bais.read();
}
};
}
|
总结
分析：获取Post请求输入流，又保证数据不丢失的步骤如下：
- 继承父类的构造方法，在自己的方法中进行数据的初始化
- 数据的初始化就是，获取输入流，写入本类的char[] bytes中
- 重新getInputStream()方法和getReader()方法，其中getInputStream()方法直接读取bytes字节流信息
- 解析application/json数据，利用JsonNode类
