java在filter中獲取POST請求中request參數(shù)以及解決ServletInputStre

OldPanda 發(fā)布于2019-08-16 13:35 / 2461人閱讀

摘要：想要回去請求中的請求參數(shù)，可以直接使用方法。流讀取錯誤流關(guān)閉錯誤這樣將獲取中的所有格式的參數(shù)信息。可以根據(jù)需求，進行驗簽或校驗等一系列操作。神奇此時的流已經(jīng)被讀取一次，相當(dāng)于已經(jīng)作廢，此時請求接口必然是報錯的。

想要回去GET請求中的請求參數(shù)，可以直接使用request.getParamMap()方法。但是POST請求的requestBody參數(shù)就必須使用流的方式來獲取。

            BufferedReader reader = null;
            String body = null;
            try {
                reader = new BufferedReader(new InputStreamReader(request.getInputStream()));
                body = IOUtils.read(reader).replaceAll("	|
|
", "");
            } catch (IOException e) {
                logger.error("流讀取錯誤："+e);
                return;
            }finally {
                if (null != reader){
                    try {
                        reader.close();
                    } catch (IOException e) {
                        logger.error("流關(guān)閉錯誤："+e);
                    }
                }
            }
            Map paramMap = JSON.parseObject(body);

這樣將獲取body中的所有json格式的參數(shù)信息。可以根據(jù)需求，進行驗簽或校驗等一系列操作。但是當(dāng)我們chain.doFilter(request, response)，驚喜的發(fā)現(xiàn)接口400了！！
WHAT？？！！
嘿嘿o(￣▽￣)ｄ
我們都知道，讀取流的時候是有標(biāo)志的，讀取一次移動一次，讀取到哪里，移動到哪里，讀到最后，返回-1，表示讀取完成。再次讀取需要重置位置，但是ServletInputStream中是沒有重置方法的，也就是說流只能被讀取一次。神奇！！Σ(⊙▽⊙"a 此時的流已經(jīng)被讀取一次，相當(dāng)于已經(jīng)作廢，此時請求接口必然是報錯的。
行吧，你既然不讓我重復(fù)讀，那我就把你的流拿過來封裝成自己的流，這樣我想讀多少次就讀多少次！ψ(｀?′)ψ
加入jar包：javax.servlet

        
        
            javax.servlet
            javax.servlet-api
            3.1.0
            provided

實現(xiàn)HttpServletRequestWrapper類

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
import java.net.URLDecoder;
import java.util.*;

/**
 * @author zhoumin
 * @create 2018-10-31 16:13
 */
public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {
    private Map paramsMap;

    @Override
    public Map getParameterMap() {
        return paramsMap;
    }

    @Override
    public String getParameter(String name) {// 重寫getParameter，代表參數(shù)從當(dāng)前類中的map獲取
        String[] values = paramsMap.get(name);
        if (values == null || values.length == 0) {
            return null;
        }
        return values[0];
    }

    @Override
    public String[] getParameterValues(String name) {// 同上
        return paramsMap.get(name);
    }

    @Override
    public Enumeration getParameterNames() {
        return Collections.enumeration(paramsMap.keySet());
    }

    private String getRequestBody(InputStream stream) {
        String line = "";
        StringBuilder body = new StringBuilder();
        int counter = 0;

        // 讀取POST提交的數(shù)據(jù)內(nèi)容
        BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
        try {
            while ((line = reader.readLine()) != null) {
                if (counter > 0) {
                    body.append("rn");
                }
                body.append(line);
                counter++;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

        return body.toString();
    }

    private HashMap getParamMapFromPost(HttpServletRequest request) {

        String body = "";
        try {
            body = getRequestBody(request.getInputStream());
        } catch (IOException e) {
            e.printStackTrace();
        }
        HashMap result = new HashMap();

        if (null == body || 0 == body.length()) {
            return result;
        }

        return parseQueryString(body);
    }

    // 自定義解碼函數(shù)
    private String decodeValue(String value) {
        if (value.contains("%u")) {
            return Encodes.urlDecode(value);
        } else {
            try {
                return URLDecoder.decode(value, "UTF-8");
            } catch (UnsupportedEncodingException e) {
                return "";// 非UTF-8編碼
            }
        }
    }

    public HashMap parseQueryString(String s) {
        String valArray[] = null;
        if (s == null) {
            throw new IllegalArgumentException();
        }
        HashMap ht = new HashMap();
        StringTokenizer st = new StringTokenizer(s, "&");
        while (st.hasMoreTokens()) {
            String pair = (String) st.nextToken();
            int pos = pair.indexOf("=");
            if (pos == -1) {
                continue;
            }
            String key = pair.substring(0, pos);
            String val = pair.substring(pos + 1, pair.length());
            if (ht.containsKey(key)) {
                String oldVals[] = (String[]) ht.get(key);
                valArray = new String[oldVals.length + 1];
                for (int i = 0; i < oldVals.length; i++) {
                    valArray[i] = oldVals[i];
                }
                valArray[oldVals.length] = decodeValue(val);
            } else {
                valArray = new String[1];
                valArray[0] = decodeValue(val);
            }
            ht.put(key, valArray);
        }
        return ht;
    }

    private Map getParamMapFromGet(HttpServletRequest request) {
        return parseQueryString(request.getQueryString());
    }

    private final byte[] body; // 報文

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        body = readBytes(request.getInputStream());

        // 首先從POST中獲取數(shù)據(jù)
        if ("POST".equals(request.getMethod().toUpperCase())) {
            paramsMap = getParamMapFromPost(this);
        } else {
            paramsMap = getParamMapFromGet(this);
        }

    }

    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {

            @Override
            public int read() throws IOException {
                return bais.read();
            }

            @Override
            public boolean isFinished() {
                return false;
            }

            @Override
            public boolean isReady() {
                return false;
            }

            @Override
            public void setReadListener(ReadListener arg0) {

            }
        };
    }

    private static byte[] readBytes(InputStream in) throws IOException {
        BufferedInputStream bufin = new BufferedInputStream(in);
        int buffSize = 1024;
        ByteArrayOutputStream out = new ByteArrayOutputStream(buffSize);

        byte[] temp = new byte[buffSize];
        int size = 0;
        while ((size = bufin.read(temp)) != -1) {
            out.write(temp, 0, size);
        }
        bufin.close();

        byte[] content = out.toByteArray();
        return content;
    }

}

解碼

/**
     * URL 解碼, Encode默認(rèn)為UTF-8.
     */
    public static String urlDecode(String part) {
        try {
            return URLDecoder.decode(part, DEFAULT_URL_ENCODING);
        } catch (UnsupportedEncodingException e) {
            throw new InvalidTokenException(part);
        }
    }

那么上面讀取參數(shù)的代碼修改為：

             ServletRequest requestWrapper = new BodyReaderHttpServletRequestWrapper(
                    (HttpServletRequest) request);
            BufferedReader reader = null;
            String body = null;
            try {
                reader = new BufferedReader(new InputStreamReader(requestWrapper.getInputStream()));
                body = IOUtils.read(reader).replaceAll("	|
|
", "");
            } catch (IOException e) {
                logger.error("流讀取錯誤："+e);
                return;
            }finally {
                if (null != reader){
                    try {
                        reader.close();
                    } catch (IOException e) {
                        logger.error("流關(guān)閉錯誤："+e);
                    }
                }
            }
            Map paramMap = JSON.parseObject(body);
            .
            .
            .
            chain.doFilter(requestWrapper, response);

OK!又是打醬油的一天。(づ??????)づ