web中gzip,deflate的压缩与解压
一，对发送请求进行gzip,deflate压缩1:gzip的情况
Sring url = "http://localhost/save";PostMethod post = new PostMethod(url);//请求体内容String body = "sample";//用gzip方式压缩请求体并赋给requestByteArrayInputStream bis = new ByteArrayInputStream(body.getBytes());ByteArrayOutputStream bos = new ByteArrayOutputStream();GZIPOutputStream gos = new GZIPOutputStream(bos);for (int c = bis.read(); c != -1; c = bis.read()) { gos.write(c);}gos.close();InputStreamRequestEntity entity = new InputStreamRequestEntity(new ByteArrayInputStream(bos.toByteArray()), "text/html");post.setRequestEntity(entity);post.addRequestHeader("Content-Encoding", "gzip");
2:deflate的情况
Sring url = "http://localhost/save";PostMethod post = new PostMethod(url);//请求体内容String body = "sample";//用deflate方式压缩请求体并赋给requestByteArrayInputStream bis = new ByteArrayInputStream(body.getBytes());ByteArrayOutputStream bos = new ByteArrayOutputStream();DeflaterOutputStream dos = new DeflaterOutputStream(bos);for (int c = bis.read(); c != -1; c = bis.read()) { dos.write(c);}dos.close();InputStreamRequestEntity entity = new InputStreamRequestEntity(new ByteArrayInputStream(bos.toByteArray()), "text/html");post.setRequestEntity(entity);post.addRequestHeader("Content-Encoding", "deflate");
二，在服务器端使用过滤器对压缩过的请求进行解压
新建一个filter继承UserAgentFilter.java,截取req,进行包装，接着继续执行别的filters
@Overridepublic void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; String ce = request.getHeader("Content-Encoding"); // gzip|deflate|inflate if (ce != null) { if (ce.indexOf("deflate") >= 0 || ce.indexOf("inflate") >= 0) { // uncompress using inflate request = new InflateRequestWrapper(request); } else if (ce.indexOf("gzip") >= 0) { // uncompress using gzip request = new GZipRequestWrapper(request); } } ...... super.doFilter(request, res, chain); ......}
下面是InflateRequestWrapper的内容，GZipRequestWrapper与之类似
public class InflateRequestWrapper extends HttpServletRequestWrapper { private BufferedServletInputStreamWrapper _stream; public InflateRequestWrapper(HttpServletRequest request) throws IOException { super(request); _stream = new BufferedServletInputStreamWrapper(new InflaterInputStream(request.getInputStream()), request.getContentLength()); } @Override public BufferedServletInputStreamWrapper getInputStream() { return _stream; } @Override public int getContentLength() { return _stream.getBytes().length; }}
下面是BufferedServletInputStreamWrapper的内容
public class BufferedServletInputStreamWrapper extends ServletInputStream { private static final int DEFAULT_READ_BUFFER_SIZE = 1024; private final byte[] EMPTY_ARRAY = new byte; private ByteArrayInputStream _is; private byte[] _bytes; /** * takes in the actual input stream that we should be buffering */ public BufferedServletInputStreamWrapper(InflaterInputStream stream, int length) throws IOException { _bytes = (length == 0) ? EMPTY_ARRAY : toBytes(stream, length); _is = new ByteArrayInputStream(_bytes); } @Override public int read() throws IOException { return _is.read(); } @Override public int read(byte[] buf, int off, int len) { return _is.read(buf, off, len); } @Override public int read(byte[] buf) throws IOException { return _is.read(buf); } @Override public int available() { return _is.available(); } /** * resets the wrapper's stream so that it can be re-read from the stream. if we're * using this somewhere were we expect it to be done again in the chain this should * be called after we're through so we can reset the data. */ public void resetWrapper() { _is = new ByteArrayInputStream(_bytes); } public byte[] getBytes() { return _bytes; } private byte[] toBytes(InputStream is, int bufferSize) throws IOException { bufferSize = (bufferSize <= 0) ? DEFAULT_READ_BUFFER_SIZE : bufferSize; ByteArrayOutputStream bos = new ByteArrayOutputStream(); byte[] buffer = new byte; int read = is.read(buffer); while (-1 != read) { bos.write(buffer, 0, read); read = is.read(buffer); } return bos.toByteArray(); }}
三，服务器对response进行压缩可参考jetty相关源码
四，java客户端对压缩过的返回值进行解压
1,gzip的情况
GZIPInputStream gzip = new GZIPInputStream(post.getResponseBodyAsStream());StringBuffer out = new StringBuffer();byte[] b = new byte;for (int n; (n = gzip.read(b)) != -1;) { out.append(new String(b, 0, n));}return out.toString();
2，deflate的情况
InflaterInputStream iis = new InflaterInputStream(post.getResponseBodyAsStream());contentLength = (contentLength <= 0) ? 1024 : contentLength;ByteArrayOutputStream bos = new ByteArrayOutputStream();byte[] buffer = new byte;int read = iis.read(buffer);while (-1 != read) { bos.write(buffer, 0, read); read = iis.read(buffer);}byte[] _bytes = (contentLength == 0) ? EMPTY_ARRAY : bos.toByteArray();ByteArrayInputStream _is = new ByteArrayInputStream(_bytes);StringBuffer out = new StringBuffer();byte[] b = new byte;for (int n; (n = _is.read(b)) != -1;) { out.append(new String(b, 0, n));}return out.toString();
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