1.網站壓縮的一個簡單示例
public class ServletDemo extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
//找一個內存緩衝字節流
ByteArrayOutputStream baos = new ByteArrayOutputStream();
//把數據壓縮到緩衝字節流流中
GZIPOutputStream gout = new GZIPOutputStream(baos);
//取出數據：壓縮後的
byte b[] = data.getBytes();//原始字節
System.out.println("原有數據大小："+b.length);
gout.write(b);
gout.close();//保證所有的數據都進入內存緩存流
//取出壓縮後的數據
b = baos.toByteArray();
System.out.println("壓縮後的數據大小："+b.length);
//輸出前一定要告知客戶端壓縮方式
response.setHeader("Content-Encoding", "gzip");
response.setContentLength(b.length);//告知客戶端正文的大小
//用服務器的響應對象輸出
ServletOutputStream out = response.getOutputStream();
out.write(b);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}2.全站壓縮過濾器的一個簡單示例
//全站壓縮過濾器
public class GzipFilter implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest req, ServletResponse resp,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
GzipHttpServletResponse gresponse = new GzipHttpServletResponse(response);
chain.doFilter(request, gresponse);//放行
//壓縮代碼寫在此處
//找一個內存緩衝字節流
ByteArrayOutputStream baos = new ByteArrayOutputStream();
//把數據壓縮到緩衝字節流流中
GZIPOutputStream gout = new GZIPOutputStream(baos);
//取出數據：壓縮後的
byte b[] = gresponse.getOldBytes();//原始字節
System.out.println("原有數據大小："+b.length);
gout.write(b);
gout.close();//保證所有的數據都進入內存緩存流
//取出壓縮後的數據
b = baos.toByteArray();
System.out.println("壓縮後的數據大小："+b.length);
//輸出前一定要告知客戶端壓縮方式
response.setHeader("Content-Encoding", "gzip");
response.setContentLength(b.length);//告知客戶端正文的大小
//用服務器的響應對象輸出
ServletOutputStream out = response.getOutputStream();
out.write(b);
}
public void init(FilterConfig filterConfig) throws ServletException {
}
}
class GzipHttpServletResponse extends HttpServletResponseWrapper{
private ByteArrayOutputStream baos = new ByteArrayOutputStream();
private PrintWriter pw;
public GzipHttpServletResponse(HttpServletResponse response){
super(response);
}
//把原始數據封裝到一個緩衝流中
@Override
public ServletOutputStream getOutputStream() throws IOException {
return new MyServletOutputStream(baos);
}
//字符流：把原始數據封裝到一個緩衝流中
@Override
public PrintWriter getWriter() throws IOException {
pw = new PrintWriter(new OutputStreamWriter(baos, super.getCharacterEncoding()));//字符流轉成字節流編碼會丟失
return pw;
}
//返回baos中的緩存數據：原始
public byte[] getOldBytes(){
try {
if(pw!=null){
pw.close();
}
baos.flush();
} catch (IOException e) {
e.printStackTrace();
}
return baos.toByteArray();
}
}
class MyServletOutputStream extends ServletOutputStream{
private ByteArrayOutputStream baos;
public MyServletOutputStream(ByteArrayOutputStream baos){
this.baos = baos;
}
@Override
public void write(int b) throws IOException {
baos.write(b);
}
}
