代碼來之哪里,不記得了

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GzipFilter

public class GzipFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("過濾器被執(zhí)行了");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {

        //1.對response進行改進
        MyResponse resp = new MyResponse((HttpServletResponse) response);       

        //2.放行，讓后臺做response做輸出操作
        chain.doFilter(request, resp);

        //3.從我們定義的“字節(jié)數(shù)組輸出流”中取出數(shù)據(jù)進行壓縮
        ByteArrayOutputStream baout = resp.getBaout();
        byte bs[] = baout.toByteArray();// 源字節(jié)數(shù)據(jù)
        System.out.println("壓縮前大小:" + bs.length);
        
        ByteArrayOutputStream zipBaout = new ByteArrayOutputStream();
        GZIPOutputStream gout = new GZIPOutputStream(zipBaout);
        gout.write(bs);// 把數(shù)據(jù)壓縮到baout中
        gout.close();
        
        bs = zipBaout.toByteArray();//得到壓縮后的字節(jié)
        System.out.println("壓縮后大小:" + bs.length);
        
        //4.再用原生的reponse輸出壓縮后的內(nèi)容
        HttpServletResponse httpResp = (HttpServletResponse) response;
        // 輸出之前告訴客戶端:我們的數(shù)據(jù)是gzip格式，然后輸出
        httpResp.setHeader("Content-Encoding", "gzip");
        httpResp.setContentLength(bs.length);
        OutputStream out = httpResp.getOutputStream();
        out.write(bs);
        
    }

    @Override
    public void destroy() {
        
    }

}

class MyResponse extends HttpServletResponseWrapper { //HttpServletResponse實現(xiàn)類
    private PrintWriter pw;
    private ByteArrayOutputStream baout = new ByteArrayOutputStream();
    /*
     * 字節(jié)數(shù)組輸了流(帶緩存功能)：所有發(fā)送到輸出流的數(shù)據(jù)保存在該字節(jié)數(shù)組緩沖區(qū)中,可以轉(zhuǎn)成字節(jié)數(shù)組
     * 在此的作用：為了將response輸出的內(nèi)容先存到字節(jié)數(shù)組緩沖區(qū)中,以便后續(xù)的壓縮處理*/
    
    public MyResponse(HttpServletResponse response) {
        super(response);
    }

    //重新實現(xiàn)response的該方法
    public ServletOutputStream getOutputStream() throws IOException {
        return new MyOutputStream(baout);
    }

    public ByteArrayOutputStream getBaout() {
        if(pw!=null){
            pw.flush();
            //這里很重要，如果不flush或close，不把字符流刷出去，baout中是不會有數(shù)據(jù)的.
        }
        return baout;
    }
    
    //重新實現(xiàn)response的該方法
    public PrintWriter getWriter() throws IOException {
        //字節(jié)流轉(zhuǎn)字符流
        pw = new PrintWriter(new OutputStreamWriter(baout, "utf-8"),true);
        return pw;
    }

}

/**
 * 自定義ServletOutputStream子類
 * 目的：保證response獲取到的outputStream是我們定義的“字節(jié)數(shù)組輸入流”
 * ,且調(diào)用write方法時,是往“字節(jié)數(shù)組輸入流”的緩存區(qū)中寫入*/
class MyOutputStream extends ServletOutputStream {
    private ByteArrayOutputStream baout = null;

    public MyOutputStream(ByteArrayOutputStream baout) {
        this.baout = baout;
    }

    @Override
    public void write(int b) throws IOException {
        baout.write(b);//把指定內(nèi)容寫入到 字節(jié)數(shù)組輸入流
    }
}

測試servlet

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//      String str = "go go go let's go";
//      //1\獲取字節(jié)數(shù)組
//      byte[] bytes = str.getBytes() ;
//      
//      System.out.println("壓縮前的長度：" + bytes.length); 
//      //2\
//      ByteArrayOutputStream baos = new ByteArrayOutputStream() ; 
//      GZIPOutputStream  gzip = new GZIPOutputStream(baos) ;
//      
//      gzip.write(bytes) ; 
//      gzip.close() ;
//      //3\
//      bytes = baos.toByteArray() ;
//      System.out.println("壓縮后的長度：" + bytes.length);
        

    
        response.setContentType("text/html;charset=utf-8");
        String str = "And I memorize each word我記住的每個字眼";
        
        OutputStream out = response.getOutputStream();
        out.write(str.getBytes("utf-8"));
        
        //response.getWriter().write(str);
    }