response（向客戶端寫入數據、對相應進行設置（狀態碼、響應頭））

一、向客戶端寫入數據

1、寫入文字

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");//設置服務器的編碼，默認是ISO-8859-1
        response.setContentType("text/html; charset = utf-8");//告訴瀏覽器服務器的編碼格式
        response.getWriter().write("你好，JAVA");
    }

 

 2、圖片

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletOutputStream out=response.getOutputStream();
        File file=new File("圖片路徑");
        FileInputStream fi = new FileInputStream(file);
        byte[] buf = new byte[1024];
        int len = 0;
        while ((len = fi.read(buf)) != -1) {
            out.write(buf, 0, len); // 將數組中的指定長度的數據寫入到輸出流中。
        }
        fi.close();
        out.close();
    }

采用了緩沖數組讀入圖片數據，減少了時間的消耗。創建ServletOutputStream對象，將數據輸出到了客戶端。

 

二、response對響應的設置

1、response對象設置響應行狀態碼：

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setStatus(404); }

 

 2、response對象添加響應頭：

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Date date=new Date(121344444);
response.addHeader("zzz","I love JAVA.");
response.addIntHeader("myself",22);
response.addDateHeader("Time:",date.getTime());
}

 

 3、response對象設置響應頭：

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    Date date=new Date(121344444); response.addHeader("zzz","I love JAVA."); response.addIntHeader("myself",22); response.addDateHeader("Time:",date.getTime()); response.setIntHeader("myself",23); }