JavaWeb之Request/Response代码修炼篇(五)

1. 解决中文字符编码问题

String str = "我爱java";
//第一种方法
response.setContentType("text/html;charset=GBK");(推荐)
//第二种方法
//response.setHeader("Content-Type","text/html;charset=UTF-8");
//第三种方法
//response.getOutputStream().write("<meta http-equiv='Content-Type' content='text/html;charset=UTF-8'>".getBytes());
response.getOutputStream().write(str.getBytes());

2. Firefox中文文件名下载问题

String path = "/WEB-INF/classes/你好.jpg";
String filename = path.substring(path.lastIndexOf("/")+1);
String absolutePath = getServletContext().getRealPath(path);
if(request.getHeader("User-Agent").contains("Firefox")) {
	response.setHeader("Content-Disposition", "attachment;filename="+encodeDownloadFilename(filename, "Firefox"));
} else {
	response.setHeader("Content-Disposition", "attachment;filename="+encodeDownloadFilename(filename, "ie"));
}
InputStream is = new FileInputStream(absolutePath);
OutputStream os = response.getOutputStream();
int len = -1;
byte buf[] = new byte[1024];
while((len=is.read(buf)) != -1) {
	os.write(buf, 0, len);
}

is.close();

public String encodeDownloadFilename(String filename, String agent) throws IOException {
	
	if(agent.contains("Firefox")) {
		filename = "=?UTF-8?B?"+new BASE64Encoder().encode(filename.getBytes("utf-8"))+"?=";
	} else {
		filename = URLEncoder.encode(filename,"UTF-8");
	}
	return filename;
}

3. 验证码图片

//控制浏览器定时刷新
response.setHeader("refresh", "10");

//定义高度和宽度
int width = 120, height = 25;
//创建一个图像缓冲区
BufferedImage bImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//得到画笔
Graphics g = bImage.getGraphics();
//设置画笔颜色画边框，填充背景，画线条，画字符串
g.setColor(Color.BLACK);
g.drawRect(0, 0, width, height);
//填充背景
g.setColor(Color.LIGHT_GRAY);
g.fillRect(1, 1, width-2, height-2);
//画线条
Random r = new Random();
g.setColor(Color.CYAN);
for(int i=0; i<20; i++) {
	g.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height));
}
//字符串,设置字体样式
Font font = new Font("楷体",Font.BOLD|Font.ITALIC, 20);
g.setFont(font);
g.setColor(Color.RED);
String base = "u7684u4e00u4e86u662fu6211u4e0du5728";
for(int i=0; i<4; i++) {
	String ch = base.charAt(r.nextInt(base.length())) +"";
	g.drawString(ch, 20+(20*i), 20);
}

//设置头信息显示数据类型
response.setHeader("Content-Type", "image/jpeg");
//清空缓存信息
response.setHeader("Expires", "0");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Pragma", "no-cache");

ImageIO.write(bImage, "jpg", response.getOutputStream());

4. 设置缓存时间

response.setContentType("text/html;charset=UTF-8");

response.setDateHeader("Expires", System.currentTimeMillis()+60*60*1000);
PrintWriter out = response.getWriter();
out.write("刘若英-十年");

5.1 获取请求参数方式1

//1. 获取获取请求参数(文本框中的值)
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");

Enumeration<String> names = request.getParameterNames();
while(names.hasMoreElements()) {
	/*String name = new String(names.nextElement().getBytes("ISO-8859-1"),"UTF-8");
	String value = new String(request.getParameter(name).getBytes("ISO-8859-1"),"UTF-8");*/
	String name = names.nextElement();
	String value = request.getParameter(name);
	
	response.getWriter().write(name+":  "+value);
}

5.2 获取请求参数方式2

// 2. 通过反射获取请求参数
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
User user = new User();
Enumeration<String> names = request.getParameterNames();
while (names.hasMoreElements()) {
	String name = names.nextElement();
	String values[] = request.getParameterValues(name);

	Class clazz = user.getClass();
	try {
		Field field = clazz.getDeclaredField(name);
		field.setAccessible(true);
		if (values != null & values.length > 1) {
			field.set(user, (Object) values);
		} else {
			field.set(user, values[0]);
		}
	} catch (Exception e) {
		throw new RuntimeException(e);
	}
}

response.getWriter().write(user.getUsername() + ">>"+ Arrays.toString(user.getPassword()));

5.3 获取请求参数方式3

// 3. 通过内省完成获取请求参数
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
User user = new User();

Map<String, String[]> map = request.getParameterMap();
for(Map.Entry<String, String[]> entry : map.entrySet()) {
	String name = entry.getKey();
	String values[] = entry.getValue();
	try {
		PropertyDescriptor pd = new PropertyDescriptor(name, User.class);
		Method m = pd.getWriteMethod();
		if(values!=null && values.length>1) {
			m.invoke(user, (Object)values);
		} else {
			m.invoke(user, values[0]);
		}
	} catch (Exception e) {
		e.printStackTrace();
	}
}
response.getWriter().write(user.getUsername() + ">>" +Arrays.toString(user.getPassword()));

5.4 获取请求参数方式4

// 4. 通过BeanUtils中setProperty()方法
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
User user = new User();

Map<String, String[]> map = request.getParameterMap();
for(Map.Entry<String, String[]> entry : map.entrySet()) {
	String name = entry.getKey();
	String values[] = entry.getValue();
	try {
		if(values!=null && values.length>1) {
			BeanUtils.setProperty(user, name, (Object)values);
		} else {
			BeanUtils.setProperty(user, name, values[0]);
		}
	} catch (IllegalAccessException | InvocationTargetException e) {
		e.printStackTrace();
	}
}
response.getWriter().write(user.getUsername() + ">>" + Arrays.toString(user.getPassword()));

5.5 获取请求参数方式5

//		5. 通过BeanUtils中的populator()方法
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
User user = new User();
try {
	BeanUtils.populate(user, request.getParameterMap());
} catch (IllegalAccessException | InvocationTargetException e) {
	e.printStackTrace();
}
response.getWriter().write(user.getUsername() + ">>" + Arrays.toString(user.getPassword()));