亿及流量多级缓存 - 客户端缓存

Cache-Control: max-age=2592000
ETag: "5d8c4a06-a0fc"  
Expires: Sat, 26 Oct 2019 15:16:24 GMT

package com.mashibing.httpcache.controller;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/cache")
public class CacheController {
	
	@RequestMapping("/")
	public ResponseEntity<String> last(@RequestHeader(value="IF-Modified-Since",required = false) Date ifModifiedSince) {
		
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss 'GMT'", Locale.US);
		
		long now = System.currentTimeMillis() / 1000 *1000;
		
		HttpHeaders headers = new HttpHeaders();
		
		String body = "<a href =''>hi点我</a>";
	
		String ETag = getMd5(body);
		
		headers.add("Date", simpleDateFormat.format(new Date(now)));
		headers.add("ETag", ETag);
		
		return new ResponseEntity<>(body,headers,HttpStatus.OK);
	}
	
	/**
	 * 字符串转md5
	 * @param msg
	 * @return
	 */
	private String getMd5(String msg) {
		MessageDigest md5 = null;
		
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		md5.update(msg.getBytes());
		byte[] digest = md5.digest();
		
		StringBuffer buf = null;
		buf = new StringBuffer(digest.length * 2);
		//遍历
		for (int i = 0; i < digest.length; i++) {
			if (((int) digest[i] & 0xff) < 0x10) { //(int) b[i] & 0xff 转换成无符号整型
				buf.append("0");
			}
			//Long.toHexString( 无符号长整数的十六进制字符串表示
			buf.append(Long.toHexString((int) digest[i] & 0xff)); 
		}
		return buf.toString();
	}

}

package com.mashibing.httpcache.controller;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Map;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/cache")
public class CacheController {
	
	private MyFile file = MyFile.getInstance();
	@RequestMapping("/")
	public ResponseEntity<String> last(@RequestHeader(value="IF-Modified-Since",required = false) Date ifModifiedSince) {
		
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss 'GMT'", Locale.US);
		
		long now = System.currentTimeMillis() / 1000 *1000;
		// 系统当前时间
		
		System.out.println(now);
		// 缓存时间
		long maxAge = 20;
		
		HttpHeaders headers = new HttpHeaders();
		
		if (null != ifModifiedSince && ifModifiedSince.getTime() == file.getLastModified() ) {
			
			System.out.println(304);
			
		}
		
		headers.add("Date", simpleDateFormat.format(new Date(now)));
		headers.add("Expires", simpleDateFormat.format(new Date(now + maxAge * 1000)));
		headers.add("Cache-Control", "max-age="+maxAge);
		headers.add("Last-Modified", simpleDateFormat.format(new Date(file.getLastModified())));
		
		String body = "<a href =''>hi点我</a>";
		return new ResponseEntity<>(body,headers,HttpStatus.OK);
	}

}

package com.mashibing.httpcache.controller;

public class MyFile {

	private String name;
	private long lastModified;
	private long expireTime;
	
	private static MyFile file ;
	
	private MyFile() {

		this.name = "file...";
		this.lastModified = System.currentTimeMillis() /1000 * 1000;
		this.expireTime = 10 *1000;
	}
	
	public long getExpireTime() {
		return expireTime;
	}
	public void setExpireTime(long expireTime) {
		this.expireTime = expireTime;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public long getLastModified() {
		return lastModified;
	}
	public void setLastModified(long lastModified) {
		this.lastModified = lastModified;
	}

	public static MyFile getInstance() {
		// TODO Auto-generated method stub
		if(file==null) {
			file = new MyFile();
		}
		return file;
	}
	
}