ID生成、异常与跨域-通用模块-Saas多租户平台开发
目录
内容
1、全局唯一ID生成
ID生成有很多种方案，这么我们选择基于’雪花算法’的ID生成，下面为生成ID的类：
package com.ihrm.common.utils;
import java.lang.management.ManagementFactory;
import java.net.InetAddress;
import java.net.NetworkInterface;
/**
* <p>名称：IdWorker.java</p>
* <p>描述：分布式自增长ID</p>
* <pre>
* Twitter的 Snowflake JAVA实现方案
* </pre>
* 核心代码为其IdWorker这个类实现，其原理结构如下，我分别用一个0表示一位，用—分割开部分的作用：
* 1||0---0000000000 0000000000 0000000000 0000000000 0 --- 00000 ---00000 ---000000000000
* 在上面的字符串中，第一位为未使用（实际上也可作为long的符号位），接下来的41位为毫秒级时间，
* 然后5位datacenter标识位，5位机器ID（并不算标识符，实际是为线程标识），
* 然后12位该毫秒内的当前毫秒内的计数，加起来刚好64位，为一个Long型。
* 这样的好处是，整体上按照时间自增排序，并且整个分布式系统内不会产生ID碰撞（由datacenter和机器ID作区分），
* 并且效率较高，经测试，snowflake每秒能够产生26万ID左右，完全满足需要。
* <p>
* 64位ID (42(毫秒)+5(机器ID)+5(业务编码)+12(重复累加))
*
* @author Polim
*/
public class IdWorker {
// 时间起始标记点，作为基准，一般取系统的最近时间（一旦确定不能变动）
private final static long twepoch = 1288834974657L;
// 机器标识位数
private final static long workerIdBits = 5L;
// 数据中心标识位数
private final static long datacenterIdBits = 5L;
// 机器ID最大值
private final static long maxWorkerId = -1L ^ (-1L << workerIdBits);
// 数据中心ID最大值
private final static long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
// 毫秒内自增位
private final static long sequenceBits = 12L;
// 机器ID偏左移12位
private final static long workerIdShift = sequenceBits;
// 数据中心ID左移17位
private final static long datacenterIdShift = sequenceBits + workerIdBits;
// 时间毫秒左移22位
private final static long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
private final static long sequenceMask = -1L ^ (-1L << sequenceBits);
/* 上次生产id时间戳 */
private static long lastTimestamp = -1L;
// 0，并发控制
private long sequence = 0L;
private final long workerId;
// 数据标识id部分
private final long datacenterId;
public IdWorker(){
this.datacenterId = getDatacenterId(maxDatacenterId);
this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
}
/**
* @param workerId
* 工作机器ID
* @param datacenterId
* 序列号
*/
public IdWorker(long workerId, long datacenterId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
if (datacenterId > maxDatacenterId || datacenterId < 0) {
throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
}
this.workerId = workerId;
this.datacenterId = datacenterId;
}
/**
* 获取下一个ID
*
* @return
*/
public synchronized long nextId() {
long timestamp = timeGen();
if (timestamp < lastTimestamp) {
throw new RuntimeException(String.format("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
if (lastTimestamp == timestamp) {
// 当前毫秒内，则+1
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
// 当前毫秒内计数满了，则等待下一秒
timestamp = tilNextMillis(lastTimestamp);
}
} else {
sequence = 0L;
}
lastTimestamp = timestamp;
// ID偏移组合生成最终的ID，并返回ID
long nextId = ((timestamp - twepoch) << timestampLeftShift)
| (datacenterId << datacenterIdShift)
| (workerId << workerIdShift) | sequence;
return nextId;
}
private long tilNextMillis(final long lastTimestamp) {
long timestamp = this.timeGen();
while (timestamp <= lastTimestamp) {
timestamp = this.timeGen();
}
return timestamp;
}
private long timeGen() {
return System.currentTimeMillis();
}
/**
* <p>
* 获取 maxWorkerId
* </p>
*/
protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
StringBuffer mpid = new StringBuffer();
mpid.append(datacenterId);
String name = ManagementFactory.getRuntimeMXBean().getName();
if (!name.isEmpty()) {
/*
* GET jvmPid
*/
mpid.append(name.split("@")[0]);
}
/*
* MAC + PID 的 hashcode 获取16个低位
*/
return (mpid.toString().hashCode() & 0xffff) % (maxWorkerId + 1);
}
/**
* <p>
* 数据标识id部分
* </p>
*/
protected static long getDatacenterId(long maxDatacenterId) {
long id = 0L;
try {
InetAddress ip = InetAddress.getLocalHost();
NetworkInterface network = NetworkInterface.getByInetAddress(ip);
if (network == null) {
id = 1L;
} else {
byte[] mac = network.getHardwareAddress();
id = ((0x000000FF & (long) mac[mac.length - 1])
| (0x0000FF00 & (((long) mac[mac.length - 2]) << 8))) >> 6;
id = id % (maxDatacenterId + 1);
}
} catch (Exception e) {
System.out.println(" getDatacenterId: " + e.getMessage());
}
return id;
}
}
2、全局异常处理
- 原理：全局异常处理基于@RestControllerAdvicet或者@ControllerAdvicet注解+@ExceptionHandler注解，详细可以自行查询相关文档
步骤如下：
-
创建common.exception包统一放在异常处理相关类
-
创建异常类RRException继承RuntimeException,代码如下：
package com.ihrm.common.exception; /** * 自定义异常 */ public class RRException extends RuntimeException { private static final long serialVersionUID = 1L; private String msg; private int code = 500; public RRException(String msg) { super(msg); this.msg = msg; } public RRException(String msg, Throwable e) { super(msg, e); this.msg = msg; } public RRException(String msg, int code) { super(msg); this.msg = msg; this.code = code; } public RRException(String msg, int code, Throwable e) { super(msg, e); this.msg = msg; this.code = code; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; } public int getCode() { return code; } public void setCode(int code) { this.code = code; } } -
创建全局异常处理类RRExceptionHandler.java,代码如下：
package com.ihrm.common.exception; import com.ihrm.common.utils.R; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.dao.DuplicateKeyException; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.bind.annotation.RestControllerAdvice; /** * 异常处理器 * * @author Mark [email protected] */ @RestControllerAdvice public class RRExceptionHandler { private Logger logger = LoggerFactory.getLogger(getClass()); /** * 处理自定义异常 */ @ExceptionHandler(RRException.class) public R handleRRException(RRException e){ R r = new R(); r.put("code", e.getCode()); r.put("msg", e.getMessage()); return r; } @ExceptionHandler(DuplicateKeyException.class) public R handleDuplicateKeyException(DuplicateKeyException e){ logger.error(e.getMessage(), e); return R.error("数据库中已存在该记录"); } // @ExceptionHandler(AuthorizationException.class) // public R handleAuthorizationException(AuthorizationException e){ // logger.error(e.getMessage(), e); // return R.error("没有权限，请联系管理员授权"); // } @ExceptionHandler(Exception.class) public R handleException(Exception e){ logger.error(e.getMessage(), e); return R.error(); } }
3、跨域配置
-
springboot中跨域配置，使用CorsFilter。为方面后续扩展其他过滤器，这么统一把过滤器放置在FilterConfig配置类中，代码如下：
package com.ihrm.common.config; import org.springframework.boot.web.servlet.FilterRegistrationBean; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.cors.CorsConfiguration; import org.springframework.web.cors.UrlBasedCorsConfigurationSource; import org.springframework.web.filter.CorsFilter; import javax.servlet.Filter; /** * Filter配置 */ @Configuration public class FilterConfig { @Bean public FilterRegistrationBean corsFilter() { FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>(); final UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource(); final CorsConfiguration corsConfiguration = new CorsConfiguration(); corsConfiguration.setAllowCredentials(true); corsConfiguration.addAllowedOrigin("*"); corsConfiguration.addAllowedHeader("*"); corsConfiguration.addAllowedMethod("*"); corsConfiguration.setMaxAge(3600L); source.registerCorsConfiguration("/**", corsConfiguration); CorsFilter corsFilter = new CorsFilter(source); registration.setFilter(corsFilter); registration.setName("corsFilter"); return registration; } }
4、说明
跨域处理一般会放置在网关模块或者业务模块中，但是这里还没有创建，等创建之后会移植到响应的模块中。
到此基础公共模块功能搭建完毕，下一步创建具体的功能模块。
后记 ：
本项目为参考某马视频开发，相关视频及配套资料可自行度娘或者联系本人。上面为自己编写的开发文档，持续更新。欢迎交流，本人QQ:806797785
前端项目源代码地址：https://gitee.com/gaogzhen/ihrm-parent // 前端后台管理系统
后端JAVA源代码地址:https://gitee.com/gaogzhen/ihrm-vue // 后端项目