本文目录导读：
我来介绍几种常见的Java公共模块封装方式及案例：
工具类模块封装
String工具类
package com.example.common.util;
import org.apache.commons.lang3.StringUtils;
/**
* 字符串工具类
*/
public class StringUtil {
/**
* 驼峰转下划线
*/
public static String camelToUnderline(String str) {
if (StringUtils.isEmpty(str)) {
return "";
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isUpperCase(c)) {
sb.append("_").append(Character.toLowerCase(c));
} else {
sb.append(c);
}
}
return sb.toString();
}
/**
* 手机号脱敏
*/
public static String maskPhone(String phone) {
if (StringUtils.isEmpty(phone) || phone.length() != 11) {
return phone;
}
return phone.substring(0, 3) + "****" + phone.substring(7);
}
}
统一返回结果封装
package com.example.common.response;
import lombok.Data;
/**
* 统一返回结果
*/
@Data
public class Result<T> {
private Integer code;
private String message;
private T data;
private Long timestamp;
private Result() {
this.timestamp = System.currentTimeMillis();
}
// 成功
public static <T> Result<T> success(T data) {
Result<T> result = new Result<>();
result.setCode(200);
result.setMessage("success");
result.setData(data);
return result;
}
// 失败
public static <T> Result<T> error(Integer code, String message) {
Result<T> result = new Result<>();
result.setCode(code);
result.setMessage(message);
return result;
}
// 带数据的失败
public static <T> Result<T> error(Integer code, String message, T data) {
Result<T> result = new Result<>();
result.setCode(code);
result.setMessage(message);
result.setData(data);
return result;
}
}
通用异常处理
package com.example.common.exception;
import com.example.common.response.Result;
import lombok.extern.slf4j.Slf4j;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
/**
* 全局异常处理器
*/
@Slf4j
@RestControllerAdvice
public class GlobalExceptionHandler {
// 业务异常
@ExceptionHandler(BusinessException.class)
public Result<Void> handleBusinessException(BusinessException e) {
log.error("业务异常：", e);
return Result.error(e.getCode(), e.getMessage());
}
// 参数校验异常
@ExceptionHandler(ValidationException.class)
public Result<Void> handleValidationException(ValidationException e) {
log.error("参数校验异常：", e);
return Result.error(400, e.getMessage());
}
// 运行时异常
@ExceptionHandler(RuntimeException.class)
public Result<Void> handleRuntimeException(RuntimeException e) {
log.error("运行时异常：", e);
return Result.error(500, "服务器内部错误");
}
}
公共配置模块
package com.example.common.config;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
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 java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
/**
* 公共配置
*/
@Configuration
public class CommonConfig {
// 时间序列化配置
@Bean
public Jackson2ObjectMapperBuilderCustomizer jsonCustomizer() {
return builder -> {
builder.serializerByType(LocalDateTime.class,
new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
};
}
// CORS配置
@Bean
public CorsFilter corsFilter() {
CorsConfiguration config = new CorsConfiguration();
config.addAllowedOrigin("*");
config.addAllowedHeader("*");
config.addAllowedMethod("*");
UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
source.registerCorsConfiguration("/**", config);
return new CorsFilter(source);
}
}
通用分页模型
package com.example.common.model;
import lombok.Data;
import java.util.List;
/**
* 分页结果
*/
@Data
public class PageResult<T> {
private List<T> records;
private long total;
private long pageSize;
private long pageNum;
private long pages;
public static <T> PageResult<T> of(List<T> records, long total, long pageNum, long pageSize) {
PageResult<T> result = new PageResult<>();
result.setRecords(records);
result.setTotal(total);
result.setPageNum(pageNum);
result.setPageSize(pageSize);
result.setPages((total + pageSize - 1) / pageSize);
return result;
}
}
Maven模块结构
<!-- common模块的pom.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.example</groupId>
<artifactId>parent-project</artifactId>
<version>1.0.0</version>
</parent>
<artifactId>common</artifactId>
<version>1.0.0</version>
<name>common</name>
<description>公共模块</description>
<dependencies>
<!-- Lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<!-- 工具类 -->
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
</dependency>
<!-- Spring Boot -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
</project>
使用示例
// 在其他模块中使用
@Service
public class UserService {
public Result<UserVO> getUser(Long id) {
User user = userMapper.selectById(id);
if (user == null) {
return Result.error(404, "用户不存在");
}
UserVO vo = new UserVO();
vo.setPhone(StringUtil.maskPhone(user.getPhone()));
return Result.success(vo);
}
public PageResult<UserVO> listUsers(int pageNum, int pageSize) {
Page<User> page = new Page<>(pageNum, pageSize);
Page<User> result = userMapper.selectPage(page, null);
List<UserVO> vos = result.getRecords().stream()
.map(this::convertToVO)
.collect(Collectors.toList());
return PageResult.of(vos, result.getTotal(), pageNum, pageSize);
}
}
这样的封装方式具有以下优点：
- 复用性强：公共代码集中管理
- 统一规范：返回格式、异常处理统一
- 易于维护：修改公共逻辑只需改动一处
- 减少重复：避免各模块重复造轮子
