背景
REST的概念这里不多过多阐述。在REST中,资源通过URL进行识别和定位。一般来说,以下这些HTTP方法通常会匹配为如下的CRUD动作:
Create:POST
Read:GET
Update:PUT或PATCH
Delete:DELETE
@ResponseBody:此注解会告知Spring,我们要将返回的对象作为资源发送给客户端,并将其转化为客户端可接受的表现形式。如果客户端的Accept头部信息表明它接受"application/json",并且jackson JSON库位于应用程序的路径下,那么会将返回结果列表转化为json格式。
@RestController:此注解能为控制器的所有处理方法应用消息转化功能。不必为每个方法都添加@ResponseBody了。
@ResponseEntity:作为@ResponseBody的替代方案,@ResponseEntity中可以包含响应相关的元数据(如头部信息和状态码)以及要转换成资源表述的对象。
@ResponseStatus:此注解可以指定状态码。
环境搭建相关
SpringMVC相关的jar包全部引入便是
c3p0相关jar包:
jackson相关jar包:
oracle jdbc 相关jar包:
spring.xml 文件代码如下图所示:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xmlns:mvc="http://www.springframework.org/schema/mvc"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <!-- 定义要扫描 controller的包 --><context:component-scan base-package="cn.com.restapi.controller" /><context:component-scan base-package="cn.com.restapi.daoimpl"/><context:component-scan base-package="cn.com.restapi.serviceimpl"/><mvc:default-servlet-handler /> <!-- 启动注解驱动 SpringMVC 功能 --><mvc:annotation-driven /><!-- 引用配置文件 --><context:property-placeholder location="classpath:jdbc.properties"/><!-- 配置视图解析器解析路径 --><bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver"><!-- 定义视图存放路径 --><property name="prefix" value="/WEB-INF/jsp/" /><!-- 定义视图后缀 --><property name="suffix" value=".jsp" /></bean><!-- 1、声明数据源对象:C3P0连接池 --><bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"><!-- 加载jdbc驱动 --><property name="driverClass" value="${driverClass}"></property><!-- jdbc连接地址 --><property name="jdbcUrl" value="${jdbcUrl}"></property><!-- 连接数据库的用户名 --><property name="user" value="${user}"></property><!-- 连接数据库的密码 --><property name="password" value="${password}"></property><!-- 数据库的初始化连接数 --><property name="initialPoolSize" value="3"></property><!-- 数据库的最大连接数 --><property name="maxPoolSize" value="10"></property><!-- 数据库最多执行的事务 --><property name="maxStatements" value="100"></property><!-- 连接数量不够时每次的增量 --><property name="acquireIncrement" value="2"></property> </bean><!-- 创建jdbcTemplate对象 --><bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate"><property name="dataSource" ref="dataSource"></property></bean></beans>
jdbc.properties 配置文件如下图所示:
整个项目的目录如下图所示:
实体类Employee.java代码:
package cn.com.restapi.model;public class Employee {private int employeeID;private String employeeName;private int age;private String address;private String sex;@Overridepublic String toString(){return "Employee[EMPLOYEE_ID=" + employeeID + ",EMPLOYEENAME=" + employeeName + ",AGE=" + age + ",ADDRESS=" + address + ",SEX=" + sex + "]";}//get and set........
}
dao层代码:
import java.util.List;
import cn.com.restapi.model.Employee;public interface EmployeeDao {public List<Employee> getEmployees();public Employee getEmployeeByID(int id);public int createEmployee(Employee employee);public int updateEmployee(Employee employee);public int deleteEmployee(Employee employee);public boolean ifEmployeeExist(Employee employee);
}
daoimpl层代码,此处使用c3p0数据源和Spring中的JdbcTemplate模板。
package cn.com.restapi.daoimpl;import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.stereotype.Repository;
import cn.com.restapi.dao.EmployeeDao;
import cn.com.restapi.model.Employee;@Repository
public class EmployeeDaoImpl implements EmployeeDao{@Autowiredprivate JdbcTemplate jdbcTemplate;private Log log = LogFactory.getLog(EmployeeDaoImpl.class.getName());@Overridepublic List<Employee> getEmployees() {// TODO Auto-generated method stubString sql = "SELECT EMPLOYEE_ID,EMPLOYEE_NAME,AGE,ADDRESS,SEX FROM EMPLOYEE";log.info(sql);return jdbcTemplate.query(sql, new EmployeeRowMapper());}@Overridepublic Employee getEmployeeByID(int id) {// TODO Auto-generated method stubString sql = "SELECT EMPLOYEE_ID,EMPLOYEE_NAME,AGE,ADDRESS,SEX FROM EMPLOYEE WHERE EMPLOYEE_ID = ?";log.info(sql);List<Employee> employees = this.jdbcTemplate.query(sql, new EmployeeRowMapper(),id);if (employees.isEmpty()) {return null;}return employees.get(0);}@Overridepublic int createEmployee(Employee employee) {// TODO Auto-generated method stubString sql = "INSERT INTO EMPLOYEE(EMPLOYEE_ID,EMPLOYEE_NAME,AGE,ADDRESS,SEX) VALUE(?,?,?,?,?)";log.info(sql);int rowNum = this.jdbcTemplate.update(sql,employee.getEmployeeID(),employee.getEmployeeName(),employee.getAge(),employee.getAddress(),employee.getSex());return rowNum;}@Overridepublic int updateEmployee(Employee employee) {// TODO Auto-generated method stubString sql = "UPDATE EMPLOYEE SET EMPLOYEE_NAME = ?,AGE = ?,ADDRESS = ?,SEX = ? WHERE EMPLOYEE_ID = ?";log.info(sql);int rowNum = this.jdbcTemplate.update(sql,employee.getEmployeeName(),employee.getAge(),employee.getAddress(),employee.getSex(),employee.getEmployeeID());return rowNum;}@Overridepublic int deleteEmployee(Employee employee) {// TODO Auto-generated method stubString sql = "DELETE EMPLOYEE WHERE EMPLOYEE_ID = ?";log.info(sql);int rowNum = this.jdbcTemplate.update(sql,employee.getEmployeeID());return rowNum;}public class EmployeeRowMapper implements RowMapper<Employee>{@Overridepublic Employee mapRow(ResultSet rSet, int rowNum) throws SQLException {// TODO Auto-generated method stubEmployee employee = new Employee();employee.setEmployeeID(rSet.getInt("EMPLOYEE_ID"));employee.setEmployeeName(rSet.getString("EMPLOYEE_NAME"));employee.setAddress(rSet.getString("ADDRESS"));employee.setAge(rSet.getInt("AGE"));employee.setSex(rSet.getString("SEX"));return employee;}}@Overridepublic boolean ifEmployeeExist(Employee employee) {// TODO Auto-generated method stubEmployee employee2 = this.getEmployeeByID(employee.getEmployeeID());if (employee2 == null) {return true;}return false;}}
Service层代码:
package cn.com.restapi.service;import java.util.List;
import cn.com.restapi.model.Employee;public interface EmployeeService {public List<Employee> getEmployees();public Employee getEmployee(int id);public int createEmployee(Employee employee);public int updateEmployee(Employee employee);public int deleteEmployee(Employee employee);public boolean ifEmployeeExist(Employee employee);
}
ServiceImpl层代码:
package cn.com.restapi.serviceimpl;import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import cn.com.restapi.dao.EmployeeDao;
import cn.com.restapi.model.Employee;
import cn.com.restapi.service.EmployeeService;@Service
public class EmployeeServiceImpl implements EmployeeService{@Autowiredprivate EmployeeDao employeeDao;@Overridepublic List<Employee> getEmployees() {// TODO Auto-generated method stubList<Employee> employees = employeeDao.getEmployees();return employees;}@Overridepublic Employee getEmployee(int id) {// TODO Auto-generated method stubEmployee employee = employeeDao.getEmployeeByID(id);return employee;}@Overridepublic int createEmployee(Employee employee) {// TODO Auto-generated method stubint rowNum = employeeDao.createEmployee(employee);return rowNum;}@Overridepublic int updateEmployee(Employee employee) {// TODO Auto-generated method stubint rowNum = employeeDao.updateEmployee(employee);return rowNum;}@Overridepublic int deleteEmployee(Employee employee) {// TODO Auto-generated method stubint rowNum = employeeDao.deleteEmployee(employee);return rowNum;}@Overridepublic boolean ifEmployeeExist(Employee employee) {// TODO Auto-generated method stubboolean b = employeeDao.ifEmployeeExist(employee);return b;}}
Controller层代码,分别对Employee表实现CRUD操作:
package cn.com.restapi.controller;import java.net.URI;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.util.UriComponentsBuilder;
import cn.com.restapi.model.Employee;
import cn.com.restapi.model.EmployeeNotFoundException;
import cn.com.restapi.model.Error;
import cn.com.restapi.service.EmployeeService;@RestController
public class EmployeeController {@Autowiredpublic EmployeeService employeeService;public Log log = LogFactory.getLog(EmployeeController.class.getName());@RequestMapping(value="/employee",method = RequestMethod.GET)public ResponseEntity<List<Employee>> getEmployees(){log.info("getEmployee method called");List<Employee> employees = employeeService.getEmployees();if (employees.isEmpty()) {return new ResponseEntity<List<Employee>>(employees,HttpStatus.NO_CONTENT);}return new ResponseEntity<List<Employee>>(employees,HttpStatus.OK);}@RequestMapping(value="/employee/{id}",method = RequestMethod.GET)public Employee getEmployeeByID(@PathVariable("id") int id){log.info("getEmployeeByID method called");Employee employee = employeeService.getEmployee(id);if (employee == null) {throw new EmployeeNotFoundException(id);}return employee;}@ExceptionHandler(EmployeeNotFoundException.class)@ResponseStatus(HttpStatus.NOT_FOUND)public ResponseEntity<Error> EmployeeNotFound(EmployeeNotFoundException e){int employeeId = e.getEmployeeId();Error error = new Error(4, "Employee [" + employeeId + "] not found");return new ResponseEntity<Error>(error,HttpStatus.NOT_FOUND);}@RequestMapping(value="/employee",method = RequestMethod.POST,consumes="application/json")public ResponseEntity<?> creatEmployee(@RequestBody Employee employee,UriComponentsBuilder ucb){if (employeeService.ifEmployeeExist(employee)) {Error error = new Error(4, "Employee [id=" + employee.getEmployeeID() + "] already exist");return new ResponseEntity<Error>(error,HttpStatus.CONFLICT);}employeeService.createEmployee(employee);HttpHeaders headers = new HttpHeaders();URI locationUri = ucb.path("/RESTAPI/").path(String.valueOf(employee.getEmployeeID())).build().toUri();headers.setLocation(locationUri);ResponseEntity<Employee> responseEntity = new ResponseEntity<Employee>(employee,headers,HttpStatus.CREATED);return responseEntity;}@RequestMapping(value="/employee",method = RequestMethod.PUT,consumes="application/json")public ResponseEntity<?> updateEmployee(@RequestBody Employee employee,UriComponentsBuilder ucb){if (!employeeService.ifEmployeeExist(employee)) {Error error = new Error(4, "Employee [id=" + employee.getEmployeeID() + "] not found");return new ResponseEntity<Error>(error,HttpStatus.NOT_FOUND);}employeeService.updateEmployee(employee);HttpHeaders headers = new HttpHeaders();URI locationUri = ucb.path("/RESTAPI/").path(String.valueOf(employee.getEmployeeID())).build().toUri();headers.setLocation(locationUri);ResponseEntity<Employee> responseEntity = new ResponseEntity<Employee>(employee,headers,HttpStatus.OK);return responseEntity;}@RequestMapping(value="/employee",method=RequestMethod.DELETE,consumes="application/json")public ResponseEntity<?> deleteEmployee(@RequestBody Employee employee){if (!employeeService.ifEmployeeExist(employee)) {Error error = new Error(4, "Employee [id=" + employee.getEmployeeID() + "] not found");return new ResponseEntity<Error>(error,HttpStatus.NOT_FOUND);}employeeService.deleteEmployee(employee);return new ResponseEntity<Employee>(HttpStatus.NO_CONTENT);}}
Controller层中有两个实体类Error,EmployeeNotFoundException。用于返回错误信息:
package cn.com.restapi.model;public class Error {private int code;private String message;public Error(int code,String message){this.code = code;this.message = message;}public int getCode(){return code;}public String getMessage(){return message;}
}
package cn.com.restapi.model;public class EmployeeNotFoundException extends RuntimeException{private int EmployeeId;public EmployeeNotFoundException(int employeeId){this.EmployeeId = employeeId;}public int getEmployeeId(){return EmployeeId;}
}