基于SpringMVC进行REST服务开发
基于SpringMVC进行REST服务开发
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.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://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;
@Override
public 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{
@Autowired
private JdbcTemplate jdbcTemplate;
private Log log = LogFactory.getLog(EmployeeDaoImpl.class.getName());
@Override
public List<Employee> getEmployees() {
// TODO Auto-generated method stub
String sql = "SELECT EMPLOYEE_ID,EMPLOYEE_NAME,AGE,ADDRESS,SEX FROM EMPLOYEE";
log.info(sql);
return jdbcTemplate.query(sql, new EmployeeRowMapper());
}
@Override
public Employee getEmployeeByID(int id) {
// TODO Auto-generated method stub
String 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);
}
@Override
public int createEmployee(Employee employee) {
// TODO Auto-generated method stub
String 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;
}
@Override
public int updateEmployee(Employee employee) {
// TODO Auto-generated method stub
String 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;
}
@Override
public int deleteEmployee(Employee employee) {
// TODO Auto-generated method stub
String 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>{
@Override
public Employee mapRow(ResultSet rSet, int rowNum) throws SQLException {
// TODO Auto-generated method stub
Employee 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;
}
}
@Override
public boolean ifEmployeeExist(Employee employee) {
// TODO Auto-generated method stub
Employee 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{
@Autowired
private EmployeeDao employeeDao;
@Override
public List<Employee> getEmployees() {
// TODO Auto-generated method stub
List<Employee> employees = employeeDao.getEmployees();
return employees;
}
@Override
public Employee getEmployee(int id) {
// TODO Auto-generated method stub
Employee employee = employeeDao.getEmployeeByID(id);
return employee;
}
@Override
public int createEmployee(Employee employee) {
// TODO Auto-generated method stub
int rowNum = employeeDao.createEmployee(employee);
return rowNum;
}
@Override
public int updateEmployee(Employee employee) {
// TODO Auto-generated method stub
int rowNum = employeeDao.updateEmployee(employee);
return rowNum;
}
@Override
public int deleteEmployee(Employee employee) {
// TODO Auto-generated method stub
int rowNum = employeeDao.deleteEmployee(employee);
return rowNum;
}
@Override
public boolean ifEmployeeExist(Employee employee) {
// TODO Auto-generated method stub
boolean 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 {
@Autowired
public 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;
}
}
