(十二) - REST 开发

REST 是一种开发风格, 遵从此风格开发软件, 符合 REST 风格, 则为 RESTFUL.

REST 有两个核心要求:

每个资源都有唯一的标识(URL);
不同的行为, 使用对应的 http-method (get, post, put, delete).

以下实例说明 REST 开发:

创建 User 类:

public class User {
    private Integer id;
    String name;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }

    public User(Integer id, String name) {
        this.id = id;
        this.name = name;
    }

    public User() {
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }
}

创建 testRest.jsp: (会根据请求方法和URL去匹配handler)

<html>
<head>
    <title>REST</title>
    <script src="js/jquery-3.5.1.js"></script>
</head>
<body>
    <input type="button" value="queryAll" onclick="queryAll()";>
    <input type="button" value="queryOne" onclick="queryOne()";>
    <input type="button" value="addUser" onclick="addUser()";>
    <input type="button" value="updateUser" onclick="updateUser()";>
    <input type="button" value="deleteUser" onclick="deleteUser()";>

    <script>
        function queryAll(){
            $.ajax({
                type: "get",
                url: "${pageContext.request.contextPath}/users",
                success: function (ret) {
                    console.log("查询所有: ");
                    console.log(ret);
                }
            })
        }

        function queryOne() {
            $.ajax({
                type: "get",
                url: "${pageContext.request.contextPath}/users/1",
                success: function (ret) {
                    console.log("查询单个用户: ");
                    console.log(ret);
                }
            })
        }
        
        function addUser() {
            var user = {id: 13, name: "欧阳冰冰"};
            $.ajax({
                type: "post",
                url: "${pageContext.request.contextPath}/users",
                data: JSON.stringify(user),
                contentType: "application/json",
                success: function (ret) {
                    console.log("增加用户: ");
                    console.log(ret);
                }
            })
        }

        function updateUser() {
            var user = {id: 1, name: "东方改名"};
            $.ajax({
                type: "put",
                url: "${pageContext.request.contextPath}/users",
                data: JSON.stringify(user),
                contentType: "application/json",
                success: function (ret) {
                    console.log("更新用户: ");
                    console.log(ret);
                }
            })
        }

        function deleteUser() {
            $.ajax({
                type: "delete",
                url: "${pageContext.request.contextPath}/users/2",
                success: function (ret) {
                    console.log("删除用户: ");
                    console.log(ret);
                }
            })
        }
    </script>
</body>
</html>

创建 MyRestController.java:

@RestController
public class MyRestController {

    // @GetMapping注解使该handler只能被get方法访问到, 其他同理
    @GetMapping("/users")
    public List<User> queryUsers(){
        System.out.println("query users with get");
        User user1 = new User(1, "パソコン");
        User user2 = new User(2, "李明");
        return Arrays.asList(user1, user2);
    }

    @GetMapping("/users/{id}")
    public User queryOne(@PathVariable Integer id){
        System.out.println("query one user with get: id=" + id);
        return new User (2, "李明");
    }

    @DeleteMapping("/users/{id}")
    public String deleteOne(@PathVariable Integer id){
        System.out.println("delete one user with delete: id=" + id);
        return "OK";
    }

    @PostMapping("/users")
    public String addUser(@RequestBody User user){
        System.out.println("add one user with post: " + user);
        return "OK";
    }

    @PutMapping("/users")
    public String updateUser(@RequestBody User user){
        System.out.println("update user with put: " + user);
        return "OK";
    }
}