Spring Boot Ajax实例(十六)

这篇博文主要用于新手学习Spring Boot，同时也记录自己学习的过程…
文章内容主要来源于易百教程

本文将展示如何使用jQuery.ajax将HTML表单请求发送到Spring REST API并返回JSON响应。
使用的工具：

• Spring Boot 2.0.3.RELEASE
• Spring 2.0.3.RELEASE
• Maven 3
• jQuery
• Bootstrap 3

1．项目结构

---

创建一个标准的Maven项目：spring-boot-ajax-example，用于演示在Spring Boot中使用Ajax技术，搜索用户信息。其结构如下图所示-



2．项目依赖

---

文件：pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.th</groupId>
    <artifactId>spring-boot-ajax-example</artifactId>
    <packaging>jar</packaging>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.3.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>

        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>3.3.7</version>
        </dependency>

        <!-- This is a web application -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- Tomcat embedded container -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

    </dependencies>
    <build>
        <!-- 打成war之后的项目名称 -->
        <finalName>springboot</finalName>

        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <configuration>
                    <warSourceExcludes>src/main/resources/**</warSourceExcludes>
                    <warName>springboot</warName>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

3．Spring REST API

---

REST控制器，接受一个SearchCriteria并返回一个ResponseEntity。
一个正常的Spring Boot依赖和一些webjars资源。文件：SearchController.java如下所示-

package com.th.controller;

import java.util.List;
import java.util.stream.Collectors;
import javax.validation.Valid;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.Errors;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import com.th.model.AjaxResponseBody;
import com.th.model.SearchCriteria;
import com.th.model.User;
import com.th.service.UserService;

@RestController
public class SearchController {

    UserService userService;

    @Autowired
    public void setUserService(UserService userService) {
        this.userService = userService;
    }

    @PostMapping("/api/search")
    public ResponseEntity<?> getSearchResultViaAjax(@Valid @RequestBody SearchCriteria search, Errors errors) {

        AjaxResponseBody result = new AjaxResponseBody();

        if (errors.hasErrors()) {

            result.setMsg(
                    errors.getAllErrors().stream().map(x -> x.getDefaultMessage()).collect(Collectors.joining(",")));
            return ResponseEntity.badRequest().body(result);
        }

        List<User> users = userService.findByUserNameOrEmail(search.getUsername());
        if (users.isEmpty()) {
            result.setMsg("no user found!");
        } else {
            result.setMsg("success");
        }

        result.setResult(users);

        return ResponseEntity.ok(result);
    }
}

一些其他的POJO类，它们分别如下所示-
文件：AjaxResponseBody.java

package com.th.model;

import java.util.List;

public class AjaxResponseBody {

    private String msg;
    private List<User> result;

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public List<User> getResult() {
        return result;
    }

    public void setResult(List<User> result) {
        this.result = result;
    }

}

文件：User.java

package com.th.model;

public class User {

    private String username;
    private String password;
    private String email;

    public User(String username, String password, String email) {
        super();
        this.username = username;
        this.password = password;
        this.email = email;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "User [username=" + username + ", password=" + password + ", email=" + email + "]";
    }

}

验证器类：SearchCriteria.java

package com.th.model;

import javax.validation.constraints.NotBlank;

public class SearchCriteria {

    @NotBlank(message = "username can't empty!")
    private String username;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

}

用于初始化一些用户进行搜索的服务。文件：UserService.java 所下所示-

package com.th.service;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

import javax.annotation.PostConstruct;

import org.springframework.stereotype.Service;

import com.th.model.User;

@Service
public class UserService {

    private List<User> users;

    // Love Java 8
    public List<User> findByUserNameOrEmail(String username) {

        List<User> result = users.stream().filter(x -> x.getUsername().equalsIgnoreCase(username)).collect(Collectors.toList());

        return result;

    }
    // Init some users for testing
    @PostConstruct
    private void iniDataForTesting() {
        users = new ArrayList<User>();

        User user1 = new User("maxsu", "password111", "maxsu@yahoo.com");
        User user2 = new User("yiflow", "password222", "yflow@yahoo.com");
        User user3 = new User("minaxu", "password333", "minaxu@yahoo.com");
        User user4 = new User("minalee", "password333", "minalee@yahoo.com");
        User user5 = new User("yiiflow", "password333", "yiiflow@gmail.com");

        users.add(user1);
        users.add(user2);
        users.add(user3);
        users.add(user4);
        users.add(user5);
    }
}

Spring Boot启动器（程序入口），参考一下代码实现。文件：SpringBootWebApplication.java如下所示-

package com.th;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootWebApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootWebApplication.class, args);
    }
}

4．HTML表单+jQuery Ajax

---

一个简单的HTML表单，用bootstrap框架装饰。
文件：index.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <title>Spring Boot Ajax实例</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>

    <link rel="stylesheet" type="text/css"
          href="webjars/bootstrap/3.3.7/css/bootstrap.min.css"/>
</head>
<body>
   <nav class="navbar navbar-inverse">
        <div class="container">
            <div class="navbar-header">
                <a class="navbar-brand" href="#">Spring Boot</a>
            </div>
            <div id="navbar" class="collapse navbar-collapse">
                <ul class="nav navbar-nav">
                    <li class="active"><a href="#">Home</a></li>
                    <li><a href="#about">About</a></li>
                </ul>
            </div>
        </div>
    </nav>
    <div class="container" style="min-height: 500px">
        <div class="starter-template">
            <h1>Spring Boot AJAX 示例</h1>
            <div id="feedback"></div>
            <form class="form-horizontal" id="search-form">
                <div class="form-group form-group-lg">
                    <label class="col-sm-2 control-label">用户名：</label>
                    <div class="col-sm-10">
                        <input type="text" class="form-control" id="username"/>
                    </div>
                </div>

                <div class="form-group">
                    <div class="col-sm-offset-2 col-sm-10">
                        <button type="submit" id="bth-search"
                                class="btn btn-primary btn-lg">搜索
                        </button>
                    </div>
                </div>
            </form>
        </div>
    </div>
    <script type="text/javascript"
            src="js/jquery.min.js"></script>
    <script type="text/javascript" src="js/main.js"></script>
</body>
</html>

获取HTML表单，并通过JSON.stringify将搜索条件转换为JSON格式，并通过jQuery.ajax发送POST请求。
文件：main.js 所下所示-

$(document).ready(function () {
    $("#search-form").submit(function (event) {
        //stop submit the form, we will post it manually.
        event.preventDefault();
        fire_ajax_submit();
    });

});

function fire_ajax_submit() {
    var search = {}
    search["username"] = $("#username").val();
    //search["email"] = $("#email").val();
    $("#btn-search").prop("disabled", true);
    $.ajax({
        type: "POST",
        contentType: "application/json",
        url: "/api/search",
        data: JSON.stringify(search),
        dataType: 'json',
        cache: false,
        timeout: 600000,
        success: function (data) {
            var json = "<h4>Ajax Response</h4><pre>"
                + JSON.stringify(data, null, 4) + "</pre>";
            $('#feedback').html(json);
            console.log("SUCCESS : ", data);
            $("#btn-search").prop("disabled", false);
        },
        error: function (e) {
            var json = "<h4>Ajax Response</h4><pre>"
                + e.responseText + "</pre>";
            $('#feedback').html(json);
            console.log("ERROR : ", e);
            $("#btn-search").prop("disabled", false);
        }
    });
}

5．运行示例
打开浏览器，访问以下地址：http://localhost:8080/ ， 应该会看到如下页面 -

如果没有输入用户名，直接点击“搜索”，那么应该会看到以下结果 -

如果输入一个存在的用户名:maxsu，直接点击“搜索”，那么应该会看到以下结果 -

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