向客户端发送JSON格式数据

「爱情、让人受尽委屈。」 2024-03-23 13:43 109阅读 0赞

一、导入jackson依赖

<dependencies>
            <dependency>
                <groupId>com.fasterxml.jackson.core</groupId>
                <artifactId>jackson-databind</artifactId>
                <version>2.11.0</version>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.module</groupId>
                <artifactId>jackson-module-parameter-names</artifactId>
                <version>2.11.0</version>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.datatype</groupId>
                <artifactId>jackson-datatype-jdk8</artifactId>
                <version>2.11.0</version>
            </dependency>
            <dependency>
                <groupId>com.fasterxml.jackson.datatype</groupId>
                <artifactId>jackson-datatype-jsr310</artifactId>
                <version>2.11.0</version>
            </dependency>
        </dependencies>

二、定义实体类

public class UserBean {
        private Integer id ;
        private String name;
        @JsonFormat(pattern = "yyyy-MM-dd")//指定对象序列化为JSON时的日期格式
        private LocalDate birthday;
        private Integer money;
        private Double payTaxes;
    }

三、业务组件

在servlet中输出 对象的JSON字符串

public class TestServlet extends HttpServlet {
        @Override
        public void init() throws ServletException {
            System.out.println("servlet初始化");
        }
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            this.doPost(req,resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            resp.setContentType("text/html;charset=utf-8");
        
            List<UserBean> list = new ArrayList<>();
            list.add(new UserBean(1,"熊大", LocalDate.parse("1997-12-08"),2500,0.0));
            list.add(new UserBean(2,"熊二", LocalDate.parse("1997-12-08"),6000,180.55));
    
            ObjectMapper om = new ObjectMapper();
            //注册时间模板
            om.registerModule(new JavaTimeModule());
            //将java对象转化为json字符串
            String str = om.writeValueAsString(list);
            resp.getWriter().println(str);
    
        }
    }

四、启动

public class MainTomcat {
        public MainTomcat(){
            Tomcat tomcat = new Tomcat();
            //设置启动端口
            tomcat.setPort(9090);
            //引导http引擎
            tomcat.getConnector();
            //创建上下文对象
            Context context = tomcat.addContext("",null);
            //注册servlet
            Wrapper wrapper = Tomcat.addServlet(context,"testServlet",new TestServlet());
            wrapper.setLoadOnStartup(1);
            //设置servlet访问路径
            wrapper.addMapping("*.yy");
          
            try {
                //启动tomcat
                tomcat.start();
            } catch (LifecycleException e) {
                throw new RuntimeException(e);
            }
        }
    
        public static void main(String[] args) {
            new MainTomcat();
        }
    }

[测试：http://localhost:9090/][http_localhost_9090]\*.yy

[http_localhost_9090]: http://localhost:9090/