Jackson使用

导入依赖

    
        SpringMVC
        com.kuang
        1.0-SNAPSHOT
    
    4.0.0

    springmvc-06-JSON

    
        8
        8
    
    
        
            com.fasterxml.jackson.core
            jackson-databind
            2.10.0
        
    

 

controller

package com.qf.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.qf.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class UserController {
      @RequestMapping("/j1")
    @ResponseBody//不会走视图解析器，将返回值，直接打印在客户端发起请求的页面
    public String json1() throws JsonProcessingException {
          //jackson,  ObjectMapper
          ObjectMapper mapper = new ObjectMapper();
          User user = new User(3, "基基", 19);
          String s = mapper.writeValueAsString(user);
          return s;

      }

}

文本默认使用“text/plain;charset=ISO-8859-1”作为ContentType,导致中文乱码

  @RequestMapping(value = "/j1",produces = "application/json;charset=utf-8")

 

 

 

package com.qf.controller;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.qf.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

//@Controller//会调用视图解析器，用来转发和重定向的，视图解析器默认是转发，加上 redirect:/
@RestController//不会走视图解析器，这类下的所有方法返回的都是响应给请求页面的字符串。
public class UserController {
      @RequestMapping(value = "/j1")
  //  @ResponseBody//不会走视图解析器，将返回值，直接打印在客户端发起请求的页面
    public String json1() throws JsonProcessingException {
          //jackson,  ObjectMapper
          ObjectMapper mapper = new ObjectMapper();
          User user = new User(3, "基基", 19);
          String s = mapper.writeValueAsString(user);
          return s;
      }
    @RequestMapping(value = "/j2")
    //  @ResponseBody//不会走视图解析器，将返回值，直接打印在客户端发起请求的页面
    public String json2() throws JsonProcessingException {
        ObjectMapper mapper = new ObjectMapper();
        User user1 = new User(1, "基基1", 19);
        User user2 = new User(2, "基基2", 19);
        User user3 = new User(3, "基基3", 19);
        User user4 = new User(4, "基基4", 19);
        List users=new ArrayList<>();
        users.add(user1);
        users.add(user2);
        users.add(user3);
        users.add(user4);
        String s = mapper.writeValueAsString(users);
        return s;
    }

    @RequestMapping(value = "/j3")
    //  @ResponseBody//不会走视图解析器，将返回值，直接打印在客户端发起请求的页面
    public String json3() throws JsonProcessingException {
        Date date = new Date();
        //ObjectMapper 时间解析过后的默认格式的为时间戳：Timestap;
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String format = sdf.format(date);
        return new ObjectMapper().writeValueAsString(format);
    }

    @RequestMapping(value = "/j4")
    //  @ResponseBody//不会走视图解析器，将返回值，直接打印在客户端发起请求的页面
    public String json4() throws JsonProcessingException {
      //将数据转化为JSON格式
        ObjectMapper mapper = new ObjectMapper();
        //不使用时间戳的方式
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);

        //ObjectMapper 时间解析过后的默认格式的为时间戳：Timestap;
        //自定义日期格式
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
       mapper.setDateFormat(sdf);
        Date date = new Date();
        String string = mapper.writeValueAsString(date);
        return string;
    }

}

封装的工具类 

package com.qf.utils;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.text.SimpleDateFormat;

public class JsonUtils {


    public static String getJson(Object o){
        return getJson(o,"yyyy-MM-dd HH-mm-ss");
    }

    public static String getJson(Object o,String dateFormat){
        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS,false);
        SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
        mapper.setDateFormat(sdf);
        try {
            return mapper.writeValueAsString(o);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }

        return null;
    }

}