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小編給大家分享一下如何使用spring boot開發(fā)時(shí)java對象和Json對象轉(zhuǎn)換的問題,相信大部分人都還不怎么了解,因此分享這篇文章給大家參考一下,希望大家閱讀完這篇文章后大有收獲,下面讓我們一起去了解一下吧!
將java對象轉(zhuǎn)換為json對象,市面上有很多第三方j(luò)ar包,如下:
jackson(最常用)
<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.11.2</version> </dependency>
gson
<!-- https://mvnrepository.com/artifact/com.google.code.gson/gson --> <dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.8.5</version> </dependency>
fastjson
<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson --> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.62</version> </dependency>
開發(fā)工具為:IDEA
后端技術(shù):Spring boot ,Maven
引入依賴
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.4.3</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>json</artifactId> <version>0.0.1-SNAPSHOT</version> <name>json</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <excludes> <exclude> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </exclude> </excludes> </configuration> </plugin> </plugins> </build> </project>
可以從上面看出,并未引入Jackson相關(guān)依賴,這是因?yàn)镾pring boot的起步依賴spring-boot-starter-web 已經(jīng)為我們傳遞依賴了Jackson JSON庫。
當(dāng)我們不用它,而采用其他第三方j(luò)ar包時(shí),我們可以排除掉它的依賴,可以為我們的項(xiàng)目瘦身。
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> <exclusions> <exclusion> <artifactId>jackson-core</artifactId> <groupId>com.fasterxml.jackson.core</groupId> </exclusion> </exclusions> </dependency>
import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; @Data @NoArgsConstructor @AllArgsConstructor public class UserEntity { private String userName; private int age; private String sex; }
代碼如下(示例):
import numpy as np import pandas as pd import matplotlib.pyplot as plt import seaborn as sns import warnings warnings.filterwarnings('ignore') import ssl ssl._create_default_https_context = ssl._create_unverified_context
Java對象轉(zhuǎn)換為json對象
@Controller public class JsonController { @GetMapping("/json1") //思考問題,正常返回它會走視圖解析器,而json需要返回的是一個(gè)字符串 //市面上有很多的第三方j(luò)ar包可以實(shí)現(xiàn)這個(gè)功能,jackson,只需要一個(gè)簡單的注解就可以實(shí)現(xiàn)了 //@ResponseBody,將服務(wù)器端返回的對象轉(zhuǎn)換為json對象響應(yīng)回去 @ResponseBody public String json1() throws JsonProcessingException { //需要一個(gè)jackson的對象映射器,就是一個(gè)類,使用它可以將對象直接轉(zhuǎn)換成json字符串 ObjectMapper mapper = new ObjectMapper(); //創(chuàng)建對象 UserEntity userEntity = new UserEntity("笨笨熊", 18, "男"); System.out.println(userEntity); //將java對象轉(zhuǎn)換為json字符串 String str = mapper.writeValueAsString(userEntity); System.out.println(str); //由于使用了@ResponseBody注解,這里會將str以json格式的字符串返回。 return str; } @GetMapping("/json2") @ResponseBody public String json2() throws JsonProcessingException { ArrayList<UserEntity> userEntities = new ArrayList<>(); UserEntity user1 = new UserEntity("笨笨熊", 18, "男"); UserEntity user2 = new UserEntity("笨笨熊", 18, "男"); UserEntity user3 = new UserEntity("笨笨熊", 18, "男"); userEntities.add(user1); userEntities.add(user2); userEntities.add(user3); return new ObjectMapper().writeValueAsString(userEntities); } }
Date對象轉(zhuǎn)換為json對象
@GetMapping("/json3") @ResponseBody public String json3() throws JsonProcessingException { ObjectMapper mapper = new ObjectMapper(); //Date默認(rèn)返回時(shí)間戳,所以需要關(guān)閉它的時(shí)間戳功能 mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false); //時(shí)間格式化問題 自定義時(shí)間格式對象 SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //讓mapper指定時(shí)間日期格式為simpleDateFormat mapper.setDateFormat(simpleDateFormat); //寫一個(gè)時(shí)間對象 Date date = new Date(); return mapper.writeValueAsString(date); }
提取工具類JsonUtils
public class JsonUtils { public static String getJson(Object object){ return getJson(object,"yyyy-MM-dd HH:mm:ss"); } public static String getJson(Object object,String dateFormat) { ObjectMapper mapper = new ObjectMapper(); //Date默認(rèn)返回時(shí)間戳,所以需要關(guān)閉它的時(shí)間戳功能 mapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false); //時(shí)間格式化問題 自定義時(shí)間格式對象 SimpleDateFormat simpleDateFormat = new SimpleDateFormat(dateFormat); //讓mapper指定時(shí)間日期格式為simpleDateFormat mapper.setDateFormat(simpleDateFormat); try{ return mapper.writeValueAsString(object); }catch (JsonProcessingException e){ e.printStackTrace(); } return null; } }
優(yōu)化后:
@GetMapping("/json4") @ResponseBody public String json4() throws JsonProcessingException { Date date = new Date(); return JsonUtils.getJson(date); }
引入上述gson依賴
Controller類
@RestController public class gsonController { @GetMapping("/gson1") public String json1() throws JsonProcessingException { ArrayList<UserEntity> userEntities = new ArrayList<>(); UserEntity user1 = new UserEntity("笨笨熊", 18, "男"); UserEntity user2 = new UserEntity("笨笨熊", 18, "男"); UserEntity user3 = new UserEntity("笨笨熊", 18, "男"); userEntities.add(user1); userEntities.add(user2); userEntities.add(user3); Gson gson = new Gson(); String str = gson.toJson(userEntities); return str; } }
引入相關(guān)依賴
Controller類
@RestController public class FastJsonController { @GetMapping("/fastjson1") public String json1() throws JsonProcessingException { ArrayList<UserEntity> userEntities = new ArrayList<>(); UserEntity user1 = new UserEntity("笨笨熊", 18, "男"); UserEntity user2 = new UserEntity("笨笨熊", 18, "男"); UserEntity user3 = new UserEntity("笨笨熊", 18, "男"); userEntities.add(user1); userEntities.add(user2); userEntities.add(user3); String str = JSON.toJSONString(userEntities); return str; } }
以上是“如何使用spring boot開發(fā)時(shí)java對象和Json對象轉(zhuǎn)換的問題”這篇文章的所有內(nèi)容,感謝各位的閱讀!相信大家都有了一定的了解,希望分享的內(nèi)容對大家有所幫助,如果還想學(xué)習(xí)更多知識,歡迎關(guān)注億速云行業(yè)資訊頻道!
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