json-json|fastjson与jackson

谁践踏了优雅 2022-05-08 01:24 223阅读 0赞

### 文章目录 ###

*  一、JSON
 *   *   *  1.JSON 对象
         *  1.JSON 数组
 *  二、阿里fastjson
 *   *   *   *  JSON对象生成字符串
             *  通过JSONArray包装对象数组
             *  json字符串转java对象（OrderInfo(orderId、orderDate)）
             *  json字符串转json对象
             *  java对象转json字符串
     *  springboot+fastjson
     *   *  1.maven依赖
         *  2.配置fastjson
         *   *  方法1
             *  方法2(效果同1)
 *  三、jackson
 *   *   *  JackSon将java对象转换为JSON字符串

# 一、JSON #

*JavaScript 对象表示法（JavaScript Object Notation）*

### 1.JSON 对象 ###

{  
    	"name":"菜鸟" ,
    	 "age":18
     }
     
    {  "flag":true }
    
    {  "runoob":null }

### 1.JSON 数组 ###

{ 
    	"sites": [
    	{  "name":"xiaoming" , "age":15}, 
    	{  "name":"xiaohong" , "age":14}
    	]
    }

# 二、阿里fastjson #

引入依赖

<dependency>
    	<groupId>com.alibaba</groupId>
    	<artifactId>fastjson</artifactId>
    	<version>1.2.15</version>
    </dependency>

#### JSON对象生成字符串 ####

import com.alibaba.fastjson.JSON; 
    import com.alibaba.fastjson.JSONObject;
    
    JSONObject jObject=new JSONObject();
    jObject.put("username", "xiejava");
    jObject.put("sex", "man");
    jObject.put("age", 38); 
    jObject.put("email", "xiejava@ishareread.com");
    String json2=jObject.toJSONString();

#### 通过JSONArray包装对象数组 ####

List<Card> cards=new ArrayList<Card>();
    cards.add(card1);
    cards.add(card2);
    JSONArray jArray=new JSONArray();
    jArray.addAll(cards);

#### json字符串转java对象（OrderInfo(orderId、orderDate)） ####

OrderInfo orderInfo = JSON.parseObject(jsonStr, OrderInfo.class);

#### json字符串转json对象 ####

String jsonStr = “{ \”orderId\” : \”1111111\”;\”orderDate\” : \”2016-11-22 11:03:00\”}”; 
    JSONObject jsonObject = JSON.parseObject(jsonStr); 
    String orderId = jsonObject.getString(“orderId”); 
    String orderDate =jsonObject.getString(“orderDate”);

#### java对象转json字符串 ####

//java对象转json字符串
    String jsonStr = JSON.toJSONString(orderInfo)
    //java对象转json对象
    JSON json = (JSON) JSON.toJSON(orderInfo);

## springboot+fastjson ##

### 1.maven依赖 ###

### 2.配置fastjson ###

#### 方法1 ####

1️⃣启动类继承WebMvcConfigurerAdapter  
2️⃣覆盖方法configureMessageConverters

@SpringBootApplication
    public class App extends WebMvcConfigurerAdapter{ 
    	
    	@Override
    	public void configureMessageConverters(List<HttpMessageConverter<?>> converters) { 
    		super.configureMessageConverters(converters);
    		// 1、需要先定义一个 convert 转换消息的对象;
    		FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
    		
    // //2、添加fastJson 的配置信息，比如：是否要格式化返回的json数据;
    		FastJsonConfig fastJsonConfig = new FastJsonConfig();
    		fastJsonConfig.setSerializerFeatures(
                    SerializerFeature.PrettyFormat
            );		
    // //3、在convert中添加配置信息.
            fastConverter.setFastJsonConfig(fastJsonConfig);
            
            //4、将convert添加到converters当中.
        	converters.add(fastConverter);
    	
    	}
    	//主方法
    	public static void main(String[] args) { 
    		SpringApplication.run(App.class, args);
    	}
    }

使用方法

//将实体属性格式化
    @JSONField(format="yyyy-MM-dd HH:mm")
    private Date createTime;//创建时间.
    
    /* * 我们不想返回remarks? * serialize:是否需要序列化属性. */
    @JSONField(serialize=false)
    private String remarks;//备注信息.

#### 方法2(效果同1) ####

@SpringBootApplication
    public class App{ 
    	/** * 在这里我们使用 @Bean注入 fastJsonHttpMessageConvert * @return */
    	@Bean
    	public HttpMessageConverters fastJsonHttpMessageConverters() { 
    		// 1、需要先定义一个 convert 转换消息的对象;
    		FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
    		
    		//2、添加fastJson 的配置信息，比如：是否要格式化返回的json数据;
    		FastJsonConfig fastJsonConfig = new FastJsonConfig();
    		fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
    		
    		//3、在convert中添加配置信息.
    		fastConverter.setFastJsonConfig(fastJsonConfig);
    		
    		
    		HttpMessageConverter<?> converter = fastConverter;
    		return new HttpMessageConverters(converter);
    	}
    	
    	//主方法
    	public static void main(String[] args) { 
    		SpringApplication.run(App.class, args);
    	}
    }

# 三、jackson #

Jackson有1.x系列和2.x系列，2.x系列有3个jar包需要下载：  
jackson-core-2.2.3.jar（核心jar包）  
jackson-annotations-2.2.3.jar（该包提供Json注解支持）  
jackson-databind-2.2.3.jar

一个maven依赖就够了

com.fasterxml.jackson.core jackson-databind 2.5.3

java

package test;
    import java.util.List;
    import java.util.Map;
     
    import com.fasterxml.jackson.databind.JavaType;
    import com.fasterxml.jackson.databind.JsonNode;
    import com.fasterxml.jackson.databind.ObjectMapper;
    /** * 日志类 * @author Administrator * */
    class Log{ 
    	private int id;
    	private String name;
    	public int getId() { 
    		return id;
    	}
    	public void setId(int id) { 
    		this.id = id;
    	}
    	public String getName() { 
    		return name;
    	}
    	public void setName(String name) { 
    		this.name = name;
    	}
    	@Override
    	public String toString() { 
    		return "log [id=" + id + ", name=" + name + "]";
    	}
    	
    }
    public class JacksonTest { 
     
    	public static void main(String[] args) throws Exception { 
    		String json = "{\"username\":\"zhangsan\",\"性别\":\"男\",\"company\":{\"companyName\":\"中华\",\"address\":\"北京\"},\"cars\":[\"奔驰\",\"宝马\"],\"logList\":[{\"id\":123,\"name\":\"abc\"},{\"id\":234,\"name\":\"efff\"}]}";  
    		//System.out.println(json);
    		ObjectMapper mapper = new ObjectMapper();
    		JsonNode rootNode = mapper.readTree(json);
    		
    		JsonNode usernameNode = rootNode.path("username");
    		String username = mapper.writeValueAsString(usernameNode);
    		System.out.println("==username==");
    		System.out.println(username);
    		
    		//转换成类型,Map类型，同样Integer,String,List，也可以同样处理
    		JsonNode companyNode = rootNode.path("company");
    		String company = mapper.writeValueAsString(companyNode);		
    		Map<String,Object> companyMap = mapper.readValue(company, Map.class);
    		System.out.println("==company==");
    		System.out.println(companyMap);
    		
    		//转换成List<Log>，类型
    		JsonNode logListNode = rootNode.path("logList");
    		String logJson = mapper.writeValueAsString(logListNode);
    		JavaType logType = mapper.getTypeFactory().constructParametricType(List.class, Log.class);
    		List<Log> logList = mapper.readValue(logJson, logType);
    		System.out.println("==logList==");
    		System.out.println(logList);		
     
    	}
     
    }

https://www.cnblogs.com/winner-0715/p/6109225.html

### JackSon将java对象转换为JSON字符串 ###

ObjectMapper mapper = new ObjectMapper();  
Fruit fruit= new Fruit(“HaMiGua”, “1001”);  
String mapJakcson = mapper.writeValueAsString(fruit);  
System.out.println(mapJakcson);